Patent GB-421054-A (GB)
Title: New leather dyestuffs
IPC: C09B39/00
Filed: 1933-06-06
Abstract: Metal-containing azo dyestuffs suitable for dyeing leather are obtained by wholly or partially satisfying the coupling capacity of old fustic by coupling it with one or more molecular proportions of a single diazo compound carrying an o-hydroxy, o-carboxy or o-alkoxy group or of two or more different diazo compounds, at least one carrying such a group, and thereafter converting the resultant dyestuff into a metal complex compound by treatment with an agent yielding metal.  Preferably, the coupling capacity is about two-thirds satisfied.  The following examples are specified.  (1) 52,5 parts of an extract of old fustic are coupled in sodium carbonate solution with an amount of diazotized 2 : 1-aminonaphthol-4-sulphonic acid sufficient to satisfy the coupling capacity of 35 parts of the extract and the solution is neutralized with hydrochloric acid and boiled for 6 hours under reflux with an addition of chromium fluoride; the chromium complex compound obtained by acidifying and salting out gives on leather level grey dyeings fast to washing and to light.  (2) A similar old fustic extract is coupled successively with specified amounts of diazotized sulphanilic acid and diazotized 3-amino-5-sulphosalicylic acid and the product is salted out and boiled for 10 hours under reflux with a solution of copper sulphate to obtain a copper complex compound giving on leather level medium brown dyeings; if the copper sulphate is replaced by chromium fluoride with boiling for 15 hours the dyeings are a slightly brighter brown.  (3) A similar old fustic extract is coupled successively with specified amounts of diazotized picramic acid and diazotized 3-amino-5-sulphosalicylic acid and the product is salted out and boiled for 12 hours under reflux with a solution of copper sulphate to obtain a copper complex compound giving on leather fast level reddish brown dyeings; if the copper sulphate is replaced by chromium fluoride with boiling for 18--20 hours, the dyeings are bluish brown.  (4) A similar old fustic extract is coupled successively with specified amounts of diazotized 2 : 1-aminonaphthol - 4 - sulphonic acid and diazotized picramic acid and the product is salted out and boiled for 5--6 hours with a solution of copper sulphate to obtain a copper complex compound giving on leather very level maroon dyeings; the corresponding chromium compound gives level grey dyeings.  (5) A similar old fustic extract is coupled successively with specified amounts of diazotized anthranilic acid and diazotized metanilic acid and the product is salted out and boiled for 6 hours under reflux with a solution of copper sulphate to obtain a copper complex compound giving on leather level tan brown dyeings; if the copper sulphate is replaced by chromium fluoride with boiling for 12 hours, the dyeings are a level brown.  (6) A similar old fustic extract is coupled successively with specified amounts of diazotized o-anisidine and diazotized 3-amino-5-sulphosalicylic acid and the solution is neutralized with hydrochloric acid and boiled for 6 hours under reflux with an addition of copper sulphate to obtain a copper complex compound giving on leather brown dyeings fast to light and washing.  Specification 12667/87, [Class 2], is referred to in the Provisional Specification.