Patent GB-585780-A (GB)
Title: Improvements in or relating to the production of pyrazolones
IPC: C07D417/10
Filed: 1944-12-01
Abstract: Pyrazole-5-ones are manufactured by reacting a diazonium compound with a compound of the formula <FORM:0585780/IV/1> wherein R1 and R2 represent the same or different groups -COOR, -CN, -COR or -CONHR, and R and R3 represent hydrogen or hydrocarbon or substituted hydrocarbon groups and may be the same or different, the reaction being effected in the presence of a weak base and completed, if necessary, by heating in the presence of a stronger base, or being effected with a quantity of diazonium compound less than two molecular equivalents (calculated with regard to the number of diazo groups present) per molecular equivalent of the other reactant and in the presence of a strong base, separating the product obtained and allowing it to stand at room temperature or elevated temperature to permit molecular rearrangement and ring-closure.  The diazonium compound may be derived from a monoamine, in which case it is preferable to use equimolecular proportions of the reactants and the reaction takes place in accordance with the equation <FORM:0585780/IV/2> wherein R4 is an aryl, substituted aryl or heterocyclic residue and Y is an acid grouping.  Alternatively, diazonium compounds containing more than one diazo group may be employed, in which case the maximum molar porportion thereof when using strong alkali is correspondingly reduced and the products contain more than one pyrazolone residue in the molecule.  When the group R2 in the product is an ester or nitrile group it may be subsequently hydrolysed to a carboxylic acid group -COOH.  Small quantities of azo dyestuffs with which the products may be contaminated may be removed by filtering an alkali solution of the product and reprecipitating the pyrazolone by the addition of acid. The products may be used as dyestuff intermediates, e.g. for the production of azo dyes (by reaction with diazonium compounds, which may be the same as or different from those used in making the pyrazolones), of azo-methine dyestuffs (e.g. in processes of colour photography) or of merocyanine dyes.  In examples: (1) aniline is diazotized and treated with an equimolecular proportion ethyl acetosuccinate in the presence of sodium hydroxide solution, or (2) in alcoholic solution in the presence of sodium acetate, sodium carbonate or borax, or (3) in aqueous pyridine solution-yielding in each case 1-phenyl 3-carbethoxypyrazole-5-one; (4) and (5) benzidine is tetrazotized and treated as in (1) or (3) to give 4 : 41 - diphenylene - bis - (3-carbethoxy-pyrazole-5-one-1); (6) the ethyl acetosuccinate in (2) is replaced by ethyl methyl acetosuccinate, producing 1 - phenyl - 3 - carbomethoxypyrazole-5-one; (7) the ethyl acetosuccinate in (3) is replaced by ethyl b  : b -diacetylpropionate, yielding 1-phenyl-3-acetylpyrazole-5-one; (8) the ethyl acetosuccinate in (3) is replaced by ethyl cyanosuccinate and the product is heated with sodium hydroxide solution to effect ring closure and hydrolysis and acidified to liberate 1-phenylpyrazole-5-one-3-carboxylic acid; (9) ethyl ethane-a  : a  : b -tricarboxylate similarly yields the same product; (10) the ethyl acetosuccinate in (2) is replaced by ethyl acetosuccinate-o-chloranilide, producing 1-phenylpyrazole-5-one-3-carboxylic acid o-chloranilide; (11) a -naphthylamine is diazotized and treated with ethyl acetosuccinate in ethyl alcohol in the presence of sodium acetate, and the product is heated with sodium hydroxide solution and acidified to yield 1-a -naphthylpyrazole-5-one-3-carboxylic acid; (12) b -naphthylamine is similarly treated; (13) the aniline in (3) is replaced by p-aminobenzenesulphonamide, producing 1-p-sulphonamidophenyl-3-carbethoxypyrazole-5-one; (14) dehydrothio-p-toluidine is diazotized and treated with ethyl acetosuccinate in aqueous pyridine solution, and the product is heated with sodium carbonate solution; (15) p-aminobenzoic acid is treated as in (3) to give 1-p-carboxyphenyl-3-carbethoxypyrazole-5-one; (16) sulphanilic acid is similarly treated and the product is heated with sodium hydroxide to yield the di-sodium salt of 1-p-sulphophenylpyrazole-5-one-3-carboxylic acid; (17) p-nitraniline is diazotized and treated as in (14), producing 1 - p - nitrophenyl - 3 - carboxy - pyrazole-5-one.  Additional starting materials specified are, on the one hand, the diazo and tetrazo compounds of toluidines, xylidines, naphthionic acid, p - aminobenzyldimethyl - amine, m-aminophenyldimethylamine, m-nitraniline, p-aminophenol, aminonaphtholsulphonic acids, aminoazobenzene and its sulphonic acids, tolidines, p : p1-diaminostilbene, p : p1-diaminodiphenylamine, 2 : 7 - diaminocarbazole, 2 : 7 - diaminofluorene, p : p1 - diaminoazobenzene, p - phenylenediamine, 1 : 4- and 1 : 5-diaminonaphthalenes and dehydrothio-p-toluidinesulphonic acid, and, on the other hand, ethyl acetosuccinate-anilide.  Acids and esters of the general formula <FORM:0585780/IV/3> are obtainable by the interaction of an alkali metal derivative (which may be formed in situ) of a reactive methylene compound R1-CH2-R2 with a monohalogen acetic acid or ester XCH2.COOR3 (where X represents a halogen atom), e.g. by the action of ethyl chloracetate on diethyl malonate, ethyl or methyl acetoacetate, ethyl cyanacetate, acetylacetone or acetoacetanilide in the presence of an alkali metal (e.g. sodium) ethoxide, or on sodio acetoacet-o-chloranilide in ethyl alcohol. The ethyl chloracetate may be replaced by the corresponding bromo or iodo derivatives or by the free acids.  Specifications 544,647, 549,202, 553,144, 555,936 and 585,781 are referred to.