Control of molecular weight and end-group functionality of polymers

A process for the production of polymers by free radical polymerization, characterized in that there is added to the polymerization system one or more compounds of the general formula (A). ##STR1## where R.sup.1 is hydrogen or a group capable activating the vinylic carbon towards free radical addition; PA0 Y is OR.sup.2 or CH.sub.2 X(R.sup.2).sub.n PA0 where R.sup.2 is an optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, or optionally substituted saturated, unsaturated or aromatic, aromatic carbocyclic or heterocyclic ring; PA0 X is an element other than carbon selected from Groups IV, V, VI or VII of the Periodic Table or a group consisting of an element selected from Groups IV, V, or VI to which is attached one or more oxygen atoms; and PA0 n is a number from 0 to 3, such that the valency of the group X is satisfied and, when n is greater than 1, the groups represented by R.sup.2 may be identical or different.

The invention relates to processes for radical-initiated polymerization of 
unsaturated species and for the control of molecular weight and end-group 
functionality of the polymeric products produced from such processes. 
Polymers of limited molecular weights, or oligomers, are useful as 
precursors in the manufacture of other polymeric materials and as 
additives in plastics, elastomerics, and surface-coating compositions, as 
well as being useful in their own right in many applications. 
In conventional polymerization practice, the manufacture of oligomers 
requires the use of an initiator which acts as a free radical source, and 
of a chain transfer agent. The chain transfer agent controls the molecular 
weight of the polymer molecule by reacting with the propagating polymer 
radical to terminate its growth. It then initiates a new polymer chain 
thus transferring the growth process from one discrete polymer molecule to 
another discrete polymer molecule. At least a part of the chain transfer 
agent is incorporated into the polymer molecule and thus is consumed 
during the process. The incorporated residue of the chain transfer agent 
can lead to undesirable end-groups on the polymer. 
The chain transfer agents most commonly used are alkanethiols, which 
possess an objectionable odour, lead to a wide distribution of molecular 
weight with certain monomers, do not allow the production of telechelic 
polymers, and offer limited scope for the preparation of polymers with a 
single functional end-group. Additionally, with thiols there is little 
scope for the chain transfer efficiency to be optimized for a particular 
polymerization. 
The present invention provides a process for the production of lower 
molecular weight polymers by free radical polymerization, which process is 
characterized by the addition of compounds of the general Formula A to the 
polymerization system. The process can, by appropriate selection of the 
compound of Formula A, produce polymers with groups capable of further 
chemical reaction at one or both ends of the polymer chain. 
##STR2## 
In Formula A, R.sup.1 can be hydrogen, but preferably represents a group 
capable of activating the vinylic carbon towards free radical addition. 
Suitable groups are phenyl and optionally substituted aromatic groups, 
alkoxycarbonyl or aryloxycarbonyl (--COOR), carboxy (--COOH), acyloxy 
(--O.sub.2 CR), carbamoyl (--CONR.sub.2) and cyano (--CN); AND 
Y is --CH.sub.2 X(R.sup.2).sub.n or --OR.sup.2 ; WHERE 
R.sup.2 represents optionally substituted alkyl, optionally substituted 
alkenyl, optionally substituted alkynyl, or optionally substituted 
saturated, unsaturated, or aromatic carbocyclic or heterocyclic ring; AND 
when Y is --CH.sub.2 X(R.sup.2).sub.n, X represents an element other than 
carbon selected from groups IV, V, VI, or VII of the Periodic Table or a 
group consisting of an element selected from groups IV, V, or VI to which 
is attached one or more oxygen atoms. Suitable elements X include sulphur, 
silicon, selenium, phosphorus, bromine, chlorine, and tin. Examples of 
oxygen containing groups include phosphonates, sulphoxides, sulphones, and 
phosphine oxides; AND 
n is a number from 0 to 3, such that the valency of the group X is 
satisfied. When n is greater than 1, the groups represented by R.sup.2 may 
be identical or different. 
In Formula A, substituted rings may have a reactive substituent group 
directly or indirectly attached to the ring by means of a methylene group 
or other side-chain. 
The reactive substituent groups referred to above for R.sup.1 and/or 
R.sup.2 in Formula A do not take part in the actual lowering of the 
molecular weight, but are installed at the ends of the polymer chains and 
may be capable of subsequent chemical reaction. The low molecular weight 
polymer containing said reactive group or groups is thereby able to 
undergo further chemical transformation, such as being joined with another 
polymer chain as described subsequently in this specification. 
Suitable reactive substituents include: hydroxy (--OH); amino (--NH.sub.2); 
halogen; phosphonate; trialkyoxysilyl; allyl; cyano (--CN); epoxy; and 
carboxylic acid (--COOH) and its derivatives, such as ester (--COOAlkyl). 
The substituents may alternatively be non-reactive such as alkoxy 
(--OAlkyl) or alkyl. 
Alkyl groups referred to in this specification may contain from 1 to 32 
carbon atoms. Alkenyl and alkynyl groups may contain from 2 to 32 carbon 
atoms. Saturated, unsaturated, or aromatic carbocyclic or heterocyclic 
rings may contain from 3 to 14 atoms. 
The process of this invention uses the compounds of general Formula A as 
alternatives to thiols or other chain transfer agents for the control of 
molecular weight. The process of this invention may be operated in a 
similar manner to conventional processes using thiols. For example, the 
process described herein is applicable to the manufacture of synthetic 
rubbers and other polymer formulations, where reduced molecular weight 
aids processing and improves properties. The process can also be used to 
produce low molecular weight polymers and oligomers for a variety of 
applications, such as high-solids surface coatings, paints, and adhesives. 
For example, low molecular weight hydroxyacrylic polymers can be prepared 
using the compounds described in this invention and these can be later 
crosslinked by reaction with polyisocyanates. 
Compounds of the general Formula A have the advantage of being simply 
prepared from inexpensive starting materials. Unlike thiols, they do not, 
in general, posses an objectionable odour. They exhibit an unexpectedly 
high activity in controlling molecular weight in polymerization reactions 
and are superior to thiols. Their activity is such that their chain 
transfer constants approach the optimum of 1.0 and this activity is not 
highly dependent, as it is with thiols, on the structure of the 
propagating radical. As is well known in the art, compounds with chain 
transfer constants close to this optimimum of 1.0 allow the production 
under convenient conditions of polymers of narrow molecular weight 
distribution. Additionally, when the chain transfer constant of a given 
compound with two or more monomers is reasonably close to 1, the 
distribution of molecular weights in copolymerizations of these monomers 
can more readily be controlled. The compounds of Formula A in general are 
superior to thiols inasmuch as their chain transfer constants are closer 
to 1.0. Additionally, with this invention there is scope for the chain 
transfer efficiency to be optimized for a particular polymerization by the 
appropriate choice of the substituent R.sup.1 in Formula A. For example, 
when R.sup.1 is electron deficient, the efficiency with electron donor 
monomers such as styrene is enhanced. 
The process of this invention utilizing compounds of the general Formula I 
[Formula A, Y=--CH.sub.2 X(R.sup.2).sub.n ], unlike processes involving 
other chain transfer agents, directly produces polymers or oligomers 
containing a polymerizable olefinic group at one end and can be used to 
prepare macromonomers, which are useful materials for the preparation of 
graft copolymers by methods well known to the art. 
When the process utilizes compounds of Formula I containing a reactive 
substituent group on at least one of the groups R.sup.2, it may be used to 
produce polymers and oligomers with said reactive substituent on the end 
remote from the olefinic group. Polymers or oligomers with reactive 
substituents on one end may also be prepared when the process utilizes 
compounds of Formula I with reactive substituents on R.sup.1 or when the 
process utilizes compounds of Formula II [Formula A, Y=--OR.sup.2 ], 
containing reactive substituents on either R.sup.1 or R.sup.2. In this 
latter case using compounds of Formula II, the resultant low molecular 
weight polymers or oligomers contain no double bonds and, therefore, do 
not have the properties associated with a macromonomer. In a number of 
instances this is desirable, for example, in processes which are taken to 
very high conversion. 
##STR3## 
Mono-end-functional polymers or oligomers, produced by the process of this 
invention, may be linked by means of the introduced reactive substituent 
directly to a polymer backbone leading to graft copolymers. They may also 
be linked with other end-functional polymers or oligomers to form AB block 
copolymers or with suitable telechelic polymers or oligomers to form ABA 
block copolymers. Block copolymers are important as compatibilizing 
agents, adhesives, and in advanced surface coating formulations. Low 
molecular weight polymers and oligomers with one functional end-group may 
also possess desirable physical attributes in their own right, such as 
surface wetting properties. 
The functional substituents installed at one or both ends of the polymer 
chains by the process described herein may be converted into other 
functional groups by performing chemical functional group transformations 
as is well known in the art. For example, ester functionality may be 
converted into carboxylic acid functionality by hydrolysis, 
tert-butyldimethylsilyloxy groups may be converted into hydroxy groups by 
treating the polymer with fluoride ion, and chloromethylphenyl groups may 
be treated with nucleophiles to afford a variety of other functional 
groups. 
Mono-end-functional polymers or oligomers that do not contain a double bond 
may also be converted to macromonomers by methods well known to the art. 
For example, --OH or --COOH terminated polymers can be prepared using II 
in which R.sup.2 carries hydroxyl or ester substituents. The 
hydroxy-terminated polymers may then be converted to macromonomers by 
reaction with acryloyl or methacryloyl chloride or similar reagents. In 
the case of --COOH terminated polymers, macromonomers can be prepared by 
reaction with glycidyl methacrylate or similar compounds. Such 
macromonomers by virtue of their chemical structure have differing 
reactivity in polymerization reactions compared with those produced 
directly by the process utilizing I. 
When the compounds of Formula A contain reactive substituents on both 
R.sup.1 and R.sup.2, the process is particularly useful for the 
preparation of telechelic or di-end-functional polymers and oligomers. 
These products of the process are especially useful and have applications 
as crosslinking agents to produce polymer networks and as building blocks 
for the preparation of multicomponent polymer systems such as segmented 
and ABA block copolymers. For example, .alpha.,.omega.-dihydroxy oligomers 
or polymers can be reacted with the readily available 
.alpha.,.omega.-diisocyanato oligomers to produce segmented polyurethanes 
which are useful as elastomers and high impact strength materials for a 
range of applications. 
The following compounds of Formula A are novel and form part of this 
invention: 
.alpha.-(t-Butanethiomethyl)styrene 
.alpha.-(n-Butanethiomethyl)styrene 
.alpha.-(Carboxymethanethiomethyl)styrene 
.alpha.-(Carboxyethanethiomethyl)styrene 
.alpha.-(2-Hydroxyethanethiomethyl)styrene 
.alpha.-(2-Aminoethanethiomethyl)styrene 
.alpha.-[3-(Trimethoxysilyl)propanethiomethyl]styrene 
.alpha.-(n-Butanesulphinylmethyl)styrene 
Ethyl .alpha.-(t-Butanethiomethyl)acrylate 
Ethyl .alpha.-(Carboxymethanethiomethyl)acrylate 
.alpha.-(Carboxymethanethiomethyl)acrylic Acid 
.alpha.-(Bromomethyl)acrylonitrile 
.alpha.-(t-Butanethiomethyl)acrylonitrile 
.alpha.-(Diethoxyphosphorylmethyl)styrene 
.alpha.-(4-Methoxycarbonylbenzyloxy)styrene 
.alpha.-Benzyloxy[4-(chloromethyl)styrene] 
.alpha.-Benzyloxy[3-(chloromethyl)styrene] 
.alpha.-(4-Cyanobenzyloxy)styrene 
.alpha.-[4-(Hydroxymethyl)benzyloxy]styrene 
.alpha.-[4-(Aminomethyl)benzyloxy]styrene 
.alpha.-(4-Methoxybenzyloxy)styrene 
.alpha.-Benzyloxy[4-(tert-butyldimethylsilyloxymethyl)styrene] 
.alpha.-Benzyloxy[3-(tert-butyldimethylsilyloxymethyl)styrene] 
.alpha.-Benzyloxy[4-(acetoxymethyl)styrene] 
.alpha.-Benzyloxy[3-(acetoxymethyl)styrene] 
.alpha.-Benzyloxy[4-(hydroxymethyl)styrene] 
.alpha.-Benzyloxy[3-(hydroxymethyl)styrene] 
.alpha.-Benzyloxy(4-chlorostyrene) 
.alpha.-Benzyloxy(3-methoxystyrene) 
.alpha.-Benzyloxy(4-methoxystyrene) 
.alpha.-(4-Methoxycarbonylbenzyloxy)[4-(acetoxymethyl)styrene] 
.alpha.-(4-Methoxycarbonylbenzyloxy)[3-(acetoxymethyl)styrene] 
.alpha.-[4-(Hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] 
.alpha.-[4-(Hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene] 
.alpha.-[4-(tert-Butyldimethylsilyloxymethyl)benzyloxy][4-(tert-butyldimeth 
ylsilyloxymethyl)styrene] 
.alpha.-[4-(tert-Butyldimethylsilyloxymethyl)benzyloxy][3-(tert-butyldimeth 
ylsilyloxymethyl)styrene] 
.alpha.-(4-Methoxycarbonylbenzyloxy)-4-cyanostyrene 
.alpha.-[4-(Hydroxymethyl)benzyloxy][4-(aminomethyl)styrene] 
.alpha.-Benzyloxyacrylonitrile 
Methyl .alpha.-Benzyloxyacrylate 
.alpha.-Benzyloxyacrylamide 
The compounds of Formula II, described in the present invention, bear 
superficial resemblance to compounds of Formula III, which have been 
disclosed previously as chain transfer agents in the Journal of 
Macromolecular Science--Chemistry, 1984, A21, 979-995; "Ring Opening 
Polymerization: Kinetics, Mechanism, and Synthesis", ACS Symposium Series 
No. 286, J. E. McGrath, Ed., Washington D.C.: 1985, chapter 4; and in 
"Reactive Oligomers", ACS Symposium Series No. 282, F. W. Harris and H. J. 
Spinelli, Eds, Washington D.C., 1985, chapter 13. 
##STR4## 
In Formula III, R.sup.1 and R.sup.2 represent alkyl, benzyl, or 
substituted benzyl groups. The compounds of the present invention exhibit 
a much greater resistance to hydrolytic decomposition, than do those of 
Formula III. In fact, processes involving compounds of the Formula III, 
unlike those of the present invention, have little practical utility for 
control of molecular weight on account of this hydrolytic lability, 
except, perhaps, under conditions where the monomers and any solvents 
used, are most rigorously purified and maintained in a strictly anhydrous 
condition. 
PREATION OF THE CHAIN TRANSFER AGENTS DESCRIBED IN THIS INVENTION 
.alpha.-(Alkanethiomethyl)styrenes 
These compounds (Formula I, X=sulphur, R.sup.1 =phenyl, R.sup.2 
=substituted or unsubstituted alkyl, aryl, alkenyl, or alkynyl, n=1) can 
be readily prepared via a nucleophilic substitution reaction involving the 
treatment of a stirred alcoholic solution of .alpha.-(bromomethyl)styrene 
with the appropriate thiol and a base, such as potassium carbonate or 
hydroxide, or sodium acetate, hydroxide or methoxide. It is usually 
desirable to use an equimolar ratio of the reagents. The starting material 
.alpha.-(bromomethyl)styrene can be obtained using a procedure described 
in The Journal of Organic Chemistry, 1957, 22, 1113, or in the Journal of 
the American Chemical Society, 1954, 76, 2705. 
.alpha.-(t-Butanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 =phenyl, 
R.sup.2 =t-butyl, n=1). [Typical procedure]. t-Butanethiol (4 ml, 35.5 
mmol) was added slowly at room temperature to a stirred suspension of 
potassium carbonate (5 g, 36 mmol) and .alpha.-(bromomethyl)styrene (7 g, 
35.5 mmol) in absolute ethanol [or methanol] (50 ml). Stirring was 
maintained for 16 h and then the reaction mixture was poured into water, 
and extracted (3.times.) with diethyl ether. The extracts were then dried 
over anhydrous Na.sub.2 SO.sub.4, filtered, and evaporated to dryness. 
Distillation of the crude product through a short column afforded 
.alpha.-(t-butanethiomethyl)styrene (5 g, 69%) as a colourless liquid: bp 
88.degree. C./3 mmHg. .sup.1 H NMR (CDCl.sup.3) .delta. 1.35 (9H, s, 
(CH.sub.3).sub.3 C), 3.60 (2H, s, allylic CH.sub.2 S), 5.30 (1H, s, 
olefinic proton), 5.40 (1H, s, olefinic proton), 7.20-7.50 (5H, m, 
aromatic protons); .sup.13 C NMR (CDCl.sub.3) .delta. 30.8, 
(CH.sub.3).sub.3 C; 33.4, allylic CH.sub.2 S; 42.7, SC(CH.sub.3).sub.3 ; 
115.0, H.sub.2 C=C; 126.2, 127.7, 128.3, 144.8, aromatic ring carbons; 
140.0, H.sub.2 C=C; MS(CH.sub.4) 207 (MH.sup.+, 13%), 179 (26% ), 151 
(100%). 
.alpha.-(n-Butanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 =phenyl, 
R.sup.2 =n-butyl, n=1). This compound was prepared using a similar 
procedure to that described above. Pure 
.alpha.-(n-butanethiomethyl)styrene was obtained in 90% yield after column 
chromatography on silica-gel (petroleum spirit eluent): .sup.1 H NMR 
(CDCl.sub.3) .delta. 0.85 (3H, t, CH.sub.3 CH.sub.2, J 7.0 Hz), 1.20-1.70 
(4H, m, CH.sub.3 CH.sub.2 CH.sub.2 CH.sub.2 S), 2.45 (2H, t, CH.sub.2 
CH.sub.2 S, J 7.0 Hz), 3.58 (2H, s, allylic CH.sub.2 S), 5.20 (1H, s, 
olefinic proton), 5.40 (1H, s, olefinic proton) 7.20-7.50 (5H, m, aromatic 
protons). 
.alpha.-(Carboxymethanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 
=phenyl, R.sup.2 =--CH.sub.2 COOH, n=1). A solution of 
.alpha.-(bromomethyl)styrene (7 g, 35.5 mmol) in methanol (15 ml) was 
added to a stirred solution at room temperature of sodium acetate (5.86 g, 
71.4 mmol) and thioglycolic acid (6.57 g, 71.4 mmol) in methanol (25 ml). 
The mixture was allowed to stir for 2 days and then was poured into a 
mixture of water and saturated NaHCO.sub.3 solution (1:1), and washed with 
diethyl ether. The aqueous basic layer was adjusted to pH 1 with 
hydrochloric acid and then extracted three times with diethyl ether. The 
combined ether layers were then dried over anhydrous MgSO.sub.4. After 
removal of the solvent, the required compound (7.1 g, 95.5%) was obtained, 
mp 74.degree.-76.degree. C. (from CCl.sub.4); .sup.1 H NMR (CDCl.sub.3) 
.delta. 3.20 (2H, s, SCH.sub.2 COOH), 3.70 (2 H, s, allylic CH.sub.2 S), 
5.25 (1H, s, olefinic proton), 5.50 (1H, s, olefinic proton), 7.20-7.50 
(5H, m, aromatic protons), 10.80 (1H, broad singlet, COOH); MS (CH.sub.4) 
209 (MH.sup.+, 100%), 191 (50%), 163 (91%), 117 (96%). 
.alpha.-(Carboxyethanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 
=phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 COOH, n=1). Similarly, treatment of 
.alpha.-(bromomethyl)styrene with 3-mercaptopropionic acid and sodium 
acetate in methanol as described above, afforded 
.alpha.-(carboxyethanethiomethyl)styrene: mp 47.degree.-49.degree. C. 
(from CCl.sub.4); .sup.1 H NMR (CDCl.sub.3) .delta. 2.60-2.90 (4H, m, 
SCH.sub.2 CH.sub.2 COOH), 3.60 (2H, s, allylic CH.sub.2 S), 5.25 (1H, s, 
olefinic proton), 5.45 (1H, s, olefinic proton), 7.20-7.50 (5H, m, 
aromatic protons), 8.35 (1H, broad singlet, COOH). 
.alpha.-(2-Hydroxyethanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 
=phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 OH, n=1). The title compound was 
prepared in 90% yield after column chromatography on silica gel (ethyl 
acetate/petroleum spirit). .sup.1 H NMR (CDCl.sub.3) .delta. 2.35 (1H, 
broad singlet, OH), 2.65 (2H, t, SCH.sub.2 CH.sub.2 OH, J 7.0 Hz), 3.60 
(2H, s, allylic CH.sub.2 S), 3.68 (2H, t, SCH.sub.2 CH.sub.2 OH, J 7.0 
Hz), 5.30 (1H, s, olefinic proton), 5.45 (1H, s, olefinic proton), 
7.20-7.50 (5H, m, aromatic protons); .sup.13 C NMR (CDC1.sub.3) .delta. 
34.4, allylic CH.sub.2 S; 36.1, SCH.sub.2 CH.sub.2 OH; 60.2, SCH.sub.2 
CH.sub.2 OH; 115.3, H.sub.2 C.dbd.C; 126.3, 128.0, 128.4, 143.6, aromatic 
ring carbons; 139.0, H.sub.2 C.dbd.C; MS (CH.sub. 4) 195 MH.sup.+, 40%), 
177 (100%), 149 (69%), 135 (42%), and 119 (87%). 
.alpha.-(2-Aminoethanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 
=phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 NH.sub.2, n=1). A solution of 
.alpha.-(bromomethyl)styrene (0.5 g, 2.55 mmol) in methanol (2 ml) was 
added to a cold stirred solution of 2-aminoethanethiol (0.197 g, 2.55 
mmol) and sodium methoxide (0.165 g, 3 mmol) in methanol (3 ml). After 15 
minutes at 0.degree. C., the mixture was allowed to stir at room 
temperature for a further one hour. The resulting mixture was then poured 
into water and acidified with dilute HCl, and then extracted with diethyl 
ether in order to remove traces of the unreacted bromide. The acidic layer 
was then brought to pH 7-8 with KOH solution (5%) and then extracted 
immediately with diethyl ether (3.times.). The combined ether extracts 
were then dried (Na.sub.2 SO.sub.4). After removal of the solvent, the 
product, .alpha.-(2 -aminoethanethiomethyl)styrene, (0.42 g, 85%) was 
obtained as a brownish liquid: .sup.1 H NMR (CDCl.sub.3) .delta. 1.75 (2H, 
broad singlet, NH.sub.2), 2.45-2.85 (4H, A.sub.2 B.sub.2 multiplets, 
SCH.sub.2 CH.sub.2 NH.sub.2), 3.55 (2H, m, allylic CH.sub.2 S), 5.15 (1H, 
m, olefinic proton), 5.40 (1H, m, olefinic proton), 7.20-7.50 (5H, m, 
aromatic protons); MS (CH.sub.4) 194 (MH.sup.+, 6%), 177 (100%), 149 
(54%). 
.alpha.-[3-(Trimethoxysilyl)propanethiomethyl]styrene (Formula I, 
X=sulphur, R.sup.1 =phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 CH.sub.2 
Si(OCH.sub.3).sub.3, n=1). This compound was prepared in 94% yield after 
rapid column chromatography on silica gel (ethyl acetate). .sup.1 H NMR 
(CDCl.sub.3) .delta. 0.75 (2H, t, CH.sub.2 Si, J 7.0 Hz), 1.75 (2H, 
quintet, SCH.sub.2 CH.sub.2 CH.sub.2 Si), 2.55 (2H, t, SCH.sub.2 CH.sub.2 
CH.sub.2 Si, J 7.0 Hz), 3.60 (2H, s, allylic CH.sub.2 S), 3.60 (9H, s, 
3.times.OCH.sub.3), 5.20 (1H, s, olefinic proton), 5.45 (1H, s, olefinic 
proton), 7.20-7.50 (5H, m, aromatic protons). 
.alpha.-(n-Butanesulphinylmethyl)styrene (Formula I, X=S(O), R.sup.1 
=phenyl, R.sup.2 =n-butyl, n=1). To a stirred solution of 
.alpha.-(n-butanethiomethyl)styrene (1 g, 4.85 mmol) in CH.sub.2 Cl.sub.2 
(25 ml) at -78.degree. C., a solution of m-chloroperbenzoic acid 90% (0.93 
g, 5.40 mmol) in CH.sub.2 Cl.sub.2 (25 ml) was added dropwise. The mixture 
was allowed to stir at -78.degree. C. for 1 h before being poured into 
aqueous saturated NaHCO.sub.3 (50 ml). The organic layer was separated and 
the aqueous phase was extracted three times with CH.sub.2 Cl.sub.2. The 
combined organic phases were then washed with water, dried over anhydrous 
Na.sub.2 SO.sub.4, filtered, and the solvent was removed to give 
.alpha.-(n-butanesulphinylmethyl)styrene (1.05 g, 97%): mp 
42.degree.-43.5.degree. C. (from petroleum spirit); .sup.1 H NMR 
(CDCl.sub.3) .delta. 0.90 (3H, t, CH.sub.2 CH.sub.3, J 7.0 Hz), 1.20-1.90 
(4H, m, CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.3), 2.65 (2H, t, S(O)CH.sub.2 
CH.sub.2, J 7.0 Hz), 3.90 (2H, AB quartet, allylic CH.sub.2 S(O), J.sub.AB 
15.0 Hz), 5.35 (1H, s, olefinic proton), 5.55 (1H, s, olefinic proton), 
7.20-7.50 (5H, m, aromatic protons); IR (film) 1040 cm.sup.-1 (S--O); MS 
(CH.sub.4) 223 (MH.sup.+, 100%), 117 (15%). 
Alkyl .alpha.-(Alkanethiomethyl)acrylates 
In principle, these compounds (Formula I, X=sulphur, R.sup.1 =--COOAlkyl, 
R.sup.2 =substituted or unsubstituted alkyl, aryl, alkenyl, or alkynyl, 
n=1) could be prepared directly via reaction of an alkyl 
.alpha.-(bromomethyl)-acrylate, the appropriate thiol, and a base. 
However, an alternative and generally more useful preparation, which is 
outlined in The Journal of the Chemical Society, Perkin Transactions I, 
1986, 1613-1619, can be conveniently used to prepare the following 
compounds. 
Ethyl .alpha.-(t-Butanethiomethyl)acrylate (Formula I, X=sulphur, R.sup.1 
=--COOCH.sub.2 CH.sub.3, R.sup.2 =t-butyl, n=1) has been previously 
reported in the article cited above. 
Ethyl .alpha.-(Carboxymethanethiomethyl)acrylate (Formula I, X=sulphur, 
R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =--CH.sub.2 COOH, n=1). 
Thioglycolic acid (2.0 g, 22 mmol) was added slowly to a stirred 
suspension of ethyl 1,3-dibromopropane-2-carboxylate (6.0 g, 21.9 mmol) 
and potassium carbonate (3.04 g, 22 mmol) in absolute ethanol (25 ml). 
After 2 h of stirring at ambient temperature, the mixture was poured into 
saturated aqueous NaHCO.sub.3, and washed with diethyl ether. The aqueous 
layer was acidified with dilute HCl and then extracted (5.times.) with 
diethyl ether. The combined ether extracts were then dried over anhydrous 
Na.sub.2 SO.sub.4. After the solvent was removed, vacuum distillation of 
the crude product afforded pure ethyl 
.alpha.-(carboxymethanethiomethyl)acrylate (1.3 g, 29%), as a slightly 
yellow liquid, bp 122.degree.-130.degree. C. (0.05 mmHg), which solidified 
upon cooling in the freezer. .sup.1 H NMR (CDCl.sub.3) .delta. 1.30 (3H, 
t, OCH.sub.2 CH.sub.3, J 7.0 Hz), 3.20 (2H, s, SCH.sub.2 COOH), 3.55 (2H, 
s, allylic CH.sub.2 S), 4.25 (2H, q, OCH.sub.2 CH.sub.3, J 7.0 Hz), 5.65 
(1H, s, olefinic proton), 6.25 (1H, s, olefinic proton), 10.55 (1H, broad 
s, exchangeable, COOH). 
.alpha.-(Alkanethiomethyl)acrylic Acids 
These compounds (Formula I, X=sulphur, R.sup.1 =--COOH, R.sup.2 
=substituted or unsubstituted alkyl, aryl, alkenyl, or alkynyl, n=1) can 
be prepared directly from the corresponding esters [alkyl 
.alpha.-(alkanethiomethyl)acrylates, prepared as described above] by 
treatment with aqueous KOH. 
.alpha.-(Carboxymethanethiomethyl)acrylic Acid (Formula I, X=sulphur, 
R.sup.1 =--COOH, R.sup.2 =--CH.sub.2 COOH, n=1). This compound was 
prepared from ethyl .alpha.-(carboxymethanethiomethyl)acrylate (0.5 g, 
2.45 mmol) and aqueous KOH (4% solution, 20 ml). The mixture was allowed 
to stir at room temperature overnight and then brought to pH 1 with 
hydrochloric acid. The resultant mixture was extracted with diethyl ether 
(5.times.). The combined extracts were then dried over anhydrous Na.sub.2 
SO.sub.4. After the solvent was removed, the product, 
.alpha.-(carboxymethanethiomethyl)acrylic acid (0.42 g, 97%), solidified. 
mp 121.degree.-125.degree. C.; .sup.1 H NMR (CD.sub.3 OD) .delta. 3.20 
(2H, s, SCH.sub.2 COOH), 3.50 (2H, s, allylic CH.sub.2 S), 4.90 (2H, broad 
singlet, 2.times.COOH), 5.70 (1H, s, olefinic proton), 6.20 (1H, s, 
olefinic proton). IR (KBr) 2500-3500 (broad), 1680, 1700 cm.sup.-1 
(C.dbd.O). MS (CH.sub.4) 177 (MH.sup.+, 5%), 159 (47%), 131 (100l %). 
.alpha.-(Alkanethiomethyl)acrylonitriles 
In general, these compounds (Formula I, X=sulphur, R.sup.1 =--CN, R.sup.2 
=substituted or unsubstituted alkyl, aryl, alkenyl, or alkynyl, n=1) can 
be prepared by reaction of a cooled, stirred alcoholic solution of 
.alpha.-(bromomethyl)acrylonitrile with the appropriate thiol and a base. 
The starting material, .alpha.-(bromomethyl)acrylonitrile, was obtained 
using a similar procedure to that described for the syntheses of ethyl 
.alpha.-(hydroxymethyl)acrylate and ethyl .alpha.-(halomethyl)acrylates in 
Synthesis, 1982, 924-926. Thus, .alpha.-(hydroxymethyl)acrylonitrile (bp 
68.degree.-70.degree. C. (0.3 mmHg)) was stirred with phosphorus 
tribromide in dry ether at -10.degree. C. to afford 
.alpha.-(bromomethyl)acrylonitrile, bp 45.degree.-47.degree. C. (2 mmHg); 
.sup.1 H NMR (CDCl.sub.3) .delta. 3.85 (2H, broad singlet, allylic 
CH.sub.2 Br), 5.95 (2H, m, olefinic protons). 
.alpha.-(t-Butanethiomethyl)acrylonitrile (Formula I, X=sulphur, R.sup.1 
=--CN, R.sup.2 =t-butyl, n=1). .alpha.-(Bromomethyl)acrylonitrile (1.18 g, 
8 mmol) was converted to the title compound by treatment with a mixture of 
t-butanethiol (0.9 ml, 8 mmol), potassium carbonate (1.12 g, 8.1 mmol) and 
absolute ethanol (10 ml) at 0.degree. C. for 1 h. The resulting mixture 
was allowed to stand at room temperature for another hour before the usual 
workup. After column chromatography on silica-gel (8% ethyl 
acetate/petroleum spirit), .alpha.-(t-butanethiomethyl)acrylonitrile (0.97 
g, 77%) was obtained as a colourless liquid: .sup.1 H NMR (CDCl.sub.3) 
.delta. 1.35 (9H, s, (CH.sub.3).sub.3 C), 3.35 (2H, m, allylic CH.sub.2 
S), 5.95 (2H, m, olefinic protons); MS (CH.sub.4) 156 (MH.sup.+, 34%), 128 
(55%), 100 (100%). 
.alpha.-(Diethoxyphosphorylmethyl)styrene (Formula I, X=P(O), R.sup.1 
=phenyl, R.sup.2 =--OCH.sub.2 CH.sub.3, n=2). .alpha.-(Bromomethyl)styrene 
was treated with an equimolar ratio of triethylphosphite at reflux for 1 
h. After the mixture was cooled to room temperature, the by-product, ethyl 
bromide, was removed under reduced pressure, and the product 
.alpha.-(diethoxyphosphorylmethyl)styrene was obtained in quantitative 
yield as a yellowish syrup: .sup.1 H NMR (CDCl.sub.3) .delta. 1.20 (6H, t, 
2.times.OCH.sub.2 CH.sub.3, J 7.5 Hz), 3.05 (2H, d, CH.sub.2 P(O), J 22.5 
Hz), 4.00 (4H, m, 2.times.OCH.sub.2 CH.sub.3), 5.35 (1H, d, olefinic 
proton, J 6.0 Hz), 5.50 (1H, d, olefinic proton, J 6 Hz), 7.25-7.55 (5H, 
m, aromatic protons). 
The following three chain transfer agents used in this invention were 
prepared according to literature procedures. 
Ethyl .alpha.-(Trimethylsilymethyl)acrylate (Formula I, X=Si, R.sup.1 
=--COOCH.sub.2 CH.sub.3, R.sup.2 =--CH.sub.3, n=3) as described in 
Synthesis, 1985, 271-272. 
Ethyl .alpha.-(Benzenesulphonylmethyl)acrylate (Formula I, X=S(O).sub.2, 
R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =phenyl, n=1) as described in 
Journal of the Chemical Society, Chemical Communications, 1986, 1339-1340. 
This compound was purified either by high vacuum distillation (bp 
136.degree.-140.degree. C./0.05 mmHg) or by chromatography on silica-gel 
(ethyl acetate:petroleum 2:3). .sup.1 H NMR (CDCl.sub.3) .delta. 1.20 (3H, 
t, OCH.sub.2 CH.sub.3, J 7.5 Hz), 4.05 (2H, q, OCH.sub.2 CH.sub.3, J 7.5 
Hz), 4.20 (2H, s, allylic CH.sub.2 S(O).sub.2), 5.90 (1H, s, olefinic 
proton) 6.50 (1H, s, olefinic proton), 7.40-8.00 (5H, m, aromatic 
protons). 
Ethyl .alpha.-(Tri-n-butylstannylmethyl)acrylate (Formula I, X=Sn, R.sup.1 
=--COOCH.sub.2 CH.sub.3, R.sup.2 =n-butyl, n=3). This compound was 
prepared from ethyl .alpha.-(benzenesulphonylmethyl)acrylate, n-Bu.sub.3 
SnH and AIBN in benzene at 80.degree. C. for 1.5 h according to the 
procedure described in Journal of the Chemical Society, Chemical 
Communications, 1986, 1339-1340. .sup.1 H NMR (CDCl.sub.3) .delta. 
0.85-1.65 (30H, m, 3.times.CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.3, OCH.sub.2 
CH.sub.3), 2.00 (2H, s, allylic CH.sub.2 Sn), 4.15 (2H, q, OCH.sub.2 
CH.sub.3, J 7.5 Hz), 5.25 (1H, s, olefinic proton), 5.75 (1H, s, olefinic 
proton). 
.alpha.-Alkoxystyrenes (Formula II, R.sup.1 =phenyl). 
One class of compound used in this invention, the .alpha.-alkoxystyrenes 
(Formula II; R.sup.1 =phenyl) can be cheaply and easily prepared from 
styrene, the appropriate alcohol, iodine and mercuric oxide, using a 
procedure based on that described in Die Makromolekulare Chemie, 1967, 
103, 68. This procedure is useful as a general synthesis and a number of 
derivatives can be prepared, including those with substituents on the 
phenyl group of the styrene or on R.sup.2. It is usually desirable to use 
an equimolar ratio of the reagents and to add a non-reactive solvent such 
as petroleum ether or diethyl ether. When the compound II contains certain 
functional groups, the procedure is best modified to use an alkoxide base, 
such as sodium methoxide (Method A) or potassium tertbutoxide (Method B), 
or an amine base (Method C) in the elimination step. The compounds can be 
purified by chromatography on basic alumina or, in some cases, by 
recrystallization or by distillation at reduced pressures. An alternative, 
but more costly method of synthesis is to react the appropriate ester with 
a titanium-aluminium complex, as described in The Journal of Organic 
Chemistry, 1985, 50, 1212. 
General Procedure for the Preparation of an .alpha.-Alkoxystyrene by Method 
A: .alpha.-(4-Methoxycarbonylbenzyloxy)styrene (Formula II, R.sup.1 
=phenyl, R.sup.2 =CH.sub.3 OC(O)C.sub.6 H.sub.4 CH.sub.2 --). Iodine (6.35 
g, 25 mmol) was added in small portions to a stirred suspension, 
maintained between 0.degree. and 10.degree. C., of yellow mercuric oxide 
(5.34 g, 25 mmol), styrene (2.6 g, 25 mmol), and methyl 
4-(hydroxymethyl)benzoate (4.15 g, 25 mmol) in ether (5 ml). The resulting 
mixture was stirred for 1 h at 0.degree. C. and then warmed to ambient 
temperature and stirred for a further 1 h. The mixture was then diluted 
with ether, and filtered. The filtrate was washed successively with water, 
aqueous sodium thiosulphate solution and a further two portions of water, 
and then dried (MgSO.sub.4). The solvent was removed to afford the 
intermediate iodoether which was converted to the alkoxystyrene by 
addition to a boiling solution of sodium methoxide in methanol [prepared 
from sodium (1.15 g, 50 mmol) and methanol (25 ml)]. After the resulting 
mixture had been heated for 1 h under reflux, it was cooled, diluted with 
water and extracted with ether. The organic layer was washed with water 
and dried (K.sub.2 CO.sub.3). After removal of the solvent, the crude 
mixture was chromatographed on basic alumina (30% CH.sub.2 Cl.sub.2 
/petroleum spirit) to afford .alpha.-(4-methoxycarbonylbenzyloxy)styrene 
(1.3 g, 20%): .sup.1 H NMR (CDCl.sub.3) .delta. 3.85 (3H, s), 4.24 (1H, d, 
J 3 Hz), 4.72 (1H, d, J 3 Hz), 4.97 (2H, s), 7.2-7.7 (7H, m), 8.03 (2H, d, 
J 8 Hz); MS (CH.sub.4) 269 (MH.sup.+, 15%), 149 (100%); IR (film) 1735 
cm.sup.-1. 
General Procedure for the Preparation of an .alpha.-Alkoxystyrene by Method 
B: .alpha.-Benzyloxy[4-(chloromethyl)styrene] and 
.alpha.-Benzyloxy[3-(chloromethyl)styrene] (Formula II, R.sup.1 
=ClCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =benzyl). Treatment of a 2:3 
mixture (7.63 g, 50 mmol) of 4-(chloromethyl)styrene and 
3-(chloromethyl)styrene with benzyl alcohol (5.4 g, 50 mmol), iodine (12.7 
g, 50 mmol), and mercuric oxide (10.8 g, 50 mmol), as described above, 
afforded the intermediate iodoether (18 g). Potassium tertbutoxide (0.28 
g, 2.5 mmol) was added to a solution of the iodoether (0.48 g, 1.2 mmol) 
in ether (10 ml) and the mixture was allowed to stir at room temperature 
for 2 h. The mixture was then poured into saturated sodium chloride 
solution and water (1:1) and extracted three times with 50% 
ether/petroleum spirit. The combined extracts were washed with water and 
dried (K.sub.2 CO.sub.3) to afford, after chromatography as described 
above, the required alkoxystyrene (260 mg): .sup.1 H NMR .delta. 4.33 (1H, 
d, J 1.9 Hz), 4.53 (2H, s), 4.73 (1H, d, J 1.9 Hz), 4.93 (2H, s), 7.1-7.7 
(9H, m); MS (CH.sub.4) 259, 261 (3:1, MH.sup.+, 1%), 91 (100%). 
General Procedure for the Preparation of an .alpha.-Alkoxystyrene by Method 
C: .alpha.-(4-Cyanobenzyloxy)styrene. (Formula II, R.sup.1 =phenyl, 
R.sup.2 =4-NCC.sub.6 H.sub.4 CH.sub.2 --). Treatment of 4-cyanobenzyl 
alcohol (5.98 g, 45 mmol) [prepared by sodium borohydride reduction (2 h, 
20.degree. C., EtOH) of 4-cyanobenzaldehyde] with styrene, iodine, and 
mercuric oxide, as described above, afforded the intermediate iodoether (9 
g, 55%). 1,5-Diazabicyclo[4.3.0]non-5-ene (DBN) (3.5 g, 28 mmol) was added 
to a stirred suspension of the iodoether (8.5 g, 23 mmol), powdered 
potassium carbonate (2.12 g, 35 mmol), and acetonitrile (12 ml). After the 
resultant mixture was stirred at ambient temperature overnight, it was 
diluted with water and extracted twice with ether. The combined ether 
extracts were washed with water and aqueous sodium bicarbonate solution, 
dried (K.sub.2 CO.sub.3), and purified by chromatography on alumina to 
afford the required compound (3.5 g, 65%), which was further purified by 
recrystallization (CH.sub.2 Cl.sub.2 /petroleum spirit): mp 
54.degree.-55.degree. C.; .sup.1 H NMR .delta. 4.20 (1H, d, J 3 Hz), 4.67 
(1H, d, J 3 Hz), 4.95 (2H, s), 7.1-7.7 (9H, m). 
The following compounds were also prepared. 
.alpha.-[4-(Hydroxymethyl)benzyloxy]styrene (Formula II, R.sup.1 =phenyl, 
R.sup.2 =4-HOCH.sub.2 C.sub.6 H.sub.4 CH.sub.2 --). This compound was 
prepared by lithium aluminium hydride reduction of 
.alpha.-(4-methoxycarbonylbenzyloxy)styrene: .sup.1 H NMR (CCl.sub.4) 
.delta. 2.65 (1H, t, J 4.5 Hz), 4.15 (1H, d, J 3 Hz), 4.43 (2H, d, J 4.5 
Hz), 4.60 (1H, d, J 3 Hz), 4.80 (2H, s), 7.1-7.7 (9H, m). 
.alpha.-[4-(Aminomethyl)benzyloxy]styrene (Formula II, R.sup.1 =phenyl, 
R.sup.2 = 4-H.sub.2 NCH.sub.2 C.sub.6 H.sub.4 CH.sub.2 --). Lithium 
aluminium hydride reduction of .alpha.-(4-cyanobenzyloxy)styrene led to 
this compound: .sup.1 H NMR (CD.sub.3 OD) .delta. 3.73 (2H, br s), 4.30 
(1H, d, J 3 Hz), 4.70 (1H, d, J 3 Hz), 4.72 (2H, s), 4.87 (2H, s), 7.1-7.7 
(9H, m). 
.alpha.-(4-Methoxybenzyloxy)styrene (Formula II, R.sup.1 =phenyl, R.sup.2 
=4-CH.sub.3 OC.sub.6 H.sub.4 CH.sub.2 --). Prepared using Method A. .sup.1 
H NMR (CDCl.sub.3) .delta. 3.73 (3H, s), 4.28 (1H, d, J 3 Hz), 4.70 (1H, 
d, J 3 Hz), 4.83 (2H, s), 6.7-7.7 (9H, m); MS (CH.sub.4) 241 (MH.sup.+, 
8%), 121 (100%). 
.alpha.-Benzyloxy[4-(tert-butyldimethylsilyloxymethyl)styrene] and 
.alpha.-Benzyloxy[3-(tert-butyldimethylsilyloxymethyl)styrene)] (Formula 
II, R.sup.1 =(tert-butyldimethylsilyloxymethyl)phenyl, R.sup.2 =benzyl). 
(Hydroxymethyl)styrene was prepared from (chloromethyl)styrene (a 2:3 
mixture of para and meta isomers) by a sequence described in Polymer, 
1973, 14, 330. It was treated with tert-butyldimethylsilyl chloride 
following the general directions found in Journal of the American Chemical 
Society, 1972, 94, 6190. Method C was used to convert the resulting 
compound to the required alkoxystyrene: .sup.1 H NMR (CCl.sub.4) .delta. 
0.70 (6H, s), 0.94 (9H, s), 4.17 (1H, d, J 2.4 Hz), 4.63 (3H, broadened 
s), 4.83 (2H, s), 7.0-7.6 (9H, m); MS (CH.sub.4) 355 (MH.sup.+, 4%), 91 
(100%). 
.alpha.-Benzyloxy[4-(acetoxymethyl)styrene] and 
.alpha.-Benzyloxy[3-(acetoxymethyl)styrene] (Formula II, R.sup.1 =CH.sub.3 
COOCH.sub.2 C.sub.6 H.sub.4 -, R.sup.2 =benzyl). (Acetoxymethyl)styrene 
was prepared from (chloromethyl)styrene by the method described in 
Polymer, 1973, 14, 330. It was converted (Method C) to the required 
alkoxystyrene: .sup.1 H NMR (CCl.sub.4) .delta. 2.02 (3H, s), 4.23 (1H, d, 
J 2 Hz), 4.67 (1H, d, J 2 Hz), 4.87 (2H, s), 5.00 (2H, s), 7.0-7.7 (9H, 
m); MS (CH.sub.4) 283 (MH.sup.+, 1%), 91 (100%); IR 1740 cm.sup.-1. 
.alpha.-Benzyloxy[4-(hydroxymethyl)styrene] and 
.alpha.-Benzyloxy[3-(hydroxymethyl)styrene] (Formula II, R.sup.1 
=HOCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =benzyl). These compounds were 
obtained by lithium aluminium hydride reduction of 
.alpha.-benzyloxy[(acetoxymethyl)styrene]. .sup.1 H NMR (CCl.sub.4) 
.delta. 2.96 (1H, t, J 4.5 Hz), 4.20 (1H, d, J 2.5 Hz), 4.40 (2H, d, J 4.5 
Hz), 4.63 (1H, d, J 2.5 Hz), 4.85 (2H, s), 7.0-7.8 (9H, m); IR 3320 
(broad) cm.sup.-1. 
.alpha.-Benzyloxy(4-chlorostyrene) (Formula II, R.sup.1 =4-ClC.sub.6 
H.sub.4 --, R.sup.2 =benzyl). Prepared using Method A. .sup.1 H NMR 
(CDCl.sub.3) .delta. 4.20 (1H, d, J 3 Hz), 4.63 (1H, d, J 3 Hz), 4.80 (2H, 
s), 7.0-7.6 (9H, m); MS (CH.sub.4) 245, 247 (3:1, MH.sup.+, 1%), 91 
(100%). 
.alpha.-Benzyloxy(3-methoxystyrene) (Formula II, R.sup.1 =3CH.sub.3 
OC.sub.6 H.sub.4 --, R.sup.2 =benzyl). Prepared using Method A. .sup.1 H 
NMR (CDCl.sub.3) .delta. 3.74 (3H, s), 4.30 (1H, d, J 3 Hz), 4.71 (1H, d, 
J 3 Hz), 4.92 (2H, s), 6.7-6.9 (1H, m), 7.1-7.5 (8H, m); MS (CH.sub.4) 241 
(MH.sup.+, 11%), 91 (100%). 
.alpha.-Benzyloxy(4-methoxystyrene). (Formula II, R.sup.1 =4CH.sub.3 
OC.sub.6 H.sub.4 --, R.sup.2 =benzyl). Prepared using Method A. .sup.1 H 
NMR (CDCl.sub.3) .delta. 3.70 (3H, s), 4.30 (1H, d, J 3 Hz), 4.60 (1H, d, 
J 3Hz), 4.90 (2H, s), 6.6-7.6 (9H, m). 
.alpha.-(4-Methoxycarbonylbenzyloxy)[4-(acetoxymethyl)styrene] and 
.alpha.-(4-Methoxycarbonylbenzyloxy)[3-(acetoxymethyl)styrene]. (Formula 
II, R.sup.1 =CH.sub.3 COOCH.sub.2 C.sub.6 H.sub.4 -, R.sup.2 =4-CH.sub.3 
OC(O)C.sub.6 H.sub.4 CH.sub.2 --). Prepared using Method C. .sup.1 H NMR 
(CCl.sub.4) .delta. 1.98 (3H, s), 3.80 (3H, s), 4.20 (1H, d, J 3 Hz), 4.68 
(1H, d, J 3 Hz), 4.8-5.0 (4H, m), 7.1-8.0 (8H, m). 
.alpha.-[4-(Hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] and 
.alpha.-[4-(Hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene] (Formula II, 
R.sup.1 =HOCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =HOCH.sub.2 C.sub.6 
H.sub.4 CH.sub.2 --). Lithium aluminium hydride reduction of 
.alpha.-(4-methoxycarbonylbenzyloxy)[4-(acetoxymethyl)styrene] and 
.alpha.-(4-methoxycarbonylbenzyloxy)[3-(acetoxymethyl)styrene] gave the 
required compounds: .sup.1 H NMR (CD.sub.3 OD) .delta. 4.33 (1H, d, J 2 
Hz), 4.58 (4H, s), 4.77 (3H, broadened s), 4.92 (2H, s), 7.1-7.7 (8H, m). 
.alpha.-[4-(tert-Butyldimethylsilyloxymethyl)-benzyloxy][4-(tert-butyldimet 
hylsilyloxymethyl)styrene] and 
.alpha.-[(tert-Butyldimethylsilyloxymethyl)-benzyloxy][3-(tert-butyldimeth 
ylsilyloxymethyl)styrene]. (Formula II, R.sup.1 
=tert-butyldimethylsilyloxymethylphenyl, R.sup.2 
=4-tert-butyldimethylsilyloxymethylbenzyl). Methyl 
4-(hydroxymethyl)benzoate was treated with tert-butyldimethylsilyl 
chloride using the general procedure described in Journal of the American 
Chemical Society, 1972, 94, 6190. The resulting product was reduced with 
lithium aluminium hydride to afford 
4-(tert-butyldimethylsilyloxymethyl)benzyl alcohol. This alcohol was 
converted into the required compound using Method C. .sup.1 H NMR 
(CCl.sub.4) .delta. 0.08 (12H, s), 0.91 (18H, s), 4.22 (1H, d, J 2 Hz), 
4.68 (5H, br s), 4.90 (2H, s), 7.1-7.6 (8H, m); MS (CH.sub.4) 483 (M.sup.+ 
-CH.sub.3, 52%), 133 100%). 
.alpha.-(4-Methoxycarbonylbenzyloxy)-4-cyanostyrene (Formula II, R.sup.I 
=4-NCC.sub.6 H.sub.4 --, R.sup.2 4-CH.sub.3 OC(O)C.sub.6 H.sub.4 CH.sub.2 
--). Prepared using Method C. .sup.1 H NMR (CCl.sub.4) .delta. 3.85 (3H, 
s), 4.23 (1H, d, J 3 Hz), 4.65 (1H, d, J 3 Hz), 4.97 (2H, s), 7.0-8.1 (8H, 
m). 
.alpha.-[4-(Hydroxymethyl)benzyloxy]]4-(aminomethyl)styrene] (Formula II, 
R.sup.1 =4-H.sub.2 NCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =4-HOCH.sub.2 
C.sub.6 H.sub.4 CH.sub.2 --). Lithium aluminium hydride reduction of 
.alpha.-(4-methoxycarbonylbenzyloxy)-4-cyanostyrene gave the required 
compound. .sup.1 H NMR (CD.sub.3 OD) .delta. 4.35 (1H, d, J 3 Hz), 4.58 
(2H, s), 4.77 (6H, broadened s), 4.93 (2H, s), 7.0-7.7 (8H, m). 
.alpha.-Alkoxyacrylonitriles 
These compounds (Formula II, R.sup.1 =--CN) were prepared by a short 
sequence described in The Journal of the Chemical Society, 1942, 520, 
using the appropriate alcohol. The elimination step was best accomplished 
by stirring of the intermediate halocompound at ambient temperatures in 
acetonitrile containing 2 molar equivalents of DBN 
(1,5-diazabicyclo[4.3.0]non-5-ene) and 1.1 molar equivalents of potassium 
carbonate (similar to Method B, above). 
.alpha.-Benzyloxyacrylonitrile (Formula II, R.sup.1 =--CN, R.sup.2 
=benzyl). This compound, which had not previously been reported, was 
obtained using the above procedure. bp 55.degree.-58.degree. C. (0.025 
mmHg); .sup.1 H NMR (CDCl.sub.3) .delta. 4.83 (2H, s), 4.93 and 5.00 (2H, 
ABq, J.sub.AB 3 Hz), 7.33 (5H, s); MS (CH.sub.4) m/e 160 (MH.sup.+, 71%), 
91 (100%); IR 2235 cm.sup.-1. 
.alpha.-Alkoxyacrylates. 
These compounds (Formula II; R.sup.1 =--COOAlkyl) can be prepared from 
esters of 2,3-dibromopropionic acid by treatment with alkoxides, following 
the procedure described in Bulletin of the Chemical Society of Japan, 
1970, 43, 2987. An alternative and generally more useful preparation is 
from a precursor to the corresponding nitrile (Formula II; R.sup.1 =--CN) 
by treatment with gaseous hydrogen chloride and a solution containing the 
appropriate alcohol, based on the procedure outlined in Bulletin of the 
Chemical Society of Japan, 1969, 42, 3207. 
Methyl .alpha.-Benzyloxyacrylate (Formula II, R.sup.1 =CH.sub.3 OC(O)--, 
R.sup.2 =benzyl). A slow stream of hydrogen chloride gas was passed for 4 
h through a solution of 2-benzyloxy-3-bromopropionitrile (16.75 g) in 
methanol (2.38 g) and ether (66 ml) which was maintained at -10.degree. C. 
The mixture was allowed to stand at 5.degree. C. overnight, and then ice 
was added in small portions to the mixture at 0.degree. C. After 20 min of 
stirring, the mixture was poured into water and the product was extracted 
with ether, washed with water and aqueous sodium bicarbonate, and dried 
(MgSO.sub.4). After the solvent was removed, the crude product was 
recrystallized from ether/CH.sub.2 Cl.sub.2 to afford, after a first crop 
of crystals of 2-benzyloxy-3-bromopropanamide, the required intermediate, 
methyl 2-benzyloxy-3-bromopropanoate. This bromoester was treated with 
DBN/potassium carbonate as described above to yield methyl 
.alpha.-benzyloxyacrylate, mp 44.5.degree.-45.5.degree. C. (from hexane); 
.sup.1 H NMR .delta. 3.80 (3H, s), 4.63 (1H, d, J 3 Hz), 4.83 (2H, s), 
5.37 (1H, d, J 3 Hz), 7.33 (5H, s); IR 1740 cm.sup.-1. Ketals of alkyl 
pyruvates, prepared according to the directions in The Journal of Organic 
Chemistry, 1967, 32,1615, also may be converted to .alpha.-alkoxyacrylates 
by an acidic catalyst, as described in Chemische Berichte, 1911, 44, 3514. 
.alpha.-Alkoxyacrylamides. 
.alpha.-Benzyloxyacrylamide (Formula II, R.sup.1 =--CONH.sub.2, R.sup.2 
=benzyl). Treatment of 2-benzyloxy-3-bromopropanamide with DBN/potassium 
carbonate following the general procedure of Method C (above) yielded 
.alpha.-benzyloxyacrylamide (Formula II; R.sup.1 =--CONH.sub.2), mp 
132.degree.-133.degree. C.; .sup.1 H NMR (CDCl.sub.3) .delta. 4.53 (1H, d, 
J 3 Hz), 4.80 (2H, s), 5.43 (1H, d, J 3 Hz), 6.50 (2H, br s), 7.33 (5H, 
s). 
The following examples illustrate the use of the invention to produce 
polymers of controlled molecular weight and end-group functionality.

EXAMPLES OF THE PROCESS 
Example 1 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-(t-Butanethiomethyl)styrene (Formula I, 
X=sulphur, R.sup.1 =phenyl, R.sup.2 =t-butyl, n=1). 
Azobisisobutyronitrile (AIBN) (49.5 mg) was dissolved in freshly distilled 
methyl methacrylate (25 ml). An aliquot (4 ml) was removed and added to an 
ampoule containing the amount of .alpha.-(t-butanethiomethyl)styrene (Ia) 
shown in Table I. The mixture was polymerized at 60.degree. C. for 1 h in 
the absence of oxygen. The contents of the ampoule were then poured into 
petroleum spirit (bp 40.degree.-60.degree. C.) and the precipitated 
polymer was collected and dried in a vacuum oven at 40.degree. C. to 
constant weight. A small portion was examined by GPC using a Waters 
Instrument connected to six .mu.-Styragel columns (10.sup.6 -, 10.sup.5 -, 
10.sup.4 -, 10.sup.3 -, 500- and 100- .ANG. pore size). Tetrahydrofuran 
was used as eluent at a flow rate of 1 ml/min and the system was 
calibrated using narrow distribution polystyrene standards (Waters). 
TABLE I 
______________________________________ 
Amount of 
Ia added (mg) % conversion 
-- M.sub.n * 
______________________________________ 
0 10.9 205,190 
9.0 10.4 46,071 
17.4 10.1 27,870 
31.4 9.4 16,795 
1.6 8.6 9,600 
______________________________________ 
*Polystyrene-equivalent number average molecular weight, obtained by GPC 
The chain transfer constant calculated from these data was 1.24, which 
compares favourably with, say, n-butanethiol (chain transfer 
constant=0.66) or t-butanethiol (chain transfer constant=0.18). These 
results show that the compound is an efficient chain transfer agent and 
that the process produces polymers of low molecular weight in a controlled 
manner. A sample of poly(methyl methacrylate) produced similarly using 298 
mg of the chain transfer agent was precipitated two further times from 
ethyl acetate/petroleum spirit to remove traces of the unreacted chain 
transfer agent. The resulting polymer of number-average molecular weight 
3230 had signals at .delta. 4.95, and 5.15 ppm in the .sup.1 H NMR 
spectrum confirming the presence of the terminal double bond. Integration 
of the spectrum showed that one of these groups was present per polymer 
chain. The .sup.13 C NMR spectrum also confirmed the presence of this 
group. 
Example 2 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Styrene 
Using .alpha.-(t-Butanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 
=phenyl, R.sup.2 =t-butyl, n=1). 
Azobisisobutyronitrile (34.3 mg) was dissolved in freshly distilled styrene 
(25 ml). Aliquots (5 ml) were removed and added to ampoules containing the 
amount of .alpha.-(t-butanethiomethyl)styrene shown below. The mixtures 
were polymerized at 60.degree. C. for 3 h in the absence of oxygen. The 
contents of the ampoules were then poured into methanol and the 
precipitated polymer was collected and dried and examined by GPC as 
described above. Samples of polystyrene prepared in this manner using 0 
mg, 10.58 mg, 20.12 mg, and 30.73 mg of the chain transfer agent had 
number-average molecular weights of 125000, 61167, 40466, and 28964, 
respectively. The chain transfer constant calculated from these data was 
0.8, which compares favourably with that of n-butanethiol (chain transfer 
constant=22) or dodecanethiol (chain transfer constant=15-19). These 
results show that .alpha.-(t-butanethiomethyl)styrene is an efficient 
chain transfer agent for styrene and that the process produces polymers of 
low molecular weight in a controlled manner. A sample of polystyrene 
produced similarly using 320 mg of the chain transfer agent was 
precipitated two further times from ethyl acetate/methanol to remove 
traces of the unreacted chain transfer agent. The resulting polymer of 
number-average molecular weight 3613 had signals at .delta. 4.7-4.8 and 
5.0-5.1 in the .sup.1 H NMR spectrum confirming the presence of a terminal 
double bond. Integration of the spectrum showed that one of these groups 
was present per polymer chain. 
Example 3 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Acrylate Using .alpha.-(t-Butanethiomethyl)styrene (Formula I, X=sulphur, 
R.sup.1 =phenyl, R.sup.2 =t-butyl, n=1). 
Azobisisobutyronitrile (9.88 mg) was dissolved in freshly distilled methyl 
acrylate (25 ml). An aliquot (4 ml) was removed and added to an ampoule 
containing thiophene-free benzene (16 ml) and the amount of 
.alpha.-(t-butanethiomethyl)styrene shown below. The mixture was 
polymerized at 60.degree. C. for 1 h in the absence of oxygen. The 
volatiles were then removed and the polymers were dried in vacuo to 
constant weight and examined by GPC. Samples of poly(methyl acrylate) 
prepared in this manner using 0 mg, 7.78 mg, 11.67 mg, and 15.55 mg of 
.alpha.-(t-butanethiomethyl)styrene had number-average molecular weights 
of 496642, 24044, 15963, and 12211, respectively. The chain transfer 
constant calculated from these data was 3.95. These results show that 
.alpha.-(t-butanethiomethyl)styrene is an efficient chain transfer agent 
for methyl acrylate and that the process produces polymers of low 
molecular weight in a controlled manner. 
Example 4 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of vinyl 
Acetate Using .alpha.-(t-Butanethiomethyl)styrene (Formula I, X=sulphur, 
R.sup.1 =phenyl, R.sup.2 =t-butyl, n=1). 
Azobisisobutyronitrile (8.0 mg) was dissolved in freshly distilled vinyl 
acetate (50 ml). Aliquots (10 ml) were removed and added to ampoules 
containing the amounts of .alpha.-(t-butanethiomethyl)styrene shown below. 
The mixtures were then polymerized at 60.degree. C. for 1 h in the absence 
of oxygen. The volatiles were then removed and the polymers were dried in 
vacuo to constant weight. The polymers were then examined by GPC as 
described above. Samples of poly(vinyl acetate) prepared in this manner 
using 0 mg, 6.3 mg, 12.4 mg, and 24.2 mg of 
.alpha.-(t-butanethiomethyl)styrene had number-average molecular weights 
of 271680, 13869, 7286, and 3976, respectively. The chain transfer 
constant calculated from these data was 19.9, which is closer to the ideal 
than that of n-butanethiol (chain transfer constant=48). These results 
show that .alpha.-(t-butanethiomethyl)styrene is an efficient chain 
transfer agent for vinyl acetate and that the process produces polymers of 
low molecular weight in a controlled manner. 
Example 5 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-(n-Butanethiomethyl)styrene (Formula I, 
X=sulphur, R.sup.1 =phenyl, R.sup.2 =n-butyl, n=1). 
Azobisisobutyronitrile (49.5 mg) was dissolved in freshly distilled methyl 
methacrylate (25 ml). An aliquot (5 ml) was removed and added to an 
ampoule containing the amount of .alpha.-(n-butanethiomethyl)styrene shown 
below. The mixture was polymerized at 60.degree. C. for 1 h in the absence 
of oxygen. The volatiles were then removed and the polymers were dried in 
vacuo to constant weight. A small portion was examined by GPC as described 
above. Samples of poly(methyl methacrylate) prepared using 0 mg and 20.4 
mg of .alpha.-(n-butanethiomethyl)styrene had number-average molecular 
weights of 280190 and 37405, respectively. The chain transfer constant 
calculated from these data is 1.10. These results show that 
.alpha.-(n-butanethiomethyl)styrene is an efficient chain transfer agent 
for methyl methacrylate and that the process produces polymers of low 
molecular weight. 
Example 6 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Styrene 
Using .alpha.-(n-Butanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 
=phenyl, R.sup.2 =n-butyl, n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 19.7 
mg, and 39.2 mg of .alpha.-(n-butanethiomethyl)styrene had number-average 
molecular weights of 118140, 45909, and 26922, respectively. The chain 
transfer constant calculated from these data was 0.68. These results show 
that .alpha.-(n-butanethiomethyl)styrene acts as an efficient chain 
transfer agent for styrene and that the process produces polymers of low 
molecular weight. 
Example 7 
Preparation of Low Molecular Weight .alpha.-carboxy, .omega.-Unsaturated 
Polymers of Methyl Methacrylate Using 
.alpha.-(Carboxymethanethiomethyl)styrene (Formula I,X.times.sulphur, 
R.sup.1 =phenyl, R.sup.2 --CH.sub.2 COOH, n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 10.0 mg, 20.0 mg, and 40.0 mg of 
.alpha.-(carboxymethanethiomethyl)styrene had number-average molecular 
weights of 224730, 60531, 31869, and 17728, respectively. The chain 
transfer constant calculated from these data was 1.30. These results show 
that .alpha.-(carboxymethanethiomethyl)styrene is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight terminated by a carboxylic acid group. A 
sample of poly(methylmethacrylate) produced similarly using 300 mg of the 
chain transfer agent (reaction time 4 h) was precipitated two further 
times from ethyl acetate/petroleum spirit to remove traces of the 
unreacted chain transfer agent. The resulting polymer of number-average 
molecular weight 3291 had signals at .delta. 4.95 and 5.15 in the .sup.1 H 
NMR spectrum confirming the presence of a terminal double bond. 
Integration of the spectrum showed that there was on average one of these 
double bonds present per polymer chain. 
Example 8; 
Preparation of Low Molecular Weight .alpha.-Carboxy, .omega.-Unsaturated 
Polystyrene Using .alpha.-(Carboxymethanethiomethyl)styrene (Formula I, 
X=sulphur, R.sup.1 =phenyl, R.sup.2 =--CH.sub.2 C00H, n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 10.0 
mg, 20.0 mg, and 30.3 mg of .alpha.-(carboxymethanethiomethyl)styrene had 
number-average molecular weights of 125000, 54700, 33800, and 26300, 
respectively. The chain transfer constant calculated from these data was 
1.00. These results show that .alpha.-(carboxymethanethiomethyl)styrene is 
an efficient chain transfer agent for styrene and that the process 
produces polymers terminated by a carboxylic acid group of low molecular 
weight. A sample of polystyrene produced similarly using 500 mg of the 
chain transfer agent was precipitated two further times from ethyl 
acetate/methanol to remove traces of the unreacted chain transfer agent. 
The resulting polymer of number-average molecular weight 2600 had signals 
at .delta. 4.7-4.8 and at .delta. 5.0-5.1 in the .sup.1 H NMR spectrum 
confirming the presence of a terminal double bond. Integration of the 
spectrum showed that one of these groups was present per polymer chain. 
The infrared spectrum of the polymer showed absorptions at 2500-3000, 
1710and 1300 cm.sup.- 1 confirming the presence of a carboxylic acid 
group. 
Example 9 
Preparation of Low Molecular Weight .alpha.-Carboxy, .omega.-Unsaturated 
Polymers of Styrene Using .alpha.-(Carboxyethanethiomethyl)styrene 
(Formula I, X=sulphur, R.sup.1 =phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 COOH, 
n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 10.3 
mg, 20.2 mg, and 40.3 mg of .alpha.-(carboxyethanethiomethyl)styrene had 
number-average molecular weights of 114340, 56829, 47871, and 30014, 
respectively. The chain transfer constant calculated from these data was 
0.70. These results show that .alpha.-(carboxyethanethiomethyl)styrene is 
an efficient chain transfer agent for styrene and that the process 
produces polymers terminated by a carboxylic acid group of low molecular 
weight. 
Example 10 
Preparation of Low Molecular Weight .alpha.-Hydroxy, .omega.-Unsaturated 
Poly(methyl methacrylate) Using .alpha.-(2-Hydroxyethanethiomethyl)styrene 
(Formula I, X=sulphur, R.sup.1 =phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 OH, 
n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 9.9 mg, 20.1 mg, and 40.0 mg of 
.alpha.-(2-hydroxyethanethiomethyl)styrene had number-average molecular 
weights of 274490, 56921, 34200, and 17808, respectively. The chain 
transfer constant calculated from these data was 1.20. These results show 
that .alpha.-(2-hydroxyethanethiomethyl)styrene is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight terminated by an alcohol group. 
Example 11 
Preparation of Low Molecular Weight .alpha.-Hydroxy, .omega.-Unsaturated 
Polymers of Styrene Using .alpha.-(2-Hydroxyethanethiomethyl)styrene 
(Formula I, X=sulphur, R.sup.1 =phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 OH, 
n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 9.9 
mg, 20.1 mg, and 29.9 mg of .alpha.-(2-hydroxyethanethiomethyl)styrene had 
number-average molecular weights of 116570, 57890, 38415, and 28855, 
respectively. The chain transfer constant calculated from these data was 
0.77. These results show that .alpha.-(2-hydroxyethanethomethyl)styrene is 
an efficient chain transfer agent for styrene and that the process 
produces polymers of low molecular weight terminated by an alcohol group. 
A sample of polystyrene produced similarly using 201 mg of the chain 
transfer agent was precipitated two further times from ethyl 
acetate/methanol to remove traces of the unreacted chain transfer agent. 
The resulting polymer of number-average molecular weight 6346 had signals 
at .delta. 3.35-3.55, 4.7-4.8, and 5.0-5.1 in the .sup.1 H NMR spectrum 
confirming the presence of a hydroxymethylene group and a terminal double 
bond. Integration of the spectrum showed that one each of these groups was 
present per polymer chain. 
Example 12 
Preparation of Low Molecular Weight .alpha.-Amino, .omega.-Unsaturated 
Polymers of Methyl Methacrylate Using 
.alpha.-(2-Aminoethanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 
=phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 NH.sub.2, n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 11.9 mg, 21.2 mg, and 41.3 mg of 
.alpha.-(2-aminoethanethiomethyl) styrene had number-average molecular 
weights of 185519, 49427, 32334, and 19065, respectively. The chain 
transfer constant calculated from these data was 1.05. These results show 
that .alpha.-(2-aminoethanethiomethyl)styrene is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight terminated by an amine group. 
Example 13 
Preparation of Low Molecular Weight .alpha.-Amino, .omega.-Unsaturated 
Polymers of Styrene Using .alpha.-(2-Aminoethanethiomethyl)styrene 
(Formula I, X=sulphur, R.sup.1 =phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 
NH.sub.2, n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 10.4 
mg, 20.2 mg, and 42.3 mg of .alpha.-(2-aminoethanethiomethyl)styrene had 
number-average molecular weights of 134116, 60766, 39861, and 21920, 
respectively. The chain transfer constant calculated from these data was 
0.79. These results show that .alpha.-(2-aminoethanethiomethyl)styrene is 
an efficient chain transfer agent for styrene and that the process 
produces polymers of low molecular weight terminated by an amino group. A 
sample of polystyrene produced similarly using 294 mg of the chain 
transfer agent was precipitated two further times from toluene/methanol to 
remove traces of the unreacted chain transfer agent. The resulting polymer 
of number-average molecular weight 8376 had signals at .delta. 3.1-3.2, 
4.7-4.8, and at 5.0-5.1 in the .sup.1 H NMR spectrum confirming the 
presence of the aminomethylene group and a terminal double bond. 
Integration of the spectrum showed that one of these groups was present 
per polymer chain. 
Example 14 
Preparation of Low Molecular Weight .alpha.-Trimethoxysilyl, 
.omega.-Unsaturated Polymers of Styrene Using 
.alpha.-[3-(Trimethoxysilyl)propanethiomethyl]styrene (Formula I, 
X=sulphur, R.sup.1 =phenyl, R.sup.2 =--CH.sub.2 CH.sub.2 CH.sub.2 
Si(OCH.sub.3).sub.3, n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, and 
400.7 mg of .alpha.-[3-(trimethoxysilyl)propanethiomethyl]styrene had 
number-average molecular weights of 92287 and 8201, respectively. The 
chain transfer constant calculated from these data was 0.40. These results 
show that .alpha.-[3-(trimethoxysilyl)propanethiomethyl]styrene is an 
efficient chain transfer agent for styrene and that the process produces 
polymers terminated by a trimethoxysilyl group of low molecular weight. 
Example 15 
Preparation of Low Molecular Weight .alpha.-Bromo, .omega.-Unsaturated 
Polymers of Methyl Methacrylate Using .alpha.-(Bromomethyl)styrene 
(Formula I, X=Br, R.sup.1 =phenyl, n=0). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 24.96 mg, and 49.30 mg of .alpha.-(bromomethyl)styrene had 
number-average molecular weights of 220453, 16118, and 7863, respectively. 
The chain transfer constant calculated from these data was 2.27. These 
results show that .alpha.-(bromomethyl)styrene is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers terminated by a bromine end-group of low molecular weight. The 
sample of poly(methyl methacrylate) with number-average molecular weight 
7863 was precipitated two further times from ethyl acetate/petroleum 
spirit to remove traces of the unreacted chain transfer agent. The 
resulting polymer had signals at .delta. 3.60, 5.00, and 5.20 in the 
.sup.1 H NMR spectrum confirming the presence of a BrCH.sub.2 group and a 
terminal double bond. 
Example 16 
Preparation of Low Molecular Weight .alpha.-Bromo, .omega.-Unsaturated 
Polymers of Styrene Using .alpha.-(Bromomethyl)styrene (Formula I, X=Br, 
R.sup.1 =phenyl, n=0). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 
15.76 mg, and 27.5 mg of .alpha.-(bromomethyl)styrene had number-average 
molecular weights of 130189, 17024, and 10157, respectively. The chain 
transfer constant calculated from these data was 2.93. These results show 
that .alpha.-(bromomethyl)styrene is an efficient chain transfer agent for 
styrene and that the process produces polymers terminated by a bromine 
end-group of low molecular weight. 
Example 17 
Preparation of Low Molecular Weight .alpha.-Bromo, .omega.-Unsaturated 
Polymers of Methyl Acrylate Using .alpha.-(Bromomethyl)styrene (Formula I, 
X=Br, R.sup.1 =phenyl, n=0). 
Samples of poly(methyl acrylate) prepared in the manner of example 3 using 
0 mg, 10.57 mg, 15.86 mg, and 21.15 mg of .alpha.-(bromomethyl)styrene had 
number-average molecular weights of 245048, 12675, 7922, and 6549, 
respectively. The chain transfer constant calculated from these data was 
5.25. These results show that .alpha.-(bromomethyl)styrene is an efficient 
chain transfer agent for methyl acrylate and that the process produces 
polymers of low molecular weight terminated by a bromine end-group. 
Example 18 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using Ethyl .alpha.-(t-Butanethiomethyl)acrylate (Formula I, 
X=sulphur, R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =t-butyl, n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 12.2 mg, 22.6 mg, and 43.1 mg of ethyl 
.alpha.-(t-butanethiomethyl)acrylate had a number-average molecular 
weights of 136696, 61799, 40776, and 24539, respectively. The chain 
transfer constant calculated from these data was 0.74. These results show 
that ethyl .alpha.-(t-butanethiomethyl)acrylate is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 19 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Styrene 
Using Ethyl .alpha.-(t-Butanethiomethyl)acrylate (Formula I, X=sulphur, 
R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =t-butyl, n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 10.3 
mg, 21.7 mg, and 40.0 mg of ethyl .alpha.-(t-butanethiomethyl)acrylate had 
number-average molecular weights of 103583, 47806, 30606, and 19359, 
respectively. The chain transfer constant calculated from these data was 
0.95. These results show that ethyl .alpha.-(t-butanethiomethyl)acrylate 
is an efficient chain transfer agent for styrene and that the process 
produces polymers of low molecular weight in a controlled manner. 
Example 20 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Acrylate Using Ethyl .alpha.-(t-Butanethiomethyl)acrylate (Formula I, 
X=sulphur, R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =t-butyl, n=1). 
Samples of poly(methyl acrylate) prepared in the manner of example 3 using 
0 mg, 5.7 mg, 8.6 mg, and 11.4 mg of ethyl 
.alpha.-(t-butanethiomethyl)acrylate had number-average molecular weights 
of 842397, 50611, 38942, and 29012, respectively. The chain transfer 
constant calculated from these data was 2.23. These results show that 
ethyl .alpha.-(t-butanethiomethyl)acrylate is an efficient chain transfer 
agent for methyl acrylate and that the process produces polymers of low 
molecular weight in a controlled manner. 
Example 21 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Vinyl 
Acetate Using Ethyl .alpha.-(t-Butanethiomethyl)acrylate (Formula I, 
X=sulphur, R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =t-butyl, n=1). 
Samples of poly(vinyl acetate) prepared in the manner of example 4 using 
4.8 mg, 11.6 mg, and 22.0 mg of ethyl .alpha.-(t-butanethiomethyl)acrylate 
had number-average molecular weights of 61816, 12764, and 1598, 
respectively. These results show that ethyl 
.alpha.-(t-butanethiomethyl)acrylate acts as a chain transfer agent for 
vinyl acetate and that the process produces polymers of low molecular 
weight. 
Example 22 
Preparation of Low Molecular Weight .alpha.-Carboxy, .omega.-Unsaturated 
Polymers of Methyl Methacrylate Using Ethyl 
.alpha.-(Carboxymethanethiomethyl)acrylate (Formula I, X=sulphur, R.sup.1 
=--COOCH.sub.2 CH.sub.3, R.sup.2 =--CH.sub.2 COOH, n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 9.8 mg, and 21.5 mg of ethyl 
.alpha.-(carboxymethanethiomethyl)acrylate had number-average molecular 
weights of 164265, 74307, and 44473, respectively. The chain transfer 
constant calculated from these data was 0.73. These results show that 
ethyl .alpha.-(carboxymethanethiomethyl)acrylate is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
carboxylic acid end-functional polymers of low molecular weight in a 
controlled manner. 
Example 23 
Preparation of Low Molecular Weight .alpha.-Carboxy, .omega.-Unsaturated 
Polymers of Styrene Using Ethyl .alpha.-(Carboxymethanethiomethyl)acrylate 
(Formula I, X=sulphur, R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 
=--CH.sub.2 COOH, n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 10.8 
mg, 21.0 mg, and 40.2 mg of ethyl 
.alpha.-(carboxymethanethiomethyl)acrylate had number-average molecular 
weights of 113921, 37477, 20894, and 12076, respectively. The chain 
transfer constant calculated from these data was 1.72. These results show 
that ethyl .alpha.-(carboxymethanethiomethyl)acrylate is an efficient 
chain transfer agent for styrene and that the process produces carboxylic 
acid end-functional polymers of low molecular weight in a controlled 
manner. A sample of polystyrene produced similarly using 186 mg of the 
chain transfer agent was precipitated two further times from 
toluene/methanol to remove traces of the unreacted chain transfer agent. 
The resulting polymer of number-average molecular weight 4014 had signals 
at .delta. 1.15, 3.9-4.1, 5.0-5.1, and 5.8-5.9 in the .sup.1 H NMR 
spectrum confirming the presence of an ethyl ester and a terminal double 
bond. Integration of the spectrum showed that one each of these groups was 
present per polymer chain. The infrared spectrum of the polymer showed 
absorptions at 3500-2300 (broad), 1705 (broad) and 1295 cm.sup.-1 
consistent with the presence of a carboxylic acid group. 
Example 24 
Preparation of Low Molecular Weight .alpha.,.omega.-Dicarboxy, 
.omega.-Unsaturated Polymers of Methyl Methacrylate Using 
.alpha.-(Carboxymethanethiomethyl)acrylic Acid (Formula I, X=sulphur, 
R.sup.1 =--COOH, R.sup.2 =--CH.sub.2 COOH, n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 10.0 mg, 20.2 mg, and 40.0 mg of 
.alpha.-(carboxymethanethiomethyl)acrylic acid had number-average 
molecular weights of 154487, 69520, 40763, and 24084, respectively. The 
chain transfer constant calculated from these data was 0.74. These results 
show that .alpha.-(carboxymethanethiomethyl)acrylic acid is an efficient 
chain transfer agent for methyl methacrylate and that the process produces 
low molecular weight polymers having carboxylic acid groups at both ends. 
Example 25 
Preparation of Low Molecular Weight .alpha.,.omega.-Dicarboxy, 
.alpha.-Unsaturated Polymers of Styrene Using 
.alpha.-(Carboxymethanethiomethyl)acrylic Acid (Formula I, X=sulphur, 
R.sup.1 =--COOH, R.sup.2 =--CH.sub.2 COOH, n=1). 
Azobisisobutyronitrile (34.3 mg) was dissolved in freshly distilled styrene 
(25 ml). Acetone (25 ml) was added to ensure that the chain transfer agent 
was soluble. Aliquots (10 ml) were removed and added to ampoules 
containing the amount of the chain transfer agent shown below. The 
mixtures were polymerized and examined as per example 2. Samples of 
polystyrene prepared using 0 mg, 10.1 mg, 20.3 mg, and 40.2 mg of 
.alpha.-(carboxymethanethiomethyl)acrylic acid had number-average 
molecular weights of 53361, 28162, 19652, and 12118, respectively. The 
chain transfer constant calculated from these data was 1.27. These results 
show that .alpha.-(carboxymethanethiomethyl)acrylic acid is an efficient 
chain transfer agent for styrene and that the process produces low 
molecular weight polymers having a carboxylic acid group at both ends. The 
polymer of number-average molecular weight 12118, was precipitated two 
further times from toluene/methanol to remove traces of the chain transfer 
agent. The IR spectrum showed absorptions at 1735 and at 1700 cm.sup.-1 
confirming the presence of the saturated and .alpha.,.beta.-unsaturated 
carboxylic acid groups at the ends of the polymer chain. 
Example 26 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-(t-Butanethiomethyl)acrylonitrile (Formula I, 
X=sulphur, R.sup.1 =--CN, R.sup.2 =t-butyl, n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 10.5 mg, 19.9 mg, and 38.3 mg of 
.alpha.-(t-butanethiomethyl)acrylonitrile had number-average molecular 
weights of 181352, 35500, 23769, and 12724, respectively. The chain 
transfer constant calculated from these data was 1.36. These results show 
that .alpha.-(t-butanethiomethyl)acrylonitrile is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 27 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Styrene 
Using .alpha.-(t-Butanethiomethyl)acrylonitrile (Formula I, X=sulphur, 
R.sup.1 =--CN, R.sup.2 =t-butyl, n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 10.5 
mg, and 30.6 mg of .alpha.-(t-butanethiomethyl)acrylonitrile had 
number-average molecular weights of 118703, 29783, and 11747, 
respectively. The chain transfer constant calculated from these data was 
1.75. These results show that .alpha.-(t-butanethiomethyl)acrylonitrile is 
an efficient chain transfer agent for styrene and that the process 
produces polymers of low molecular weight in a controlled manner. A sample 
of polystyrene produced similarly using 200 mg of the chain transfer agent 
was precipitated two further times from ethyl acetate/methanol to remove 
traces of the unreacted chain transfer agent. The resulting polymer of 
number-average molecular weight 5491 had signals at .delta. 5.3-5.4 in the 
.sup.1 H NMR spectrum confirming the presence of a terminal double bond. 
Integration of the spectrum showed that one of these groups was present 
per polymer chain. The infrared spectrum of the polymer showed an 
absorption of 2220 cm.sup.-1 confirming the presence of a cyano group. 
Example 28 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Acrylate Using .alpha.-(t-Butanethiomethyl)acrylonitrile (Formula I, 
X=sulphur, R.sup.1 =--CN, R.sup.2 =t-butyl, n=1). 
Samples of poly(methyl acrylate) prepared in the manner of example 3 using 
0 mg, 8.0 mg, 12.1 mg, and 16.1 mg of 
.alpha.-(t-butanethiomethyl)acrylonitrile had number-average molecular 
weights of 224288, 37084, 26347, and 21079, respectively. The chain 
transfer constant calculated from these data was 1.64. These results show 
that .alpha.-(t-butanethiomethyl)acrylonitrile is an efficient chain 
transfer agent for methyl acrylate and that the process produces polymers 
of low molecular weight in a controlled manner. 
Example 29 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Vinyl 
Acetate Using .alpha.-(t-Butanethiomethyl)acrylonitrile (Formula I, 
X=sulphur, R.sup.1 =CN, R.sup.2 =t-butyl, n=1). 
Samples of poly(vinyl acetate) prepared in the manner of example 4 using 0 
mg, 5.6 mg, 10.7 mg, and 22.1 mg of 
.alpha.-(t-butanethiomethyl)acrylonitrile had number-average molecular 
weights of 243721, 10438, 2905, and 1079, respectively. The chain transfer 
constant calculated from these data was 60. These results show that 
.alpha.-(t-butanethiomethyl)acrylonitrile acts as a chain transfer agent 
for vinyl acetate and that the process produces polymers of low molecular 
weight. 
Example 30 
Preparation of Low Molecular Weight .alpha.-Bromo, .omega.-Unsaturated 
Polymers of Methyl Methacrylate Using Ethyl .alpha.-(Bromomethyl)acrylate 
(Formula I, X=Br, R.sup.1 =--COOCH.sub.2 CH.sub.3, n=0). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 26.62 mg, and 51.33 mg of ethyl .alpha.-(bromomethyl)acrylate 
had number-average molecular weights of 220453, 20690, and 11668, 
respectively. The chain transfer constant calculated from these data was 
1.45. These results show that ethyl .alpha.-(bromomethyl)acrylate is an 
efficient chain transfer agent for methyl methacrylate and that the 
process produces bromine end-functional polymers of low molecular weight 
in a controlled manner. 
Example 31 
Preparation of Low Molecular Weight .alpha.-Bromo, .omega.-Unsaturated 
Polymers of Methyl Acrylate Using Ethyl .alpha.-(Bromomethyl)acrylate 
(Formula I, X=Br, R.sup.1 =--COOCH.sub.2 CH.sub.3, n=0). 
Samples of poly(methyl acrylate) prepared in the manner of example 3 using 
0 mg and 31.3 mg of ethyl .alpha.-(bromomethyl)acrylate had number-average 
molecular weights of 496642 and 9888, respectively. The chain transfer 
constant calculated from these data was 2.33. These results show that 
ethyl .alpha.-(bromomethyl)acrylate is an efficient chain transfer agent 
for methyl acrylate and that the process produces polymers of low 
molecular weight. 
Example 32 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-(Diethyoxyphosphorylmethyl)styrene (Formula I, 
X=P(O), R.sup.1 =phenyl, R.sup.2 =ethoxy, n=2). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 11.4 mg, 22.6 mg, and 43.8 mg of 
.alpha.-(diethoxyphosphorylmethyl)styrene had number-average molecular 
weights of 210866, 124132, 88457, and 63441, respectively. The chain 
transfer constant calculated from these data was 0.35. These results show 
that .alpha.-(diethoxyphosphorylmethyl)styrene is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 33 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using Ethyl .alpha.-(Trimethylsilylmethyl)acrylate (Formula 
I, X=Si, R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =methyl, n=3). 
Samples of poly(methyl methacrylate) prepared in the manner of example 
5using 0 mg and 19.4 mg of ethyl .alpha.-(trimethlsilylmethyl)acrylate had 
number-average molecular weights of 181352 and 137986, respectively. The 
chain transfer constant calculated from these data was 0.08. These results 
show that ethyl .alpha.-(trimethylsilylmethyl)acrylate acts as a chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of lowered molecular weight. 
Example 34 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using Ethyl .alpha.-(Tri-n-butylstannylmethyl)acrylate 
(Formula I, X=Sn, R.sup.1 =--COOCh.sub.2 Ch.sub.3, R.sup.2 =n-butyl, n=3). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 12.6 mg, 23.0 mg, and 37.7 mg of ethyl 
.alpha.-(tri-n-butylstannylmethyl)acrylate had number-average molecular 
weights of 196981, 36232, 22349, and 15473, respectively. The chain 
transfer constant calculated from these data was 3.01. These results show 
that ethyl .alpha.-(tri-n-butylstannylmethyl)acrylate is an efficient 
chain transfer agent for methyl methacrylate and that the process produces 
polymers of low melecular weight in a controlled manner. 
Example 35 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using Ethyl .alpha.-(Benzenesulphonylmethyl)acrylate (Formula 
I, X=S(O).sub.2, R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =phenyl, n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 
5using 0 mg, 10.3 mg, 20.1 mg, and 30.0 mg of ethyl 
.alpha.-(benzenesulphonylmethyl)acrylate had number-average molecular 
weights of 181352, 64607, 38949, and 29612, respectively. The chain 
transfer constant calculated from these data was 1.14. These results show 
that ethyl .alpha.-(benzenesulphonylmethyl)acrylate is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low melecular weight in a controlled manner. 
Example 36 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Styrene 
Using Ethyl .alpha.-(Benzenesulphonylmethyl)acrylate (Formula I, 
X=S(O).sub.2, R.sup.1 =--COOCH.sub.2 CH.sub.3, R.sup.2 =phenyl, n=1). 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 10.9 
mg, 20.4 mg, and 40.1 mg of ethyl .alpha.-(benzenesulphonylmethyl)acrylate 
had number-average molecular weights of 112707, 15520, 9099, and 4728, 
respectively. The chain transfer constant calculated from these data was 
5.75. These results show that ethyl 
.alpha.-(benzenesulphonylmethyl)acrylate is an efficient chain transfer 
agent for styrene and that the process produces polymers of low molecular 
weight in a controlled manner. The sample of polystyrene of number-average 
molecular weight 4728 was precipitated two further times from ethyl 
acetate/methanol to remove traces of the unreacted chain transfer agent. 
The resulting polymer had signals at .delta. 5.0-5.1, and 5.8-5.9 in the 
.sup.1 H NMR spectrum confirming the presence of the terminal double bond. 
Example 37 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using .delta.-(n-Butanesulphinylmethyl)styrene (Formula I, 
X=S(O), R.sup.1 =phenyl, R.sup.2 =n-butyl, n=1). 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 10.2 mg, and 20.3 mg of ethyl 
.alpha.-(n-butanesulphinylmethyl)styrene had number-average molecular 
weights of 236818, 40155, and 24323, respectively. The chain transfer 
constant calculated from these data was 1.89. These results show that 
ethyl .alpha.-(n-butanesulphinylmethyl)styrene is an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight. 
Example 38 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-(Benzenesulphonylmethyl)vinyl Acetate (Formula 
I, X=S(O).sub.2, R.sup.1 =--OAc, R.sup.2 =phenyl, n=1) 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 27.3 mg, 49.0 mg, and 100.8 mg of 
.alpha.-(benzenesulphonylmethyl)vinyl acetate had number-average molecular 
weights of 269320, 194204, 163144, and 104847, respectively. The chain 
transfer constant calculated from these data was 0.065. These results show 
that .alpha.-(benzenesulphonylmethyl)vinyl acetate acts as a chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 39 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Styrene 
Using .alpha.-(Benzenesulphonylmethyl)vinyl Acetate (Formula I, 
X=S(O).sub.2, R.sup.1 =--OAc, R.sup.2 =phenyl, n=1) 
Samples of polystyrene prepared in the manner of example 2 using 0 mg, 20.0 
mg, 40.0 mg, and 80.4 mg of .alpha.-(benzenesulphonylmethyl)vinyl acetate 
had number-average molecular weights of 105213, 102276, 97437, and 89049, 
respectively. The chain transfer constant calculated from these data was 
0.02. These results show that .alpha.-(benzenesulphonylmethyl)vinyl 
acetate acts as a chain transfer agent for styrene and that the process 
produces polymers of low molecular weight in a controlled manner. 
Example 40 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Acrylate Using .alpha.-(Benzenesulphonylmethyl)vinyl Acetate (Formula I, 
X=S(O).sub.2, R.sup.1 =--OAc, R.sup.2 =phenyl, n=1) 
Samples of poly(methyl acrylate) prepared in the manner of example 3 using 
22.8 mg, 50.0 mg, and 99.4 mg of .alpha.-(benzenesulphonylmethyl)vinyl 
acetate had number-average molecular weights of 107713, 73613, and 40108, 
respectively. The chain transfer constant calculated from these data was 
0.20. These results show that .alpha.-(benzenesulphonylmethyl)vinyl 
acetate is an efficient chain transfer agent for methyl acrylate and that 
the process produces polymers of low molecular weight in a controlled 
manner. 
Example 41 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Vinyl 
Acetate Using .alpha.-(Benzenesulphonylmethyl)vinyl Acetate (Formula I, 
X=S(O).sub.2, R.sup.1 =--OAc, R.sup.2 =phenyl, n=1) 
Samples of poly(vinyl acetate) prepared in the manner of example 4 using 0 
mg, 5.1 mg, 10.3 mg, and 20.5 mg of .alpha.-(benzenesulphonylmethyl)vinyl 
acetate had number-average molecular weights of 144664, 113338, 64712, and 
39212, respectively. The chain transfer constant calculated from these 
data was 2.8. These results show that 
.alpha.-(benzenesulphonylmethyl)vinyl acetate is an efficient chain 
transfer agent for vinyl acetate and that the process produces polymers of 
low molecular weight in a controlled manner. 
Example 42 
Preparation of Low Molecular Weight .alpha.-Bromo, .omega.-Unsaturated 
Polymers of Methyl Methacrylate Using .alpha.-(Bromomethyl)acrylonitrile 
(Formula I, X=Br, R.sup.1 =--CN, n=0) 
Samples of poly(methyl methacrylate) prepared in the manner of example 5 
using 0 mg, 24.0 mg, 49.0 mg, and 99.8 mg of 
.alpha.-(bromomethyl)acrylonitrile had number-average molecular weights of 
234433, 10029, 5263, and 3124, respectively. The chain transfer constant 
calculated from these data was 2.22. These results show that 
.alpha.-(bromomethyl)acrylonitrile is an efficient chain transfer agent 
for methyl methacrylate and that the process produces polymers of low 
molecular weight in a controlled manner. 
Example 43 
Preparation of Low Molecular Weight .alpha.-Bromo, .omega.-Unsaturated 
Polymers of Methyl Acrylate Using .alpha.-(Bromomethyl)acrylonitrile 
(Formula I, X=Br, R.sup.1 =--CN, n=0) 
Samples of poly(methyl acrylate) prepared in the manner of example 5 using 
22.8 mg, 50.0 mg, and 99.4 mg of .alpha.-(bromomethyl)acrylonitrile had 
number-average molecular weights of 107713, 73613, and 40108, 
respectively. The chain transfer constant calculated from these data was 
3.0. These results show that .alpha.-(bromomethyl)acrylonitrile is an 
efficient chain transfer agent for methyl acrylate and that the process 
produces polymers of low molecular weight in a controlled manner. 
Example 44 
Preparation of Low Molecular Weight .alpha.-Chloro, .omega.-Unsaturated 
Polymers of Methyl Acrylate Using .alpha.-(Chloromethyl)acrylonitrile 
(Formula I, X=Cl, R.sup.1 =--CN, n=0) 
Samples of poly(methyl acrylate) prepared in the manner of example 3 using 
0 mg, 11.8 mg, 24.8 mg, and 50.8 mg of .alpha.-(chloromethyl)acrylonitrile 
had number-average molecular weights of 502537, 232619, 158821, and 74136, 
respectively. The chain transfer constant calculated from these data was 
0.05. These results show that .alpha.-(chloromethyl)acrylonitrile acts as 
a chain transfer agent for methyl acrylate and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 45 
Preparation of Low Molecular Weight Polyacrylonitrile Using 
.alpha.-(t-Butanethiomethyl)acrylonitrile (Formula I, X=sulphur, R.sup.1 
=--CN, R.sup.2 =t-butyl, n=1). 
Azobisisobutyronitrile (7.4 mg) was dissolved in freshly distilled 
acrylonitrile (10 ml). An aliquot (2 ml) was removed and added to 
.alpha.-(t-butanethiomethyl)acrylonitrile (14.5 mg) and the mixture was 
polymerized in the absence of oxygen for 1 h at 60.degree. C. The 
resulting polymer was precipitated in toluene. A portion (100 mg) of the 
dried polymer was dissolved in dimethylformamide (10 ml) and the viscosity 
was measured using a Gardiner Bubble viscometer. The resulting polymer had 
a viscosity less than that of tube B. A similar polymer prepared without 
added chain transfer agent had a viscosity equal to that of tube E. This 
result shows that the polymer prepared using 
.alpha.-(t-butanethiomethyl)acrylonitrile had a lower molecular weight 
than that prepared without, and that 
.alpha.-(t-butanethiomethyl)acrylonitrile acts as a chain transfer agent 
for acrylonitrile. 
Example 46 
Preparation of Low Molecular Weight Polyacrylonitrile Using 
.alpha.-(t-Butanethiomethyl)styrene (Formula I, X=sulphur, R.sup.1 
=phenyl, R.sup.2 =t-butyl, n=1). 
A polymer prepared as above (Example 45) using 
.alpha.-(t-butanethiomethyl)-styrene (15.6 mg) was precipitated in 
toluene. A portion (100 mg) of the dried polymer was dissolved in 
dimethylformamide (10 ml) and the viscosity was measured using a Gardiner 
Bubble viscometer. The resulting polymer had a viscosity less than that of 
tube B. A similar polymer prepared without added chain transfer agent had 
a viscosity equal to that of tube E. This result shows that the polymer 
prepared using .alpha.-(t-butanethiomethyl)styrene had a lower molecular 
weight than that prepared without, and that 
.alpha.-(t-butanethiomethyl)styrene acts as a chain transfer agent for 
acrylonitrile. 
Example 47 
Preparation of Low Molecular Weight Polymers of Methyl Methacrylate (MMA) 
Using .alpha.-Benzyloxystyrene (Formula II, R.sup.1 =phenyl, R.sup.2 
=benzyl). 
Azobisisobutyronitrile (19.4 mg) was dissolved in freshly distilled methyl 
methacrylate (10.00 ml). An aliquot (2.00 ml) was removed and added to an 
ampoule containing the amount of the chain transfer agent, 
.alpha.-benzyloxystyrene, shown in Table II. The mixture was polymerized 
at 60.degree. C. for 1 h in the absense of oxygen. The contents of the 
ampoule were then poured into pentane and the precipitated polymer was 
collected and dried in vacuo to constant weight. A small portion was 
examined by GPC using a Waters Instrument connected to six .mu.-Styragel 
columns (10.sup.6 -, 10.sup.5 -, 10.sup.4 -, 10.sup.3 -, 500- and 100- 
.ANG. pore size). Tetrahydrofuran was used as eluent and the system was 
calibrated using narrow distribution polystyrene standards (Waters). 
TABLE II 
______________________________________ 
added (mg).alpha.-Benzyloxystyrene 
##STR5## -- M.sub.n * 
version% Con- 
______________________________________ 
0 0 207,000 11.8 
4.0 1.02 .times. 10.sup.-3 
96,564 12.2 
10.3 2.62 .times. 10.sup.-3 
41,395 10.1 
15.8 4.02 .times. 10.sup.-3 
28,123 11.0 
22.0 5.60 .times. 10.sup.-3 
21,275 10.7 
25.3 6.44 .times. 10.sup.-3 
18,688 10.6 
37.0 9.42 .times. 10.sup.-3 
13,397 10.0 
41.0 1.04 .times. 10.sup.-2 
11,849 12.1 
48.0 1.22 .times. 10.sup.-2 
10,380 10.0 
______________________________________ 
*Polystyrene-equivalent numberaverage molecular weight, obtained by GPC. 
The chain transfer constant calculated from these data was 0.76, which 
compares favourably with that from n-butanethiol (chain transfer 
constant=0.66). These results show that .alpha.-benzyloxystyrene is an 
efficient chain transfer agent for methyl methacrylate and that the 
process produces polymers of low molecular weight in a controlled manner. 
Example 48 
Preparation of Low Molecular Weight Polymers of Styrene Using 
.alpha.-Benzyloxystyrene (Formula II, R.sup.1 =phenyl, R.sup.2 =benzyl). 
Azobisisobutyronitrile (70.4 mg) was added to freshly distilled styrene (50 
ml). An aliquot (10 ml) of this mixture was removed and added to an 
ampoule containing the amount of benzyloxystyrene shown (Table III). The 
mixture was polymerized for 1 h at 60.degree. C. in the absence of oxygen. 
The contents of the ampoule were then poured into methanol (110 ml) and 
the precipitated polymer was collected, dried and examined by GPC as 
described previously. 
TABLE III 
______________________________________ 
added (mg).alpha.-Benzyloxystyrene 
##STR6## -- M.sub.n * 
version% Con- 
______________________________________ 
0.0 0.00 137,320 2.8 
44.5 2.43 .times. 10.sup.-3 
78,812 3.2 
45.6 2.49 .times. 10.sup.-3 
78,010 2.9 
49.1 2.68 .times. 10.sup.-3 
76,022 3.0 
91.6 5.00 .times. 10.sup.-3 
50,674 2.4 
144.9 7.91 .times. 10.sup.-3 
38,146 3.0 
170.3 9.29 .times. 10.sup.-3 
32,928 3.4 
231.4 1.26 .times. 10.sup.-2 
26,802 3.0 
261.5 1.43 .times. 10.sup.-2 
23,417 3.5 
______________________________________ 
The chain transfer constant calculated from these data was 0.26, which is 
closer to the ideal than that from n-butanethiol (chain transfer 
constant=22). These results show that .alpha.-benzyloxystyrene is an 
efficient chain transfer agent for styrene and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 49 
Preparation of Low Molecular Weight Polymers of Methyl Acrylate Using 
.alpha.-Benzyloxystyrene (Formula II, R.sup.1 =phenyl, R.sup.2 =benzyl). 
Azobisisobutyronitrile (9.1 mg) was dissolved in a mixture of thiophenefree 
benzene (80 ml) and freshly distilled methyl acrylate (20 ml). Aliquots 
(10 ml) were removed and added to ampoules containing the amounts of 
.alpha.-benzyloxystyrene shown below. The mixtures were then polymerized 
at 60.degree. C. for 1 h in the absence of oxygen. The volatiles were then 
removed and the polymers were dried in vacuo to constant weight. The 
polymers were then examined by GPC as described above. Samples of 
poly(methyl acrylate) prepared in this manner using 0 mg, 4.8 mg, and 10.2 
mg of .alpha.-benzyloxystyrene had number-average molecular weights of 
577200, 14652, and 6866, respectively. The chain transfer constant 
calculated from these data was 5.7. These results show that 
.alpha.-benzyloxystyrene is an efficient chain transfer agent for methyl 
acrylate and that the process produces polymers of low molecular weight in 
a controlled manner. 
Example 50 
Preparation of Low Molecular Weight Polymers of Vinyl Acetate Using 
.alpha.-Benzyloxystyrene (Formula II, R.sup.1 =phenyl, R.sup.2 =benzyl). 
Azobisisobutyronitrile (8.0 mg) was dissolved in freshly distilled vinyl 
acetate (50 ml). Aliquots (10 ml) were removed and added to ampoules 
containing the amounts of .alpha.-benzyloxystyrene shown below. The 
mixtures were then polymerized at 60.degree. C. for 1 h in the absence of 
oxygen. The volatiles were then removed and the polymers were dried in 
vacuo to constant weight. The polymers were then examined by GPC as 
described above. Samples of poly(vinyl acetate) prepared in this manner 
using 0 mg, 2.3 mg, 5.1 mg, 10.0 mg, and 20.7 mg of 
.alpha.-benzyloxystyrene had number-average molecular weights of 260760, 
75723, 35337, 22116, and 9458, respectively. The chain transfer constant 
calculated from these data was 9.7, which is closer to the ideal than that 
of n-butanethiol (chain transfer constant =48). These results show that 
.alpha.-benzyloxystyrene is an efficient chain transfer agent for vinyl 
acetate and that the process produces polymers of low molecular weight in 
a controlled manner. 
Example 51 
Preparation of Low Molecular Weight Polymers of Methyl Methacrylate Using 
.alpha.-Benzyloxyacrylonitrile (Formula II, R.sup.1 =--CN, R.sup.2 
=benzyl). 
Azobisisobutyronitrile (19.4 mg) was dissolved in freshly distilled methyl 
methacrylate (10 ml). Aliquots (2 ml) were removed and added to ampoules 
containing the amounts of .alpha.-benzyloxyacrylonitrile shown below. The 
mixtures were then polymerized at 60.degree. C. for 1 h in the absence of 
oxygen. The contents of the ampoules were added to separate portions of 
petroleum spirit (30 ml) and the preciptiated polymers were collected and 
dried in vacuo to constant weight. The polymers were then examined by GPC 
as described above. Samples of poly(methyl methacrylate) prepared in this 
manner using 0 mg, 10.0 mg, 12.4 mg, and 34.7 mg of 
.alpha.-benzyloxyacrylonitrile had number-average molecular weights of 
200810, 132040, 124140, and 69706, respectively. The chain transfer 
constant calculated from these data was 0.082. These results show that 
.alpha.-benzyloxyacrylonitrile acts as a chain transfer agent for methyl 
methacrylate and that the process produces polymers of lower molecular 
weight in a controlled manner. 
Example 52 
Preparation of Low Molecular Weight Polymers of Styrene Using 
.alpha.-Benzyloxyacrylonitrile (Formula II, R.sup.1 =--CN, R.sup.2 
=benzyl). 
Samples of polystyrene prepared in the manner of example 48 using 42.8 mg, 
86.4 mg, and 153.2 mg of .alpha.-benzyloxyacrylonitrile had number-average 
molecular weights of 107460, 95028, and 83280, respectively. The chain 
transfer constant calculated from these data was 0.038. These results show 
that .alpha.-benzyloxyacrylonitrile acts as a chain transfer agent for 
styrene and that the process produces polymers of controlled molecular 
weight. 
Example 53 
Preparation of Low Molecular Weight Polymers of Methyl Acrylate Using 
.alpha.-Benzyloxyacrylonitrile (Formula II, R.sup.1 =--CN, R.sup.2 
=benzyl). 
Samples of poly(methyl acrylate) prepared in the manner of example 49 using 
0 mg, 10.4 mg, 40.0 mg, and 66.6 mg of .alpha.-benzyloxyacrylonitrile had 
number-average molecular weights of 500000, 75781, 23038, and 14779, 
respectively. The chain transfer constant calculated from these data was 
0.30. These results show that .alpha.-benzyloxyacrylonitrile acts as an 
efficient chain transfer agent for methyl acrylate and that the process 
produces polymers of low molecular weight in a controlled manner. 
Example 54 
Preparation of Low Molecular Weight Polymers of Vinyl Acetate Using 
.alpha.-Benzyloxyacrylonitrile (Formula II, R.sup.1 =--CN, R.sup.2 
=benzyl). 
Samples of poly(vinyl acetate) prepared in the manner of example 50 using 0 
mg, 2.0 mg, and 2.0 mg of .alpha.-benzyloxyacrylonitrile had 
number-average molecular weights of 225319, 46036, and 6032, respectively. 
The chain transfer constant calculated from these data was 11. These 
results show that .alpha.-benzyloxyacrylonitrile acts as an efficient 
chain transfer agent for vinyl acetate and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 55 
Preparation of Low Molecular Weight Polymers of Methyl Methacrylate Using 
Methyl .alpha.-Benzyloxyacrylate (Formula II, R.sup.1 =COOCH.sub.3, 
R.sup.2 =benzyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 7.9 mg, 16.3 mg, 26.3 mg, and 40.1 mg of methyl 
.alpha.-benzyloxyacrylate had number-average molecular weights of 99822, 
73462, 55557, and 41633, respectively. The chain transfer constant 
calculated from these data was 0.16. These results show that methyl 
.alpha.-benzyloxyacrylate acts as a chain transfer agent for methyl 
methacrylate and that the process produces polymers of low molecular 
weight in a controlled manner. 
Example 56 
Preparation of Low Molecular Weight Polymers of Styrene. Using Methyl 
.alpha.-Benzyloxyacrylate (Formula II, R.sup.1 =COOCH.sub.3, R.sup.2 
=benzyl). 
Samples of polystyrene prepared in the manner of example 48 using 0 mg, 
20.2 mg, and 80.4 mg of methyl .alpha.-benzyloxyacrylate had 
number-average molecular weights of 106391, 92060, and 71658, 
respectively. The chain transfer constant calculated from these data was 
0.042. These results show that methyl .alpha.-benzyloxyacrylate acts as a 
chain transfer agent for styrene and that the process produces polymers of 
lower molecular weight. 
Example 57 
Preparation of Low Molecular Weight Polymers of Methyl Acrylate Using 
Methyl .alpha.-Benzyloxyacrylate (Formula II, R.sup.1 =--COOCH.sub.3, 
R.sup.2 =benzyl). 
Samples of methyl acrylate prepared in the manner of example 49 using 0 mg, 
10.1 mg, 25.0 mg, and 60.2 mg of methyl .alpha.-benzyloxyacrylate had 
number-average molecular weights of 442463, 41424, 18894, and 8964, 
respectively. The chain transfer constant calculated from these data was 
0.56. These results show that methyl .alpha.-benzyloxyacrylate acts as an 
efficient chain transfer agent for methyl acrylate and that the process 
produces polymers of low molecular weight in a controlled manner. 
Example 58 
Preparation of Low Molecular Weight Polymers of Vinyl Acetate Using Methyl 
.alpha.-Benzyloxyacrylate (Formula II, R.sup.1 =--COOCH.sub.3, R.sup.2 
=benzyl). 
Samples of poly(vinyl acetate) prepared in the manner of example 50 using 0 
mg, 4.8 mg, 10.1 mg, and 20.2 mg of methyl .alpha.-benzyloxyacrylate had 
number-average molecular weights of 245714, 17851, 8382, and 4252, 
respectively. The chain transfer constant calculated from these data was 
20.8. These results show that methyl .alpha.-benzyloxyacrylate acts as a 
chain transfer agent for vinyl acetate and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 59 
Preparation of Low Molecular Weight Polymers of Methyl Methacrylate Using 
.alpha.-Benzyloxyacrylamide (Formula II, R.sup.1 =--CONH.sub.2, R.sup.2 
=benzyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 7.3 mg, 15.2 mg, 25.3 mg, and 40.3 mg of .alpha.-benzyloxyacrylamide 
had number-average molecular weights of 57642, 36026, 23419, and 15687, 
respectively. The chain transfer constant calculated from these data was 
0.47. These results show that .alpha.-benzyloxyacrylamide acts as an 
efficient chain transfer agent for methyl methacrylate and that the 
process produces polymers of low molecular weight in a controlled manner. 
Example 60 
Preparation of Low Molecular Weight Polymers of Styrene Using 
.alpha.-Benzyloxyacrylamide (Formula II, R.sup.1 =--CONH.sub.2, R.sup.2 
=benzyl). 
Samples of polystyrene prepared in the manner of example 48 using 0 mg, 
20.1 mg, 39.6 mg, and 80.6 mg of .alpha.-benzyloxyacrylamide had 
number-average molecular weights of 66537, 48539, 42313, and 33687, 
respectively. The chain transfer constant calculated from these data was 
0.13. These results show that .alpha.-benzyloxyacrylamide acts as a chain 
transfer agent for styrene and that the process produces polymers of low 
molecular weight in a controlled manner. 
Example 61 
Preparation of Low Molecular Weight Polymers of Methyl Acrylate Using 
.alpha.-Benzyloxyacrylamide (Formula II, R.sup.1 =--CONH.sub.2, R.sup.2 
=benzyl). 
Samples of poly(methyl acrylate) prepared in the manner of example 49 using 
0 mg, 9.8 mg, 24.7 mg, and 58.2 mg of .alpha.-benzyloxyacrylamide had 
number-average molecular weights of 529892, 26913, 11193, and 5431, 
respectively. The chain transfer constant calculated from these data was 
1.10. These results show that .alpha.-benzyloxyacrylamide acts as an 
efficient chain transfer agent for methyl acrylate and that the process 
produces polymers of low molecular weight in a controlled manner. 
Example 62 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-Allyloxystyrene (Formula II; R.sup.1 =phenyl, 
R.sup.2 =allyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 14.6 mg, and 30.1 mg of .alpha.-allyloxystyrene had 
number-average molecular weights of 238380, 28873, and 14953, 
respectively. The chain transfer constant calculated from these data was 
0.62. These results show that .alpha.-allyloxystyrene acts as an efficient 
chain transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight. A sample of poly(methyl methacrylate) 
produced similarly using 294 mg of .alpha.-allyloxystyrene was 
precipitated two further times from ethyl acetate/pentane to remove traces 
of the unreacted chain transfer agent. The resulting polymer of 
number-average molecular weight 2418 had signals at .delta. 4.8-5.0 and at 
.delta. 5.5-5.8 in the .sup.1 H NMR spectrum confirming the presence of a 
terminal double bond. Integration of the spectrum showed that one of these 
groups was present per polymer chain. 
Example 63 
Preparation of Low Molecular Weight Olefin-Terminated Polymers of Styrene 
Using .alpha.-Allyloxystyrene (Formula II, R.sup.1 =phenyl, R.sup.2 
=allyl). 
Samples of polystyrene prepared in the manner of example 48 using 0 mg, 
97.0 mg, and 197.0 mg of .alpha.-allyloxystyrene had number-average 
molecular weights of 137320, 53106, and 31889, respectively. The chain 
transfer constant calculated from these data was 0.18. These results show 
that .alpha.-allyloxystyrene acts as an efficient chain transfer agent for 
styrene and that the process produces polymers of low molecular weight in 
a controlled manner. 
Example 64 
Preparation of Low Molecular Weight Polymers of Methyl Methacrylate Using 
.alpha.-Isopropyloxystyrene (Formula II, R.sup.1 =phenyl, R.sup.2 
=isopropyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 20.5 mg, and 39.1 mg of .alpha.-isopropyloxystyrene had 
number-average molecular weights of 247208, 48601, and 26986, 
respectively. The chain transfer constant calculated from these data was 
0.25. These results show that .alpha.-isopropyloxystyrene acts as a chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight in a controlled manner. 
Example 65 
Preparation of Low Molecular Weight Polymers of Methyl Methacrylate Using 
.alpha.-Methoxystyrene (Formula II, R.sup.1 =phenyl, R.sup.2 =methyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 17.0 mg, and 32.4 mg of .alpha.-methoxystyrene had 
number-average molecular weights of 240673, 198460, and 151800, 
respectively. The chain transfer constant calculated from these data was 
0.02. These results show that .alpha.-methoxystyrene acts as a chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of lower molecular weight. 
Example 66 
Preparation of Ester-Terminated Low Molecular Weight Polymers of Styrene 
Using .alpha.-(4-Methoxycarbonylbenzyloxy)styrene (Formula II, R.sup.1 
=phenyl, R.sup.2 =4-CH.sub.3 OC(O)C.sub.6 H.sub.4 CH.sub.2 --). 
Samples of polystyrene prepared in the manner of example 48 using 0 mg, 
132.1 mg, and 267.4 mg of .alpha.-(4-methoxycarbonylbenzyloxy)styrene had 
number-average molecular weights of 137000, 51580, and 31553, 
respectively. The chain transfer constant calculated from these data was 
0.22. These results show that .alpha.-(4-methoxycarbonylbenzyloxy)styrene 
acts as a chain transfer agent for styrene and that the process produces 
polymers of lower molecular weight. A sample of polystyrene produced 
similarly using 745 mg of .alpha.-(4-methoxycarbonylbenzyloxy)styrene was 
precipitated two further times from ethyl acetate/methanol to remove 
traces of the unreacted chain transfer agent. The resulting polymer of 
number-average molecular weight 8298 had signals at .delta. 3.83 in the 
.sup.1 H NMR spectrum confirming the presence of the methyl ester group. 
Integration of the spectrum showed that one of these groups was present 
per polymer chain. The infrared spectrum of the polymer showed an 
absorption at 1720 cm.sup.-1, also confirming the presence of an ester 
group. The polymer could be hydrolysed by methods well known to the art to 
give a polymer terminated at one end with a carboxylic acid group. 
Example 67 
Preparation of Ester-Terminated Low Molecular Weight Polymers of Methyl 
Methacrylate Using .alpha.-(4-Methoxycarbonylbenzyloxy)styrene (Formula 
II, R.sup.1 =phenyl, R.sup.2 =4-CH.sub.3 OC(O)C.sub.6 H.sub.4 CH.sub.2 --) 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 26.4 mg, and 44.1 mg of 
.alpha.-(4-methoxycarbonylbenzyloxy)styrene had number-average molecular 
weights of 246550, 24429, and 14955, respectively. The chain transfer 
constant calculated from these data was 0.70. These results show that 
.alpha.-(4-methoxycarbonylbenzyloxy)styrene acts as a chain transfer agent 
for methyl methacrylate and that the process produces ester-terminated 
polymers of low molecular weight. 
Example 68 
Preparation of Low Molecular Weight Hydroxy-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-[4-(Hydroxymethyl)benzyloxy]styrene (Formula 
II, R.sup.1 =phenyl, R.sup.2 =HOCH.sub.2 C.sub.6 H.sub.4 CH.sub.2 --). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 9.9 mg, 19.8 mg, and 39.9 mg of 
.alpha.-[4-(hydroxymethyl)benzyloxy]styrene had number-average molecular 
weights of 189492, 95120, 41752, and 20829, respectively. The chain 
transfer constant calculated from these data was 0.5. These results show 
that .alpha.-[4-(hydroxymethyl)benzyloxy]styrene acts as an efficient 
chain transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight in a controlled manner. A sample of 
poly(methyl methacrylate) produced similarly using 436 mg of 
.alpha.-[4-(hydroxymethyl)benzyloxy]styrene was precipitated two further 
times from ethyl acetate/pentane to remove traces of the unreacted chain 
transfer agent. The resulting polymer of number-average molecular weight 
1764 had signals at .delta. 4.52 in the .sup.1 H NMR spectrum confirming 
the presence of a (hydroxymethyl)phenyl group. Integration of the spectrum 
showed that one of these groups was present per polymer chain. 
Example 69 
Preparation of Low Molecular Weight Hydroxy-Terminated Polymers of Styrene 
Using .alpha.-[4-(Hydroxymethyl)benzyloxy]styrene (Formula II, R.sup.1 
=phenyl, R.sup.2 =HOCH.sub.2 C.sub.6 H.sub.4 CH.sub.2 --). 
Samples of polystyrene prepared in the manner of example 48 using 0 mg, 
20.1 mg, 40.1 mg, and 80.3 mg of 
.alpha.-[4-(hydroxymethyl)benzyloxy]styrene had number-average molecular 
weights of 112326, 76147, 56570, and 37926, respectively. The chain 
transfer constant calculated from these data was 0.24. These results show 
that .alpha.-[4-(hydroxymethyl)benzyloxy]styrene acts as an efficient 
chain transfer agent for styrene and that the process produces polymers of 
low molecular weight in a controlled manner. A sample of polystyrene 
produced similarly using 1.30 g of 
.alpha.-[4-(hydroxymethyl)benzyloxy]styrene was precipitated two further 
times from ethyl acetate/methanol to remove traces of the unreacted chain 
transfer agent. The resulting polymer of number-average molecular weight 
10239 had signals at .delta. 4.50 in the .sup.1 H NMR spectrum confirming 
the presence of a (hydroxymethyl)phenyl group. Integration of the spectrum 
showed that one of these groups was present per polymer chain. 
Example 70 
Preparation of Low Molecular Weight Hydroxy-Terminated Polymers of Methyl 
Acrylate Using .alpha.-[4-(Hydroxymethyl)benzyloxy]styrene (Formula II, 
R.sup.1 =phenyl, R.sup.2 =HOCH.sub.2 C.sub.6 H.sub.4 CH.sub.2 --). 
Samples of poly(methyl acrylate) prepared in the manner of example 49 using 
0 mg, 11.7 mg, and 25.3 mg of .alpha.-[4-(hydroxymethyl)benzyloxy]styrene 
had number-average molecular weights of 358538, 7064, and 3222, 
respectively. The chain transfer constant calculated from these data was 
5.5. These results show that .alpha.-[4-(hydroxymethyl)benzyloxy]styrene 
acts as an efficient chain transfer agent for methyl acrylate and that the 
process produces polymers of low molecular weight in a controlled manner. 
A sample of poly(methyl acrylate) produced similarly using 41.6 mg of 
.alpha.-[4-(hydroxymethyl)benzyloxy]styrene was precipitated five further 
times from ethyl acetate/methanol and once from ethyl acetate/pentane at 
low temperature to remove traces of the unreacted chain transfer agent. 
The resulting polymer of number-average molecular weight 15548 had signals 
at .delta. 4.53 in the .sup.1 H NMR spectrum confirming the presence of a 
(hydroxymethyl)phenyl group. Integration of the spectrum showed that one 
of these groups was present per polymer chain. 
Example 71 
Preparation of Low Molecular Weight Hydroxy-Terminated Polymers of Vinyl 
Acetate Using .alpha.-[4-(Hydroxymethyl)benzyloxy]styrene] (Formula II, 
R.sup.1 =phenyl, R.sup.2 =HOCH.sub.2 C.sub.6 H.sub.4 CH.sub.2 --). 
Samples of poly(vinyl acetate) prepared in the manner of example 50 using 0 
mg, 4.9 mg, 10.2 mg, and 20.0 mg of 
.alpha.-[4-(hydroxymethyl)benzyloxy]styrene had number-average molecular 
weights of 291871, 44164, 25185, and 11349, respectively. The chain 
transfer constant calculated from these data was 9.0. These results show 
that .alpha.-[4-(hydroxymethyl)benzyloxy]styrene acts as an efficient 
chain transfer agent for vinyl acetate and that the process produces 
hydroxy-terminated polymers of low molecular weight in a controlled 
manner. 
Example 72 
Preparation of Low Molecular Weight Nitrile-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-(4-Cyanobenzyloxy)styrene (Formula II, R.sup.1 
=phenyl, R.sup.2 =NCC.sub.6 H.sub.4 CH.sub.2 --). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 10.0 mg, 21.8 mg, and 42.6 mg of 
.alpha.-(4-cyanobenzyloxy)styrene had number-average molecular weights of 
242138, 46269, 26366, and 14551, respectively. The chain transfer constant 
calculated from these data was 0.77. These results show that 
.alpha.-(4-cyanobenzyloxy)styrene acts as an efficient chain transfer 
agent for methyl methacrylate and that the process produces 
nitrile-terminated polymers of low molecular weight in a controlled 
manner. 
Example 73 
Preparation of Low Molecular Weight Nitrile-Terminated Polymers of Styrene 
Using .alpha.-(4-Cyanobenyloxy)styrene (Formula II, R.sup.1 =phenyl, 
R.sup.2 =NCC.sub.6 H.sub.4 CH.sub.2 --). 
Samples of polystyrene prepared in the manner of example 48 using 0 mg, 
40.0 mg, and 81.0 mg of .alpha.-(4-cyanobenzyloxy)styrene had 
number-average molecular weights of 107520, 75745, and 58482, 
respectively. The chain transfer constant calculated from these data was 
0.21. These results show that .alpha.-(4-cyanobenzyloxy)styrene acts as an 
efficient chain transfer agent for styrene and that the process produces 
polymers of low molecular weight in a controlled manner. The infrared 
spectrum of the polymer showed an absorption at 2220 cm.sup.-1 confirming 
the presence of a nitrile group. 
Example 74 
Preparation of Low Molecular Weight Methoxy-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-(4-Methoxybenzyloxy)styrene (Formula II, 
R.sup.1 =phenyl, R.sup.2 =CH.sub.3 OC.sub.6 H.sub.4 CH.sub.2 --). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 15.9 mg and 39.4 mg of .alpha.-(4-methoxybenzyloxy)styrene had 
number-average molecular weights of 37329 and 16096, respectively. The 
chain transfer constant calculated from these data was 0.66. These results 
show that .alpha.-(4-methoxybenzyloxy)styrene acts as an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
methoxy-terminated polymers of low molecular weight in a controlled 
manner. 
Example 75 
Preparation of Low Molecular Weight Methoxy-Terminated Polymers of Styrene 
Using .alpha.-(4-Methoxybenzyloxy)styrene (Formula II, R.sup.1 =phenyl, 
R.sup.2 =CH.sub.3 OC.sub.6 H.sub.4 CH.sub.2 --). 
Samples of polystyrene prepared in the manner of example 48 using 122.3 mg 
and 263.4 mg of .alpha.-(4-methoxybenzyloxy)styrene had number-average 
molecular weights of 56648 and 33395, respectively. The chain transfer 
constant calculated from these data was 0.19. These results show that 
.alpha.-(4-methoxybenzyloxy)styrene acts as an efficient chain transfer 
agent for styrene and that the process produces methoxy-terminated 
polymers of low molecular weight in a controlled manner. 
Example 76 
Preparation of Low Molecular Weight Amine-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-[4-(Aminomethyl)benzyloxyl]styrene (Formula II, 
R.sup.1 =phenyl, R.sup.2 =H.sub.2 NCH.sub.2 C.sub.6 H.sub.4 CH.sub.2 --). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 11.2 mg, 20.9 mg, and 39.8 mg of 
.alpha.-[4-(aminomethyl)benzyloxy]styrene had number-average molecular 
weights of 262866, 24717, 16088, and 7115, respectively. The chain 
transfer constant calculated from these data was 1.54. These results show 
that .alpha.-[4-(aminomethyl)benzyloxy]styrene acts as an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
amine-terminated polymers of low molecular weight in a controlled manner. 
Example 77 
Preparation of Low Molecular Weight (Chloromethyl)phenyl-Terminated 
Polymers of Methyl Methacrylate Using a Mixture of 
.alpha.-Benzyloxy[4-(chloromethyl)styrene] and 
.alpha.-Benzyloxy[3-(chloromethyl)styrene] (Formula II, R.sup.1 
=ClCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =benzyl--). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 25.3 mg, 44.1 mg, and 72.8 mg of 
.alpha.-benzyloxy[4-(chloromethyl)styrene] and 
.alpha.-benzyloxy[3-(chloromethyl)styrene] had number-average molecular 
weights of 246550, 35572, 23907, and 17418, respectively. The chain 
transfer constant calculated from these data was 0.44. These results show 
that .alpha.-benzyloxy[(chloromethyl)styrene] acts as an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
polymers of low molecular weight in a controlled manner. A sample of 
poly(methyl methacrylate) produced. similarly using 300 mg of the chain 
transfer agent was precipitated two further times from ethyl 
acetate/pentane to remove traces of the unreacted chain transfer agent. 
The resulting polymer of number-average molecular weight 8034 had signals 
at .delta. 4.67 in the .sup.1 H NMR spectrum confirming the presence of a 
(chloromethyl)phenyl group. Polymers terminated with this benzylic 
chloride group react with a variety of nucleophiles to give products in 
which the chlorine atom is replaced by the nucleophile. For example, 
reaction with cyanate ion leads to polymers terminated with an isocyanate 
group. 
Example 78 
Preparation of Low Molecular Weight tert-Butyldimethylsilyloxy-Terminated 
Polymers of Methyl Methacrylate Using 
.alpha.-Benzyloxy[4-(tert-butyldimethylsilyloxymethyl)styrene] and 
.alpha.-Benzyloxy[3-(tert-butyldimethylsilyloxymethyl)styrene] (Formula 
II, R.sup.1 =(tert-butyldimethylsilyloxymethyl)phenyl, R.sup.2 =benzyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 38.8 mg, 72.4 mg, and 117.3 mg of a mixture of 
.alpha.-benzyloxy[4-(tert-butyldimethylsilyloxymethyl)styrene] and 
.alpha.-benzyloxy[3-(tert-butyldimethylsilyloxymethyl)styrene] had 
number-average molecular weights of 27555, 13147 and 8436, respectively. 
The chain transfer constant calculated from these data was 0.66. These 
results show that the compounds act as efficient chain transfer agents for 
methyl methacrylate and that the process produces polymers of low 
molecular weight in a controlled manner. A sample of poly(methyl 
methacrylate) produced similarly using 392 mg of the mixture was 
precipitated two further times from ethyl acetate/pentane to remove traces 
of the unreacted chain transfer agent. The resulting polymer of 
number-average molecular weight 4414 had signals at .delta. 0.12 in the 
.sup.1 H NMR spectrum confirming the presence of the 
tert-butyldimethylsilyloxy group. Such a group can be readily converted by 
well-known methods (such as stirring with tetrabutylammonium fluoride in a 
solvent) to a hydroxyl group. 
Example 79 
Preparation of Low Molecular Weight Hydroxy-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-Benzyloxy[4-(hydroxymethyl)styrene] and 
.alpha.-Benzyloxy[3-(hydroxymethyl)styrene] (Formula II, R.sup.1 
=HOCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =benzyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 10.8 mg, and 20.1 mg of a mixture of 
.alpha.-benzyloxy[4-(hydroxymethyl)styrene] and 
.alpha.-benzyloxy[3-(hydroxymethyl)styrene] had number-average molecular 
weights of 182396, 110353, and 41759, respectively. The chain transfer 
constant calculated from these data was 0.41. These results show that the 
compounds act as efficient chain transfer agents for methyl methacrylate 
and that the process produces hydroxy-terminated polymers of low molecular 
weight. A sample of poly(methyl methacrylate) produced similarly using 345 
mg of the mixture was precipitated two further times from ethyl 
acetate/pentane to remove traces of the unreacted chain transfer agent. 
The resulting polymer of number-average molecular weight 10975 had signals 
between .delta. 4.5 and 4.7 in the .sup.1 H NMR spectrum confirming the 
presence of a hydroxymethylphenyl group. 
Example 80 
Preparation of Low Molecular Weight Acetoxy-Terminated Polymers of Styrene 
Using .alpha.-Benzyloxy[4-(acetoxymethyl)styrene] and 
.alpha.-Benzyloxy[3-(acetoxymethyl)styrene] (Formula II, R.sup.1 =CH.sub.3 
CO.sub.2 CH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =benzyl). 
Samples of polystyrene prepared in the manner of example 48 using 100.2 mg, 
151.6 mg, and 198.6 mg of a mixture of 
.alpha.-benzyloxy[4-(acetoxymethyl)styrene] and 
.alpha.-benzyloxy[3-(acetoxymethyl)styrene] had number-average molecular 
weights of 48465, 38481, and 31175, respectively. The chain transfer 
constant calculated from these data was 0.33. These results show that the 
mixture acts as an efficient chain transfer agent for styrene and that the 
process produces acetoxy-terminated polymers of low molecular weight in a 
controlled manner. A sample of polystyrene prepared similarly using 2 g of 
the mixture was precipitated two further times from ethyl acetate/methanol 
to remove traces of the unreacted chain transfer agent. The resulting 
polymer of number-average molecular weight 7673 had signals at .delta. 
5.06 in the .sup.1 H NMR spectrum confirming the presence of an 
(acetoxymethyl)phenyl group. Integration of the spectrum showed that one 
of these groups was present per polymer chain. The infrared spectrum of 
the polymer showed an absorption at 1740 cm.sup.-1 also confirming the 
presence of the ester group. This group could be readily hydrolysed to an 
OH group. 
Example 81 
Preparation of Low Molecular Weight Chlorophenyl-Terminated Polymers of 
Methyl Methacrylate Using .alpha.-Benzyloxy(4-chlorostyrene) (Formula II, 
R.sup.1 =4-chlorophenyl, R.sup.2 =benzyl) 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 22.8 mg and 49.1 mg of .alpha.-benzyloxy(4-chlorostyrene) had 
number-average molecular weights of 25000, and 11900 respectively. The 
chain transfer constant calculated from these data was 0.75. These results 
show that .alpha.-benzyloxy(4-chlorostyrene) acts as an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
chlorophenyl-terminated polymers of low molecular weight in a controlled 
manner. 
Example 82 
Preparation of Low Molecular Weight Methoxy-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-Benzyloxy(3-methoxystyrene) (Formula II, 
R.sup.1 =3-CH.sub.3 OC.sub.6 H.sub.4 --, R.sup.2 =benzyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 24.8 mg and 40.2 mg of .alpha.-benzyloxy(3-methoxystyrene) had 
number-average molecular weights of 20423 and 12707, respectively. The 
chain transfer constant calculated from these data was 0.83. These results 
show that .alpha.-benzyloxy(3-methoxystyrene) acts as an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
methoxy-terminated polymers of low molecular weight in a controlled 
manner. 
Example 83 
Preparation of Low Molecular Weight Methoxy-Terminated Polymers of Methyl 
Methacrylate Using .alpha.-Benzyloxy(4-methoxystyrene) (Formula II, 
R.sup.1 =4-CH.sub.3 OC.sub.6 H.sub.4 --, R.sup.2 =benzyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 20.7 mg and 44.7 mg of .alpha.-benzyloxy(4-methoxystyrene) had 
number-average molecular weights of 38931 and 19947, respectively. The 
chain transfer constant calculated from these data was 0.46. These results 
show that .alpha.-benzyloxy(4-methoxystyrene) acts as an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
methoxy-terminated polymers of low molecular weight in a controlled 
manner. 
Example 84 
Preparation of Low Molecular Weight .alpha.-Acetoxy, 
.omega.-Methoxy-carbonyl Polystyrene Using 
.alpha.-(4-Methoxycarbonylbenzyloxy)[4-(acetoxymethyl)styrene] and 
.alpha.-(4-Methoxycarbonylbenzyloxy)[3-(acetoxymethyl)styrene] (Formula 
II, R.sup.1 =CH.sub.3 CO.sub.2 CH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 
=CH.sub.3 OC(O)CH.sub.2 C.sub.6 H.sub.4 CH.sub.2 --). 
Samples of polystyrene prepared in the manner of example 48 using 0 mg, 
40.0 mg, 80.4 mg, and 160.0 mg of a mixture of 
.alpha.-(4-methoxycarbonylbenzyloxy) [4-(acetoxymethyl)styrene]and 
.alpha.-(4-methoxycarbonylbenzyloxy)[3-(acetoxymethyl)styrene] had 
number-average molecular weights of 120702, 97477, 78326, and 57711, 
respectively. The chain transfer constant calculated from these data was 
0.18. These results show that the mixture acts as an efficient chain 
transfer agent for styrene and that the process produces 
bis-end-functional polymers of low molecular weight in a controlled 
manner. A sample of polystyrene produced similarly using 966 mg of che 
mixture was precipitated two further times from ethyl acetate/methanol to 
remove traces of the unreacted chain transfer agents. The resulting 
polymer of number-average molecular weight 10873 had signals at .delta. 
3.82 and 5.05 in the .sup.1 H NMR spectrum confirming the presence of 
methyl ester groups and acetoxymethyl groups. Integration of the spectrum 
showed that one of each of these groups was present per polymer chain. The 
infrared spectrum of the polymer showed absorptions at 1720 and 1740 
cm.sup.-1 also confirming the presence of the ester groups. The resultant 
polymer could be readily hydrolysed by methods well known to the art to 
give a polymer terminated at one end with a hydroxyl group and terminated 
at the other end by a carboxylic acid moiety. 
Example 85 
Preparation of Low Molecular Weight .alpha.,.omega.-Dihydroxypoly(methyl 
methacrylate) Using 
.alpha.-[4-(Hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] and 
.alpha.-[4-(Hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene] (Formula 
II, R.sup.1 =HOCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =HOCH.sub.2 C.sub.6 
H.sub.4 CH.sub.2 --). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 10.1 mg, 18.9 mg, and 42.7 mg of a mixture of 
.alpha.-[4-(hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] and 
.alpha.-[4-(hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene] had 
number-average molecular weights of 173410, 42227, 26264, and 15222, 
respectively. The chain transfer constant calculated from these data was 
0.73. These results show that the compounds act as an efficient chain 
transfer agent for methyl methacrylate and that the process produces 
bis-hydroxy end-functional polymers of low molecular weight in a 
controlled manner. A sample of poly(methyl methacrylate) produced 
similarly using 374 mg of the mixture was precipitated one further time 
from ethyl acetate/pentane and three times from ethyl acetate/methanol 
remove traces of the unreacted chain transfer agent. The resulting polymer 
of number-average molecular weight 36422 had signals at .delta.4.5-4.7 in 
the .sup.1 H NMR spectrum confirming the presence of hydroxymethylphenyl 
groups. The infrared spectrum of the polymer showed a broad absorption at 
3505 cm.sup.-1 confirming the presence of the hydroxyl groups. 
Example 86 
Preparation of Low Molecular Weight .alpha.,.omega.-Dihydroxypolystyrene 
Using .alpha.-[4-(Hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] and 
.alpha.-[4-(Hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene] (Formula 
II, R.sup.1 =HOCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =HOCH.sub.2 C.sub.6 
H.sub.4 CH.sub.2 --). 
A sample of polystyrene produced in the manner of example 48 using 1.9 g of 
a mixture of 
.alpha.-[4-(hydroxymethyl)benzyloxy][4-(hydroxymethyl)styrene] and 
.alpha.-[4-(hydroxymethyl)benzyloxy][3-(hydroxymethyl)styrene] was 
precipitated three times from ethyl acetate/methanol to remove traces of 
the unreacted chain transfer agents. The resulting bis-end-functional 
polymer of number-average molecular weight 8942 had signals at .delta. 
4.4-4.7 in the .sup.1 H NMR spectrum confirming the presence of 
hydroxymethylphenyl groups. 
Example 87 
Preparation of Low Molecular Weight 
.alpha.,.omega.-bis(t-Butyldimethylsilyloxymethyl)poly(methyl 
methacrylate) Using 
.alpha.-[4-(t-butyldimethylsilyloxymethyl)benzyloxy][4-(t-butyldimethylsil 
yloxymethyl)styrene] and 
.alpha.-[4-(t-butyldimethylsilyloxymethyl)benzyloxy][3-(t-butyldimethylsil 
yloxymethyl)styrene] (Formula II, R.sup.1 
=(t-bytldimethylsilylxoymethyl)phenyl, R.sup.2 
=4-(t-butyldimethylsilyloxymethyl)benzyl). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, 34.3 mg, 70.1 mg, and 97.5 mg of a mixture of 
.alpha.-[4-(t-butyldimethylsilyloxymethyl)benzyloxy][4-(t-butyldimethylsil 
yloxymethyl)styrene] and 
.alpha.-[4-(t-butyldimethylsilyloxymethyl)benzyloxy][3-(t-butyldimethylsil 
yloxymethyl)styrene] had number-average molecular weights of 227540, 32925, 
18286, and 14520, respectively. The chain transfer constant calculated 
from these data was 0.65. These results show that these compounds act as 
an efficient chain transfer agent for methyl methacrylate and that the 
process produces bis-silyloxy end-functional polymers of low molecular 
weight in a controlled manner. A sample of poly(methyl methacrylate) 
produced similarly using 369 mg of the mixture was precipitated two 
further times from ethyl acetate/pentane to remove traces of the unreacted 
chain transfer agent. The resulting polymer of number-average molecular 
weight 5907 had signals at .delta. 0.0-0.14 and 4.6-4.8 in the .sup.1 H 
NMR spectrum confirming the presence of the 
t-butyldimethylsilyloxymethylphenyl groups. Integration of the spectrum 
showed that two of these groups were present per polymer chain. 
Example 88 
Preparation of Low Molecular Weight .alpha.-Hydroxy-, .omega.-Amino 
Poly(methyl methacrylate) Using 
.alpha.-[4-(Hydroxymethyl)benzyloxy][4-(aminomethyl)styrene] (Formula II, 
R.sup.1 =H.sub.2 NCH.sub.2 C.sub.6 H.sub.4 --, R.sup.2 =HOCH.sub.2 C.sub.6 
H.sub.4 CH.sub.2 --). 
Samples of poly(methyl methacrylate) prepared in the manner of example 47 
using 0 mg, and 31.0 mg of 
.alpha.-[4-(hydroxymethyl)benzyloxy][4-(aminomethyl)styrene] had 
number-average molecular weights of 236538, and 24233, respectively. The 
chain transfer constant calculated from these data was 0.6. These results 
show that .alpha.-[4-(hydroxymethyl)benzyloxy][(aminomethyl)styrene] acts 
as an efficient chain transfer agent for methyl methacrylate and that the 
process produces polymers of low molecular weight terminated by an amino 
group and a hydroxyl group. 
Example 89 
Preparation of Low Molecular Weight Polyacrylonitrile Using 
.alpha.-Benzyloxystyrene (Formula II, R.sup.1 =phenyl, R.sup.2 =benzyl). 
Azobisisobutyronitrile (7.4 mg) was dissolved in freshly distilled 
acrylonitrile (10 ml). An aliquot (2 ml) was removed and added to 
.alpha.-benzyloxystyrene (18.5 mg) and the mixture was polymerized in the 
absence of oxygen for 1 h at 60.degree. C. The resulting polymer was 
precipitated in toluene. A portion (100 mg) of the dried polymer was 
dissolved in dimethylformamide (10 ml) and the viscosity was measured 
using a Gardiner Bubble viscometer. The resulting polymer had a viscosity 
less than that of tube B. A similar polymer prepared without added chain 
transfer agent had a viscosity equal to that of tube E. This result shows 
that the polymer prepared using .alpha.-benzyloxystyrene had a lower 
molecular weight than that prepared without, and that 
.alpha.-benzyloxystyrene acts as a chain transfer agent for acrylonitrile.