GB291768A - Manufacture of derivatives of vat-dyestuffs and process of printing therewith - Google Patents

Abstract

291,768. Soc. of Chemical Industry in Basle. June 8, 1927, [Convention date]. Leuco compounds of vat dyes, derivatives of.- Derivatives of vat dyes are obtained by treating the leuco compounds of indigoid dyestuffs with fatty acids containing an exchangeable halogen atom, such as monohalogenacetic acids, #-chlorpropionic acids and the like. The products mav be used for printing, development being effected by means of oxidizing agents. In examples, (1) leucothioindigo is dissolved in aqueous caustic soda solution and heated with chloracetic acid or #-chlorpropionic acid dissolved in water with addition of calcined sodium carbonate; the product, obtained by filtering from unchanged leucothioindigo and acidifying with hydrochloric acid is a reddish-brown powder insoluble in water and dilute acids but readily soluble in dilute alkalies, and (2) indigo white is similarly treated with chloracetic acid; the product is a grey-brown powder insoluble in water and acids but soluble in alkalies. The Specification, as open to inspection under Sect. 91 (3) (a) is not restricted to the products obtained from indigoid dyestuffs and halogenated fatty acids, but comprises the production of derivatives of vat dyes in general by treating their leuco-compounds with acids which have a teadily exchangeable halogen atom, benzylchloride sulphonic acid being mentioned as an example of the latter. This subject-matter does not appear in the Specification as accepted.