RU2777539C2 - Method for production of keto-functionalized aromatic (meth)acrylates - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to a method for the production of keto-functionalized aromatic (meth)acrylates by introducing keto-functionalized aromatic alcohols or keto-functionalized aromatic amines with (meth)acrylic anhydride into the reaction, wherein keto-functionalized aromatic alcohol or keto-functionalized aromatic amine contains its keto-functional group adjacent to an aromatic system, contains either a free NH₂ group or a free OH group connected by means of a separation link to its aromatic systems, while the separation link is or contains simple oligoethers, alkyl-, aryl-, -esters, -simple thioesters, -amines, -composite esters, -composite thioesters or -amides, where reagents, products and a catalyst selected from strong inorganic or organic acids or bases are present together in a reaction matrix at a reaction temperature from 50°C to 120°C, characterized in that the staying time of reagents, products and catalysts is limited from 0.1 to no more than 4 hours, and (meth)acrylic anhydride is used with the content (meth)acrylic acetic anhydride mixed with (meth)acrylic anhydride, amounting to <4.5 wt.%.

EFFECT: obtaining keto-functionalized aromatic (meth)acrylates.

13 cl, 19 ex

Description

The present invention relates to a process for the preparation of keto-functionalized aromatic (meth)acrylates.

The prior art describes a process for preparing [(meth)acryloyloxy]benzophenone starting from (meth)acrylic anhydride (JP 2003261506, Mitsubishi Rayon). Triethylamine is used as a catalyst and reagent. Since the amine forms a salt with the methacrylic acid formed during the reaction, the amine must be equimolar with respect to the hydroxybenzophenone. Accordingly, equimolar amounts of salt are obtained, which must be disposed of as waste. Therefore, the economy of the method is low. In addition, the operation is carried out at very moderate temperatures (30°C), which, despite the large amount of catalyst, leads to long reaction times of >5 h. The process is thus also unfavorable in terms of volumetric productivity.

The more recent application WO 2017/146444 describes the enzymatic reaction of (meth)acrylic esters (eg vinyl acrylate) with 4-hydroxybenzophenone. The reaction takes place at moderate temperatures of about 60°C, reaction times are 8 hours. For isolation, drying is carried out for several days at 50°C. Thus, reaction times and isolation costs are uneconomical. The high yield and high purity of the product that can be achieved are mentioned to justify the excessive costs.

WO 2017/147040 describes a microflow reactor reaction between 4-hydroxybenzophenone and methacryloyl chloride in the presence of superstoichiometric amounts of triethylamine. The amount of salt produced that must be removed or recycled makes the process uneconomical and expensive.

Other prior art methods involve reacting (meth)acryloyl chloride with hydroxy-functional benzophenones and reacting this starting material with glycidyl methacrylate. When handling (meth)acryloyl chloride, the corrosive and caustic properties must be taken into account, and, in addition, stoichiometric amounts of a base, such as triethylamine, are always used. This makes this method very expensive. The use of glycidyl methacrylate is disadvantageous due to high toxicity.

WO 2010/072479 describes the preparation of [(meth)acryloyloxy]benzophenone in the presence of catalytic amounts of sulfuric acid. When the reaction is complete, the catalyst must be neutralized with an aqueous solution of sodium hydroxide and removed by filtration as sodium sulfate. Although this method is technically feasible, the long residence time of 4-8 hours however means that the volumetric rates are not advantageous. Despite the long residence time, the conversion of hydroxybenzophenone is incomplete, which is disadvantageous for subsequent use in the form of a polymer, for example, as an additive for paints and dyes. As is known, residual monomers and other molecules that have not been covalently incorporated into the polymer migrate throughout the life of the application and thus may be released into the environment, which is undesirable. No mention is made of other by-products that cannot be bonded, such as the monomer in the polymer.

WO 2015/049200 describes a process for the preparation of [(meth)acryloyloxy]benzophenone in the presence of catalytic amounts of basic salts. In this case, the reaction requires high residence times, typically 5 hours at 90°C. In addition, the process described there requires high stabilizer concentrations of over 2600 ppm Topanol A (based on 4-hydroxybenzophenone), which results in a high stabilizer concentration in the product of over 800 ppm. In this case, the by-products of the reaction are also quantified, namely the unreacted 4-hydroxybenzophenone and 4-acetoxybenzophenone, which in each case are of the order of a few percent with respect to the target products and remain in the product. Therefore, from the point of view of volumetric productivity, as well as the achievable quality of the product, this method is not optimal.

DE 1720603 describes a process for the preparation of aqueous dispersions of easily crosslinkable polymers. It involves the copolymerization of acrylic and methacrylic esters with photoactive unsaturated olefin-type monomers, with the optional concomitant use of photoactive non-ionic emulsifiers.

EP 0346788 describes a process for preparing radiation-sensitive carbamoylbenzo- and acetophenones containing at least one methacrylate or acrylate end group. It involves the introduction of the reaction of isocyanatoalkyl(meth)acrylates with hydroxyacetophenones or hydroxybenzophenones using a basic catalyst. In this case, it is necessary to work in the absence of moisture. In addition, only anhydrous non-nucleophilic solvents can be used.

The aim was to provide an improved process for the preparation of keto-functionalized aromatic (meth)acrylates.

The goal was achieved with a process for the preparation of keto-functionalized aromatic (meth)acrylates by reacting keto-functionalized aromatic alcohols or keto-functionalized aromatic amines and (meth)acrylic anhydride, in which the reactants, products and catalyst are present together in the reaction matrix at reaction temperature from 50°C to 120°C, characterized in that the residence time of the reagents, products and catalysts is limited from 0.1 to no more than 4 hours, and (meth)acrylic anhydride is used with a content of (meth)acrylic acetic anhydride, which is <4.5%.

Surprisingly, it has been found that with the process according to the invention, high conversions are achieved and the amount of by-products is significantly reduced.

It was found that the disadvantage of the method according to the present invention is only a small amount of salt, which is either used as a catalyst or is formed when the catalytic acid is neutralized during isolation. The (meth)acrylic acid generated as a by-product can be used in the subsequent polymerization of keto-functionalized aromatic (meth)acrylate monomers as a comonomer or can be processed to produce new (meth)acrylic anhydride.

Keto-functionalized aromatic (meth)acrylates

Presented are keto-functionalized aromatic (meth)acrylates,

where A = alkyl, aryl, heteroaryl, substituted by any desired selection from H, alkyl, aryl, halides, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ = different or identical to each other, selected from H, alkyl, halide, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

this also explicitly includes the closure of the ring between A and one of the radicals R _1-5 , for example, as a derivative of fluorenone;

and while one of the substituents R _1-5 is described by the following formula:

where n = 0-10, preferably n = 1-6;

R=alkyl, aryl, oligoether, CO;

R' = H, Me;

X = O, S, NH;

Y = O, NH.

Preferably:

presented keto-functionalized aromatic (meth)acrylates,

where A = alkyl, aryl, heteroaryl, substituted by any desired selection from H, alkyl, aryl, halides, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ = different or identical to each other, selected from H, alkyl, halide, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

this also explicitly includes the closure of the ring between A and one of the radicals R _1-5 , for example, as a derivative of fluorenone;

where R' = H, Me;

Y = O, NH.

and while one of the substituents R _1-5 is described by the following formula:

More preferably:

presented keto-functionalized aromatic (meth)acrylates,

where A = alkyl, aryl, heteroaryl, substituted by any desired selection from H, alkyl, aryl, halides, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ = different or identical to each other, selected from H, alkyl, halide, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

and while one of the substituents R _1-5 is described by the following formula:

where R' = H, Me;

Y = O, NH.

Even more preferably:

presented keto-functionalized aromatic (meth)acrylates,

where A = alkyl, aryl, substituted by any desired selection of H, alkyl, aryl, halides, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ = different or identical to each other, selected from H, alkyl, halide, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

and while one of the substituents R _1-5 is described by the following formula:

where R' = H, Me;

Y = O, NH.

Particularly preferred:

presented keto-functionalized aromatic (meth)acrylates,

where A = aryl, substituted by any desired selection of H, alkyl, aryl, halides, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ = different or identical to each other, selected from H, alkyl, halide, O-alkyl, NO ₂ , OH, sulfonyl, NH ₂ , N-alkyl ₂ ;

and while one of the substituents R _1-5 is described by the following formula:

where R' = H, Me;

Y = O, NH.

Most preferred:

presented keto-functionalized aromatic (meth)acrylates,

where A = aryl, substituted by any desired selection of H, alkyl, halides, O-alkyl, sulfonyl, N-alkyl ₂ ;

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ = different or identical to each other, selected from H, alkyl, halide, O-alkyl, sulfonyl, N-alkyl ₂ ;

and while one of the substituents R _1-5 is described by the following formula:

where R' = H, Me;

Y = O, NH.

Most preferred:

presented keto-functionalized aromatic (meth)acrylates,

where A = aryl substituted with any desired selection from H, alkyl, halides, O-alkyl, sulfonyl, N-alkyl2;

R1, R2, R3, R4 = different or identical to each other, selected from H, alkyl, halide, O-alkyl, sulfonyl, N-alkyl2;

R' = H, Me;

Y = O, NH.

Illustrative, non-limiting examples of keto-functionalized aromatic (meth)acrylates

The designation "(meth)acrylate" in this case means both methacrylate, such as methyl methacrylate, ethyl methacrylate, etc., and acrylate, such as methyl acrylate, ethyl acrylate, etc., and mixtures thereof.

Keto-functionalized aromatic alcohols and keto-functionalized aromatic amines

The keto functionalized aromatic alcohols or keto functionalized aromatic amines used are characterized in that they contain a keto functional group directly adjacent to the aromatic system and additionally contain an NH ₂ or OH group in the aromatic system (phenylamine/aniline; phenyl alcohol/phenol) or a spacer with a free NH ₂ or OH group (eg benzylamine, benzyl alcohol). The spacer may be or contain oligoethers, alkyl, aryl, ethers, thioethers, amines, esters, thioesters or amides. Preference is given to keto functionalized aromatic alcohols or amines which have an NH ₂ or OH group in the aromatic system. In addition, preference is given to derivatives in which two substituents representing keto functional groups are not directly linked to each other. In addition, preference is given to those keto-functionalized aromatic alcohols or amines which do not contain heteroatoms. Particularly preferred representatives of keto-functionalized aromatic alcohols or amines are benzophenone derivatives, most preferably benzophenone derivatives which are substituted with H, alkyl, halide, alkoxy, sulfonyl or dialkylamine groups. In this case, particular preference is given to derivatives of benzophenone, NH ₂ - or OH-functional group which is in para-position relative to the keto-functional group. The most preferred keto-functionalized alcohols or amines are the corresponding compounds which, according to the reaction of the present invention, provide the keto-functionalized aromatic (meth)acrylates of the present invention. Keto-functionalized aromatic alcohols or amines are typically >96% pure. This degree of purity can contribute to the achievement of low product color.

Catalyst

The reaction between keto-functionalized aromatic alcohols or keto-functionalized aromatic amines and (meth)acrylic anhydride can take place in the presence of acids, preferably conventional strong inorganic or organic acids having _a pKa value <2, and particularly preferably in the presence of sulfuric acid or alkyl- or arylsulfonic acids. Alternatively, bases have also proven to be suitable catalysts. Preferred bases in this case are carboxylate salts or other strong bases having a pK _b value < 9, such as sodium hydroxide, sodium methoxide or potassium hydroxide and mixtures thereof, since they form the corresponding (meth)acrylate salt in situ by reaction with ( meth)acrylic anhydride.

Preferably, the reaction is carried out in the presence of catalytic amounts of concentrated sulfuric acid or aqueous sodium hydroxide solution. Catalytic amounts are preferably from 0.01 to 3 mol. %, based on the (meth)acrylic anhydride used, and is particularly preferably 0.2 to 1.5 mol. % based on the (meth)acrylic anhydride used.

Stabilizer

Suitable stabilizers are known to those skilled in the art. These include, for example, phenothiazine, substances containing an oxyl radical such as 2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl ( TEMPOL) or 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidinyl-N-oxyl (TEMPOL-(meth)acrylate), as well as phenol derivatives such as hydroquinone monomethyl ether (HQME), 2.4 -dimethyl-6-tert-butylphenol (DMBP), 2,6-di-tert-butylphenol or 4-methyl-2,6-di-tert-butylphenol (BHT). Mixtures of different stabilizers can also be used. Preference is given to the use of hindered phenols; particular preference is given to the use of HQME, DMBP, BHT, as well as mixtures of these substances. Applications for keto-functionalized aromatic (meth)acrylates typically require colorless products. Therefore, in the case of unsaturated compounds, preference is given to non-staining stabilizers or coloring stabilizers in very small amounts. The amount of stabilizer used depends on the starting materials.

The amount of stabilizer at the beginning of the reaction is adjustable from 0 to 5000 ppm depending on the keto-functionalized aromatic alcohols or amines used. Preferably, the amount of stabilizer at the start of the reaction is adjusted in the range from 0 to 3000 ppm, based on the keto functionalized aromatic alcohols or amines used, particularly preferably from 50 to 2000 ppm.

(Meth)acrylic anhydride

(Meth)acrylic anhydride is added in slight excess to keto-functionalized aromatic alcohols or amines. In this case, the molar ratio of alcohol or amine to (meth)acrylic anhydride is selected from 1:1.01 to 1:4, preferably from 1:1.03 to 1:2, particularly preferably from 1:1.05 to 1 :1.5. (Meth)acrylic anhydride is used in a purity of >93%, preferably >94%, particularly preferably >96%, most preferably >98%.

Both the acetoxy derivative and the remaining alcohol or amine do not react during radical polymerization and are therefore present in the polymer in unbound form. These substances can migrate and therefore interfere with the control of polymer properties. In addition, toxic substances can potentially be released into the environment in this way. The high conversion of the alcohol or amine used is therefore of decisive importance. As a result, the above purity requirements are directly applicable to (meth)acrylic anhydride. The acetoxy derivative, in turn, comes from a mixed anhydride of (meth)acrylic acid and acetic acid, which is a typical impurity of (meth)acrylic anhydride. This substance preferentially carries an acetyl radical. To limit the content of the acetoxy derivative in the product, the (meth)acrylic anhydride used should contain a mixed anhydride of (meth)acrylic acid and acetic acid, hereinafter referred to as (meth)acrylic acetic anhydride, in an amount of <4.5 wt. %, preferably <3 wt. %, particularly preferably <1.5 wt. %.

Reaction conditions

The reaction is carried out at temperatures from 50°C to 120°C, preferably from 60°C to 95°C, particularly preferably from 70°C to 90°C, with a residence time of 0.1 to 4 hours, preferably from 1 to 3 hours.

To avoid the formation of undesirable by-products, the reaction is terminated after >90%, preferably >95%, particularly preferably >97% conversion of the reactant used.

Neutralization and isolation

When acids are used as a catalyst, the neutralization is carried out with aqueous base solutions, preferably with an aqueous alkali metal hydroxide solution or with an ammonia solution. Basic catalysts do not need to be neutralized. During the treatment of the catalyst, in the simplest case of neutralization, a color change may occur.

High purity keto-functionalized aromatic (meth)acrylates can be directly dissolved from the crude product in common organic solvents, (meth)acrylic esters, preferably methyl methacrylate, n-butyl methacrylate, isobutyl methacrylate and/or styrene, and also subsequently store and subsequently subject to reactions.

Preference is given to a mixture of 10-50 wt. % keto-functionalized aromatic (meth)acrylate in 30-80 wt. % methyl methacrylate in the presence of <15 wt. % (meth)acrylic acid; particular preference is given to a mixture of 25-35 wt. % keto-functionalized aromatic (meth)acrylate in 55-65 wt. % methyl methacrylate in the presence of 8-12 wt. % (meth)acrylic acid.

Subsequent isolation of the crude monomer can be carried out by adding water. In this case, the keto-functionalized aromatic (meth)acrylate precipitates upon addition of excess water and is isolated as a solid by filtration. It is also possible to introduce the crude monomer into the water. In this way, the (meth)acrylic acid formed during the reaction, the catalyst and the salts formed during its neutralization, and other water-soluble impurities are separated. However, as expected, significant depletion of unreacted reactant or acetylated by-product is not achieved in this way, indicating that (meth)acrylic anhydride with as low a mixed anhydride (meth) content as possible must be used to obtain a particularly pure product. acrylic acid and acetic acid.

An alternative isolation of the crude monomer can be carried out by adding organic solvents to the crude product at elevated temperatures, for example from 60 to 100°C. It is also possible to add the crude monomer to the organic solvent with the same result. Possible solvents are organic esters, for example methyl methacrylate or butyl acetate, linear or cyclic alkanes, preferably methylcyclohexane, or aromatic compounds, preferably toluene. In this case, the keto-functionalized aromatic (meth)acrylate is first dissolved and precipitated upon subsequent cooling to room temperature. The target product is isolated in solid form by filtration. Thus, methacrylic acid is separated, as well as the catalyst or salts formed during its neutralization. In addition, there is a slight decrease in the content of the by-product 4-(acetoxy)benzophenone.

Also, on the basis of the isolated pure product, it is possible to obtain corresponding solutions in common organic solvents, in (meth)acrylic esters, preferably in methyl methacrylate, in n-butyl methacrylate, in isobutyl methacrylate and/or in styrene.

Preferred method options

1. A method is presented for the preparation of keto-functionalized aromatic (meth)acrylates by introducing keto-functionalized aromatic alcohols or amines and (meth)acrylic anhydride into the reaction, in which the reagents, products and catalyst are present together in the reaction matrix at a reaction temperature of 50°C up to 120°C, which is characterized by the fact that the residence time of the reagents, products and catalysts is limited from 0.1 to no more than 4 hours, (meth)acrylic anhydride is used with a content of (meth)acrylic acetic anhydride of <4.5%, the amount of stabilizer at the start of the reaction is adjusted to between 0 and 5000 ppm, based on the keto-functionalized aromatic alcohols or amines used, and (meth)acrylic anhydride is used in >93% purity.

2. A method is presented for the preparation of keto-functionalized aromatic (meth)acrylates by introducing keto-functionalized aromatic alcohols or amines and (meth)acrylic anhydride into the reaction, in which the reagents, products and catalyst are present together in the reaction matrix at a reaction temperature of 50°C up to 120°C, which is characterized by the fact that the residence time of the reagents, products and catalysts is limited from 0.1 to no more than 4 hours, (meth)acrylic anhydride is used with a content of (meth)acrylic acetic anhydride of <4.5%, the amount of stabilizer at the start of the reaction is adjusted between 0 and 5000 ppm based on the keto-functionalized aromatic alcohols or amines used, and the reaction is terminated after >90% conversion of the reactant used.

3. A method is presented for the preparation of keto-functionalized aromatic (meth)acrylates by introducing keto-functionalized aromatic alcohols or amines and (meth)acrylic anhydride into the reaction, in which the reagents, products and catalyst are present together in the reaction matrix at a reaction temperature of 50°C up to 120°C, which is characterized by the fact that the residence time of the reagents, products and catalysts is limited from 0.1 to no more than 4 hours, (meth)acrylic anhydride is used with a content of (meth)acrylic acetic anhydride of <4.5%, the amount of stabilizer at the beginning of the reaction is adjusted in the range from 0 to 5000 ppm in terms of the keto-functionalized aromatic alcohols or amines used, and the reaction is carried out in the presence of catalytic amounts of acid.

4. A method is presented for the preparation of keto-functionalized aromatic (meth)acrylates by introducing keto-functionalized aromatic alcohols or amines and (meth)acrylic anhydride into the reaction, in which the reagents, products and catalyst are present together in the reaction matrix at a reaction temperature of 50°C up to 120°C, which is characterized by the fact that the residence time of the reagents, products and catalysts is limited from 0.1 to no more than 4 hours, (meth)acrylic anhydride is used with a content of (meth)acrylic acetic anhydride of <4.5%, the amount of stabilizer at the beginning of the reaction is adjusted in the range from 0 to 5000 ppm in terms of the keto-functionalized aromatic alcohols or amines used, and the keto-functionalized aromatic (meth)acrylate precipitates when water or an organic solvent is added to the reaction mixture, and it is isolated in a solid form by filtering.

5. A method is presented for the preparation of keto-functionalized aromatic (meth)acrylates by introducing keto-functionalized aromatic alcohols or amines and (meth)acrylic anhydride into the reaction, in which the reagents, products and catalyst are present together in the reaction matrix at a reaction temperature of 50°C up to 120°C, which is characterized by the fact that the residence time of the reagents, products and catalysts is limited from 0.1 to no more than 4 hours, (meth)acrylic anhydride is used with a content of (meth)acrylic acetic anhydride of <4.5%, the amount of stabilizer at the beginning of the reaction is adjusted in the range from 0 to 5000 ppm in terms of the keto-functionalized aromatic alcohols or amines used, and the keto-functionalized aromatic (meth)acrylate is obtained by adding liquid (meth)acrylic ester or styrene to the resulting mixture in in the form of a solution in said ester or in styrene.

In the coating and paint application, the Hazen color (also known as Pt-Co color) of the starting materials used is of decisive importance. The color of the products described herein can be reduced by the use of adsorbents, preferably activated carbon. In principle, various adsorbents are suitable which reduce the Pt-Co color after the reaction; these adsorbents are added to the crude mixture as a slurry and then removed again or, alternatively, they operate as a fixed bed. So, when using 10 wt. % activated charcoal, an APHA color reduction of about 100 is achieved in less than 2 hours. Since activated charcoal cannot be directly reused, this method is very expensive. Therefore, it is advantageous to maintain a low color even during the reaction, so that additional isolation is not required. To this end, the steps of the method according to claims 1-3 and 5-13 of the claims in the method of the present invention are preferably combined so that the APHA Pt-Co color scale for 30 wt. % solution of the reaction product after neutralization of the catalyst with a base of 60 wt. % MMA and 10 wt. % methacrylic acid was set to <500, preferably <400, particularly preferably <350.

Keto-functionalized aromatic (meth)acrylates can also be used for post-crosslinking polymers with daylight or UV light as polymeric photoinitiators (as described in WO 2010112474 A1 and references therein).

Keto-functionalized aromatic (meth)acrylates can additionally be used as a comonomer for polymerization reactions.

The following examples better illustrate the present invention, but without limiting the present invention to the features disclosed therein.

EXAMPLES

Abbreviations used:

4-HBP 4-hydroxybenzophenone

BpMA 4-(methacryloyloxy)benzophenone

GC Gas Chromatography

MAAH methacrylic anhydride

MAA methacrylic acid

MMA methyl methacrylate

Example 1

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.8%: 300 g;

1.70 mol MAAH (purity 98.48% (GC), methacrylic acetic anhydride 1.131%,

acetic anhydride was not detected;

stabilized with 1871 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

total stabilizer content at the start of the reaction: 1639 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.57 g (50% strength) aqueous sodium hydroxide solution;

esterification of excess methacrylic anhydride with 9.7 g of methanol (0.3 mol);

to obtain a solution in MMA with a concentration of 30%: 600 g MMA.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 3 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. The color of the reaction mixture changed from red to yellow. Then, stirring was carried out for 1 hour at 60°C, and then 600 g of methyl methacrylate was added to the mixture while stirring. The resulting solution was cooled to room temperature with stirring and filtered. A solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate has the following composition, determined by gas chromatography (numbers in wt%):

57.8% methyl methacrylate;

10.0% methacrylic acid;

0.30% 4-hydroxybenzophenone;

0.62% 4-(acetoxy)benzophenone;

29.4% 4-(methacryloyloxy)benzophenone;

The water content is 0.09%, the stabilizer content is 22 ppm 2,4-dimethyl-6-tert-butylphenol. The Pt-Co APHA color scale is 194.

During the reaction, samples were taken and isolated separately (cooling to 60° C., neutralization with aqueous sodium hydroxide solution, reaction with MeOH, dilution with MMA). The degree of conversion was determined by comparing the 4-HBP signal with the original value using GC.

Yield: 1285 g (95% of theory).

Example 2

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.7%: 300 g;

1.70 mol MAAH (purity 98.59% (GC), methacrylic acetic anhydride 0.40%,

acetic anhydride was not detected;

stabilized with 2070 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

total stabilizer content at the start of the reaction: 1813 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.8 g of an aqueous solution of sodium hydroxide dissolved in 10 g of water;

esterification of excess methacrylic anhydride with 22.4 g of methanol.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 2 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. Then, stirring was carried out for 1 hour at 60°C, and then 600 g of methyl methacrylate was added to the mixture while stirring. The resulting solution was cooled to room temperature with stirring and filtered. A solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate has the following composition, determined by gas chromatography (numbers in wt%):

57.9% methyl methacrylate;

10.0% methacrylic acid;

0.28% 4-hydroxybenzophenone;

0.32% 4-(acetoxy)benzophenone;

29.8% 4-(methacryloyloxy)benzophenone;

The water content is 0.08%, the stabilizer content is 53 ppm 2,4-dimethyl-6-tert-butylphenol. The Pt-Co APHA color scale is 152.

A direct comparison with Example 1 shows that the initial concentration of methacrylic acetic anhydride in methacrylic anhydride is critical to the amount of 4-(acetoxy)benzophenone found in the product.

Yield: 1350 g (99.7% of theory).

Example 3

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.7%: 300 g;

1.70 mol MAAH (purity 98.59% (GC), methacrylic acetic anhydride 0.40%,

acetic anhydride was not detected;

stabilized with 2070 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

total stabilizer content at the start of the reaction: 1813 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.8 g of an aqueous solution of sodium hydroxide dissolved in 10 g of water;

esterification of excess methacrylic anhydride with 22.4 g of methanol.

Theoretical yield: 402.1 g

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 2 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify unreacted methacrylic anhydride. Stirring was then carried out for 1 hour at 60°C, then the mixture was poured with stirring (metal paddle stirrer, electric motor) in a thin stream into 1.5 l of water. After 0.5 h of stirring, the precipitate was filtered off under vacuum on a glass frit filter, washed twice, in each case with 1 L of water, and then dried in air on a vacuum filter. The solid was then dried in air.

Yield: 397.2 g (98.8% of theoretical).

Analysis: Water content: 0.10%;

2,4-dimethyl-6-tert-butylphenol: 120 ppm.

Gas Chromatography:

0.059% methyl methacrylate;

0.011% methacrylic acid;

0.659% 4-hydroxybenzophenone;

0.723% 4-(acetoxy)benzophenone;

98.23% 4-(methacryloyloxy)benzophenone;

Color by Pt-Co for a solution in acetone with a concentration of 20%: 135.

Direct comparison with example 2 shows that the content of 4-hydroxybenzophenone and 4-(acetoxy)benzophenone does not significantly decrease during precipitation. This indicates the importance of (meth)acrylic anhydride with as low a content of (meth)acrylic acetic anhydride as possible for a pure product.

Example 4

Setup: 2 L round bottom flask with mechanical stirrer and reflux condenser.

Mixture:

1 kg of the following solution:

30% 4-(methacryloyloxy)benzophenone dissolved in 60% methyl methacrylate and 10% methacrylic acid directly from the method similar to example 1, but with higher color;

100 g activated carbon rods (from Donau Carbon, type Norit 0.8 Supra).

Procedure

The mixture was weighed in its entirety and stirred at room temperature. At this time, samples were taken continuously and filtered with a pleated filter and a syringe filter (PTFE, pore size 0.45 µm).

In this case, the content of the stabilizer and the content of 4-(methacryloyloxy)benzophenone, methyl methacrylate and methacrylic acid remained constant within the measurement accuracy.

Example 5

Setup: 2 L round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1 kg of the following solution:

30% 4-(methacryloyloxy)benzophenone dissolved in 60% methyl methacrylate and 10% methacrylic acid directly from the method similar to example 1, but with higher color;

100 g activated carbon rods (from Donau Carbon, type Norit 0.8 Supra).

Procedure

The mixture was weighed in full and stirred at 40°C. At this time, samples were taken continuously and filtered with a pleated filter and a syringe filter (PTFE, pore size 0.45 µm).

In this case, the content of the stabilizer and the content of 4-(methacryloyloxy)benzophenone, methyl methacrylate and methacrylic acid remained constant within the measurement accuracy.

Example 6

Setup: 2 L round bottom flask with mechanical stirrer and reflux condenser.

Mixture:

800 g of the following solution:

30% 4-(methacryloyloxy)benzophenone dissolved in 60% methyl methacrylate and 10% methacrylic acid directly from the method similar to example 1, but with higher color;

80 g activated carbon rods (from Donau Carbon, type Norit 0.8 Supra).

Procedure

The mixture was weighed in its entirety, stirred at room temperature for 1 hour and filtered with a pleated filter.

300 ml of methyl methacrylate was added to the filtered activated carbon, stirred for 10 minutes at room temperature, and then filtered with a vacuum filter. 50 g of a solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate and methacrylic acid was added to 5 g of dried activated carbon, stirred for 1/2 hour at room temperature, and filtered with a pleated filter.

Example 7

Installation: 250 ml glass beaker, magnetic stirrer.

Mixture:

50 g of the following solution:

30% 4-(methacryloyloxy)benzophenone dissolved in 60% methyl methacrylate and 10% methacrylic acid directly from the method similar to example 1, but with higher color;

5 g Tonsil.

Procedure

The mixture was weighed in its entirety, stirred at room temperature for 1/2 hour and filtered with a pleated filter.

Example 8

Installation: see example 1, but with a 4 l flask.

Mixture:

4.0 mole 4-hydroxybenzophenone: 796.0 g;

4.4 mol methacrylic anhydride (purity 98.65% (GC), methacrylic acetic anhydride 0.62%,

acetic anhydride was not detected;

stabilized with 1980 ppm 2,4-dimethyl-6-tert-butylphenol): 694.8 g;

0.023 mol H ₂ SO ₄ , conc., 0.15% mixture: 2.26 g (1.23 ml);

2,4-dimethyl-6-tert-butylphenol, 1000 ppm prod. = 1065 mg.

Neutralization of H ₂ SO ₄ : 0.052 mol NaOH = 2.08 g dissolved in 10 g H ₂ O.

Hydrolysis of excess methacrylic anhydride: 25.6 g MeOH (0.80 mol).

Theoretical Yield: 1051.7g

Procedure The mixture was weighed in its entirety, then heated to 90° C. with air introduced. Reaction time: 4 hours (checking the degree of conversion by GC). Then cooling was carried out to approximately 60°C and NaOH dissolved in H ₂ O was added to neutralize H ₂ SO ₄ and MeOH to hydrolyze methacrylic anhydride. Stirring was then carried out for 1 hour at 60° C. and then the mixture was completely cooled. Then the mixture was poured with stirring (metal paddle mixer, electric motor) in a thin stream into 3 liters of water. After 1/2 hour stirring, the precipitate was suction filtered off on a glass frit filter, washed again with 2.0 L of H ₂ O (stirred for about 30 minutes in a glass beaker with a metal paddle motor) and then dried. using evacuation on a vacuum filter. The solid was then dried in air to constant weight (7 days).

Yield: 1051.7 g = 98.7% of theoretical.

Example 9

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

0.20 mol 4-chloro-4'-hydroxybenzophenone: 47.48 g;

0.22 mol MAAH, (purity 97.92% (GC), methacrylic acetic anhydride 1.59%,

acetic anhydride was not detected;

stabilized with 2035 ppm 2,4-dimethyl-6-tert-butylphenol): 35.07 g;

0.0013 mol concentrated sulfuric acid: 0.124 g;

total stabilizer content at the start of the reaction: 1503 ppm as 4-chloro-4'-hydroxybenzophenone.

Theoretical Yield: 60.15 g

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90°C is 4 hours. Then the mixture was poured with stirring (metal blade stirrer, electric motor) in a thin stream into 0.18 l of water. After 0.5 h of stirring, the precipitate was filtered off under vacuum on a glass frit filter, washed twice, in each case with 0.18 L of water, and then dried in air on a vacuum filter. The solid was then dried in air.

Yield: 56.6 g (94% of theory).

Gas Chromatography:

1.344% 4-chloro-4'-hydroxybenzophenone;

1.307% 4-chloro-4'-acetoxybenzophenone;

96.17% 4-chloro-4'-(methacryloyloxy)benzophenone;

Example 10

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.8%: 300 g;

1.70 mol MAAH (purity 98.48% (GC), methacrylic acetic anhydride 1.131%,

acetic anhydride was not detected;

stabilized with 1871 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0227 mol NaOH (50% in H ₂ O): 1.816 g;

total stabilizer content at the start of the reaction: 1639 ppm as 4-hydroxybenzophenone.

esterification of excess methacrylic anhydride with 9.7 g of methanol (0.3 mol);

to obtain a solution in MMA with a concentration of 30%: 600 g MMA.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 3 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. Then, stirring was carried out for 1 hour at 60°C, and then 600 g of methyl methacrylate was added to the mixture while stirring. The resulting solution was cooled to room temperature with stirring and filtered. A solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate has the following composition, determined by gas chromatography (numbers in wt%):

59.1% methyl methacrylate;

10.5% methacrylic acid;

0.32% 4-hydroxybenzophenone;

0.46% 4-(acetoxy)benzophenone;

29.1% 4-(methacryloyloxy)benzophenone;

The water content is 0.10%, the stabilizer content is 203 ppm 2,4-dimethyl-6-tert-butylphenol. The Pt-Co APHA color scale is 111.

Yield: 1347 g (99% of theory).

Example 11

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube, electrically heated oil bath and pressure filter.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.8%: 300 g;

1.70 mol MAAH (purity 98.48% (GC), methacrylic acetic anhydride 1.131%,

acetic anhydride was not detected;

stabilized with 1871 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

0.30 mol MMA: 30 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

total stabilizer content at the start of the reaction: 1639 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.57 g (50% strength) aqueous sodium hydroxide solution;

esterification of excess methacrylic anhydride with 9.7 g of methanol (0.3 mol);

Theoretical yield: 402.1 g

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 2 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. Then, stirring was carried out for 1 hour at 60°C, and then 400 g of methylcyclohexane was added to the mixture with stirring. The resulting solution was cooled to room temperature with stirring, and the solid that then precipitated was filtered through a pressure filter. The filter residue was dried in air.

Yield: 278.25 g (69.2% of theoretical).

Gas Chromatography:

0.032 area% methyl methacrylate;

0.008 area% methacrylic acid;

0.329 area% 4-hydroxybenzophenone;

0.289% area of 4-(acetoxy)benzophenone;

98.71 area% 4-(methacryloyloxy)benzophenone;

Example 12

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.7%: 300 g;

1.70 mol MAAH (purity 98.59% (GC), methacrylic acetic anhydride 0.40%,

acetic anhydride was not detected;

stabilized with 2070 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol sulfuric acid (50% in H ₂ O): 1.692 g;

total stabilizer content at the start of the reaction: 1813 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.8 g of an aqueous solution of sodium hydroxide dissolved in 10 g of water;

esterification of excess methacrylic anhydride with 22.4 g of methanol.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 3.5 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. Then, stirring was carried out for 1 hour at 60°C, and then 600 g of methyl methacrylate was added to the mixture while stirring. The resulting solution was cooled to room temperature with stirring and filtered. A solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate has the following composition, determined by gas chromatography (numbers in wt%):

57.8% methyl methacrylate;

10.1% methacrylic acid;

0.45% 4-hydroxybenzophenone;

0.35% 4-(acetoxy)benzophenone;

29.6% 4-(methacryloyloxy)benzophenone;

The water content is 0.10%, the stabilizer content is 61 ppm 2,4-dimethyl-6-tert-butylphenol. The APHA Pt-Co color scale is 142.

Yield: 1346 g (99.4% of theory).

Example 13

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.7%: 300 g;

1.70 mol MAAH (purity 98.59% (GC), methacrylic acetic anhydride 0.40%,

acetic anhydride was not detected;

stabilized with 2070 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol trifluoromethanesulfonic acid: 1.306 g;

total stabilizer content at the start of the reaction: 1813 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.8 g of an aqueous solution of sodium hydroxide dissolved in 10 g of water;

esterification of excess methacrylic anhydride with 22.4 g of methanol.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 3 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. Then, stirring was carried out for 1 hour at 60°C, and then 600 g of methyl methacrylate was added to the mixture while stirring. The resulting solution was cooled to room temperature with stirring and filtered. A solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate has the following composition, determined by gas chromatography (numbers in wt%):

57.7% methyl methacrylate;

10.2% methacrylic acid;

0.41% 4-hydroxybenzophenone;

0.43% 4-(acetoxy)benzophenone;

29.7% 4-(methacryloyloxy)benzophenone;

The water content is 0.07%, the stabilizer content is 48 ppm 2,4-dimethyl-6-tert-butylphenol. The Pt-Co APHA color scale is 158.

Yield: 1348 g (99.4% of theory).

Example 14

Setup: 100 ml three-necked round bottom flask with magnetic stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

0.05 mol 2-amino-5-chlorobenzophenone: 11.6 g;

0.053 mol MAAH (purity 98.51% (GC), methacrylic acetic anhydride 0.20%,

acetic anhydride was not detected;

stabilized with 2160 ppm 2,4-dimethyl-6-tert-butylphenol): 8.2 g;

0.4 mmol concentrated sulfuric acid: 0.039 g;

total stabilizer content at the beginning of the reaction: 1527 ppm, calculated as 2-amino-5-chlorobenzophenone.

Theoretical Yield: 15.0 g

Procedure

The mixture was weighed in its entirety, then heated to 70°C with stirring and with the introduction of air. The reaction time at 70°C is 4 hours. Then the mixture was poured with stirring (metal paddle stirrer, electric motor) in a thin stream into 0.18 l of water. After 0.5 h of stirring, the precipitate was filtered off under vacuum on a glass frit filter, washed twice, in each case with 0.18 L of water, and then dried in air on a vacuum filter. The solid was then dried in air.

Yield: 14.0 g (93% of theory).

Gas Chromatography:

0.11% 2-amino-5-chlorobenzophenone;

0.32% 2-acetamido-5-chlorobenzophenone;

97.835% N-(2-benzoyl-4-chlorophenyl)methacrylamide.

Comparative Example 1

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.7%: 300 g;

1.70 mol MAAH (purity 98.59% (GC), methacrylic acetic anhydride 0.40%,

acetic anhydride was not detected;

stabilized with 2070 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

total stabilizer content at the start of the reaction: 1813 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.57 g (50% strength) aqueous sodium hydroxide solution;

esterification of excess methacrylic anhydride with 9.7 g of methanol (0.3 mol);

to obtain a solution in MMA with a concentration of 30%: 600 g MMA.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90°C was 5 hours. The mixture polymerized upon subsequent cooling to 60°C.

Exit: -.

Comparative Example 2

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.7%: 300 g;

1.70 mol MAAH (purity 98.72% (GC), methacrylic acetic anhydride 0.827%,

acetic anhydride was not detected;

stabilized with 1059 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

273 mg 2,4-dimethyl-6-tert-butylphenol;

total stabilizer content at the start of the reaction: 1835 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.57 g (50% strength) aqueous sodium hydroxide solution;

esterification of excess methacrylic anhydride with 9.7 g of methanol (0.3 mol);

to obtain a solution in MMA with a concentration of 30%: 600 g MMA.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90°C is 5.5 hours. After 5 hours of reaction, a sample was taken and isolated separately (cooling to 60°C, neutralization with aqueous sodium hydroxide solution, reaction with MeOH, dilution with MMA). After 5.5 hours the mixture polymerized.

Exit: -.

Analysis: After isolation, the sample showed an APHA color of 600 after 5 hours of reaction, and a stabilizer content of 9 ppm 2,4-dimethyl-6-tert-butylphenol.

Comparative Example 3

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.8%: 300 g;

1.70 mol MAAH (purity 82.63% (GC), methacrylic acetic anhydride 1.668%,

acetic anhydride was not detected;

stabilized with 2870 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

total stabilizer content at the start of the reaction: 2514 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.57 g (50% strength) aqueous sodium hydroxide solution;

esterification of excess methacrylic anhydride with 9.7 g of methanol (0.3 mol);

to obtain a solution in MMA with a concentration of 30%: 600 g MMA.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 6 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. Then, stirring was carried out for 1 hour at 60°C, and then 600 g of methyl methacrylate was added to the mixture while stirring. The resulting solution was cooled to room temperature with stirring and filtered. A solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate has the following composition, determined by gas chromatography (numbers in wt%):

60.3% methyl methacrylate;

9.1% methacrylic acid;

2.35% 4-hydroxybenzophenone;

1.06% 4-(acetoxy)benzophenone;

25.5% 4-(methacryloyloxy)benzophenone;

The water content is 0.11%, the stabilizer content is 330 ppm 2,4-dimethyl-6-tert-butylphenol. The APHA Pt-Co color is 147. Thus, the content of unreacted keto-functionalized aromatic phenol, compared to the content of keto-functionalized aromatic methacrylate, is high enough that significant amounts may migrate or adversely affect the properties of the polymer when used.

Yield: 1346 g (99% of theory).

Comparative Example 4

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.8%: 300 g;

1.70 mol MAAH (purity 86.86% (GC), methacrylic acetic anhydride 4.96%,

acetic anhydride was not detected;

stabilized with 1270 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

117 mg 2,4-dimethyl-6-tert-butylphenol;

total stabilizer content at the start of the reaction: 1502 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.57 g (50% strength) aqueous sodium hydroxide solution;

esterification of excess methacrylic anhydride with 9.7 g of methanol (0.3 mol);

to obtain a solution in MMA with a concentration of 30%: 600 g MMA.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 6 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. Then, stirring was carried out for 1 hour at 60°C, and then 600 g of methyl methacrylate was added to the mixture while stirring. The resulting solution was cooled to room temperature with stirring and filtered. A solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate has the following composition, determined by gas chromatography (numbers in wt%):

59.4% methyl methacrylate;

11.4% methacrylic acid;

0.79% 4-hydroxybenzophenone;

2.83% 4-(acetoxy)benzophenone;

26.0% 4-(methacryloyloxy)benzophenone;

The water content is 0.08%, the stabilizer content is 140 ppm 2,4-dimethyl-6-tert-butylphenol. The APHA Pt-Co color is 165. Thus, the content of acetylated keto-functionalized aromatic phenol compared to that of keto-functionalized aromatic methacrylate is high enough that significant amounts may migrate or adversely affect polymer properties when used.

Yield: 1351 g (99% of theory).

Comparative Example 5

Setup: 2 L four neck round bottom flask with mechanical stirrer, reflux condenser, Pt100 temperature probe, air inlet tube and electrically heated oil bath.

Mixture:

1.51 moles 4-hydroxybenzophenone, 99.8%: 300 g;

1.70 mol MAAH (purity 86.86% (GC), methacrylic acetic anhydride 4.96%,

acetic anhydride was not detected;

stabilized with 1270 ppm 2,4-dimethyl-6-tert-butylphenol): 262.8 g;

1.80 mol MMA: 180 g;

0.0087 mol concentrated sulfuric acid: 0.846 g;

117 mg 2,4-dimethyl-6-tert-butylphenol;

total stabilizer content at the start of the reaction: 1502 ppm as 4-hydroxybenzophenone.

Neutralization of the catalyst acid with 1.57 g (50% strength) aqueous sodium hydroxide solution;

esterification of excess methacrylic anhydride with 9.7 g of methanol (0.3 mol);

to obtain a solution in MMA with a concentration of 30%: 600 g MMA.

Theoretical Yield: 1354

Procedure

The mixture was weighed in its entirety, then heated to 90°C with stirring and with the introduction of air. The reaction time at 90° C. is 2 hours. Cooling was then carried out to approximately 60° C. and sodium hydroxide dissolved in water was added to neutralize the catalytic sulfuric acid, as well as methanol to esterify the unreacted methacrylic anhydride. Then, stirring was carried out for 1 hour at 60°C, and then 600 g of methyl methacrylate was added to the mixture while stirring. The resulting solution was cooled to room temperature with stirring and filtered. A solution of 4-(methacryloyloxy)benzophenone in methyl methacrylate has the following composition, determined by gas chromatography (numbers in wt%):

59.6% methyl methacrylate;

11.0% methacrylic acid;

2.53% 4-hydroxybenzophenone;

2.62% 4-(acetoxy)benzophenone;

24.1% 4-(methacryloyloxy)benzophenone;

The water content is 0.09%, the stabilizer content is 178 ppm 2,4-dimethyl-6-tert-butylphenol. The Pt-Co APHA color scale is 126. Thus, the content of unreacted as well as acetylated keto-functionalized aromatic phenol compared to the content of keto-functionalized aromatic methacrylate is high enough that significant amounts could migrate or adversely affect the properties of the polymer when used. .

Yield: 1348 g (99% of theory).

Claims (13)

1. A process for the preparation of keto-functionalized aromatic (meth)acrylates by reacting keto-functionalized aromatic alcohols or keto-functionalized aromatic amines with (meth)acrylic anhydride, wherein the keto-functionalized aromatic alcohol or keto-functionalized aromatic amine contains its keto- a functional group adjacent to the aromatic system contains either a free NH ₂ group or a free OH group linked via a spacer to its aromatic systems, where the spacer is or contains oligoethers, alkyl-, aryl-, -simple ethers, -thioethers, -amines, -esters, -thioesters, or -amides, wherein the reactants, products, and a catalyst selected from strong inorganic or organic acids or bases are present together in a reaction matrix at a reaction temperature of 50° C. to 120°C, characterized in that the residence time of the reagents, products and catalysts is limited from 0.1 to no more than 4 hours, and (meth)acrylic anhydride is used with a content of (meth)acrylic acetic anhydride in mixture with (meth)acrylic anhydride of <4.5 wt.%. 2. The method according to claim 1, wherein the keto-functionalized aromatic alcohol is selected from the group consisting of 4-hydroxybenzophenone, 4-chloro-4'-hydroxybenzophenone, and the keto-functionalized aromatic amine is selected from 2-amino-5- chlorobenzophenone. 3. The method according to p. 2, characterized in that the keto-functionalized aromatic alcohol is 4-hydroxybenzophenone. 4. Process according to any one of the preceding claims, characterized in that the amount of stabilizer at the beginning of the reaction is adjusted in the range from 0 to 5000 ppm depending on the keto functionalized aromatic alcohols or amines used. 5. Process according to any one of the preceding claims, characterized in that (meth)acrylic anhydride with a purity of >93% is used. 6. The method according to any one of the preceding claims, characterized in that the previous steps of the method are carried out in such a way that after neutralization of the catalyst with a base, the color on the Pt-Co APHA scale is set to <500 (by measuring a 30 wt.% solution of a keto-functionalized aromatic ( methacrylate in 60 wt.% methyl methacrylate and 10 wt.% methacrylic acid). 7. The method according to any one of paragraphs. 1-6, characterized in that the crude product is treated with an adsorbent, and after treatment, the adsorbent is removed again, which provides a color according to the Pt-Co APHA scale at a level of <500 (by measuring a 30 wt.% solution of keto-functionalized aromatic (meth)acrylate in 60 wt% methyl methacrylate and 10 wt% methacrylic acid). 8. Process according to any one of the preceding claims, characterized in that the reaction is terminated after >90% conversion of the reagent used. 9. Process according to any one of the preceding claims, characterized in that the reaction is carried out in the presence of catalytic amounts of acid, preferably in the presence of sulfuric acid, alkyl or arylsulfonic acid. 10. Process according to claim 9, characterized in that, after the reaction, the catalytic amounts of acid are neutralized with aqueous solutions of bases, preferably aqueous alkali metal hydroxide or ammonia solution. 11. The method according to any of the preceding paragraphs, characterized in that the reaction is carried out for 0.1-4 hours at 60-95°C. 12. Process according to any one of the preceding claims, characterized in that the keto-functionalized aromatic (meth)acrylate precipitates upon addition of water or an organic solvent to the reaction mixture and is isolated in solid form by filtration. 13. Process according to any one of the preceding claims, characterized in that the keto-functionalized aromatic (meth)acrylate is obtained by adding liquid (meth)acrylic ester or styrene to the reaction mixture as a solution in said ester or styrene.