Benzophenone derivatives and polymers containing phenolic hydroxyl groups.

0001The invention relates to polymers of the formulas (II), (ie IIa and IIb)<chemistry id="chem0001" num="0001"><img file="EP0442068A2_D0001.tif" /></chemistry> wherein A = residue of a polymer of anionically polymerizable vinyl compounds Y = OH o = 1, 2, R = C₁-C₄-alkyl, C₁-C₄-alkoxy, l, m = 0, 1, 2 but l + m ≧ 1 n = 0, 1, 2; and a process for their manufacture.

0002The polymers of the formula (II) can be prepared by combining anionic "living" polymers with benzophenone derivatives of the formula (I)<chemistry id="chem0002" num="0002"><img file="EP0442068A2_D0002.tif" /></chemistry> wherein Z = -OSi (C₁-C₄-alkyl) ₃ and the remaining recte are reacted as in formula (II) and the reaction products are solvolized in a neutral or acidic environment.

0003Preferred benzophenone derivatives of the formula (I) are those in which l + m = 1, 2 or 3. They can be prepared in a manner known per se by reacting those compounds of the formula (I) in which Z is —OH with trialkylchlorosilanes in the presence an acid scavenger, or by reaction with other known silylating agents such as hexamethylenedisilane resins or hexamethylsilylformamide. Suitable starting materials are, for example 2-hydroxy-benzophenone 4-hydroxy-benzophenone 2-hydroxy-4'-methyl-benzophenone 4-hydroxy-4'-methyl-benzophenone 6-hydroxy-3-methyl-benzophenone 4-hydroxy-2-methoxy-benzophenone 2-hydroxy-4-methoxy-benzophenone 4-hydroxy-3-methoxy-benzophenone 3-hydroxy-4'-methoxy-benzophenone 4-hydroxy-4'-methoxy-benzophenone 3-hydroxy-2,4-dimethoxy-benzophenone 2-hydroxy-3,4-dimethoxy-benzophenone 2-hydroxy-4,5-dimethoxy-benzophenone 2-hydroxy-4,6-dimethoxy-benzophenone 2-hydroxy-4,4'-dimethoxy-benzophenone 2-hydroxy-3,4'-dimethoxy-benzophenone 3-hydroxy-2 ', 4'-dimethoxy-benzophenone 4-hydroxy-3,5-dimethoxy-benzophenone 4-hydroxy-3,4'-dimethoxy-benzophenone 2,4-dihydroxy-benzophenone 2,6-dihydroxy-benzophenone 2,5-dihydroxy-benzophenone 3,4-dihydroxy-benzophenone 2,4-dihydroxy-3'-methoxy-benzophenone 2,4-dihydroxy-4'-methoxy-benzophenone 2,5-dihydroxy-4-methoxy-benzophenone 2,6-dihydroxy-4-methoxy-benzophenone 4,4'-dihydroxy-benzophenone 3,3'-dihydroxy-benzophenone 3,4'-dihydroxy-benzophenone 2,3'-dihydroxy-benzophenone 2,2'-dihydroxy-benzophenone 3,4'-dihydroxy-benzophenone 2,2'-dihydroxy-4-methoxy-benzophenone 2,4,4'-trihydroxybenzophenone 2,4,2 ', 4'-tetrahydroxybenzophenone

0004Are particularly suitable 4-hydroxy-benzophenone 4,4'-dihydroxy-benzophenone 2,4-dihydroxy-benzophenone

0005These benzophenones are known (see Beilstein 8 (4) 1262-1263, 2442-2453, 3160-3167).

0006The "living" polymers are known per se. They are anionically polymerized mono- and bifunctional polymers that are still polymerization-active. "Living" polymers can be prepared by polymerizing anionically polymerizable vinyl compounds in inert organic solvents with the aid of alkali metal alkyls or aryls. Suitable anionically polymerizable monomers are, for example Styrene, para-methylstyrene, vinylpyridine, vinylnaphthalene, isopropenylnaphthalene, 1,3-butadiene, isoprene, alkyl methacrylates, especially methyl methacrylate. Styrene, butadiene, isoprene and mixtures thereof are preferred.

0007Inert solvents for the polymerization are, for example, aromatic and aliphatic hydrocarbons such as toluene, benzene, xylene, pentane, hexane, cyclohexane or ethers such as tetrahydrofuran, tetrahydropyran, dioxane. Mixtures of solvents can also be used.

0008To produce monofunctional "living" polymers which lead to polymers of the formula II with o = 1, alkali metal alkyls such as n-butyl; s-butyl; 1,1-diphenylhexyl-; Cumyl lithium or potassium, n-butyl and s-butyllithium are preferred.

0009Alkali metal aryls, in particular naphthalene sodium, naphthalene potassium, oligo-α-methylstyrene sodium or potassium, 1.3 are used as initiators for the preparation of bifunctional “living” polymers which lead to polymers of the formula II with o = 2 -Phenylene-bis (3-methyl-1-phenylpentylidene) bis (lithium). The polymerization generally takes place at -100 to + 100 °, preferably at -80 to + 80 ° C. The most favorable reaction temperature also depends on the solvent.

0010The polymerization is carried out according to the known rules of anionic polymerization. In particular, conditions must be observed under which carbanions are stable (exclusion of oxygen and moisture).

0011To produce the polymers according to the invention, the living polymer anions are reacted with compounds of the formula (I) at -50 to + 100 ° C., preferably at 0 to 50 ° C. A small molar excess is preferably used, for example from 0.01 to 0.3 mol. This reaction also works with "living" carbanions and must therefore also be carried out under conditions under which carbanions are stable.

0012The polymers according to the invention are formed from the reaction product of the "living" polymers with the compounds of the formula (I) by elimination of the silyl ether groups and, if appropriate, by elimination of water.

0013Solvolysis of the silyl ethers is possible by reacting the reaction products with water, alcohols or weak acids. Suitable solvolytics are lower aliphatic alcohols such as methanol, ethanol, isopropanol and the various butanols. Suitable weak acids are carbonic acid, formic acid, acetic acid, propionic acid, succinic acid, adipic acid. These solvolytics are generally used in excess. This type of solvolysis gives polymers of the formula (IIa). In order to produce products of the formula (IIb), strong acids are used as solvolytics and the process is carried out at elevated temperature, for example 40 to 150 ° C. Suitable strong acids are, for example, hydrogen chloride, hydrogen bromide, sulfuric acid, sulfonic acid, phosphoric acid, phosphorous acid, phosphonic acid, trichloroacetic acid and oxalic acid. Toluene sulfonic acid, phosphoric acid, phosphorous acid and oxalic acid are particularly suitable. These acids are used as aqueous solutions or together with alcohol, also in excess.

0014The polymers of the formulas (II) can be obtained from the reaction products thus obtained by precipitation with alcohols or by evaporation. The polymers of the formulas (II) generally have molecular weights of 500 to 500,000 g / mol, preferably 1000 to 250,000 g / mol and particularly preferably 1500 to 150,000 g / mol. They are suitable as precursors for the production of block copolymers and block condensates due to the convertible aromatic hydroxyl groups.

Examples

example 1

4-trimethylsilyloxy benzophenone

0015A mixture of 99 g (0.5 mol) of 4-hydroxybenzophenone, 50 g (0.5 mol) of dry triethylamine and 800 ml of dry xylene was added dropwise with 55 g (0 , 5 mol) of freshly distilled trimethylchlorosilane and stirred at 50 ° C for 2 hours. After filtration and washing the filter cake with dry xylene, the combined filtrates were evaporated and the high-boiling residue was distilled under high vacuum. 133 g (approx. 100 % of theory) 4-trimethylsilyloxy-benzophenone an almost colorless liquid of bp 110 to 115 ° C / 0.9 to 1.1 mbar and a refractive index of n<maths id="math0001" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>20</mtext></mrow><mrow><mtext>D</mtext></mrow></mfrac></mrow></math><img file="EP0442068A2_D0003.tif" /></maths> = 1.5636 and a purity of 99.2% determined by gas chromatography.

Example 2

2,4-bis (trimethylsilyloxy) benzophenone

0016A mixture of 107 g (0.5 mol) of 2,4-dihydroxybenzophenone, 100 g (1 mol) of dry triethylamine and 1100 ml of dry xylene was added dropwise with 109 g (1 Mol) of freshly distilled trimethylchlorosilane are added and the mixture is stirred at 50 ° C. for a further 3 hours. After filtration and washing the filter cake with dry xylene, the combined filtrates were evaporated and the high-boiling residue was distilled under high vacuum. 177 g (approx. 99 % of theory) 2,4-bis (trimethylsilyloxy) benzophenone of a light oil with a kP of 185 to 190 ° C / 1.2 to 1.4 mbar and a refractive index of n<maths id="math0002" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>20</mtext></mrow><mrow><mtext>D</mtext></mrow></mfrac></mrow></math><img file="EP0442068A2_D0004.tif" /></maths> = 1.5582 and a purity of 98.7% determined by gas chromatography.

Example 3

4,4'-bis (trimethylsilyloxy) benzophenone

0017To a mixture of 214 g (1 mol) of 4,4-dihydroxybenzophenone, 210 g (2.1 mol) of dry triethylamine and 1500 ml of dry xylene were added under nitrogen and stirring at about 50 ° C for 1.5 hours 229 g ( 2.1 mol) of freshly distilled trimethylchlorosilane and stirred for 5 hours at 50 to 120 ° C. After filtering the hot mixture and washing the filter cake with hot dry xylene, the combined filtrates were evaporated and the residue was distilled under high vacuum. This gave 323 g (about 90% of theory) of 4,4'-bis (trimethylsilyloxy) benzophenone of a light oil with a bp of 186 to 190 ° C / 1.1 to 1.3 mbar, a refractive index of n<maths id="math0003" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>20</mtext></mrow><mrow><mtext>D</mtext></mrow></mfrac></mrow></math><img file="EP0442068A2_D0005.tif" /></maths> = 1.5429 and a purity of 98.2% determined by gas chromatography.

Example 4

Reaction of polystyryllithium with 4-trimethylsilyloxy-benzophenone (molar mass M

w

2600 g / mol)

0018To a mixture of 150 ml of toluene and 12 ml of s-butyllithium (1.3 molar solution in cyclohexane / isopentane (92: 8)) 25 ml (0.218 mol) of styrene were added under N₂ atmosphere within 15 minutes at 20 ° C and added with stirring. After a polymerization time of 60 minutes, a sample was taken from the polymer solution. The polymer was isolated by precipitation in methanol, filtration and drying (yield: 3.6 g) (sample 1). 6 g (0.022 mol) of 4-trimethylsilyloxy-benzophenone were then added to the orange-red polystyryllithium solution. The solution turned dark green. After a reaction time of 120 minutes, the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and subsequent drying. The yield was 16.3 g. For elimination of water and silyl ether , the polymer was dissolved in 150 ml of tetrahydrofuran, 10 ml of 1 molar methanolic phosphoric acid were added and the mixture was heated under reflux for 3 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis (polystyrene calibration):

0019<dl id="dl0001"><dt>Sample 1:</dt><dd><o ostyle="single">M</o>_n = 1600 g / mol, <o ostyle="single">M</o>_w = 1700 g / mol</dd><dt>End product:</dt><dd><o ostyle="single">M</o>_n = 2100 g / mol, <o ostyle="single">M</o>_w = 2600 g / mol, absorption at the wavenumber 3585 cm⁻¹</dd></dl> (<o ostyle="single">M</o>_n = Number average molecular weights, <o ostyle="single">M</o>_w = Weight average molecular weights).

Example 5

Reaction of polystyryllithium with 4-trimethylsilyloxy-benzophenone (molar mass M

w

= 3000 g / mol)

0020To a mixture of 150 ml of toluene and 6 ml of s-butyllithium (1.3 molar solution in cyclohexane / isopentane (92: 8)) 25 ml (0.218 mol) of styrene were added under N₂ atmosphere within 15 minutes at 20 ° C. and added with stirring. After a polymerization time of 60 minutes, a sample was taken from the polymer solution. The polymer was isolated by precipitation in methanol, filtration and drying (yield: 4.5 g) (sample 1). 3 g (0.011 mol) of 4-trimethylsilyloxybenzophenone were then added to the orange-red polystyryllithium solution. The solution turned dark green. After a reaction time of 120 minutes, the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and subsequent drying. The yield was 19.4 g. For elimination of water and silyl ether, the polymer was dissolved in 150 ml of tetrahydrofuran, 10 ml of 1 molar methanolic phosphoric acid were added and the mixture was heated under reflux for 3 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis of the end product (polystyrene calibration):

0021M_n = 2600 g / mol, M_w = 3000 g / mol Absorption at the wavenumber 3585 cm⁻¹

Example 6

Reaction of polystyryllithium with 4-trimethylsilyloxy-benzophenone (molar mass M

w

= 180,000 g / mol)

0022To a mixture of 300 ml of toluene and 50 ml (0.436 mol) of styrene were 0.7 ml of s-butyllithium (1.3 molar solution in cyclohexane / isopentane (92: 8)) at 20 ° C and under an N₂ atmosphere Stir given. After a polymerization time of 4 h at 40 ° C, the orange-red polystyryllithium solution was mixed with 0.5 g (1.85 x 10⁻³ mol) of 4-trimethylsilyloxy-benzophenone. The solution turned green. After a reaction time of 2 h, the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and subsequent drying. The yield was 30.7 g. For elimination of water and silyl ether, the polymer was dissolved in 150 ml of tetrahydrofuran, 10 ml of 1 molar methanolic phosphoric acid were added and the mixture was heated under reflux for 3 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis (polystyrene calibration):

0023M_n = 55,000 g / mol, M_w = 180,000 g / mol

Example 7

Reaction of bifunctional polystyryl sodium with 4-trimethylsilyloxybenzophenone (molar mass M

w

49,000 g / mol)

002450 g (0.48 mol) of styrene were added dropwise to a solution of 0.01 mol of naphthalene sodium in 210 ml of tetrahydrofuran at -78 ° C. A sample was taken after a polymerization time of 1 hour at this temperature.

0025The polymer was isolated by precipitation in methanol, filtration and drying (yield: 2.9 g) (sample 1). 4 g (0.0148 mol) of 4-trimethylsilyloxybenzophenone were then added to the orange-red polystyryl sodium solution. After a further 2 h at -78 ° C the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and drying (yield: 40.7 g) (sample 2). For elimination of water and silyl ether, 25 g of the polymer were dissolved in 150 ml of tetrahydrofuran, 20 ml of 1 molar methanolic hydrochloric acid were added and the mixture was heated under reflux for 2 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis (polystyrene calibration:

0026<dl id="dl0002"><dt>End product:</dt><dd> M_n = 28,000 g / mol; M_w = 49,000 g / mol</dd></dl>

Example 8

Reaction of polystyryllithium with 4,4'-bis (trimethylsilyloxy) benzophenone (molar mass M

w

= 4700 g / mol)

0027To a mixture of 400 ml of toluene and 8.5 ml of n-butyllithium (3.6 molar solution in hexane), 50 ml (0.436 mol) of styrene were added under N₂ atmosphere within 15 minutes at 20 ° C. and with stirring. After a polymerization time of 60 minutes, 37 g of polymer solution were removed and the product was isolated by precipitation in methanol, filtration and drying (yield: 4.6 g) (sample 1). 15 g (0.042 mol) of 4,4'-bis (trimethylsilyloxy) benzophenone in 20 ml of toluene were then added to the orange-red polystyryllithium solution. The solution turned dark green. After a reaction time of 120 minutes, the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and subsequent drying. The yield was 37.3 g (sample 2). For elimination of water and silyl ether, 27 g of sample 2 were dissolved in 150 ml of tetrahydrofuran, 20 ml of 1 molar methanolic hydrochloric acid were added and the mixture was heated under reflux for 3 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis of the end product (polystyrene calibration):

0028M_n = 3600 g / mol, M_w = 4700 g / mol<dl id="dl0003"><dt>IR spectroscopy:</dt><dd> Absorption bands of the hydroxyl functions at 3610 cm⁻¹, 1260 cm⁻¹, 1170 cm⁻¹</dd></dl>

Example 9

Reaction of polystyryllithium with 4,4'-bis (trimethylsilyloxy) benzophenone (molar mass M

w

6000 g / mol)

0029To a mixture of 400 ml of toluene and 4 ml of n-butyllithium (3.6 molar solution in hexane), 50 ml (0.436 mol) of styrene were added within 15 minutes at 20 ° C. and with stirring under an N₂ atmosphere. After a polymerization time of 60 minutes, 38 g of polymer solution were removed and the product was isolated by precipitation in methanol, filtration and drying (yield: 4.9 g) (sample 1). 9 g (0.025 mol) of 4,4'-bis (trimethylsilyloxy) benzophenone in 12 ml of toluene were then added to the orange-red polystyryllithium solution. The solution turned dark green. After a reaction time of 120 minutes, the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and subsequent drying. The yield was 42.3 g (sample 2). For elimination of water and silyl ether, 32 g of sample 2 were dissolved in 150 ml of tetrahydrofuran, 20 ml of 1 molar methanolic hydrochloric acid were added and the mixture was heated under reflux for 3 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis of the end product (polystyrene calibration):

0030M_n = 4600 g / mol, M_w = 6000 g / mol<dl id="dl0004"><dt>IR spectroscopy:</dt><dd> Absorption bands of the hydroxyl functions at 3610 cm⁻¹, 1260 cm⁻¹, 1170 cm⁻¹</dd></dl>

Example 10

Reaction of polystyryllithium with 4,4'-bis (trimethylsilyloxy) benzophenone (molar mass M

w

26 500 g / mol)

00311.75 ml of s-butyllithium (1.3 molar solution in cyclohexane / isopentane (92: 8)) at 20 ° C. and with stirring were added to a mixture of 400 ml of toluene and 50 ml (0.436 mol) of styrene under an N₂ atmosphere given. After a polymerization time of 3 h at 40 ° C, the orange-red polystyryllithium solution was mixed with 1.6 g (4.5 x 10⁻³ mol) of 4,4'-bis (trimethylsilyloxy) benzophenone in 2 ml of toluene. The solution turned green. After a reaction time of 2 h, the solution was poured into 1000 ml of methanol.

0032The precipitated polymer was obtained by filtration and subsequent drying. The yield was 45 g. For elimination of water and silyl ether, the polymer was dissolved in 150 ml of tetrahydrofuran, 10 ml of 1 molar methanolic phosphoric acid were added and the mixture was heated under reflux for 3 h. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis of the end product (polystyrene calibration):

0033M_n = 23,500 g / mol, M._w = 26,500 g / mol

Example 11

0034Reaction of polystyryllithium with 4,4'-bis (trimethylsilyloxy) benzophenone (molar mass M_w 95,000 g / mol)

0035To a mixture of 400 ml of toluene and 50 ml (0.436 mol) of styrene was 0.7 ml of s-butyllithium (1.3 molar solution in cyclohexane / isopentane (92: 8)) at 20 ° C and under N₂ atmosphere Stir given. After a polymerization time of 4 hours at 40 ° C, the orange-red polystyryllithium solution was mixed with 1 g (2.8 x 10⁻³ mol) of 4,4'-bis (trimethylsilyloxy) benzophenone in 1.3 ml of toluene. After a reaction time of 2 hours, the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and subsequent drying. The yield was 43.3 g. For elimination of water and silyl ether, the polymer was dissolved in 150 ml of tetrahydrofuran, 10 ml of 1 molar methanolic phosphoric acid were added and the mixture was heated under reflux for 3 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis of the end product (polystyrene calibration):

0036M_n = 75,000 g / mol, M_w = 95,000 g / mol

Example 12

Reaction of polystyryllithium with 4,4'-bis (trimethylsilyloxy) benzophenone (molar mass M

w

285,000 g / mol)

0037To a mixture of 400 ml of toluene and 50 ml (0.436 mol) of styrene were 0.35 ml of s-butyllithium (1.3 molar solution in cyclohexane / isopentane (92: 8)) at 20 ° C and under N₂ atmosphere Stir given. After a polymerization time of 6 hours at 40 ° C, the orange-red polystyryllithium solution was mixed with 1 g (2.8 x 10⁻³ mol) of 4,4'-bis (trimethylsilyloxy) benzophenone in 1.3 ml of toluene. The solution turned green. After a reaction time of 2 h, the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and subsequent drying. The yield was 29.1 g. For elimination of water and silyl ether, the polymer was dissolved in 150 ml of tetrahydrofuran, 10 ml of 1 molar methanolic phosphoric acid were added and the mixture was heated under reflux for 3 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis of the end product (polystyrene calibration):

0038M_n = 140,000 g / mol, M_w = 285,000 g / mol

Example 13

Reaction of polyisopropenyllithium with 4,4'-bis (trimethylsilyloxy) benzophenone (molar mass M

w

2300 g / mol)

0039To a mixture of 150 ml of toluene and 6.7 ml of n-butyllithium (2.5 molar solution in hexane) 25 g (0.733 mol) of isoprene were added within 15 minutes at 20 ° C. and with stirring under an N₂ atmosphere. After a polymerization time of 2 hours, 7.5 g (0.021 mol) of 4,4'-bis (trimethylsilyloxy) benzophenone in 5 ml of toluene were added to the reaction mixture, the solution turning yellow-green. After a reaction time of 2 hours, the solution was poured into 1000 ml of methanol. The polymer settled like a gel. The supernatant solvent / precipitant mixture was decanted off. For elimination of water and silyl ether, the polymer gel was dissolved in 50 ml of tetrahydrofuran, 5 ml of 1 molar methanolic hydrochloric acid were added and the mixture was heated under reflux for 3 hours. The polymer was then recovered by pouring the solution into methanol, decanting the solvent / precipitant, washing with methanol and drying (yield 24 g).

GPC analysis of the end product (polystyrene calibration):

0040M_n = 1800 g / mol, M_w = 2300 g / mol Absorption at the wavenumber 3585 cm⁻¹

Example 14

Reaction of a "living" styrene / isoprene block copolymer with 4,4'-bis (trimethylsilyloxy) benzophenone

00425 ml of s-butyllithium (1.3 molar solution in cyclohexane / isopentane (92: 8)) at 20 ° C. and under were added to a mixture of 3 l of toluene and 125 g (1.20 mol) of styrene under an N₂ atmosphere Stir given. After a polymerization time of 1 hour at 40 ° C., 375 g (5.50 mol) of isoprene were added to the orange-red polystyryllithium solution, the solution turning light yellow. After a further 3 hours at 40 ° C, 3 g (8.4 x 10⁻³ mol) of 4,4'-bis (trimethylsilyloxy) benzophenone in 2 ml of toluene were added. The solution now turned green. After 2 hours at 20 ° C., 20 ml of 1 molar methanolic hydrochloric acid and 2 l of toluene were added. The solution was refluxed for 3 hours. The solution was then concentrated and the polymer was obtained by precipitation in about 10 l of methanol, filtration and drying (yield 456 g).

GPC analysis of the end product (polystyrene calibration):

0043M_n = 95,000 g / mol, M_w = 130,000 g / mol

Example 15

Reaction of bifunctional polystyryl sodium with 4,4'-bis (trimethylsilyloxy) benzophenone (molar mass M

w

9400 g / mol)

004425 g (0.24 mol) of styrene were added dropwise to a solution of 0.033 mol of naphthalene sodium in 130 ml of tetrahydrofuran at -78 ° C. After a polymerization time of 2 hours at this temperature, 20 g (0.056 mol) of 4,4'-bis (trimethylsilyloxy) benzophenone were added to the orange-red polystyryl sodium solution. After a further 2 hours at -78 ° C the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and drying (yield: 22.7 g). For elimination of water and silyl ether, the polymer was dissolved in 150 ml of tetrahydrofuran, 20 ml of 1 molar methanolic hydrochloric acid were added and the mixture was heated under reflux for 2 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis of the end product (polystyrene calibration):

0045M_n = 4900 g / mol, M_w = 9400 g / mol

Example 16

Reaction of polystyryllithium with 2,4-bis (trimethylsilyloxy) benzophenone (molar mass M

w

2500 g / mol)

0046To a mixture of 200 ml of toluene and 12 ml of s-butyllithium (1.3 molar solution in cyclohexane / isopentane (92: 8)) 25 ml (0.218 mol) of styrene were added at 20 ° C. and with stirring under an N₂ atmosphere . After a polymerization time of 5 hours at 20 ° C., the orange-red polystyryllithium solution was mixed with 6 g (0.017 mol) of 2,4-bis (trimethylsilyloxy) benzophenone dissolved in toluene, the solution turning reddish-brown. After a reaction time of 2 hours, the solution was poured into 1000 ml of methanol. The precipitated polymer was obtained by filtration and subsequent drying. The yield was 21.7 g. For elimination of water and silyl ether, the polymer was dissolved in 100 ml of tetrahydrofuran, 10 ml of 1 molar methanolic hydrochloric acid were added and the mixture was heated under reflux for 2 hours. The polymer was then isolated by precipitation in methanol, filtration and drying.

GPC analysis of the end product (polystyrene calibration):

0047M_n = 2000 g / mol, M_w = 2500 g / mol Absorption at the wavenumber 3585 cm⁻¹