Patent GB-430580-A (GB)
Title: Improvements in and relating to the manufacture of azo compounds
IPC: C09B29/42
Filed: 1933-12-23
Abstract: Processes are described for the manufacture of bactericidal azo compounds of the type RN : NR<1>, where R is a radicle of the benzene series substituted in the p-position or in two positions by a sulphonamide group or groups, and R<1> is an aromatic carbocyclic nucleus, e.g. a benzene or naphthalene nucleus, or a heterocylic nucleus, which contains a basic nitrogen atom linked to or forming part of the ring and is further substituted by at least one hydroxyl or amino group.  The compounds may contain additional substituents such as halogen atoms or alkyl, alkoxy, phenoxy and nitro groups, but free acid groups must not be present.  The sulphonamide group or groups attached to the radicle R may be substituted on the nitrogen atom by one or two saturated or unsaturated alkyl or cycloalkyl groups such as methyl, ethyl, allyl, butyl, isoamyl or cyclohexenyl, or by aralkyl groups such as benzyl or phenylethyl, or the sulphonamide nitrogen may form part of a heterocyclic ring such as a pyrrolidyl or piperidyl ring.  The amino group which may be linked to the nucleus R<1> may be substituted by alkyl groups.  The compounds may be prepared (1) by coupling a diazotized p-aminosulphonamide or aminodisulphonamide of the benzene series with an aromatic amine or heterocyclic nitrogen compound further substituted by at least one amino or hydroxyl group; (2) by condensing a p-aminosulphonamide or aminodisulphonamide of the benzene series with the nitroso compound of an aromatic amine or heterocyclic nitrogen compound substituted as indicated above; (3) by the action of ammonia or a primary or secondary amine on azo compounds of the type R<11>N : NR<1>, where R<1> has the meaning given above and R<11> is a radicle of the benzene series substituted in the p-position or in two positions with a sulphohalide or sulphonic ester group or groups; (4) by introducing an amino or hydroxyl group into an azo compound of the type RN : NR<1>, where R has the meaning given above and R<1> is an aromatic, a carbocyclic or heterocylic nucleus which contains a basic nitrogen atom linked to or forming part of the ring, and is further substituted by a substituent convertible into an amino or hydroxyl group; the convertible substituent may be (a) a nitro or nitroso group, which is reduced without reducing the azo group, or (b) an acylamino, sulphamic acid or azomethine group, which is saponified without saponifying the sulphonamide group, or (c) a protected hydroxyl group, which is converted into a free hydroxyl group, or (d) an amino group, which is converted into a hydroxyl group by way of the azo group.  The use of compounds containing the pyrazole nucleus or hydrocupreine ring system is excluded from all the above methods. In the examples, (1) 4 - aminobenzenesulphonamide, 4 - aminobenzenesulphomethylamide, 4 - aminobenzenesulphonethylamide, 4 - aminobenzenesulphohydroxyethylamide, 4 - aminobenzenesulphodimethylamide, or 4 - aminobenzenesulphodiethylamide is diazotized and coupled with m - phenylenediamine; (2) 4 - aminobenzenesulphonamide is diazotized and coupled with 2 : 6-diaminopyridine; (3) aminobenzene-3 : 5-disulphonamide is diazotized and coupled with m-phenylenediamine; (4) 4-aminobenzenesulphonamide is diazotized and coupled with m-aminophenol or (example 5) with 2 : 4-dioxy-6-methylpyridine; (6) 4-aminobenzenesulphonamide is diazotized and coupled with 8-oxyquinoline, 5-oxyquinoline, 6-oxyquinoline, 7-oxyquinoline, 6 - chloro - 8 - oxyquinoline, 5 - methyl - 8 - oxyquinoline, 8 - methyl - 5 - oxyquinoline, or 6 : 8-dioxyquinoline; (7) 4<1>-sulphodimethylamide - 2 : 4 - tetraethyldiaminoazo benzene is prepared by heating 4-aminobenzenesulphodimethylamide with 4-nitroso-1 : 3-tetraethyldiaminobenzene (obtainable by introducing the nitroso group into 1 : 3-tetraethyldiaminobenzene in hydrochloric acid solution); (8) diazotized aniline-p-sulphonic acid is coupled with tetraethyl-m-phenylenediamine, and the sulphonic group in the product is converted into a sulphochloride group by means of chlorsulphonic acid, and then into a sulphonamide group by means of ammonia; (9) diazotized aniline-p-sulphonic acid is coupled with m-dimethylaminophenol, and the sulpho-group in the product is converted into a sulphonamide group as in example 8; (10) diazotized 4-aminobenzenesulphodimethylamide is coupled with 2-nitrophenol, and the product is heated with aqueous ammonia, whereby the hydroxyl group is replaced by an amino group; the nitro group is then reduced by means of aqueous ferrous sulphate, and 4<1>-sulphodimethylamide-3 : 4-diaminoazobenzene is obtained; (11) diazotized 4-aminobenzenesulphonamide is coupled with 1-acetylamino-3-diethylaminobenzene, and the product is heated with aqueous hydrochloric acid, whereby the acetyl group is removed; (12) diazotized 4-aminobenzenesulphodimethylamide is coupled with 2-nitrophenol, and the nitro group in the product is reduced with aqueous ammoniacal ferrous sulphate; (13) diazotized 4 - aminobenzenesulphonamide is coupled with 3-acetylaminophenol, and the product is treated as in example 11 to remove the acetyl group; (14) diazotized 4-amino-benzenesulphonamide is coupled with 4<1>-nitrobenzal-3-aminophenol and the product is heated with aqueous hydrochloric acid, whereby nitrobenzaldehyde is liberated and 2-amino-4-oxyazobenzene - 4<1> - sulphonamide is obtained. Specification 149,428, [Class 2 (iii)], is referred to.  Samples have been filed under Sect. 2 (5) of the following compounds, prepared analogously to the products of examples 1 and 2: (1) 4<1>-sulphonamide - 2 - amino - 4 - diethylaminoazobenzene hydrochloride; (2) 3<1>-methyl-4<1>-sulphonamide-2 : 4-diaminoazobenzene hydrochloride; (3) 4<1>-sulphonamidebenzeazo-2-hydroxy - 6 - aminopyridine hydrochloride; (4) 4<1> - sulphonamidebenzeneazo - 6 - aminoquinoline hydrochloride; (5) 4<1>-sulphonamidebenzeneazo - 5 - aminoquinoline hydrochloride; (6) 4<1> - sulphonamidebenzeneazo - 5 - aminoisoquinoline.