POLYMERS AND THEIR PREPARATION AND USE

Abstract: Polymers and in particular new polyalkylsiloxane derivatives of general formula (I), wherein m is a number not less than (2), and in at least one monomer unit each of Y and Z is a substituted carbon group and together form a chain linkage of at least 4 atoms and X is an optionally substituted alkyl or aryl or heterocyclic group, and in any remaining monomer units X, Y and Z together represent an alkyl or aralkyl or alkyl heterocyclic or aralkyl heterocyclic group, R is an alkyl group, and R<1> and R<2> are the same or different and each is a generally unreactive polymer chain terminating group which is an optionally substituted alkyl or aryl or heterocyclic group. The present invention also relates to a method of making a polyalkysiloxane derivative of general formula (I) and the use of compounds of formula (I) in chromatographic fractionation.

Description: -- l- r . POLYMERS ' AND THEIR PREPARATION AND USE The present invention relates to new polymers and in particular new polyalkylsiloxane derivatives, and their ' preparation and use. The present invention provides polyalkylsiloxane derivatives of the general formula (I) wherein m is a number not less than 2, and in at least one monomer unit each of Y and Z is a substituted carbon group and together form a chain linkage of at least 4 atoms and X is an optionally substituted alkyl or aryl or heterocyclic group, and in any remaining monomer units X,Y and Z together represent an alkyl or aralkyl or alkyl heterocyclic or aralkyl heterocyclic group, R is an alkyl group, preferably lower alkyl, most preferably methyl, and R 1 and R2 are the same or different and each is a generally unreactive polymer chain terminating group which is an optionally substituted alkyl or aryl or heterocyclic group. Preferably the polyalkylsiloxane derivative is substantially pure, and most preferably is at least 99% pure. In a further aspect the present invention provides a method of makinga polyalkylsiloxane derivative of the general formula I as defined hereinbefore comprising reaction of an unsaturated polyalkylsiloxane compound of general formula II R (II) wherein m is a number not less than 2, R,R1, and R2 have the same meaning as in Formula I and in at least one monomer unit Z is an unsaturated substituted carbon group, and m is a positive number, with a compound of the general formula III x _ Y 1 (i n ) wherein X is optionally substituted alkyl or aryl or heterocyclic group and Y is an unsaturated substituted carbon group such that Z and Y together have at least four carbon atoms, and in any remaining units Z represents an alkyl or aralkyl group, so as to form a said derivative of general formula I and separating said compound of general formula I from the reaction mixture. Preferably the reaction is carried out under free radical forming conditions, for example, in the presence of ultraviolet radiation and/or one or more free radical forming materials selected from ozone, an azo compound, and dicumyl peroxide. The reaction may be carried out at various temperatures and pressures over a wide range, optimum results depending on the particular reaction route and reactants selected. In general though the reaction may be carried out at ambient pressure and at a temperature in the range from ambient temperature up to the boiling point of the reaction mixture. Where the reaction is carried out in a solvent this is desirably a non-polar solvent, such as for example pentane or toluene. Suitable examples of the groups Y and Z that ma be mentioned include alkenyl preferably ethenyl and vinyl, and cyano. The polyalkylsiloxane derivatives of the general formula I are particularly useful as the stationary phase in capillary column gas chromatography for use in the chromatographic fractionation of compounds of the general formula X wherein X is an optionally substituted alkyl or aryl or heterocyclic compound having a formula similar to that of X as defined hereinbefore. Thus in a still further aspect the present invention provides a capillary column suitable for use in capillary column gas chromatograph and coated with a polymethylsiloxane derivative of the genera formula I as defined hereinbefore. In a yet further aspect the present invention provides a method of chromatographic fractionation of a mixture of at least two different compounds of the general formula X as defined hereinbefore characterized by the use of a capill column of the invention. By means of the present invention it is possible to achieve chromatographic fractionation of mixtures of closely similar substances such as for example barbiturates with a high degree of selectivity. By way of illustration one preferred embodiment of the present invention will now be described with reference to barbiturate fractionation and materials suitable for use therein though it should be understood that the invention extends to the fractionation of various other materials whether more or less difficult to fractionate, as well as materials suitable for use in such fractionations and their preparation. EXAMPLES In the following examples, unless otherwise stated, NMR spectra were recorded in. In a yet further aspect the present invention provides a method of chromatographic fractionation of a mixture of at least two different compounds of the general formula X as defined hereinbefore characterized by the use of a capillary column of the invention. By means of the present invention it is possible to achieve chromatographic fractionation of mixtures of closely similar substances such as for example barbiturates with a high degree of selectivity. By way of illustration one preferred embodiment of the present invention will now be described with reference to barbiturate fractionation and materials suitable for use therein though it should be understood that the invention extends to the fractionation of various other materials whether more or less difficult to fractionat as well as materials suitable for use in such fractionations and their preparation. EXAMPLES In the following examples, unless otherwise stated, NMR spectra were recorded in SUBSTITUTESHEET deuterated chloroform solution with a Perkin-Elmer R32 n.m.r. spectrometer, and are given in parts per million (^) downfie from an internal tetra ethylsilane (TMS) standard. The abbreviations s,d,t,q, and m refer to singlet, doublet, triplet, quartet and multiplet respectively. Infrared (IR) spectra were recorded on a Perkin-Elmer 157 prism spectro- photometer. The abbreviations, s, m, w refer to strong, medium and weak respectively. Synthesis of 5-(2-vinyl dimethyl siloxy propyl)-5-(1-methyl butyl)-barbituric acid (I) (a) Conversion of 5-ally1-5-(1-methyl butyl) barbituric acid into 5-(2-hydroxypropyl)-5-(1-methyl butyl)-barbituric acid Concentrated sulphuric acid (25ml) was added to 5-allyl-5- (1-methylbutylj barbituric acid (5g) in a round bottomed flask equipped with a magnetic stirrer bar for 12 in at room temperature. The yellowish brown solution was poured into ice-water (150 ml) . The white precipitate formed was filtered, washed with water (50 ml) and dried in an oven at 100 C. The product was recrystallised from ethanol to give colourless crystals of 5-(2-hydroxy propyl)-5-(1-methyl butyl) barbituric acid (4.2g; 78%), m.p. 189-93° (lit. 215 - 216°) . IR(Nujol) 3350 cm "1 (m,o-H), 3050(m,N-H) ,1700(s, C=0) NMR((CD 3 ) 2 C0) 9.90(s, 2H, NH) , 3.80(m, 2H, CH 2 -C-C=0) . (b) Conversion of 5-(2-hydroxypropyl)-5-(1-methyl butyl)- barbituric acid into 5-(2-vinyl dimethyl siloxy propyl)- SUBSTITUTE SHEET 5-(1-methyl butyl)-barbituric acid (I) To a solution of 5-(2-hydroxy propyl)-5-(1-methyl butyl)- barbituric acid (2g) in dimethyl formamide (distilled; 6ml) in a flask equipped with stirrer and reflux condenser, was added imidazole (eg; 6 equiv.), moisture being kept out by means of Drierite-filled tube. Vinyl dimethyl ethoxy silane (2ml; 1.5 equiv.; Petrarch system, Bristol, PA, USA) was added at room temperature. The reaction was stirred over¬ night at 80 C to give the desired product after purification by column chromatography (silica gel 60; 1:4 v/v ether: chloroform, R p 0.35). The product was recrystallised with petrol-ether 40 -60 to give colourless crystals, m.p. 138- 40°. IR(Nujol) 3100cm "*1 (m,N-H) , 1680(s, C=0) , 1260(w, SiMe~) , 800(m, Si-Me 2 ) . NMR (CDC1-. with no TMS added) 0.15(s, 6H, SiCH 3 ) , 3.85(m, 1H, CH-O-Si) , 5.50-6.10(m, 3H, CH=CH ) , 8.50(s, 2H, NH) . Synthesis of 1,3-dimethyl-5-allyl-5-(1-methyl butyl)- barbituric acid (II) To a mixture of 5-ally1-5-(1-methyl butyl)-barbituric acid (lOg) in aqueous sodium hydroxide (4g in 40ml water; 2.5 equi was added dimethyl sulphate (20ml; ca. 5 equiv.). The reaction was exothermic and completed in about 30 min. TLC on silica gel showed complete conversion into product after 30 min (R„ 0.49; 1:4 v/v ether:chloroform) . Water (50ml) was added to the reaction mixture, and the product was extracted into ether (100mlx3) , washed with water (30ml) , dried (anhydrous Na 2 SO.) and filtered. After removal of solvent, a crude product was obtained in the form of a pale-yellow oil. Purification by column chromatography (silica gel 60; 1:4 v/v ether:chloroform) yielded a colourless oil (8g) . IR (film) 1660cm "1 (s, C=0) , 920(s, =C-H) . NMR(CDC1 3 ) 2.70(d, 2H, CH 2 "C=C) , 3.25(s, 6H, -CH 3 ) , 4.90-5.80(m, 3H, CH=CH 2 ) . Synthesis of 1,3 diallyl-5-ethyl-5-isoamyl barbituric acid (III) . To a mixture of 5-ethyl-5-isoamyl barbituric acid (2g) and a catalytic amount of fine copper powder in aqueous sodium hydroxide (0.8g in 80ml water; 2.2. equiv.), was added allyl bromide (4ml; 5 equiv.). The reaction was exothermic and the colour of the reaction mixture changed from colourless to milky. TLC on silica gel showed complete conversion into product in about 5h (R_ 0.65; 3:7 v/v acetσne:chloroform) . Water (20ml) was added to the reaction mixture and the product was extracted into ether (100mlx3) , washed with sodium hydroxide (1M; 50ml) , water (50ml), dried (anhydrous Na 2 S0.) and filtered. After removal of solvent, a crude product was obtained in the form of a pa ' le-yellow oil. After purification by column chromatography (silica gel 60; 3:7 v/v acetone:chloroform) a colourless oil (1.46g; 62%) was obtained. IR (film) 3050cm~ 1 (m, =C-H str) , 1680(s, C=0) , 1000 and .940(s, =C-H bend) . NMR(CDC1 3 ) ^4.50(d, 4H, n-CH , 5.00-5.50(m, 4H, CH 2 BSTI TE SHEET = C) 5 . 50-6 . 20 (m, 2H , CH=C) . Preparation of Non-polar Immobilised Polymethylsiloxane Columns Cleaning and Drawing of Glass Tubing Glass capillaries (0.2-0.4 mm I.D. and c_a. 0.80mm O.D.) were drawn from Pyrex glass tubes (3.5mm I.D. and 6.0mm O.D.) on a Carlo Erba GCDM 60 glass-drawing machine. Before drawing, the glass tubes were cleaned with chromic acid for lh, washed with water, acetone, and finally dried with a stream of dry nitrogen. Leaching The capillary column was filled with 20% hydrochloric acid (Aristar grade; BDH) by means of a water pump. The column was then removed from the hydrochloric acid solution and air was allowed to be drawn into the column for 8% of the column length. The full end was sealed and the other end sealed under vacuum. The column was placed in an oven at 180 C for 13h. Rinsing and Dehydration Both ends of the leached column were opened and the hydrochloric acid inside was displaced by one volume of 2% hydrochloric acid (pH3) employing a water pump. This solution was, in turn, displaced by half a volume of methanol (Analar grade; BDH). The rate of rinsing being not more than 2cms . The methanol was flushed out and the column placed in an oven at 250° for 2h. This dehydration step was accomplished under a slow SUBSTITUTE^HΞET carrier gas flow of nitrogen. Deactivation by Persilylation Persilylation was performed as described below with diphenyl tetramethyl disalazane (DPTMDS) although in some experiments, octamethyl cyclotetrasiloxane (D.) and hexamethyl disilazane (HMDS) were used instead. All silylating agents were obtained from Fluka (Bucks, Switzerland) . By means of a syringe, the silylating agent was sucked into the column until it filled 10% of its volume. This plug was then moved through the column by nitrogen pressure at a rate of 0.5cms~ for DPTMDS (lcrns- for D 4 and 2cms ~ for HMDS) and the nitrogen flow stopped immediately after the plug had left the column. Both ends of the column were then vacuum sealed (oil pump) , and the column placed in an oven, the temperature of which was programmed from 50 C to 400°C at 5°C/min and held at 400°C for 16h. The column was allowed to cool slowly in the closed oven for lh and one end of the persilylated column then opened under methylene chloride (Analar grade; BDH) . The percentage of the column length filled with methylene chloride was a rough estimate of the degree of persilylation . Filling to about 70% was generally achieved. Finally the capillar was rinsed with 5ml of methylene chloride and dried in an oven at 150 C for 2h. This dehydration step was accomplis under a slow carrier gas flow of nitrogen. Coating Solutions for static coating were prepared using pentane BSTITUTE- (Analar grade; BDH) as solvent for SE54 (Phasesep) . When the stationary phase had dissolved, 0.1-1% w/w of dicu yl peroxide (2% in toluene; BDH) was added and the resulting coating solution degassed for 1 min (ultrasonic bath) . The column was completely filled with coating solution from a syringe under pressure. A further 10% of this solution continued to be passed through the column before the pressure was discontinued. One end of the column containing no liquid phase was drawn out into a fine capillary and the solution pressurised into the vacant volume. The fine end of the column was then sealed with molten wax. About 30 min was allowed for the wax to solidify and a vacuum (oil pump) was applied to the other end, evaporation of the solvent being assisted by immersing the column in a waterbath at room temperature. Care must be taken not to allow the wax in the sealed end to touch the water in the waterbath. Evaporation was terminated when only 1-2 coils at the sealed end were still filled with solvent. This normally took about 13h for a 23m column. Immobilisation After static coating, the column was flushed with nitrogen 2 for lh and cured according to the method of Blomberg et al For this the capillary was sealed under vacuum and then placed in an oven at 140 C for 30 min. In some experiments, 3 columns were cured according to the method of Grob et al , in which the vacuum sealed capillaries were kept for lh at 180 C. After curing, the oven was rapidly cooled and the columns flushed with dry nitrogen at room temperature. The columns were then conditioned at 250 C for lh and SUBSTITUTE SHEET their performance tested with the Grob test mixture 4 » 5 . Finally the columns were washed slowly with 5ml of methylene chloride over a period of 5-6h, dried in a stream of nitrogen and conditioned overnight at 300 β C before re-testing. Preparation of Selective Medium Polar Polymethylsiloxane Columns Cleaning of the glass tubing, leaching, rinsing, dehydration and deactivation by persilylation were carried out as described for the non^polar columns. A solution for static coating was prepared by first dissolving SE54 in pentane and then adding from 5 to 50% w/w of the unsaturated barbiturate monomers (I, II or III). Finally, 0.5-10% w/w dicumyl peroxide (2% in toluene; DCUP) was added. The ratio of barbiturate monomer to that of dicumyl peroxide was varied in order to find the optimal amount for each barbiturate monomer • . After static coating as described above, the column was flushed with dry nitrogen for lh and cured according to the method of Blomberg 2 detailed above. The oven was cooled rapidly and the column flushed with dry nitrogen at room temperature. The ends of the columns were straightened under a flow of nitrogen using a Carlo Erba GESM 102-20 automatic electrical end-straightening machine. The column was conditioned at 250°C for lh and tests run. Finally the column was washed with 5ml methylene chloride, dried in a stream of nitrogen and re-conditioned overnight at 300°C before re-testing. REFERENCES 1. K. Grob, G. Grob and K. Grob, Jr., J. High Resolut. Chromatogr. Chromatogr. Commun., ' 2: (1979) 677. 2. L. Blomberg, J. Buijten, K. Markides, and T. Wannman, J. High Resolut. Chromatogr. Chromatogr. Commun., 4_ (1981) 578. 3. K. Grob, G. Grob, W. Blum, and W. Walther, J. Chromatogr. 244 (1982) 197. 4. K. Grob, Jr., G. Grob, and K. Grob, J. Chromatogr., 156 (1978) 1. 5. K. Grob, G. Grob, and K. Grob, Jr., J. Chromatogr., 219 (1981) 13. Gas Chromatography Capillary GC was performed with a standard Hewlett Packard Model 5710A GC modified for capillary GC analysis and equipped with a flame ionisation detector. The carrier gas was nitrogen with injector and detector temperatures of 300°C. An equimolar mixture of butobarbital (1) and butalbital (2) was chromatographed on a reference column of known type and on a column prepared in accordance with the present invention. The reference column was an SE 54 column with 1% by weight DCUP; P23m x 0.23 mm; DPTMDS persilylated. The new column was an SE 54 column with 30% by weight of the new barbiturate monomer 1,3 diallyl-5-ethyl -5- isoamyl barbituric acid, incorporated and 3% by weight DCUP; P23 x 0.23 mm; DPTMDS persilylated. RESULTS Fig. 1 shows the chromatogram obtained on the reference column in which the butobarbital (1) and butalbital (2) are unresolved, while Fig. 2 shows the same substances substantially resolved on the new column of the present invention described above.

Claims: CLAIMS 1. Polyalkylsiloxane derivatives of the general formula wherein m is a number not less that 2, and in at least one monomer unit each of Y and Z is a substituted carbon group and together form a chain linkage of at least 4 atoms and X is an optionally substituted alkyl or aryl or heterocyclic group, and in any remaining monomer units X,Y and Z together represent an alkyl or aralkyl or alkyl heterocyclic or aralkyl heterocyclic group, R is an alkyl group and R and 2 R are the same or different and each is a generally unreactive polymer chain terminating group which is an optionally substituted alkyl or aryl or heterocyclic group. 2. A derivative according to claim 1 wherein at least one of Y and Z is an optionally substituted -CH 2 -CH_- moiety. 3. A derivative according to claim 1 or claim 2 wherein one of Y and Z is an optionally substituted -CH = N - moiety. 4. A derivative according to any one of claims 1 to 3 wherein X represents an optionally further substituted alkyl, or aryl or heterocyclic group substituted by a group of the formula -Y-Z-Q wherein Y and Z have the same meaning as in formula I and Q is an alkyl-substituted polysiloxane whereby said derivative comprises a cross- linked polysiloxane. 5. A derivative according to any one of claims 1 to 4 wherein X represents an optionally further substituted alkyl, or aryl or heterocyclic group substituted by a group of the formula -Y-Z-J wherein Y and Z have the same meaning as in formula I and J represents another monomer unit of the polysiloxane polymer chain of the derivative of formula I whereby X is divalently bonded to different monomer units of the same polysiloxane polymer chain. 6. A derivative according to any one of claims 1 to 5 wherein X represents an optionally substituted barbituric acid moiety. 7. A derivative according to any one of claims 1 to 6 which is at least 99% pure. 8. A method of making a polyalkylsiloxane derivative of the general formula I according to claim 1 which method comprises the steps of reaction of an unsaturated polyalkylsiloxane compound of general formula II R wherein m is a number not less than 2, R, R 1, and R2 have the same meaning as in formula I and in at least one monomer unit Z is an unsaturated substituted carbon group, and m is a positive number, with a compound of the general formula ' III χ _ y l (III) wherein X is optionally substituted alkyl or aryl or heterocyclic group and Y is an unsaturated substituted carbon group such that Z and Y together have at least four carbon atoms and in any remaining units Z represents an alkyl or aralkyl group, so as to form a said derivative of general formula I and separating said compound of general formula I from the reaction mixture. 9. A method according to claim 8 wherein the reaction is carried out under free radical-forming conditions. 10. A capillary column suitable for use in capillary column gas chromatography and coated with a polymethylsiloxane derivative of the general formula I according to claim 1. 11. A method of chromatographic fractionation of a mixture of at least two different compounds of the general formula X as defined hereinbefore characterized by the use of a capillary column according to claim 10.

Inventors: CADDY BRIAN, CADDY, BRIAN
Applicants: UNIV STRATHCLYDE, UNIVERSITY OF STRATHCLYDE
Application year: 1985
Main classification: C08G77
IPC codes: B01J20, C08G77