Maleimidic derivatives containing acrylic residues

Abstract: Maleimidic derivatives containing acrylic residues having the general formula (I): wherein R is equal to H, CH₃; A represents a cycloalkyl radical containing from 5 to 10 carbon atoms or an aryl radical containing from 6 to 12 carbon atoms and with the acryloxy residue -[-OCOC(R)=CH₂] in an ortho, meta or para position.

Description: The present invention relates to a process for preparing a group of maleimidic derivatives. More specifically the present invention relates to a process for preparing a group of maleimidic derivatives containing acrylic or methacrylic residues. These products are used as thermostabilizing agents in structural adhesives with an acrylic base. The nearest prior art is represented by US-A-5 021 487, disclosing a curable acrylic ester formulation, containing a maleimide thermal additive, and by GB-A-2 030 983, disclosing a class of N-substituted imides and bis-imides, as intermediates for the preparation of silicon-modified adhesion promoter of formula Xa. In particular the present invention relates to a process for preparing maleimidic derivatives having the general formula (I) : wherein R is equal to H, CH₃; A represents a cycloalkyl radical containing from 5 to 10 carbon atoms or an aryl radical containing from 6 to 12 carbon atoms and with the acryloxy residue -[OCOC(R)=CH₂] in an ortho, meta or para position, according to claim 1. Products having the general formula (I) which are preferable for the present invention are those wherein A is a cyclohexyl or a phenyl; particularly preferred are phenylmaleimide methacrylate (MPM) and phenylmaleimide acrylate. The products having general formula (I) can be obtained with a procedure which involves reacting an acryloyl halide with an N-substituted maleimide. The reaction is carried out in the presence of molecular sieves, in an aprotic solvent, for example dichloroethane, at a temperature ranging from 60 to 90°C. The molecular sieves, or zeolites, are composed of hydrous aluminosilicates of alkaline or earth-alkaline metals. Preferred molecular sieves are those of the type 3 A. More specifically the products having general formula (I) can be obtained by means of the following reaction: wherein R and A have the meanings specified above, and Alg is a halogen such as chlorine. Compound (III) is well-known and can be synthesized as described in Japanese Patents 61/106.554, 79/66.671 (1979) and 79/66.670 (1979). The following examples provide a better illustration of the present invention but do not limit it in any way. EXAMPLE 1 12 g (0.064 moles) of N-[4-hydroxyphenyl]maleimide dissolved in 400 cc of dichloroethane are charged into a two-necked flask equipped with a mechanical stirrer, cooler, nitrogen valve and drip funnel. 16 g of molecular sieves (Union Carbide Type 3A) dried at 100°C under vacuum for 16-18 hours, and then 30 cc (0.32 moles) of distilled methacryloylchloride are added and the mixture is heated to reflux temperature (80-90°C) for 26 hours, supplying fresh molecular sieves every 7-8 hours. The solution is then washed with a solution of 2% NaOH, then with water and dried on anhydrous sodium sulphate. The product, obtained by evaporation of the solvent, is finally washed with hexane. 7.3 g of N-[4-phenylmethacrylate]maleimide are obtained with a yield of 44.4%. Melting point: 150-152°C. IR (KBr); imidic CO; 1720 cm⁻¹, ester CO; 1740 c⁻¹. ¹H-NMR (200MHz, CDCl₃): δ 2.1(methylic H), δ 5.8-6.35(ethylenic H); δ 6.85(maleimidic H); δ 7.2-7.4(aromatic H). EXAMPLE 2 (applicative) The product synthesized in Example 1 is used as a thermostabilizing additive in an acrylic adhesive. 34.5 g of ethylmethacrylate are added to a mixture composed of: 30 g of polyethylene chlorosulphonate (commercially known as Hypalon 20), 33.8 g of methacrylic acid and 1.0 g of ethylenglycoldimethylacrylate. The whole quantity is mixed at room temperature, until all of the polymer has dissolved (time required: 24 hours approx.). The adhesive paste thus obtained is completed by adding 0.3 g of di-terbutylparacresol, 0.4 g of a free radical generator of the normal type (initiator) composed of cumene hydroperoxide and 2.05 g of phenylmaleimide methacrylate (MPM). The Brookfield of the paste is 34.000 mPa x sec. Steel test samples 120 x 25 x 1.5 mm, treated with abrasive paper no.120, are prepared. A layer of paste of about 0.5 mm in thickness is spread on one test sample, and on another an activator, composed of the condensation product between butyraldehyde and aniline, containing 0.1% by weight of monovalent copper, introduced as copper saccharinate. The two adherends are coupled and compressed at a pressure of about 2 N/m². The adhesive is post-cured at 100°C for 1 hour after the test-samples have been joined together. The following results are obtained: set time: 30 seconds; cut resistance: 20 N/mm²; cut resistance after treatment at 150°C: 16 N/mm². The same adhesive prepared without the addition of MPM gave a cut resistance after treatment at 150°C of 10 N/mm².

Claims: Process for preparing Maleimidic derivatives having the general formula (I): wherein R is equal to R, CH₃; A represents a cycloalkyl radical containing from 5 to 10 carbon atoms or an aryl radical containing from 6 to 12 carbon atoms and with the acryloxy residue -[-OCOC(R)=CH₂] in an ortho, meta or para position, including reacting an acryloyl halide with an N-substituted maleimide according to the scheme: wherein R and A have the above defined meanings, and Alg is a halogen such as chlorine, in presence of molecular sieves or zeolites composed of hydrous aluminosilicates of alkaline or earth-alkaline metals of the type 3A, at a temperature ranging of from 60°C to 90°C. Process according to claim 1, wherein A is a cyclohexyl or a phenyl. Process according to claims 1 or 2, wherein the derivative of formula (I) is phenylmaleimide methacrylate. Process according to claims 1 or 2, wherein the derivative of formula (I) is phenylmaleimide acrylate.

Inventors: DI RUOCCO VITTORIO, GARBASSI FABIO, GILA LILIANA, DI RUOCCO, VITTORIO, GARBASSI, FABIO, GILA, LILIANA
Applicants: MINI RICERCA SCIENT TECNOLOG, MINISTERO DELL' UNIVERSITA' E DELLA RICERCA SCIENTIFICA E TECNOLOGICA
Application year: 1992
Main classification: C07D207
IPC codes: C08K5, C07D207