GB459891A - Manufacture of indigoid dyestuffs of the pyrene series and intermediates therefor - Google Patents

Abstract

4 : 3-Pyrene-3<1>-oxythiophenes are prepared by treating a 3-cyanopyrene-4-sulphohalide with a reducing agent, condensing the resulting mercaptan with a monohalogenacetic acid and effecting ring closure. Indigoid dyestuffs are obtained by oxidizing the 4 : 3-pyrene-3<1>-oxythiophenes or by condensing the latter or their 2<1>-derivatives or the corresponding 4 : 3-pyrenethiophenquinones with the usual thioindigo components. In examples: (1) 4 : 3-pyrene-3<1>-oxythiophen is obtained from 3-cyanopyrene-4-sulphochloride by reducing with tin and hydrochloric acid in hot chlorbenzene, condensing with chloracetic acid and treating with sodium sulphide to effect ring closure; the resulting precipitate is extracted with alcohol; (2) the product obtained as in example 1 by condensation with chloracetic acid is heated with caustic soda to hydrolyze the cyano group and the resulting thioglycolcarboxylic acid subjected to ring closure by means of acetic anhydride; the acetyl compound is hydrolized with alcoholic potash; (3) 4 : 3-pyrene-3<1>-oxythiophen is oxidized to the dyestuff by means of potassium ferricyanide; 4 : 3 : 4<1> : 3<1>-bis-pyrenethiophenindigo is also obtained by heating 3-cyanopyrene-4-thioglycollic acid with alkali or by condensing 4 : 3-pyrene-3<1>-oxythiophen with its 2-anil; (4) 4 : 3-pyrene-3<1>-acetoxythiophen is condensed in alcohol or chlorbenzene with 5 : 7-dichlorisatin or 5 : 7-dichlorisatinchloride. Samples have been furnished under Sect. 2 (5) of dyestuffs prepared by condensing 4 : 3-pyrene-3<1>-oxythiophen with 5 : 7-dichlor-3-oxythionaphthene-p-dimethylaminoanil and with acenaphthenequinone. 3-Cyanpyrene-4-sulphonic acid is obtained from 3-aminopyrene-4-sulphonic acid (see Specifications 434,128 and 434,160) by diazotizing and cyanogenating the diazo sulphonic acid. 4 : 3-Pyrenethiophenquinone may be obtained by saponifying 4 : 3-pyrene-3<1>-oxythiophene-p-dimethylaminoanil. The Specification as open to inspection under Sect. 91 comprises also the condensation of 4 : 3 - pyrene - 3<1> - oxythiophen with the p-dimethylamino anils of 2 : 1-naphthoxythiophene, 5-chlor-7-methyloxythionaphthene and of 4 : 7 - dimethyl - 5 - chloroxythionaphthene. This subject-matter does not appear in the Specification as accepted.