DIPHENYLKETENE

Diphenylketene is used for acylation of carboxylic acids to give mixed anhydrides; cycloaddition with a variety of unsaturated compounds; synthetic source of diphenylallenes.

Preparative Methods of Diphenylketene: originally prepared by zinc reduction of α-chlorodiphenylacetyl chloride; oxidation of benzil monohydrazone with yellow Mercury(II) Oxide followed by thermal rearrangement of the α-diazo ketone; dehydrohalogenation of diphenylacetyl chloride with Triethylamine; debromination of α- bromodiphenylacetyl bromide by the action of Triphenylphosphine.

Journal of the American Chemical Society, 93, p. 4604, 1971 DOI: 10.1021/ja00747a050
Organic Syntheses, Coll. Vol. 3, p. 356, 1955

Diphenylketene stored in a tightly stoppered bottle at 0 °C is stable for several weeks. Trace amounts of hydroquinone and storage under nitrogen inhibit polymerization and lead to increased stability. Given the reactivity of diphenylketene with amino acids, care should be taken to avoid skin contact.