Process for the preparation of 3-anilino-5-pyrazolones

Details Process for the preparation of 3-anilino-5-pyrazolones Process for the preparation of 3-anilino-5-pyrazolones

1976-11-15

1978-09-12

Trousof, Natalie

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

560 35, C07D23152

Patent

active

041139542

ABSTRACT:
In accordance with the present invention, it has been found that 3-anilino-5-pyrazolones can be prepared in high yields by a multi-step process using available starting materials. In the first step of the process, an alkyl .beta.-alkoxy-.beta.-iminopropionate salt is reacted with a suitable alkanol to form an orthoester intermediate in situ. The orthoester then is converted in high yields to the corresponding imidic ester by condensation with an aniline while simultaneously removing alkanol from the reaction mixture to drive the equilibrium reaction to completion. In a preferred form of the invention, formation of the imidic ester is carried out in a high boiling solvent whose presence enables the condensation to be carried out effectively at a high temperature, and which facilitates distillation of the more volatile alkanol by-product from the reaction mixture at atmospheric pressure.

REFERENCES:
patent: 3798234 (1974-03-01), Meier et al.
patent: 3979412 (1976-09-01), Arai et al.

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