Patent · US Expired

Process for the preparation of pyrazole

US4434292A · kind A · utility

4Cited by

1References

5Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Ulrich Heinemann · Leichlingen, DE
Rudolf Thomas · Haan, DE
Reinhard Lantzsch · Leverkusen, DE
Klaus Ditgens · Wuppertal, DE
Erhard Weber · Bocholt, DE

Key dates

Filing date	Sep 8, 1981
Grant date	Feb 28, 1984
Priority date	—
Expiry date	Sep 8, 2001

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC07D249/08
WIPO fieldOrganic fine chemistry
WIPO sectorChemistry

Abstract

Process for the preparation of pyrazole from hydrazine hydrate and acrolein comprising reacting hydrazine hydrate with acrolein in an aqueous-organic medium at a temperature between 20.degree.-80.degree. C. and then oxidizing the 2-pyrazoline formed, of the formula ##STR1## either directly or after first being isolated, with chlorine or an alkali metal hypochlorite or an alkaline earth metal hypochlorite and water or an aqueous-organic medium at a temperature between 0.degree. and 60.degree. C.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.