Methyleneketenes and methylenecarbenes. X. Precursors for the generation of methyleneketene and deuterated methyleneketenes for microwave spectroscopy

Abstract

The synthesis of a mixture of deuterated cyclopentadiene adducts (3) required for the pyrolytic generation of CHD=C=C=O and CD₂=C=C=O is described. Methyleneketene is conveniently generated for microwave spectroscopy by flash vacuum pyrolysis of acrylic anhydride at 510- 560°. Pyrolysis of diphenylmethyl propiolate gives benzophenone and methyleneketene (or its decomposition products)as the major process, but minor processes leading to diphenylmethane, fluorene and 3-phenylphthalide also occur.