Process for the preparation of bisphenols

Processes for the preparation of bisphenols from phenols and substituted vicinal glycols, or unsaturated alcohols or substituted dienes resulting in bisphenols represented by the general formula: ##STR1## wherein: R.sup.1 and R.sup.2 are independently selected from monovalent hydrocarbon and monovalent hydrocarbonoxy radicals of one to four carbon atoms, or from halogen radicals; PA0 R.sup.3, R.sup.4 and R.sup.5 is each a lower alkyl radical, preferably of one to four carbon atoms, aryl radicals, alkaryl radicals, aralkyl radicals, and cycloalkyl radicals, and is the same or different; R.sup.5 may also be hydrogen. PA0 n and n.sup.1 are independently selected from whole numbers having a value of from 0 to 4 inclusive.

FIELD OF THE INVENTION 
The invention relates to a process for the preparation of bisphenols that 
are suitable for the preparation of polyesters, such as polycarbonates, 
copolycarbonates, copolyestercarbonates, polyarylates, aliphatic 
polyesters, polyurethanes, polyepoxides and other polymer systems prepared 
from bisphenols. 
BACKGROUND OF THE INVENTION 
Polycarbonates are well-known, commercially available materials which have 
achieved wide acceptance in the plastics industry. Generally speaking, 
such polymers exhibit excellent properties of toughness, flexibility, 
tensile strength, dimensional stability and impact strength surpassing 
that of many other thermoplastic materials. 
Such polymers are prepared by reacting a carbonate precursor, such as 
phosgene, for example, with a dihydric phenol, such as 
2,2-bis(4-hydroxyphenyl)propane, herein refered to as "bisphenol-A," to 
provide a linear polymer consisting of dihydric phenol units bonded to one 
another through carbonate linkages. 
The dihydric phenols, in turn, are prepared by the reaction of a phenol 
with a carbonyl compound, usually ketone or aldehyde, and usually in the 
presence of acids. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there are provided novel 
processes for the preparation of bisphenols from phenols and substituted 
vicinal glycols, or unsaturated alcohols or substituted dienes resulting 
in the formation of bisphenols represented by the general formula 
##STR2## 
wherein: R.sup.1 and R.sup.2 are independently selected from monovalent 
hydrocarbon and monovalent hydrocarbonoxy radicals of one to four carbon 
atoms, or from halogen radicals; 
R.sup.3, R.sup.4 and R.sup.5 is each a lower alkyl radical, preferably of 
one to four carbon atoms, aryl radicals, alkaryl radicals, aralkyl 
radicals, and cycloalkyl radicals, and is the same or different; R.sup.5 
may also be hydrogen. 
n and n.sup.1 are independently selected from whole numbers having a value 
of from 0 to 4 inclusive. 
DESCRIPTION OF THE INVENTION 
In accordance with the present invention there are provided novel processes 
for the preparation of bisphenols by the reaction of a phenol of the 
general formulae 
##STR3## 
with a difunctional agent of the group 
1. a vicinal glycol of the formula 
##STR4## 
2. an unsaturated alcohol of the formula 
##STR5## 
3. a diene of the formulae 
##STR6## 
where R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, n and n' are as defined 
hereinafore, R.sup.3' and R.sup.4' is each a lower alkylidene radical 
preferably of one to four carbon atoms aralkylidene and cycloalkylidene 
radicals under the influence of acid catalysis. The structure of the 
resultant bisphenols is represented by the general formula 
##STR7## 
where R.sup.1, R.sup.3, R.sup.3, R.sup.4, R.sup.5, n and n' are as defined 
above. 
While it is known that in the presence of acids certain vicinal glycols, 
sometimes referred to as pinacols, do rearrange to a corresponding 
carbonyl compound, also referred to as a pinacolone, and the rearrangement 
is the well-known, classic pinacol-pinacolone rearrangement, the resultant 
bisphenols are not derivable, hence do not derive, from the reaction of 
the pinacolone with phenols. For instance, the prototype of the 
rearrangement is that of pinacol itself (2,3-dimethyl-2,3-butanediol), 
which forms pinacolone(3,3-dimethyl-2-butanone), as shown by the following 
equation: 
##STR8## 
Pinacolone itself, possessing a carbonyl function, could yield in the 
presence of acids and phenol a bisphenol of the following structure: 
##STR9## 
which is, however, not the bisphenol obtained in the present invention, 
which thus is truly surprising and novel. Instead, the bisphenol formed is 
the one corresponding to general formula VII, that is: 
##STR10## 
consisting of the 4,4'- (or p, p'-) isomer, which is major, and some of 
the 2,4'- (or o,p'-) and very little of the 2,2'- (or o,o'-) isomers. 
The mechanism of the pinacol-pinacolone rearrangement is discussed in most 
textbooks of organic chemistry, such as, for example, in "Basic Principles 
of Organic Chemistry, 2d edition" by J. D. Roberts and M. C. Caserio: W. 
A. Benjamin, Inc., 1977, New York, N.Y., p. 720; or "Mechanism and 
Structure in Organic Chemistry" by E. S. Gould: Holt, Rinehart and 
Winston, 1959, New York, N.Y., pp. 601-610. 
Structure proof of bisphenol VIII was accomplished by isolating the pure 
p,p'-bisphenol, VIII A, as shown in the examples 
##STR11## 
and determining its physical constants and spectral characteristics. While 
the mass spectrum confirmed the molecular weight, .sup.1 H and .sup.13 C 
nuclear magnetic resonance established the structure of the aliphatic 
moiety and the 4,4'-substitution pattern. To further confirm structure 
VIII A, phenol was reacted with 2,3-dimethylbutyraldehyde, as shown in 
Comparative Example 4, below, and the isolated 4,4'-isomer of the 
resultant bisphenol was found to be identical with the reaction product of 
pinacol and phenol, by a complete match of its physical and spectral 
parameters. 
##STR12## 
While bisphenols of the general formula VIII are accessible by the 
condensation process involving the specific precursor aldehydes, no 
aldehydes of suitable structure, such as IX, are readily available or 
manufactured commercially. Although they can be synthesized by classical 
methods by the oxidation of the corresponding alcohols or reduction of the 
acids, the aldehyde precursors themselves are not readily available. 
In contrast, several of the vicinal glycols used in the present invention 
are commercially available or are readily accessible. The usually 
symmetrical pinacols are readily available by the reductive coupling of 
ketones, electrolytically or by various amalgams (sodium, magnesium or 
aluminium). 
##STR13## 
Examples of diols represented by general formula III, in addition to 
pinacol itself, are 2,3-dimethyl-2,3-pentanediol, 
2,3-dimethyl-2,3-hexanediol, 2,3-diphenyl-2,3-butanediol, 
2-methyl-3-phenyl-2,3-butanediol, 2-methyl-3-ethyl-2,3-hexanediol, 
2-metyl-2,3-butanediol, 3-methyl-2,3-pentanediol, 
2,3-di(p-tolyl)-2,3-butanediol, and the like. 
Suitable starting materials for the construction of the aliphatic moiety of 
bisphenols VIII are also dienes V and VI, which react with phenols and 
acids to yield bisphenols VII: 
##STR14## 
Examples of dienes V and VI are: 2,3-dimethyl-1,3-butadiene, isoprene, 
2,3-dimethyl-1,3-pentadiene, 2-methyl-3-phenyl-1,3-butadiene, 
2-methyl-1,3-hexadiene, 2-phenyl-1,3-pentadiene. Like the glycols, many of 
dienes V or VI are commercially available. 
Yet a third route to bisphenols VII consists in the reaction of allylically 
unsaturated alcohols represented by the general formulae IV A, IV B and IV 
C: 
##STR15## 
all of which react with electrophilically substitutable phenols to form 
bisphenols represented by the general formula VII. 
Examples of the suitable allylic alcohols are: 2-hydroxy-2-methyl-3-butane, 
2,3-dimethyl-3-hydroxy-1-pentene, 2-hydroxy-3-methyl-2-phenyl-3-butane, 
3-hydroxy-2,3,4-trimethyl-4-pentene, and the like, some of which are 
commercially available. 
Suitable phenols that form bisphenols of the general formula VII are those 
that have at least one replaceable hydrogen on the aromatic ring, i.e., 
where n for R.sup.1 or R.sup.2 is not more than four. 
The preferred halogen radicals represented by R.sup.1 and R.sup.2 are 
chlorine and bromine. 
The monovalent hydrocarbon radicals represented by R.sup.1 and R.sup.2 are 
selected from alkyl radicals, aryl radicals, alkaryl radicals, aralkyl 
radicals, and cycloalkyl radicals. The preferred alkyl radicals 
represented by R.sup.1 and R.sup.2 are those containing from 1 to about 6 
carbon atoms. These preferred alkyl radicals include the straight chain 
and the branched alkyl radicals. Some non-limiting illustrative examples 
of these preferred alkyl radicals include methyl, ethyl, propyl, 
isopropyl, butyl, isobutyl, tertiary-butyl, and the like. The preferred 
aryl radicals represented by R.sup.1 and R.sup.2 are those containing from 
6 to 12 carbon atoms and include phenyl, naphthyl and biphenyl. The 
preferred alkaryl and aralkyl radicals represented by R.sup.1 and R.sup.2 
are those containing from 7 to about 14 carbon atoms and include benzyl, 
tolyl, ethylphenyl, and the like. The preferred cycloalkyl radicals 
represented by R.sup.1 and R.sup.2 are those containing from 3 to about 8 
ring carbon atoms and include cyclopropyl, cyclopentyl, cyclohexyl, and 
the like. 
The monovalent hydrocarbonoxy radicals represented by R.sup.1 and R.sup.2 
are preferably selected from alkoxy radicals and aryloxy radicals. The 
preferred alkoxy radicals are those containing from 1 to about 6 carbon 
atoms. The preferred aryloxy radical is the phenoxy radical. 
In the dihydric phenols of Formula VII when more than one R.sup.1 
substituent is present, i.e., when n is equal to from 2 to 4, they may be 
the same or different. The same is true for the R.sup.2 substituent. If n 
or n' is zero, then the ring carbon atoms of the aromatic nuclear residue 
are substituted with hydrogen atoms. 
The monovalent hydrocarbon radicals represented by R.sup.3, R.sup.4 and 
R.sup.5 are selected from alkyl radicals, cycloalkyl radicals, aryl 
radicals, alkaryl radicals, and aralkyl radicals. 
The preferred alkyl radicals represented by R.sup.3, R.sup.4 and R.sup.5 
are those containing from 1 to about 8 carbon atoms. These alkyl radicals 
include the branched alkyl radicals and the straight chain alkyl radicals. 
Some illustrative non-limiting examples of these preferred alkyl radicals 
include methyl, ethyl, propyl, butyl, isobutyl, tertiary-butyl, pentyl, 
neopentyl, and the like. 
The preferred aryl radicals represented by R.sup.3, R.sup.4 and R.sup.5 are 
those containing from 6 to 12 carbon atoms, i.e., phenyl, naphthyl and 
biphenyl. The preferred alkaryl and aralkyl radicals are those containing 
from 7 to about 14 carbon atoms, e.g., benzyl, tolyl, ethylphenyl, etc. 
The preferred cycloalkyl radicals represented by R.sup.3, R.sup.4 and 
R.sup.5 are those containing from 4 to about 8 ring carbon atoms. Some 
illustrative non-limiting examples of these preferred cycloalkyl radicals 
include cyclobutyl, cyclopentyl, cyclohexyl, and the like. 
The divalent hydrocarbon radicals represented by R.sup.3' and R.sup.4' are 
selected fro alkylidene radicals, aralkylidene radicals and 
cycloalkylidene radicals. 
The preferred alkylidene radicals represented by R.sup.3' and R.sup.4' are 
those containing from 1 to about 8 carbon atoms. Some illustrative 
non-limiting examples of these preferred alkylidene radicals include 
methylene, ethylidene, propylidene, ispropylidene, neopentylidene and the 
like. 
The preferred cycloalkylidene radicals represented by R.sup.3' and R.sup.4' 
are those containing from 4 to 8 ring carbon atoms. Some illustrative 
non-limiting examples of these cycloalkylidene radicals include 
cyclobyutylidene, cyclopentylidene, cyclohexylidene and cyclooctylidene. 
In order to obtain the dihydric phenols of Formula VII, one mole of the 
reactants of Formulae III, IV, V and VI is reacted with two moles of a 
phenol of Formula I or II, or with one mole of a phenol of Formula I and 
one mole of a phenol of Formula II in the presence of an acid catalyst. 
Some illustrative non-limiting examples of suitable acid catalysts that 
may be employed include hydrochloric acid, hydrobromic acid, poly(styrene 
sulfonic acid), sulfuric acid, benzene sulfonic acid, and the like. The 
phenols of Formulae I and II are reacted with the glycol, diene or allylic 
alcohol of Formulae III, IV, V and VI in the presence of said acid 
catalyst, such that coreaction between said phenols and said reactants 
will occur to form the dihydric phenol of Formula VII. The reaction, 
generally, proceeds satisfactorily at about one atmosphere of pressure and 
at temperatures of from about 0.degree. to room temperature to about 
100.degree. C. 
The amount of the acid catalyst employed is a catalytic amount. By 
catalytic amount is meant an amount effective to catalyze the reaction 
between the aldehyde and the phenol. Generally this amount is in the range 
of from about 0.1 to about 10%. However, in actual practice it is usually 
somewhat higher since the water coproduct formed in the reaction dilutes 
the acid catalyst and makes it somewhat less effective (slowing the 
reaction) than in its undiluted state. 
The phenols of Formulae I and II may, of course, be the same. In that case, 
one mole of the reactants of Formulae III, IV, V and VI is reacted with 
two moles of the phenol. 
Some non-limiting illustrative examples of the dihydric phenols represented 
by Formula VII include: 
##STR16## 
These bisphenols are suitable for the preparation of polycarbonates, 
copolycarbonates, copolyestercarbonates, polyesters, including 
polyarylates, polyurethanes, polyepoxides and other polymer systems 
prepared from bisphenols. 
The novel carbonate polymers of the invention contain repeating structural 
units represented by the general formula 
##STR17## 
wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, n and n' are as 
defined above. 
The carbonate precursor may be a carbonyl halide, a diarylcarbonate, or a 
bishaloformate. The preferred carbonate precusors are the carbonyl 
halides. The preferred carbonyl halides include carbonyl chloride, 
carbonyl bromide, and mixtures thereof. The preferred carbonyl halide is 
carbonyl chloride, also known as phosgene. 
These high molecular weight aromatic carbonate polymers generally have an 
average molecular weight in the range of from about 10,000 to about 
150,000, preferably from about 20,000 to about 100,000. 
One method of preparing the high molecular weight aromatic carbonate 
polymers of the present invention involves the heterogeneous interfacial 
polymerization system utilizing an aqueous caustic solution, an organic 
water immiscible solvent such as methylene chloride, at least one dihydric 
phenol selected from phenols represented by Formulae I and II, a carbonate 
precursor such as phosgene, a catalyst, and a molecular weight regulator. 
The catalysts which are employed herein can be any of the suitable 
catalysts that aid the polymerization of a dihydric phenol with phosgene. 
Suitable catalysts include, but are not limited to, tertiary amines such 
as triethylamine, quaternary ammonium compounds, and quaternary 
phosphonium compounds. 
Another useful method for preparing the carbonate polymers of the present 
invention involves the use of an organic solvent system wherein the 
organic solvent system may also function as an acid acceptor, at least one 
dihydric phenol of Formula I and/or II, a molecular weight regulator, and 
a carbonate precursor such as phosgene. 
The molecular weight regulators employed may be any of the known compounds 
which regulate the molecular weight of the carbonate polymer by a chain 
terminating mechanism. These compounds include, but are not limited to, 
phenol, tertiary butyl phenol, and the like. 
The temperature at which phosgenation reaction proceeds may vary from below 
0.degree. C. to above 100.degree. C. The reaction proceeds satisfactorily 
at temperatures from room temperature, about 25.degree. C. to 50.degree. 
C. Since the reaction is exothermic, the rate of phosgene addition or a 
low boiling solvent such as methylene chloride, or just plain external 
cooling, may be used to control the reaction temperature. 
The carbonate polymers of the present invention may optionaly have admixed 
therewith certain commonly known and used additives such as antioxidants; 
antistatic agents; fillers such as glass fibers, mica, talc, clay, and the 
like; impact modifiers; ultraviolet radiation absorbers such as the 
benzophenones and the benzotriazoles; plasticizers; hydrolytic stabilizers 
such as the epoxides disclosed in U.S. Pat. Nos. 3,489,716; 4,138,379 and 
3,839,247, all of which are incorporated herein by reference; color 
stabilizers such as the organophosphites disclosed in U.S. Pat. Nos. 
3,305,520 and 4,118,370, both of which are incorporated herein by 
reference, and flame retardants. 
Some particularly useful flame retardants are the alkali and alkaline earth 
metal salts of sulfonic acids. These types of flame retardants are 
disclosed in U.S. Pat. Nos. 3,933,734; 3,948,851; 3,926,908; 3,919,167; 
3,909,490; 3,953,396; 3,931,100; 3,978,024; 3,953,399; 3,917,559; 
3,951,910 and 3,940,366, all of which are incorporated herein by 
reference. 
Another embodiment of the present invention is a carbonate copolymer 
obtained by reacting, as essential components, (i) a carbonate precursor, 
(ii) at least one dihydric phenol selected from the dihydric phenols 
represented by Formula VII, and (iii) at least one dihydric phenol 
represented by the general formula 
##STR18## 
wherein A represents an alkylene radical, a cycloalkylene radical, an 
alkylidene radical, a cycloalkylidene radical, 
##STR19## 
The dihydric phenols of Formula IX are well known and are generally used in 
making conventional polycarbonates. 
In Formula IX each X' and X is independently selected from halogen 
radicals, such as chlorine and bromine; monovalent hydrocarbon radicals; 
and monovalent hydrocarbonoxy radicals. The monovalent hydrocarbon 
radicals are selected from alkyl radicals, preferably those containing 
from 1 to about 6 carbon atoms; aryl radicals, preferably those containing 
from 6 to 12 carbon atoms, such as phenyl, naphthyl and biphenyl; alkaryl 
radicals and aralkyl radicals, preferably those containing from 7 to about 
14 carbon atoms; and cycloalkyl radicals, preferably those containing from 
4 to about 8 ring carbon atoms. 
The monovalent hydrocarbonoxy radicals represented by X and X' are 
preferably selected from alkoxy radicals and aryloxy radicals. The letters 
a and a' independently represent whole numbers having a value of from 0 to 
4, inclusive. The letter b is either zero or one. 
The alkylene radicals represented by A are those containing from 2 to about 
6 carbon atoms. The alkylidene radicals represented by A are those 
containing from 1 to about 6 carbon atoms. The cyclalkylene and 
cycloalkylidene radicals represented by A are those containing from 4 to 
about 7 ring carbon atoms. The alkylene and alkylidene radicals 
represented by A are straight chain alkylene and alkylidene radicals. 
In the dihydric phenol compounds represented by Formula IX when more than 
one X substituent is present, they may be the same or different. The same 
is true for the X' substituents. Where b is zero in Formula IX, the 
aromatic rings are directly joined with no intervening alkylene or other 
bridge. The positions of the hydroxyl groups and X or X' on the aromatic 
nuclear residues can be varied in the ortho, meta or para positions, and 
the groupings can be in a vicinal, asymmetrical or symmetrical 
relationship, where two or more ring carbon atoms of the aromatic 
hydrocarbon residue are substituted with X or X' and hydroxyl groups. 
Some non-limiting illustrative examples of suitable dihydric phenols 
represented by Formula IX include: 
1,1-bis(4-hydroxyphenyl)cyclohexane; 
2,2-bis(4-hydroxyphenyl)propane(bisphenol-A); 
3,3-bis(3-methyl-4-hydroxyphenyl)pentane; 
1,1-bis(3-methyl-4-hydroxyphenyl)ethane; 
2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane; 
3,3'-dichloro-4,4'-dihydroxydiphenyl; 
bis(3-chloro-4-hydroxyphenyl)sulfone; 
3,3'-diethyl-4,4'-dihydroxydiphenyl; 
bis(4-hydroxyphenyl)sulfide; and the like. 
The carbonate copolymers obtained by reacting (i) a carbonate precursor, 
(ii) at least one dihydric phenol selected from dihydric phenols 
represented by Formula VII, and (iii) at least one dihydric phenol 
represented by Formula IX will contain the following repeating structural 
units: 
##STR20## 
wherein X, X', a, a', A and b are as defined hereinafore. 
The procedures for producing the carbonate copolymers are generally similar 
to those described hereinafore for producing the polymers of the instant 
invention. The carbonate copolymers may likewise have admixed therewith 
the various additives described supra. 
Yet another embodiment of the present invention is a polycarbonate resin 
blend comprised of (i) at least one polycarbonate resin of the present 
invention (hereinafter referred to as resin A); and (ii) at least one 
polycarbonate resin derived from (a) a carbonate precursor, and (b) at 
least one dihydric phenol of Formula IX (hereinafter referred to as resin 
B). These blends may generally contain from about 10 to about 90 weight 
percent of resin A, based on the total amount of resins A and B present in 
the blends. The present blends are prepared by first preforming the 
various resins and thereafter physically mixing or blending these resins 
together. These blends may optionally contain the various additives 
described supra.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The following examples are set forth in order to more fully and clearly 
illustrate the present invention. It is intended that the examples be 
considered as illustrative rather than limiting the invention as disclosed 
and claimed herein. In the examples, all parts and percents are on a 
weight basis unless otherwise indicated. 
The following examples illustrate the preparation of the novel dihydric 
phenols of the present invention. 
EXAMPLE 1 
This example illustrates the preparation of 2,3-dimethyl-butylidene 
bisphenol (dihydric phenol represented by Formula VIII) from pinacol. 
Into a warm solution of 39.4 g (0.3 mole) of 2,3-dimethyl-2,3-butanediol 
(pinacol) in 282 g. (3.0 mole) of molten phenol there was introduced 
gaseous hydrogen chloride at a rate of ca. 1 bubble per second while 
maintaining the reaction temperature at near 50.degree. C. At about every 
hour a small sample was taken for gas chromatographic analysis, which 
indicated the gradual formation of products in the bisphenol range. After 
about 5 hours, after the concentration of the bisphenols reached its peak, 
the excess phenol was removed by distillation in water aspirator vacuum 
and the residue, which solidified on cooling, was slurried with methylene 
chloride and filtered. The slightly off-white crystals, which had a 
melting point of 165.5.degree. to 167.degree. C., were identified as the 
p,p'-isomer of the title compound by carbon and proton nuclear magnetic 
resonance, gas chromatography, and infrared spectroscopy. The methylene 
chloride wash contained, in addition to some of the p,p'-, also the o,p'- 
and some o,o'-isomers. 
EXAMPLE 2 
This example illustrates the preparation of 
4,4'-(2,3-dimethylbutylidene)bisphenol from phenol and 
2,3-dimethylbutadiene. 
The procedure of Example 1 was repeated, except that instead of hydrogen 
chloride, 65 g. of an acidic ion-exchange resin (Amberlyst 15) was used as 
the catalyst at the temperature range of from 40.degree. to 55.degree. C. 
After about 7 hours the catalyst was filtered off and the phenol solution 
was worked-up as in Example 1, yielding the title compound as residue. 
EXAMPLE 3 
Preparation of 4,4'-(2,3-dimethylbutylidene)bisphenol from phenol and the 
commercially available 2,3-dimethyl-3-buten-2-ol. 
Repeating the procedure of Example 1 with 30.0 g. (0.3 mole) of 
2,3-dimethyl-3-buten-2-ol, instead of pinacol, yielded with phenol and 
hydrogen chloride the title compound of melting point 
165.5.degree.-167.degree. C. 
COMATIVE EXAMPLE 4 
This example illustrates the preparation 
4,4'-(2,3-dimethylbutylidene)bisphenol by conventional means from 
2,3-dimethylbutyraldehyde and phenols, and it is outside the scope of the 
present invention. 
The commercially available 2,3-dimethyl-1-butanol was oxidized to the 
commercially not available 2,3-dimethyl-butyraldehyde by adding, at 
ambient temperature, to a solution of 7.1 g. (0.07 mole) of the alcohol in 
100 ml. of methylene chloride a solution of 23.7 g. (0.11 mole) of 
pyridinium chlorochromate in 200 ml. of methylene chloride, in the course 
of one hour, during which the temperature rose from 20.degree. to 
31.degree. C. After stirring at ambient temperature for another hour, the 
solution was decanted from the black sludge, washed twice with 150 ml., 
each, of concentrated hydrochloric acid and the somewhat hazy solution 
with a green cast was passed through a 15 cm. high bed of Florisil. After 
distilling off methylene chloride, the aldehyde distilled over between 
102.degree. and 111.degree. C. and was found to be 94% pure by gas 
chromatography. 
The preparation of the bisphenol was carried out by saturating with 
hydrogen chloride a solution of 5.0 g. (0.05 mole) of the aldehyde in 47 
g. (0.5 mole) of warm phenol, stirring the reaction mixture for 1 hour at 
between 45.degree. and 52.degree. C. and stripping off the acid and excess 
phenol mixture in aspirator vacuum. Trituration of the solid distillation 
residues left behind pale yellow crystals that were identified as 
4,4'-(2,3-dimethylbutylidene)bisphenol by carbon and proton nuclear 
magnetic resonance, infrared spectroscopy, and gas chromatography and 
whose melting point was 164.degree. to 167.degree. C., undepressed when 
mixed with the crystals of the bisphenol prepared in Example 1. 
EXAMPLE 5 
This example illustrates the preparation of bisphenols from pinacol and an 
alkyl substituted phenol. 
The procedure of Example 1 was repeated by using 11.8 g. (0.1 mole) of 
2,3-dimethyl-2,3-butanediol and 122 g. (1.0 mole) of 
2,6-xylenol(2,6-dimethylphenol), except that the solid residue obtained 
after the distillation of the xylenol was recrystallized twice from 
cyclohexane. The resultant white crystals had a melting point of 
153.degree. to 154.5.degree. C. and were found to be 100% pure by gas 
chromatography. Carbon and proton nuclear magnetic resonance spectroscopy 
confirmed their structure as 
2,2',6,6'-tetramethyl-4,4'-(2,3-dimethylbutylidene)bisphenol. 
COMATIVE EXAMPLE 6 
This example describes the preparation of the bisphenol by conventional 
means from 2,6-xylenol and 2,3-dimethylbutyraldehyde and is outside the 
scope of the present invention. 
The procedure of Example 4 was repeated by using 11.8 g. (0.118 mole) of 
2,3-dimethylbutyraldehyde (obtained as described in Example 4) and 122 g. 
(1.0 mole) of 2,6-xylenol. The structure of the resultant bisphenol was 
found identical with that of Example 5. 
EXAMPLE 7 
This example illustrates the preparation of a bisphenol from a diene and a 
disubstituted phenol. 
The procedure of Example 2 was repeated, except that 10.3 g. (0.125 mole) 
of 2,3-dimethyl-1,3-butadiene, 152.8 g (1.25 mole) of 2,6-xylenol, and 50 
g. Amberlyst 15 ion exchange resin catalyzed was utilized. The reduction 
product was found to be identical with those of Examples 5 and 6.