Patent GB-418011-A (GB)
Title: Manufacture of diazo compounds
IPC: H01J35/10
Filed: 1933-05-22
Abstract: Diazo compounds of high molecular weight are obtained by treating an aromatic diazo compound with a compound containing a reactive carbonyl group in the presence of an acid condensing agent and under conditions precluding the destruction of the azo group, i.e. at atmospheric temperature or below.  The diazo compounds used as starting materials may contain substituents, e.g. a hydroxy, sulpho or carboxyl group, or a substituted or unsubstituted amino group. The carbonyl compound may be an aliphatic or aromatic aldehyde, ketone or quinone; specified carbonyl compounds are formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, anthraquinone - 2 - aldehyde, isatin, phenanthrenequinone, phenanthrenequinonesulphonic acid, aceanthrenequinone, and acetophenone; the carbonyl compound may contain substituents, e.g. a nitro, amino, hydroxy, methoxy, or sulpho group.  In the examples, (1) diazotized 4-aminodiphenylamine is treated with paraformaldehyde and sulphuric acid in the cold; the product is a resinous diazo compound which gives a dull brown colour when coupled with phloroglucinol on filter paper; (2) the cadmium chloride double salt of unilaterally diazotized p-phenylenediamine is treated with paraformaldehyde in cold sulphuric acid; the product couples with R-salt to yield a violet dye; the unilaterally diazotized p-phenylenediamine used as starting material is obtainable by diazotizing p-aminoacetanilide in hydrochloric acid solution, saturating the solution with hydrochloric acid, and allowing it to stand for some time; (3) diazotized 4-aminodiphenylamine is treated with isatin in sulphuric acid; the product couples with phloroglucinol to yield a reddish-brown dye; (4) the p-chlorobenzenesulphonate of diazotized p-aminophenol is treated with paraformaldehyde in sulphuric acid; the product couples with R-salt to yield a red dye; (5) diazotized 4-aminodiphenylamine is treated with phenanthrenequinonesulphonic acid in sulphuric acid; the product couples with phloroglucinol to yield a brownish-violet material. Samples have been filed, under Sect. 2 (5) of the Acts, of products prepared similarly from (1) acetone and diazotized 4-aminodiphenylamine; (2) crotonaldehyde and diazotized 4-aminodiphenylamine, the product being isolated as a zinc chloride double salt; (3) 2 : 4-dichlorobenzaldehyde and diazotized 4 - aminodiphenylamine; (4) 4 - nitrobenzaldehyde and diazotized 4-aminodiphenylamine; (5) 3 - aminobenzaldehyde and diazotized 4-aminodiphenylamine, the product being isolated as a zinc chloride double salt; (6) 3-amino-2<1>-carboxybenzophenone and diazotized 4-aminodiphenylamine, the product being isolated as a zinc chloride double salt; (7) 2-oxybenzaldehyde and diazotized 4-aminodiphenylamine.  The products may be used in preparing tanned photographic images, as described in Specification 401,898.  The Specification as open to inspection under Sect. 91 states that the diazo compounds used as starting materials may contain a methyl group or a halogen atom, and refers generally to the use of o- or p-hydroxydiazo compounds, o, p-dihydroxydiazo compounds, and o-hydroxy-p-aminodiazo compounds.  It includes also the following examples: (1) diazotized 4-aminodiphenylamine is treated with acetophenone in sulphuric acid; the product couples with phloroglucinol to yield a brown material; (2) diazotized 3-aminocarbazole (as zinc chloride double salt) is treated with paraformaldehyde in sulphuric acid; (3) diazotized 2 : 6-dichloro-4-aminodiphenylamine is treated with paraformaldehyde in sulphuric acid; the product couples with phloroglucinol to yield a yellow material; (4) diazotized m-aminofluorene (as zinc chloride double salt) is treated with paraformaldehyde in sulphuric acid; (5) diazotized 2-aminophenol is treated with paraformaldehyde in sulphuric acid; the product couples with R-salt to yield a red material; (6) diazotized aminochrysene is treated with paraformaldehyde in sulphuric acid; (7) diazotized aminopyrene is treated with formaldehyde in sulphuric acid.  This subject-matter does not appear in the Specification as accepted.