1-Phenylpyrazole and nitrophenylpyrazoles have been converted into trinitro-compounds by mixed acids a t loo", and the products orientated by synthesis. Some di-and the tri-nitrophenylpyrazoles give colours in the Janovsky reaction.l* NITRATION of l-phenylpyrazole with mixed acids at 100" gives 1-(2 : 4-dinitrophenyl)-4nitropyrazole ; the course of the reaction is indicated by nitration of l-phenylpyrazole at 12" and 22" which gives the intermediates l-p-nitrophenyl-and 4-nitro-l-p-nitrophenylpyrazole, respectively. Nitration of both these compounds a t 100" gives the trinitrocompound, which is also obtained by other nitrations (see Table ).1-(2 : 4-Dinitrophenyl)-4-nitropyrazole was characterised by its reaction with boiling methanolic sodium methoxide to give 4-nitropyrazole and 2 : 4-dinitroanisole. It was synthesised by condensation between 4-nitropyrazole [from pyrazole,* by nitration with mixed acids at 100" (cf. Buchner and F r i ~c h , ~ and Huttel et aZ.6)] and l-chloro-2 : 4-dinitrobenzene in ethanolic potassium hydroxide. Nitration of l-m-nitrophenyl-and 4-nitro-1-m-nitrophenyl-pyrazole with mixed acids at 100" gives 1 -(3 : 4-dinitrophenyl)-4-nitropyrazole, the orientation of which was established as follows. One nitro-group underwent nucleophilic replacement in ethanolic ammonia at loo", to give an amine which, on deamination, gave 4-nitro-l-~-nitrophenylpyrazole, the presence of a 9-nitro-group in the trinitro-compound being thus established. This trinitro-compound was synthesised as follows : Partial reduction of 4-nitro-l-p-nitrophenylpyrazole with ammonium hydrogen sulphide gave l-~-aminophenyl-4-nitropyrazole (the structure being shown by deamination

Various pyrazoles have been formylated, and these derivatives oxidised to the corresponding acids. Thionyl chloride reacts directly with l-phenylpyrazole to give the dipyrazolyl sulphoxide which has been oxidised to the sulphone. 4-Fomyl-l-phenylpyrazole gives the expected alcohols with Grignard reagents, except that ethylmagnesium halide gave 4-propenyl-1phenylpyrazole and a dimer. The alcohols have been oxidised to the ketones, and some of these reduced to alkyl compounds by the Clemmensen method. Both 4-fomyl-l-phenylpyrazole and 1-phenylpyrazole-4-carboxyIic acid have been reduced by lithium aluminium hydride to 4-hydroxymethyl-lphenylpyrazole. Two bipyrazolyls and one terpyrazole have also been prepared.

The preparation of 1 -phenylpyrazole from epichlorohydrin and phenylhydrazine has been improved, and the method has been extended to include the use of nitrophenylhydrazines. Some 4-substituted derivatives of 1-phenylpyrazole have been prepared, and their properties have been investigated.

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