V. P. Litvinov

Investigation of selenides of the thiophene and furan series

As in the case of alkyl 2-thienyl selenides, replacement of the alkylseleno group to form the corresponding lithium derivative is observed when n-butyllithium acts on alkyl 2-furyl and alkyl 2-selenienyl selenides. The alkylselenide function is also replaced when alkyl 2-thienyl selenides are treated with excess bromine. A scheme of the mechanism for the reaction of alkyl 2-hetaryl selenides with n-butyllithium is proposed. Alkyl 2-furyl selenides undergo the diene synthesis with maleic anhydride to give phthalic anhydride without a selenide function as the final product.

Synthesis of some selenides and sulfides of the thiophene and furan series

1. A method has been developed for synthesizing selenides of the thiophene and furan series. 2. The production of certain substituted sulfides of the furan series was described.

Condensed heteroaromatic systems including a thiophene ring. XXXIII. Catalytic liquid-phase oxidation of 3-methyl-substituted thieno[2,3-b]thiophenes and thieno[3,2-b]thiophenes

It is shown that the catalytic liquid-phase oxidation of 3-methylthieno[2,3-b]-thiophene and 3-methylthieno[3,2-b]thiophene in acetic acid in the presence of cobalt acetate and sodium bromide at 90–110° gives thieno[2,3-b]thiophene-3-carboxylic acid and thieno[3,2-b]-3-formylthiophene, respectively.

Research on thiophenes

Thieno[2, 3-b]thiophene is prepared in a way similar to that previously described for the synthesis of thieno[3, 2-b]thiophene, the method being based on intramolecular condensation of methyl (3-formyl-2-thienylmercapto) acetate. The IR and PMR spectra of thieno[2, 3-b]-thiophene, 2-ethylthieno[2, 3-b] thiophene and 2-ethylthieno[3, 2-b]-thiophene are investigated.

Investigation in the thiophthene series

1. A new method was developed for the preparation of alkylthiophthenes in yields of up to 70% by the cyclization of (acetonylthio)thiophenes in benzene in presence of aluminum chloride. 2. Under the action of aluminum chloride in benzene on 2-(acetonylthio)-5-ethylthiophene the latter appears to be partially isomerized into 3-(acetonyl)-5-ethylthiophene. As a result, in the subseqent cyclization a mixture of 2-ethyl-6-methylthieno[3,2-b]thiophene and 2-ethyl-4-methylthiophthene is formed. 3. A method of preparing (acetonylthio)thiophenes was developed.

Condensed heteroaromatic systems including a thiophene ring: XXXI. Chelates based on benzo[b]thiophene and stabilization of polycaproamide fibers

A number of complexes based on 3-hydroxy-2-benzo[b]formylthiophene and its Schiff bases were obtained and investigated as stabilizers for polycaproamide fibers. It was established that {N,N-bis(3-hydroxy-2-benzo[b]thenylidene)ethylenediaminato}-copper (II) which makes it possible to simultaneously improve the thermal stability and photostability of polycaproamide fibers, is the most effective stabilizer of the investigated compounds.

Condensed heteroaromatic systems including a thiophene ring. XXXII. Preparation and magnetic properties of chelates based on 2-mercapto-3-benzo[b]formylthiophene, 2-mercapto-3-iminomethylbenzo[b]thiophene, and N,N′-bis(2-mercapto-3-benzo[b]thenylidene)ethylenediamine

A convenient method was worked out for the preparation of 2-mercapto-3-benzo[b]-formylthiophene from 3-bromobenzo[b]thiophene. 2-Mercapto-3-benzo[b]formylthiophene and Schiff bases from it react readily with metal salts to give complexes. The magnetic properties of the chelates were studied, and it was found that the dependence of the magnetic susceptibility on the temperature passes through a minimum for (2-mercapto-3-benzo[b]formylthiophenato)Co and {N,N′-bis(2-mercapto-3-benzo[b]thenylidene) ethylenediaminato}cobalt. On the basis of the magnetic susceptibility data it was concluded that the chelates have planar structures.

KONDENSIERTE HETEROCYCLISCHE SYSTEME MIT THIOPHEN‐RINGEN 30. MITT. HERSTELLUNG UND EINIGE EIGENSCHAFTEN NEUER KOMPLEXBILDENDER UND CHELAT‐VERBINDUNGEN AUF DER BASIS VON BENZO(B)THIOPHEN

Durch Erhitzen von 2-Brom-benzo(b)thiophen (I) in methanolischer Kalilauge auf 200°C entsteht 2-Hydroxy-benzo(b)thiophen (II).

Condensed heteroaromatic systems that contain a thiophene ring: Communucation 28. Metalation of selenopheno[3,2-b]thiophene

1. When selenopheno[3,2-b]thiophene is metalated with n-butyllithium the lithium attacks theα-position of both the selenophene and thiophene fragments of the molecule. 2. Based on the data of the competing metalation reaction, the following order in the relative reactivity of the studied compounds was derived: selenopheno[3,2-b]thiophene > thieno [3,2-b]thiophene>selenophene>thiophene.

Magnetic susceptibility of copper (II) chelates with 3-hydroxy-2-formyl-benzo[b]thiophene and its schiff bases

The magnetic susceptibilities of copper (II) chelates with 3-hydroxy-2-formyl-benzo[b]thiophene and its Schiff bases were determined and make it possible to assume a square or square-pyramidal structure for the chelate units.