CN-112566892-B - Preparation of (meth) acrylic esters

Abstract

The present invention relates to a process for preparing (meth) acrylic esters from (meth) acrylic anhydride.

Inventors

• M - tresckow
• S. Bayer
• SCHUETZ THOMAS
• S. CRIER

Assignees

• 赢创运营有限公司

Dates

Publication Date

20260508

Application Date

20190731

Priority Date

20180816

Claims (14)

1. 1. A process for preparing a (meth) acrylate, said process comprising at least the following step (a): (a) Reaction between (meth) acrylic anhydride of formula (I) and a substrate in the presence of a first catalyst Wherein R1 is a hydrogen atom or a methyl group; Thereby forming a product mixture comprising (meth) acrylate; The method is characterized in that The substrate is selected from primary, secondary and tertiary alcohols having one hydroxyl group, and The first catalyst comprises a halide of magnesium; wherein the temperature is maintained between 60 ℃ and 90 ℃ during step (a).
2. 2. The process according to claim 1, wherein the first catalyst is selected from the group consisting of magnesium bromide, magnesium iodide and magnesium chloride.
3. 3. The process according to claim 1 or 2, wherein the total amount of the first catalyst in step (a) is between 0.001 mol% and 10 mol% based on the amount of substrate.
4. 4. The process according to claim 1 or 2, wherein the total amount of the first catalyst in step (a) is between 0.01 and 1.0 mole% based on the amount of substrate.
5. 5. The process according to claim 1 or 2, wherein the total amount of the first catalyst in step (a) is between 0.1 and 0.5 mole% based on the amount of substrate.
6. 6. The process according to claim 1 or 2, wherein the molar ratio of (meth) acrylic anhydride to substrate in step (a) is between 5:1 and 1:5.
7. 7. The process according to claim 1 or 2, wherein the molar ratio of (meth) acrylic anhydride to substrate in step (a) is between 3:1 and 1:3.
8. 8. The process according to claim 1 or 2, wherein the molar ratio of (meth) acrylic anhydride to substrate in step (a) is between 2:1 and 1:2.
9. 9. The method according to claim 1 or 2, wherein the method further comprises the following steps (b) and (c) performed after step (a): (b) Adding a secondary alcohol to the product mixture obtained in step (a), thereby forming a product mixture comprising the (meth) acrylate and a (meth) acrylate of a secondary alcohol, and (C) Removing the (meth) acrylate of the auxiliary alcohol from the product mixture obtained in step (b); Wherein the auxiliary alcohol is a primary or secondary alcohol having a boiling point measured at 105Pa of no more than 150 ℃.
10. 10. The process according to claim 9, wherein the auxiliary alcohol has a boiling point measured at 105Pa of no more than 120 ℃.
11. 11. The process according to claim 9, wherein the auxiliary alcohol has a boiling point measured at 105Pa of no more than 80 ℃.
12. 12. The method according to claim 9, wherein the auxiliary alcohol is selected from methanol, ethanol, n-propanol, isopropanol or mixtures thereof.
13. 13. The method according to claim 9, wherein the auxiliary alcohol is methanol.
14. 14. Use of a first catalyst as a catalyst in a reaction between (meth) acrylic anhydride of formula (I) and a substrate Wherein R1 is a hydrogen atom or a methyl group; the reaction produces a product mixture comprising (meth) acrylate esters, wherein the substrate is selected from primary, secondary and tertiary alcohols having one hydroxyl group; The first catalyst comprises a halide of magnesium.

Description

Preparation of (meth) acrylic esters Technical Field The present invention relates to a process for preparing (meth) acrylic esters from (meth) acrylic anhydride. Background (Meth) acrylates are commonly used as monomers for preparing various poly (meth) acrylates and corresponding copolymers. Accordingly, various methods for obtaining (meth) acrylic esters are known. These processes include, in particular, transesterification reactions in which methyl methacrylate is reacted with an alcohol. Another common possibility is the acylation of alcohols with (meth) acrylic anhydride. The acylation of alcohols using (meth) acrylic anhydride, in particular methacrylic anhydride, is generally carried out in the presence of an acid, such as sulfuric acid. Under these conditions, unwanted reactions, such as polymerization of anhydrides, often occur, and thus the product yield of (meth) acrylic esters is only moderate. In addition, the preparation of (meth) acrylic esters of sterically hindered alcohols is known to suffer from low reaction yields, since these alcohols not only have low reactivity towards (meth) acrylic anhydrides, but also tend to undergo unwanted dehydration under the reaction conditions normally used. For these reasons, (meth) acrylic anhydride is generally used in large excess in order to achieve reasonable conversions of the sterically hindered alcohol and phenol. This is disadvantageous from an economical and environmental point of view because (meth) acrylic anhydride is quite expensive and recovery of unreacted excess (meth) acrylic anhydride is difficult. In the past, considerable methods have been developed for acylating alcohols with non-polymerizable anhydrides, such as acetic anhydride. However, it is well known that these processes are generally ineffective for (meth) acrylic anhydride, since the reactivity and chemical behavior of (meth) acrylic anhydride are significantly different from acetic anhydride. US 4,540,743A describes the acylation of polyvinyl alcohol by esterifying polyvinyl alcohol with activated (meth) acrylic anhydride in the presence of a tertiary amine. This procedure requires a relatively large amount of tertiary amine. Thus, it is necessary to separate the tertiary amine from the product mixture in a separate washing step, which generates a considerable amount of aqueous waste. Disclosure of Invention In view of the above technical problems of the prior art, an object of the present invention is to develop a more efficient industrially applicable process for producing (meth) acrylic esters from (meth) acrylic anhydride. Such a method should ideally provide the following advantages: High product yields and high conversions of (meth) acrylates Short reaction time Low excess of (meth) acrylic anhydride Low amounts of acylation catalyst, which can be easily separated from the resulting product, if desired. In addition, the process should be suitable for preparing di-or poly (meth) acrylates on an industrial scale in an efficient and inexpensive manner. The present invention is based on the surprising discovery that the activation of (meth) acrylic anhydride can be achieved in an efficient manner by using salts of magnesium or rare earth elements as catalysts. Accordingly, one aspect of the present invention relates to a process for preparing (meth) acrylic esters, said process comprising at least the following step (a): (a) Reaction between (meth) acrylic anhydride of formula (I) and substrate in the presence of magnesium salt or rare earth element salt Wherein R1 is a hydrogen atom or a methyl group, Thereby forming a product mixture comprising (meth) acrylate. The terms "(meth) acrylate" and "(meth) acrylic" as used herein may refer to both acrylates and methacrylates. The (meth) acrylic anhydride of formula (I) may be acrylic anhydride (R1 is a hydrogen atom) or methacrylic anhydride (R1 is a methyl group). The first catalyst used in step (a) catalyzes the reaction between the (meth) acrylic anhydride of formula (I) and the substrate. According to the invention, the first catalyst comprises a magnesium salt or a salt of a rare earth element. The term "rare earth element" as used herein refers to an element selected from the group consisting of cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, promethium, samarium, scandium, terbium, thulium, ytterbium, and yttrium. In a particularly preferred embodiment, the term "rare earth element" refers to an element selected from lanthanum, ytterbium, yttrium and scandium. In principle, essentially any magnesium salt or salt of the rare earth elements listed above is suitable for use as the first catalyst in the present invention. However, if the salt is selected from the group consisting of fluoride, chloride, bromide, iodide, acetate, sulfate, perchlorate and triflate, the catalytic activity of the first catalyst is particularly high. In a particularly preferred embodiment, t