Process for the preparation of 1-phenyl-3-carbamoyl-5-pyrazolone

Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...


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The invention relates to the preparation of 1-phenyl-3-carbamoyl-5-pyrazolones of the formula: ##STR1## in which the two symbols R and R' may be the same or different and each represents a hydrogen atom, an alkyl radical or a substituted alkyl radical containing 1 to 4 carbon atoms.
An aqueous paste of diethyl oxalacetate phenylhydrazone is heated at a temperature not greater than C. until the hydrazone is completely melted, and the aqueous phase is then removed and the remaining hydrazone is treated with 2 to 12 molar equivalents of a compound of the formula HNRR' at a temperature between and C. The formation of 1-phenyl-3-carboxy-5-pyrazolone is thus avoided.

patent: 2153615 (1939-04-01), Dahlen et al.
patent: 2459226 (1949-01-01), Kendall et al.
patent: 2659720 (1953-11-01), Kuster
Beilsteins Handbuch der Organischen Chemie, 4th Editn., vol. 25, 1936, (Springer, Berlin), pp. 204-218.
Weissberger et al., J. Am. Chem. Soc., 1942, vol. 64, pp. 2133-2136.


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