Patent GB-888167-A (GB)
Title: Monoazo dyestuffs containing pyrazole rings
IPC: C09B29/033
Filed: 1958-12-24
Abstract: Polyacrylonitrile is dyed in the mass using dyestuffs of formula:- p <FORM:0888167/IV (a)/1> wherein R1 is hydrogen or an aliphatic, aromatic or heterocyclic radical, R2 and R3 are aromatic or aliphatic radicals which may be combined to give a carbocyclic or heterocyclic ring and R4 is a coupling component radical, the dyestuffs being free of carboxylic and sulphonic acid groups or quaternized derivatives thereof (see Group IV(c)).  In an example the dyestuff 1-phenyl - 3:4 - dimethyl - 5 - aminopyrazole-->1-methyl-3-dimethylaminobenzene is quarternized with dimethyl sulphate.  A solution of the quaternized dyestuff in dimethyl formamide is added to a polyacrylonitrile spinning solution which is spun in known manner to give red fibres. Dyestuffs give similar results are obtained by replacing 1-methyl-3-dimethylaminobenzene by N:N-dimethylaniline, 2:5-dimethoxyaniline, N-ethyl-diphenylamine, 1-amino- or -dimethylamino- or N-methyl-N-ethyl-amino- or -propionylamino-naphthalene, 1:3-di(dimethylamino)-benzene and 1-dimethylamino-7-naphthol.  Reference has been directed by the Comptroller to Specification 791,932.ALSO:Aminopyrazoles of formula <FORM:0888167/IV (b)/1> wherein R1 is hydrogen or an aliphatic, aromatic or heterocyclic radical and R2 and R3 are aromatic or aliphatic radicals which may be combined to give a carbocyclic or heterocyclic ring are prepared by reacting b -ketonitriles of formula <FORM:0888167/IV (b)/2> in aqueous acid with hydrazine or substituted hydrazines.  They are used in the preparation of azo dyestuffs (see Group IV(c)). In an example a -acetylpropionitrile is added dropwise to a hydrochloric acid solution of hydrazine and the mixture is cooled to precipitate 3 : 4-dimethyl-5-aminopyrazole.  The following 5-aminopyrazoles are similarly prepared: 1-phenyl-3 : 4-trimethylene- or -tetramethylene-, 1-b -hydroxyethyl- or -b -cyanoethyl-3 : 4-dimethyl-, 1 phenyl- or -(41-methoxyphenyl)-3 : 4-dimethyl-, 1-[benzthiazolyl-(21)]-3 : 4-dimethyl-, 1-b -cyanoethyl- or -phenyl-3-ethyl-4-methyl-, 1-b -hydroxy- or -cyano-ethyl-3 : 4-tri- or tetramethylene-, and 3-methyl-4-phenyl-5-aminopyrazoles, 1-phenyl- or - b  - cyanoethyl - 5 - aminothiophano - [31 : 41 : 3 : 4]-pyrazole, 1-phenyl-5-amino-N-methylpyrrolidino-[31 : 41 : 3 : 4]-pyrazole and 3 - (31 : 41 - dimethyl - 51 - aminopyrazolyl) - tetrahydrothiophene - 1,1 - dioxide.  1 - (31 - nitrophenyl) - 3:4 - dimethyl - 5 - aminopyrazole is also specified.  Reference has been directed by the Comptroller to Specification 791,932.ALSO:The invention comprises monoazo dyestuffs of formula <FORM:0888167/IV (c)/1> wherein R1 is hydrogen or an aliphatic, aromatic or heterocyclic radical, R2 and R3 are aromatic or aliphatic radicals which may be combined to form a carbocyclic or heterocyclic ring and R4 is a coupling component radical, the dyestuffs being free of carboxylic and sulphonic acid groups, and quaternised products thereof.  The dyestuffs are prepared by diazotising a suitable aminopyrazole (see Group IV(b)), coupling with a coupling component and quaternising the monoazo dyestuff in known manner, if desired. Specified quaternising agents are dialkyl sulphates, alkyl halides and p-toluenesulphonic acid esters.  The dyestuffs give red and yellow shades on polyester, polyamide, cellulose acetate and polyacrylonitriles (see Group IV(a)).  In examples dyes are prepared from the following components and in some cases treated with dimethyl sulphate in chlorobenzene; 3 : 4-dimethyl-5-aminopyrazole, 1-phenyl- or -(31-nitrophenyl)-3 : 4-dimethyl-5-aminopyrazole, 1-phenyl-3 : 4-trimethylene- or -tetramethylene - 5 - aminopyrazole, 1 - phenyl - 3 - ethyl - 4 - methyl - 5 - aminopyrazole, 1 - phenyl - 3 - methyl - 4 - phenyl - 5 - aminopyrazole, 1 - b  - cyanoethyl - 3 : 4 - dimethyl - 5 -aminopyrazole, 3 - (31 : 41 - dimethyl - 51 - aminopyrazolyl) - tetrahydrothiophene - 1 : 1 : dioxide and 3 - methyl - 4 - phenyl - 5 - aminopyrazole; dimethyl - aniline, 3 - dimethylamino - toluene, N - methyl - N - b  - dimethylaminoethylaniline, 2 : 5 - dimethoxyaniline, N - ethyldiphenylamine, 1 - aminonaphthalene, 1 : 3 - di(dimethylamino) - benzene, 1 - dimethylamino - or - N - methyl - N - methyl - or - propionylamino - naphthalene, 1 - dimethylamino - 7 - naphthol, N - methyl - N - b  - cyanoethyl - aniline, N - ethyl - N - p - cyanoethyl - m - toluidine, N : N - di(b  - hydroxyethyl) - m - toluidine, N - methyl - N - b  - thiocyanoethyl - aniline, 3 - cyanomethyl - phenol, 1 - phenyl - 3 - methyl - 5 - pyrazolone and N - ethyl - N - b  - cyanoethyl-aniline.  Many other components are specified.  Reference has been directed by the Comptroller to Specification 791,932.