GB247003A - The manufacture of new dyestuffs of the pyrone series - Google Patents

Abstract

247,003. Carpmael, W., (Farbenfabriken vorm. F. Bayer & Co.). Jan. 31, 1925. Phthalein dyes; anthraquinone dyes. - Dyestuffs of the pyrone series are prepared by condensing 2 : 4- or 2 : 6-dioxybenzoic acid or a derivative or mixture thereof with an aromatic aldehyde substituted or not in the o-position but not containing an hydroxyl group in the o- or p-position to the carbonyl group, and oxidizing the resulting leuco compound. The dyes may be sulphonated before or after oxidation. In an example 2 : 4-dioxy-3-methylbenzoic acid is condensed with 2 : 6-dichlorbenzaldehyde by stirring in strong sulphuric acid solution and the leuco acid oxidized with nitrous acid, nitric acid, or a nitrocompound such as m.-nitrobenzene sulphonic acid, the melt being poured on ice and filtered. The dystuff dyes wool scarlet from an acid bath and an intense red if after-chromed. Examples also show the sulphonation of the leuco acid and subsequent oxidation and also sulphonation of the dyestuff itself, the shades on wool of the resulting dyestuffs being similar to those obtained above. Instead of 2 4-dioxy-3-methylbenzoic acid may be used 2:4- or 2 : 6-dioxybenzoic acid, and as aldehydes the following :- benzaldehyde, o-sulphobenzaldehyde, o-chlorbenzaldehvde. 2 - chlor - 5-sulphobenzaldehyde, 2 : 6-dichlor-3-oxybenzaldehyde, 2:4: 6-triohlor- 3-oxybenzaldehyde, 2-chlor-4-diethylaminobenzaldehyde, 1 3-diohlor-2-anthraquinone aldehyde 3- or 4-chlorbenzaldehyde, 4-chlor-3-sulphobenzaldehyde, 4-nitrobenzaldehyde, and 4-diethylaminobenzaldehyde. 4-Chlor-3-sulphobenzaldehyde may be prepared by heating 4-chlorbenzaldehyde. with strong cleum at 100‹ C.