The yield of allene (11) was considerably increased and the irradiation time reduced by the addition of 1% of formic acid. No allene-type product was detected on irradiation of 5% aqueous potassium sorbate. Ir- radiation of a 1% solution of methyl sorbate in ether containing 10% formic acid resulted in an 8% yield of the methyl ester of 11. This product could not be detected when the irradiation was carried out in the absence of formic acid, although a low (0.1%) yield of the allene ...
