Patent GB-868037-A (GB)
Title: Improvements in or relating to monoazo dyestuffs of the benzothiazol-azobenzene or -azoquinoline series
IPC: C09B29/033
Filed: 1959-02-04
Abstract: 2-Aminobenzthiazoles of formula:  <FORM:0868037/IV (b)/1> (wherein R3 is an alkyl or alkenyl radical with 1 to 4 carbon atoms or an amino group one or both hydrogen atoms of which may be substituted by alky, aralkyl, cycloalkyl or aryl radicals which may contain further substituents, R4 is hydrogen or alkyl with 1-4 carbon atoms and R5 is halogen or a nitro or sulphonic acid group), are prepared by (a) halogenating nitrating or sulphonating a compound of formula: <FORM:0868037/IV (b)/2> or (b) by converting a compound of formula: <FORM:0868037/IV (b)/3> or an N-acyl derivative thereof (i) into the sulphinic acid and alkylating or (ii) into a sulphonamide by reaction with ammonia or an amine, and splitting of the acyl group if necessary.  The compounds are used as intermediates in the preparation of azo dyes (see Group IV(c)).  In Examples (1) 2-amino-6-methylsulphonylbenzthiazole is nitrated with a mixture of nitric and sulphuric acids to give the 4-nitro-derivative; (2) as in (1) but reacting with oleum to give 2-amino-6-methylsulphonylbenzthiazole-4-sulphonic acid; (3) as in (1) but reacting with bromine in glacial acetic acid and propionic acid to give the 4-bromo-derivative.ALSO:The invention comprises dyestuffs of formula:  <FORM:0868037/IV(c)/1> wherein R1 is an alkylene radical with 1 to 4 carbon atoms, R2 is a mono- or di-hydroxyalkyl, alkoxyalkyl, acetoxyalkyl which may be further substituted, cyanoalkyl, di- or tri-fluoromethyl, fluorated cyanoalkyl, carbamoyloxyalkyl which may be further substituted or carbalkoxyalkyl radical, R3 is an alkyl or alkenyl radical with 1 to 4 carbon atoms or an amino group one or both hydrogen atoms of which may be substituted by alkyl, aralkyl, cycloalkyl or aryl radicals which may be further substituted, R4 is hydrogen or alkyl with 1 to 4 carbon atoms, R5 is halogen or a nitro or sulphonic acid group, M is hydrogen, hydroxy, alkoxy, acetoxy which may be further substituted or a carbamoyloxy radical, Y is hydrogen, halogen, an alkyl or alkoxy group with 1 to 4 carbon atoms, trifluoromethyl, trifluoroacetylamino or an alkanoylamino radical with up to 4 carbon atoms and Z is hydrogen, halogen an alkyl or alkoxy group with 1 to 4 carbon atoms or together with <FORM:0868037/IV(c)/2> and the adjacent benzene nucleus forms a tetrahydroquinoline ring.  They are prepared by diazotizing a suitable aminobenzthiazole (see Group IV(b)) and coupling with a suitable substituted aniline or tetrahydroquinoline. The dyes may be used for dyeing wool, silk, animalized cellulosic fibres, cellulose esters, synthetic polyamides and polyacrylonitriles and also for pigmenting lacquers, oils and resins in blue, violet and red shades.  In Examples:-(1) 2-amino-4-nitro-6-methylsulphonylbenzthiazole is ground with phosphoric acid, diazotized by the addition of solid sodium nitrite and N-cyanoethyl-N-hydroxy-ethyl-aniline is added; (2) a mixture of concentrated sulphuric acid and sodium nitrite is heated and cooled and a mixture of 2-amino-6-methyl-sulphonylbenzthiazole-4-sulphonic acid in glacial acetic and propionic acids is added followed by N-ethyl-N-hydroxyethyl-aniline.  The preparation of many further dyestuffs of the above formula is specified.