GB2270912A

GB2270912A - Preparation of hydroxyalkyl acrylic or methacrylic acid esters

Info

Publication number: GB2270912A
Application number: GB9317736A
Authority: GB
Inventors: Martina Bader; Joachim Knebel
Original assignee: Roehm GmbH; Roehm GmbH Darmstadt
Current assignee: Roehm GmbH; Roehm GmbH Darmstadt
Priority date: 1992-08-26
Filing date: 1993-08-26
Publication date: 1994-03-30
Anticipated expiration: 2013-08-26
Also published as: FR2695124A1; GB2270912B; GB9317736D0; DE4228397A1; NL9301381A

Description

2270912 Preparation of Hydroxyalkyl(neth)acrylic acid esters The present

invention relates to a novel process for preparing acrylic or methacrylic acid esters of Formula I R 0 1 11 H2C = C - C - 0 - A - OH (wherein R represents hydrogen or a methyl group, and A is a branched or unbranched C3-14-alkylene or cycloalkylene group, optionally containing one or more oxygen atoms).

OH-functional (meth)acrylic acid esters are of interest as comonomers in acrylate copolymers which may be used for example in aqueous coating dispersions, as textile auxiliary agents, as varnishing resins and for preparing unsaturated polyurethane resins. The Phydroxyalkylesters of acrylic and methacrylic acid are frequently used, in particular P-hydroxyethylacrylic acid ester, P-hydroxyethylmethacrylic acid ester, Phydroxypropylacrylic acid ester and Phydroxypropylmethacrylic acid ester. Such compounds can be prepared on a large industrial scald by the reaction of acrylic acid or methacrylic acid with ethylene oxide or propylene oxide, for example according to DE-P 12 55 104, in the presence of iron acrylate And/or iron methacrylate as catalytically active compounds.

w-Hydroxyalkylacrylic acid esters and methacrylic acid esters are conventionally prepared by esterification of alkane diols with acrylic acid or methacrylic acid in the presence of acid esterification catalysts. In such reactions, the corresponding diesters are also produced in a considerable amount, in addition to the monoesters. According to DE-AS 15 18 572, monoesters and diesters are separated in such a process by extraction. The diester is then returned to the esterification process and is further reacted with the alkane diol by alcoholysis to form.the monoester.

Attempts to produce monoacrylic acid or monomethacrylic acid esters of diols which are diester free, such as are necessary for preparing non-cross linked polymers, by means of a distillation separation of corresponding ester mixtures, have in most cases been unsuccessful because of the small boiling point difference in the reaction products to be separated and the high boiling points thereof. As the molecular weight and the boiling point increases, the risk of polymerisation in the distillation separation increases.

The separation of the ester mixture by column chromatography, as described in Makromol. Chem. Rapid Commun., 9(7): 503 - 511 (1988), represents no viable alternative to the prior art, since the method is restricted to laboratory amounts due to the low space- time yield and the high solvent requirement. similar considerations apply to the preparation of the w-hydroxy esters of acrylic or methacrylic acid by enzymatic hydrolysis of corresponding diesters, as disclosed in JP 63 237 791 (see C.A. 110, 378 22). 25 According to Makromol. Chem., 176 (8): 2473-8, the reaction of 1,10- decanediol with methacrylic acid chloride also results in monoesterdiester mixtures. There therefore remains a need to be able to provide a selective method in an industrial process for preparing hydroxyalkyl(meth)acrylates in which the alkylene group has at least 3 C-atoms between the ester group and the OH group.

It has now been found that salts of acrylic and methacrylic acid together with hydroxy-alkyl halides having k 3 C-atoms in the alkyl group may be-used as starting materials in a novel process for the 1 selective preparation of hydroxy alkyl(meth)acrylates, "inore, particularly w-hydroxyalkyl(meth)acrylates.

Thus, the present invention provides a process for preparing an acrylic or nethacrylic acid ester of formula I 5 R 0 1 11 H2C = C - C - 0 - A - OH I (wherein R is hydrogen or a methyl group and A is a branched or unbranched C3-14-alkylene or cycloalkylene group, optionally containing one or more oxygen atoms and having at least three carbon atoms between the ester and hydroxyl functions) comprising the reaction of a 15 salt of an acrylic or methacrylic acid of Formula II R 0 H 1 11 - + 2C = C - C - 0 M (wherein R is as hereinbefore defined and M+ is an alkali metal ion or an optionally substituted ammonium ion) with a hydroxy halide compound of Formula III X - A - OH III (wherein A is as hereinbefore defined and X is a halogen atom).

Group X in Formula III preferably represents chlorine, bromine or iodine.

The reaction is, advantageously, carried out at an elevated temperature, for example in the range of from 30 to 20WC, and preferably in the presence of a solvent or thinning agent. Specific additives in small amounts, such as iodide salts, have an accelerating effect on the reaction speed.

Reactions of salts of carbonic acid with alkyl halides to form carbonic acid esters have been known for a long time and are common knowledge (see Gattermann - 4 Wieland, die Praxis des organischen Chemikers, 43. Ed. p. 298; Walter de Gruyter, Berlin - New York 1982). The novel reaction of the present invention to form (meth)acrylic acid hydroxyalkyl esters of Formula I is, however, surprisingly selective since it would be expected that as a result of the bifunctional character of the compound of Formula III in the presence of the basic (meth)acrylic acid salt, diesters of acrylic acid or methacrylic acid would be increasingly produced by subsequent reactions e.g. re-esterifications. If so, the reaction of the present invention would have no advantage over the prior art reactions in which monoand diesters are generally produced in the ratio of 1: 1. By contrast, the diester formation in the process according to the invention is less than 2%, based on the total weight of the ester monomers produced. As expected, base-catalyzed Michael-Addition products are also produced subsequent to, or concurrently with, the reaction according to the invention. However, and surprisingly, such compounds are not obtained in noticeable quantities in the process according to the invention.

The process according to the invention may be represented by the following reaction equation:

R 0 (Cat) R 0 H2C=C-C-0-M++X-A-OH 0,H2C=C-C-O-A-0H +MX femp.

The compounds of Formula II, used in the reaction, include the alkali metal salts of acrylic acid and methacrylic acid, in particular the Li, Na and K salts of said acids. But ammonium salts of said acids with 1k+ = N+R1R2R3R41 wherein R, F R21 R3 and R4 represent hydrogen and/or aliphatic or aromatic hydrocarbon groups having up to 8 carbon atoms, in which the groups may be the same or different, may also be used as starting substances of Formula II for the reaction.

The starting substances of Formula Ill are aliphatic halohydrin compounds which contain between 3 and 14 carbon atoms in group A, wherein said group is a branched or unbranched alkylene or cycloalkylene group, optionally containing one or more oxygen heteroatoms. X is a halogen atom, preferably iodine, bromine, or chlorine, particularly preferably chlorine, and the OH group is, preferably, a primary alcohol. The carbon atoms carrying the two substituents are separated from each other by at least a further carbon atom of the alkylene chain. The compounds of Formula Ill used are, most preferably, those in which the X- and OH-functions are at either end of the molecule.

Compounds which meet the given criteria for the starting substance of Formula Ill and which may be used for preparing acrylic and methacrylic acid esters of Formula I, according to the method of the invention, include:

3-chloropropan-l-ol, 3-bromopropan-l-ol, 4-chlorobutan-l-ol, 4-bromopentan-l-ol, 5-chloropentan-l-ol, 6-chlorohexan-l-ol, 6-bromohexan-l-ol, 7-bromoheptan-l-ol, 8-chlorooctan-l-ol, 8-bromooctan-l-ol, 9-bromononan-l-ol, 10-chlorodecan-l-ol, 10-bromodecan-l-ol, 11-bromoundecan-l-ol, 12-bromododecan-l ol, 1-bromo-3-buten-2-ol, 2-(2-chloroethoxy)ethanol, 2-(2 [2chloroethoxy]ethoxy)ethanol, 2-chlorocyclohexanol and 4 chlorocyclohexanol.

The reaction of Compounds of Formulae II and Ill to form esters of Formula I may be accelerated by the addition of iodide salts such as alkali metal iodide, or quaternary ammonium and phosphonium compounds, or crown ethers and cryptate compounds, particularly when the reaction is carried out under the conditions of phase transfer catalysis. These catalytically acting compounds may be added in amounts of 0.01 to 10 mol t, based on the halohydrin compound Ill. The reaction components II and Ill may be used in the reaction in 6 molar ratios of 0.1: 1 to 1 0.1, more particularly of about 1: 1. The reaction is, preferably, carried out using an excess of the halohydrin comp9nent acting as solvent provided the properties of compound III and the 5 subsequent separation operations permit this.

The reaction is, advantageously, carried out in the presence of conventional polymerisation inhibitors such as hydroquinone, hydroquinonemonomethylether or phenothiazine, particularly in the presence of oxygen, which is, advantageously, passed slowly in the form of air through the reaction mixture. The reaction is conveniently carried out at reaction temperatures within the range of from 30 to 2000C, preferably from 50 to 1500C, more particularly 15 from 60 to 130'C. It may be carried out at normal pressure, low or excess pressure and in a continuous or discontinuous process. Depending on the reaction temperature and the catalyst used, the.reaction times generally range from about 1 to 30 hours. 20 The reaction medium may be water, in which the acrylic or methacrylic acid salts are soluble and in which they may conveniently be prepared from acid and base in a previous reaction step. The nucleophilic substitution of the halogen atom by the (meth)acryloxy group is problem-free in both non-polar and protic or aprotic polar solvents. Suitable solvents include e.g. toluene, xylene, cyclohexane, dimethylformamide, dinethylacetamide, dimethylsulphoxide and butanone. In the presence of water and a solvent non-miscible with water, the reaction may advantageously-be carried out in a two- or multi- phase system.

The reaction product I may be obtained from the reaction mixture in the usual manner, for example following treatment with water and phase separation as well as evaporation of the excess component III from the organic phase, and may, optionally, then be purified by distillation.

1 7 The present invention will now be illustrated by way of the following non- limiting Examples.

EXAMPLES 5 Preparation of 6-hvdroxvhexvlmethacrylate A) 58.8 g of 6-chlorohexanol are added dropwise to a solution of 86.4 g of sodium methacrylate (stabilised with 1000 ppm of hydroquinone mono methylether) and 0.6 g of sodium iodide in 100 ml of distilled water. The mixture is heated for 34 hours while introducing air and refluxing. The organic phase formed is separated off and washed with sodium hydrogen carbonate solution. 64.5 g of unrefined ester are obtained (87% of theory, composition see Table).

B) 7.35 g of 6-chlorohexanol, 6.50 g of sodium methacrylate (stabilised with 20 mg of hydroquinone monomethylether) and 80 mg of sodium iodide are dissolved in 30 ml of dimethylformamide and are heated for 5 hours, while refluxing and introducing air. After cooling, the reaction mixture is filtered, and the solvent is removed from the rotation evaporator. 7.0 g of unrefined ester are obtained (70% of theory, composition see Table).

C) 14.7 g of chlorohexanol, 12.96 g of sodium methacrylate (stabilised with 40 mg of hydroquinone monomethylether) and 0.9 g of sodium iodide are heated for 5 hours in 30 ml xylene, while refluxing and introducing air. After filtration of the salts and removal of the salt by distillation, 14.3 g of unrefined ester are obtained (71%_of theory, composition see Table).

TABLE

Composition of the unrefined esters following analysis by gas chromatography (GC). 5 Preparation 6-hydroxyhexyl- (Given in area percentage GC) Mixture methacrylate 1,6-hexanediol- 6-chloro- content dimethacrylate hexanol A 94 2.3 2.9 B 96.3 2.1 1.0 c 84.5 1.9 4.6 j.

r 9

Claims

1. A process for preparing an acrylic or methacrylic acid ester of formula I 5 R 0 1 11 H2C = C - C - 0 - A - OH (wherein R is hydrogen or a methyl group and A is a branched or unbranched C3-14-alkylene or cycloalkylene group, optionally containing one or more oxygen atoms and having at least three carbon atoms between the ester and hydroxyl functions) comprising the reaction of a 15 salt of an acrylic or methacrylic acid of formula II R 0 1 11 H2C = C - C - o-k' II (wherein R is as hereinbefore defined and k+ is an alkali metal ion or an optionally substituted ammonium ion) with a hydroxy halide compound of formula III X - A - OH III (wherein A is as hereinbefore defined and X is a halogen atom).

2. A process as claimed in claim 1 wherein X represents chlorine, bromine or iodine.

3. A process as claimed in claim 1 or claim 2, wherein said reaction is carried out at a temperature of from 30 to 2000C.

4. A process as claimed in any one of claims 1 to 3, wherein said reaction is carried out in the presence of non-polar or polar solvents.

5. A process as claimed in any preceding claim, wherein said reaction is carried out in the presence of a catalyst.

6. A process as claimed in claim 5, wherein said catalyst is an iodide salt, a quaternary ammonium or phosphonium compound, a crown ether or a cryptate.

7. A process as claimed in claim 6, wherein said iodide salt is an alkali metal iodide.

8. A process as claimed in any preceding claim, wherein said reaction is carried out using compounds of formula III which contain a primary OHgroup.

9. A compound of formula I as prepared by a process as claimed in any preceding claim.

10. A process for preparing an acrylic or Tnethacrylic acid ester of formula I substantially as herein described with reference to any one of the Examples.