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

By I. L. FINAR and R. J. HURLOCK.4-Amino-l-phenylpyrazole has been converted by the Skraup reaction into l'-phenylpyrazolo(4' : 5'-2 : 3)pyridine the structure of which has been proved by synthesis and ultraviolet absorption spectroscopy. Some pyrazolylquinolines have also been prepared from l-aminophenylpyrazoles by the Skraup reaction. 4-AMINO-1-PHENYLPYRAZOLEJ previously obtained from glucosazoneJ1 was more conveniently prepared by the reduction of 4-nitro-l-phenylpyrazole with hydrazine hydrate and palladised ~h a r c o a l . ~ Two isomers can theoretically be obtained from this amine in the Skraup reaction, by ring closure in the 5-or the 3-position of the pyrazole ring to give compound (I or 11; R = H).Attempts to cause ring closure with 75% and 85% sulphuric acid4 and arsenic pentoxide as oxidising agent failed; small amounts of unchanged amhe were recovered.

Bromination of cumene with N-bromosuccinimide yielded 1 2-dibromo-2-phenylpropane, whereas 4-hydroxycumene gave either 3-bromo-4-hydroxycumene, 3.5-dibromo-4-hydroxycumene, or 1.3-dibromo-2-(3,5-dibromo-4-hydroxypheny1)propene depending on the excess of reagent used. Similarly 4-hydroxy-3.5-di-t-butylcumene gave either 1,3-dibromo-2-(4-hydroxy-3,5-di-t-butylphenyl)propene or 1.3-dibromo-2-(2-bromo-4-oxo-3,5-di-t-butylcyclohexa-2,5-dienyl) propene.

No abstract

A series of substituted N-benzylpiperidines has been prepared, and their reaction with carbon disulphide studied. When the benzyl group possesses a 4-hydroxy-substituent together with 3.5-substituents such as alkyl and methoxythe reaction leads to dithiocarbamate formation by ' insertion ' of carbon disulphide between the benzylic carbon atom and nitrogen. A three-stage mechanism is proposed, one stage involving the formation of ap-quinone methide as a transient intermediate. An alternative two-stage mechanism is considered but shown to be less likely.WHEREAS the reaction between carbon disulphide and primary or secondary amines is well-known, that between carbon disulphide and tertiary amines has been less studied. With certain tertiary amines, dithiocarbamate formation occurs by ' insertion ' of carbon disulphide into a carbon-nitrogen bond of the amine. Thus, the Mannich base N-(4-hydroxy-3,5-di-t-butyl-benzy1)piperidine (Ia) was recently shown to yield-4-hydro~y-3~5-di-t-butylbenzyl piperidine-l-carbodithioate (IIa) on treatment with carbon disulphide, and