Patent GB-497327-A (GB)
Title: Process for the manufacture of leuco esters of vattable compounds
IPC: C09B9/02
Filed: 1937-06-11
Abstract: Leuco compounds of vat dyes, esters of.-Water-soluble leuco esters of vattable compounds are manufactured by causing organic acylating agents having, in addition to the acylating group, at least one substituent capable of forming a salt or capable of being converted into a quaternary ammonium compound (with the exclusion of phthalic anhydride), to react upon vattable compounds in the presence of a tertiary base, e.g. pyridine, quinoline or dimethylaniline, and a metal, e.g. copper, iron or zinc, if desired with the addition of an indifferent organic solvent, e.g. benzene, toluene, xylene, mono-, di- or trichlorobenzene.  The starting materials may be vattable compounds of the anthraquinone or benzanthrone series, or indigoid compounds such as indigo, thioindigo or mixed indigoid compounds. Suitable acylating agents are monohalides or anhydrides (preferably intramolecular anhydrides) of aromatic sulphocarboxylic acids, e.g. m- and p-benzoic acid sulphochlorides, naphthoic acid sulphochlorides, and diphenylcarboxylic acid sulphochlorides, dihalides or anhydrides of aliphatic, hydroaromatic or aromatic dicarboxylic or polycarboxylic acids, e.g. isophthalic, terephthalic and adipic acid chlorides and maleic anhydride (the reaction when employing dihalides being carried out in such a manner that only one of the acid halide groups reacts, the other being subsequently saponified to the free acid group or a salt thereof, in some cases in the presence of hydrogen sulphide or a water-soluble salt thereof), and also compounds having in addition to the acylating group such substituents as combine with tertiary bases to form quaternary ammonium compounds, e.g. chloracetyl chloride, o -chloro-p-toluic acid chloride and 4-chloro-3-nitrobenzoyl chloride (the transformation into the quaternary ammonium compound being carried out during or after the acylation reaction).  In examples: (1) Bz2 : Bz121-dimethoxydibenzanthrone is heated with benzoic acid-m-sulphochloride, pyridine and copper powder; on heating the product in the air with dilute caustic soda lye or aqueous potassium carbonate solution, the original dyestuff is regenerated; (2) the benzoic acid-m-sulphochloride of (1) is replaced by the sulphochloride of naphthalene-2-carboxylic acid (obtainable by heating naphthalene-2-carboxylic acid with chlorsulphonic acid); (3) tetrabromindigo is heated with benzoic acid-m-sulphochloride, pyridine and iron powder; (4) thioindigo is treated as in (1); (5) Bz2 : Bz121-dimethoxydibenzanthrone is heated with o-sulphobenzoic acid anhydride, pyridine and copper powder; (6) the vat dyestuff of the formula <FORM:0497327/IV/1> is similarly treated; the product may be reconverted into the original dyestuff by treating it with sodium hydrosulphite in caustic soda solution, or with nitrite or chromate in mineral acid solution; (7) Bz2 : Bz121-dimethoxydibenzanthrone is heated with isophthaloyl chloride, pyridine and copper powder; the product may be reconverted into the original dyestuff by treatment with dilute sodium carbonate solution or caustic soda lye, with access of air or with the addition of oxidizing agents, e.g. hydrogen peroxide, or by treatment with nitrite-containing dilute hydrochloric acid; the copper powder may be replaced by zinc or iron powder, and the isophthaloyl chloride by terephthaloyl chloride; (8) Bz2 : Bz121-dimethoxydibenzanthrone is heated with isophthaloyl chloride, dimethylaniline and copper powder; (9) the reaction of (7) is carried out in the presence of chlorobenzene; (10) tetrabromindigo is treated as in (7); (11) Bz2 : Bz121-dimethoxydibenzanthrone is heated with adipic acid dichloride, pyridine and copper powder; (12) the adipic acid dichloride of (11) is replaced by maleic anhydride; (13) Bz2 : Bz121-dimethoxydibenzanthrone is stirred with o -chloro-p-toluic acid chloride, pyridine and copper powder, and the product is then heated to convert the o -chloro-p-toluic ester into the pyridinium compound; tetrabromindigo may be similarly treated; 4-chloro-3-nitrobenzoyl chloride may alternatively be used as acylating agent; (14) thioindigo is heated with o -chloro-p-toluic acid chloride, pyridine and copper powder; (15) Bz2 : Bz121 - dimethoxydibenzanthrone is stirred at room temperature with chloracetyl chloride, pyridine and copper powder, and the mixture is then heated. Specifications 317,428 and 330,579, [both in Class 2 (iii)], are referred to.