SU1574600A1 - Method of obtaining 2-mercaptobenzimidazolon - Google Patents

Abstract

The invention relates to heterocyclic compounds, in particular, the method of producing 1- (2,3-epitiopropyl) -3- (2,3-epoxypropyl) -benzimidazolone-2 for the manufacture of heat-resistant adhesives, and can be used in mechanical engineering. The purpose of the invention is to simplify the process and increase the yield of the target product. The process is carried out by the reaction of benzimidazole-2-thione with epichlorohydrin at 20-100 ° C (better at 50-60 ° C), followed by treatment of the reaction mixture with alkali at 10-100 ° C (better at 20-50 ° C). The method allows to simplify the process and increase the yield to 90-100% against 30% in the known method. 1 hp f-ly.

Description

The invention relates to a new process for the preparation of 1- (2,3-epitropyl) -3- (2,3-epoxypropyl) -benzimidazolone-2 of formula

O (1)

about i s

which can be used in engineering, aviation and other industries for the preparation of heat-resistant adhesives.

The purpose of the invention is to simplify the process, to increase the yield of the target product - due to the fact that benzimidazole-2-thion is reacted with epichporhydrin at 20-100 ° C, followed by treatment of the reaction mixture with alkali at 10 - 100 ° C.

The invention is illustrated by the following examples.

Example 1. In a three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, 90 g (0.6 mol) of pre-triturated benzimidazolthion-2 and 940 ml (12 mol) ECG are loaded. The suspension is stirred at 50 ° C until the initial benzimidazolthion-2 is dissolved P55 h) and another 8.5 at 60 ° C. The resulting pale yellow solution is cooled to 20-50 ° C and at this temperature 48 g (1.2 mol) of caustic soda are slowly added in portions to it within 2-5 h. Then continue stirring the reaction mixture under the same conditions for 1-2 h. The precipitate is filtered off, the filtrate soared in vacuum at 50 ° C and the resulting pale yellow resin is dried at the same temp.

at

h

Ј 3

Uh

tour. 143-157 g (90-100%) of technical 1- (2,3-epitiopropyl) - 3- (2,3-epoxypropyl) -benzimidazolone-2 are obtained. The content of three-membered cycles is 7.16 mol / kg for the Stc. After recrystallization from a mixture of hexane-ethanol (10: 1), a pure monomer is obtained with m.p. 70-72 ° C. Rf 0.85 (eluent-chloroform-methanol 10: 1), PMR spectrum (in CC14), o, ppm: 6.97 m, 3.37 - 4.30 m, 3.03 m, 2.50 m, IR spectrum, cm -1: 1700 s, 1615 s, 3060 s, 965 sr, 920 s, 855 s.

Technical product - SEG (content of epoxy groups) 3.8 mol / kg, ST (content of tyrant groups) 3.36 mol / kg. After recrystallization, 99% g (62-69%) of the product is obtained, SEG 3.79 mol / kg, STP 3.70 mol / kg.

The authenticity of compound I obtained by the proposed method with a sample obtained by the prototype method was proved by mixing samples, in which the melting point dispersion was not observed, by IR spectroscopy method - by the identity of the fingerprint areas and by TLC.

Example 2: Carried out analogously to example I, starting from 1.12 g (7.5 mmol) of benzimidazolthion-2, condensation at 20 ° C for 60 hours. 1.81 g (92%) is obtained. monomer. STC 7.05 mol / kg.

Technical product - SEG 3.7 mol / kg, STG 3.35 mol / kg. After recrystallization, 1.27 g (64%) are obtained, SEG 3.77 mol / kg, C T

3.72 mol / kg.

Prize, Conducted as in Example 1, starting from 1.12 g (75 mmol) of benzimidazolthion-2, condensation at 100 ° C for 70 minutes. 1.85 g (94%) of monomer is obtained. STC 6.10 mol / kg.

Technical product - SEG, 3.10 mol / kg, STG 3.00 mol / kg. The yield of purified product is 1.11 g (50%). SEG 3.62 mol / kg, STG 3.50 mol / kg,

PRI me R 4. Conducted analogously to example 1, dehydrochlorination

at 100 ° C, respectively, for 0.5 h. 1.79 g (91%) of monomer is obtained. STC 6.56 mol / kg.

Technical product - SEG 3.41 mol / kg, STG 3.15 mol / kg. Output of the purified product - 1.16 g (59%), SEG, 3.65 mol / kg, ST 3.54 mol / kg.

EXAMPLE 5 Analogously to Example I, the dehydrochlorination was carried out at 10 ° C for 5 hours. 1.83 g (93%) of monomer was obtained. Stc 6.90 mol / kg.

Technical product - SEG 3.56 mol / kg, STG 3.34 mol / kg. The yield of the purified product is 1.19 g (60%), SEG 3.66 mol / kg, ST 3.59 mol / kg.

Thus, the proposed method allows to simplify the process, and also significantly increase the yield of the target product.

Claims (2)

1. Method for preparing 1- (2,3-epiti propyl) -3- (2,3-epoxypropyl) -benzimidazolone-2 of the formula o and s o on the basis of the benzimidazole derivative under heating; in order to simplify the process and increase the yield of the target product, benzimidazole-2-tion is used as the benzimidazole derivative, which is reacted with epichlorohydrin at 20-100 ° C subsequent treatment of the reaction mixture with alkali at GO - 100 & C. 2. Method of claim 1, characterized in that the reaction of benzimidazole-2-thione with epichlorohydrin is carried out mainly at 50 - 60 °, the treatment of the reaction mixture with alkali - at 20 - 50 ° C,