Sulfuric Acid → anthra(1,9-cd)pyrazol-6(2H)-one

Participants

Reaction Conditions

Reaction Steps

To 55 parts of a moist filter cake containing 24 parts of 1-anthraquinonyl hydrazine (dry weight) obtained by the the procedure described in any one of Examples 1 to 11 are added 150 parts by volume of concentrated sulfuric acid, such that the temperature does not rise above 100° C. (about 1/2 hour). The reaction mixture is then stirred for 2 hours at 100° to 110° C., subsequently cooled to 40° C. and diluted dropwise with 150 parts by volume of water. The suspension is then poured into a mixture of ice and water and filtered. The filter cake is washed neutral with water and dried, affording 22.2 parts of pyrazolanthrone of the formula. ##STR6##

Provenance & Evidence