Method for producing methacrylated benzophenones

Abstract

The invention relates to a process for preparing methacrylic esters of hydroxyl-functional benzophenones and to their use. Methacrylated benzophenones (benzophenone (meth)acrylates) can be prepared in high purity by the process of the invention, in a simple way and in a high yield.

Claims

1. A process for preparing a benzophenone (meth)acrylate, comprising: reacting a hydroxybenzophenone and a (meth)acrylic anhydride in the presence of a catalytic amount of a salt; wherein the molar ratio of (meth)acrylic anhydride to hydroxybenzophenone is in the range from 1.0:1.0 to 1.6:1.0; and wherein the salt is present in an amount of 0.2 to 5.0 mol % relative to the amount of (meth)acrylic anhydride.

2. The process according to claim 1, wherein the molar ratio is in the range from 1.05:1.0 to 1.5:1.0.

3. The process according to claim 1, wherein the hydroxybenzophenone is 4-hydroxybenzophenone.

4. The process according to claim 1, wherein the (meth)acrylic anhydride is methacrylic anhydride or acrylic anhydride.

5. The process according to claim 1, wherein the salt is sodium methacrylate.

6. The process according to claim 1, wherein the salt is present in an amount of 0.2 to 0.7 mol % relative to the amount of (meth)acrylic anhydride.

7. The process according to claim 1, wherein the reacting, takes place at a temperature in the range from 50 to 120 C.

8. The process according to claim 1, wherein the reacting takes place over 1 to 13 h.

9. The process according to claim 1, wherein the benzophenone (meth)acrylate is precipitated in water.

10. The process according to claim 1, wherein the benzophenone (meth)acrylate is employed as a monomer, a comonomer, or both in a polymerization process.

11. The process according to claim 1, wherein the benzophenone (meth)acrylate is employed as a photocrosslinker of a polymer.

12. The process according to claim 1, wherein the benzophenone (meth)acrylate is employed as a polymeric photoinitiator.

13. The process according to claim 1, further comprising at least one selected from the group consisting of quenching by contacting with water to precipitate the benzophenone (meth)acrylate, and esterifying unreacted (meth)acrylic anhydride by the addition of methanol.

14. A process for preparing a benzophenone (meth)acrylate, comprising: reacting a hydroxybenzophenone and a (meth)acrylic anhydride in the presence of a catalytic amount of a salt; wherein the molar ratio of (meth)acrylic anhydride to hydroxybenzophenone is 1.0:1.0 to 1.6:1.0; and wherein the salt is selected from the group consisting of sodium acetate, lithium acetate, potassium acetate, lithium (meth)acrylate, sodium eth acrylate, potassium (meth)acrylate and mixtures thereof.

15. The process according to claim 14, wherein the salt is sodium methacrylate.

16. The process according to claim 14, wherein the salt is present in an amount of 0.2 to 5.0 mol % relative to the amount of (meth)acrylic anhydride.

17. The process according to claim 14, wherein the molar ratio of (meth)acrylic anhydride to hydroxybenzophenone is 1,0:1,0 to 1.2:1.0.

18. The process according to claim 15, wherein the sodium (meth)acrylate is generated in situ from sodium methoxide.

19. A process for preparing a benzophenone (meth)acrylate, comprising: reacting a hydroxybenzophenone and a (meth)acrylic anhydride in the presence of a catalytic amount of a salt selected from the group consisting of sodium acetate, lithium acetate, potassium acetate, lithium (meth)acrylate, sodium (meth)acrylate. potassium (meth)acrylate and mixtures thereof; and quenching by contacting with water to precipitate the benzophenone (meth)acrylate.

20. The process according to claim 19, further comprising: esterifying unreacted (meth)acrylic anhydride by the addition of methanol prior to the quenching.

Description

EXAMPLES

(1) Abbreviations:

(2) MAAH (meth)acrylic anhydride MeOH methanol MMA methyl methacrylate MAA methacrylic acid NM30 solution sodium methoxide, 30% strength in methanol, from Evonik GC area % area percentages by gas chromatography GC; wt % weight percentages by gas chromatography HQME hydroquinone monomethyl ether AN acid number in mg KOH/g Topanol A 2,4-dimethyl-6-tert-butylphenol (polymerization inhibitor)

(3) Gas-chromatographic analysis: Instrument: Agilent 7820A with FID

(4) Capillary column DB5, 30 m long, diameter 0.25 mm, layer thickness 0.25 pm

(5) Injector temperature 250 C., detector temperature 300 C.

(6) Temperature programme: 80 C. for 2 min, then heat at 16 C./min to 300 C., and hold this temperature for 6 min.

Example 1

Sodium Methacrylate Catalyst Generated In Situ

(7) Apparatus: 2 l four-necked round-bottom flask with mechanical stirring, reflux condenser, air inlet, Pt100 temperature sensor, oil bath.

(8) Batch: 1.5 mol (297.9 g) of 4-hydroxybenzophenone, 1.65 mol (270.3 g) of MAAH, 0.0087 mol (1.6 g) of NM30 solution, 399 mg of 2,4-dimethyl-6-tert-butylphenol (Topanol A);

(9) Preparation of a 30% strength solution of 4-(methacryloyloxy)benzophenone in MMA: Addition of a total of 772 g of MMA

(10) Theoretical yield of 4-(methacryloyloxy)benzophenone: 399 g

(11) Procedure: 4-Hydroxybenzophenone was weighed out, and 126 g of the subsequently required MMA were added; a readily stirrable composition was formed. Then MAAH, Topanol A stabilizer and NM30 catalyst were added, air was introduced, and the batch was heated to 90 C. The course of the reaction was monitored by gas chromatography (a sample (approximately 1.5 ml) taken, diluted with approximately 5 ml of acetone, and filtered). After a total of 5 h at 90 C., the batch was cooled to 60 C., 30 g of methanol were added for conversion of the remaining MAAH, and the batch was stirred 60 C. for 1 h. The remainder of the MMA (646 g) was then added to the batch, to produce a 30% strength solution. After cooling with accompanying stirring, filtering took place through a pressure filter with Seitz T1000 filter layer (14 cm). Yield: 1320.4 g

(12) Analyses:

(13) Water content according to Karl Fischer: 0.03% Topanol A: 538 ppm GC area %: 52.543% MMA 9.491% MAA 0.829% 4-hydroxybenzophenone 0.701% 4-acetoxybenzophenone 34.921% 4-(methacryloyloxy)benzophenone GC; wt %: MMA 57.9% MAA 10.9% 4-(methacryloyloxy)benzophenone 28.5% Hazen colour number: 315 AN: 69=10.58% MAA

Example 2

Preparation of 4-(methacryloyloxy)benzophenone as Solid with Sodium Methacrylate Catalyst Produced In Situ

(14) Apparatus: see Example 1

(15) Batch: 4.0 mol (794.7 g) of 4-hydroxybenzophenone, 4.4 mol (723.7 g) of MAAH, 0.0228 mol (4.2 g) of NM30 solution, 1055 mg of Topanol A;

(16) Theoretical yield: 4-(methacryloyloxy)benzophenone: 1055.2 g

(17) Procedure: The batch was weighed out completely and then heated to 90 C. After a reaction time of 6 h, the 4-hydroxybenzophenone fraction was still 2.2% (GC analysis); a further 2 ml of NM30 solution was added and heating was continued.

(18) After a total of 11 h at 90 C., the batch was cooled to 60 C. and 80 g of methanol were added for esterification of the unreacted MAAH. The batch was subsequently stirred at 60 C. for 1 h. Then the batch was poured with stirring (metal paddle stirrer, stirring motor) as a thin stream into 3 I of water. After 0.5 h of stirring, the precipitate was isolated by suction filtration on a glass filter frit, washed once again with 2.0 I of water (stirred for 30 minutes in a glass beaker with a stirring motor with metal paddle stirrer) and then dried with suction on the suction filter. The solid was subsequently dried to constant mass in air. Yield: 1042.3 g

(19) Analyses:

(20) Water content (Karl Fischer): <0.1% Topanol A: 808 ppm GC: 0.066% MAA 1.239% 4-hydroxybenzophenone 1.785% 4-acetoxybenzophenone 95.574% 4-(methacryloyloxy)benzophenone Hazen colour number, 20% strength in acetone: 154

Example 3

Preparation of 4-(methacryloyloxy)benzophenone as Solid with Separately Prepared Sodium Methacrylate Catalyst

(21) Apparatus: see Example 1

(22) Batch: 0.5 mol (99.4 g) of 4-hydroxybenzophenone, 0.55 mol (88.3 g) of MAAH, 0.0125 mol (1.35 g) of sodium methacrylate, 133 mg of HQME, 133 mg of Topanol A;

(23) Theoretical yield of 4-(methacryloyloxy)benzophenone: 133.15 g

(24) Procedure: The batch was weighed out completely and then heated to 90 C. with introduction of air. The conversion was monitored by means of gas chromatography (GC). Composition after 1.5 h: 18.42% MAA, 2.5% MAAH, 0.83% hydroxybenzophenone, 75.84% 4-(methacryloyloxy)benzophenone. Cooling took place to 60 C., methanol (10 g) was added, and the batch was stirred at 60 C. for 1 h.

(25) Then the batch was poured with stirring (metal paddle stirrer, stirring motor) as a thin stream into 500 ml of water. After 0.5 h of stirring, the precipitate was isolated by suction filtration on a glass filter frit, washed twice again with 500 ml of water (stirred for 15 minutes each time in a glass beaker with a stirring motor with metal paddle stirrer) and then dried with suction on the suction filter. The solid was subsequently dried to constant mass in air. Yield: 131.1 g

(26) Analyses:

(27) Water content according to Karl Fischer: 0.21% HQME: 13 ppm Topanol A: 1305 ppm GC: 0.012% MMA 0.331% MAA 1.573% 4-hydroxybenzophenone 94.594% 4-(methacryloyloxy)benzophenone Colour number, 20% strength in acetone: 82

Example 4

Preparation of 4-(methacryloyloxy)benzophenone with Sodium Methacrylate Catalyst; Conversion Control

(28) Apparatus: see Example 1

(29) Batch: 0.5 mol (99.4 g) of 4-hydroxybenzophenone, 0.55 mol (88.3 g) of MAAH, 0.003 mol (0.32 g) of sodium methacrylate, 133 mg of HQME, 133 mg of Topanol A;

(30) Theoretical yield of 4-(methacryloyloxy)benzophenone: 133.15 g

(31) Procedure: The batch was weighed out completely and then heated to 90 C. The conversion was monitored by means of GC.

(32) Composition in wt %:

(33) TABLE-US-00001 4- Reaction Hydro- (Methacryloyloxy)benzo- time MAA MAAH xybenzophenone phenone 1 h 16.69 6.47 4.66 69.72 2 h 18.03 4.39 2.83 72.07 3 h 18.95 3.46 1.21 73.96 4 h 17.69 2.96 1.25 74.88

(34) Cooling took place to 60, methanol (9.6 g) was added to esterify the remaining

(35) MAAH, and the batch was stirred at 60 C. for 1 h. Then the batch was poured with stirring (metal paddle stirrer, stirring motor) as a thin stream into 500 ml of water. After 0.5 h of stirring, the precipitate was isolated by suction filtration on a glass filter frit, washed twice again with 500 ml portions of water (stirred for about 15 minutes each time in a glass beaker with a stirring motor with metal paddle stirrer) and then dried with suction on the suction filter.

(36) The solid was subsequently dried to constant mass in air. Yield: 136.7 g

(37) Analyses:

(38) H2O: 0.25% HQME: 15 ppm Topanol A: 1530 ppm GC: 1.064% MAA 2.571% 4-hydroxybenzophenone 92.754% 4-(methacryloyloxy)benzophenone Colour number, 20% strength in acetone: 144

Example 5

Sodium Acetate Catalyst

(39) Apparatus: 2 l four-necked round-bottom flask with mechanical stirrer, reflux condenser, air inlet tube and Pt100 temperature sensor, oil bath

(40) Batch:

(41) 0.5 mol of 4-hydroxybenzophenone, purity 99.9%=99.2 g

(42) 0.55 mol of methacrylic anhydride, purity 97.7%=86.9 g

(43) 0.0125 mol of sodium acetate, anhydrous=1.025 g

(44) Topanol A=93.2 mg

(45) For esterifying the excess methacrylic acid: 9.6 g of methanol

(46) Theoretical yield of 4-(methacryloyloxy)benzophenone: 133.2 g

(47) Procedure: 4-Hydroxybenzophenone was weighed out. Methacrylic anhydride, Topanol A and sodium acetate were then added and the batch was subsequently heated to 90 C. with supply of air. It was stirred for 6 h, then cooled to 60 C., and the methanol for esterifying the remaining methacrylic anhydride was added. Stirring took place for a further 1 h at 60 C. The batch was then introduced with stirring to 500 ml of H.sub.2O, stirred for 0.5 h, filtered with suction, and the solid was washed once again with 500 ml of water in a glass beaker, and then dried with suction on the suction filter. The product was dried in air.

(48) Yield: 130 g of 4-(methacryloyloxy)benzophenone

(49) Analyses:

(50) Water content: 0.36% Topanol A: 1390 ppm Hazen colour number (10% in acetone): 16 GC area %: 0.011% MMA 0.650% MAA 1.834% 4-hydroxybenzophenone 2.928% 4-acetoxybenzophenone 91.560% 4-(methacryloyloxy)benzophenone