The photochemical decarboxylation of acyl hypoiodites has been investigated and shown to provide an efficient method for the preparation of the corresponding nor-iodides. Primary and secondary carboxylic acids are readily decarboxylated by using the lead tetra-acetate-iodine reagent. The recently discovered t-butyl hypoiodite has been shown to form acyl hypoiodites at room temperature. With this reagent primary, secondary, and tertiary acids, as well as the hitherto intractable glutaric and adipic acids, can be decarboxylated without difficulty.Some aspects of our work have already been reported in preliminary form.1 THE Hunsdiecker method for the decarboxylation of acids is well It suffers from certain disadvantages amongst which the difficulty and expense of preparing dry silver salts may be mentioned. Recently Cristol et aL3 introduced a modified Hunsdiecker procedure, using mercuric salts, which has certain advantages. At the initiation of our own worktye argued that if acyl hypoiodites could be prepared conveniently they might well be induced to decompose photochemically at relatively low temperatures into iodide and carbon dioxide. The important discovery of Wettstein and his collaborators that the hypoiodites from alcohols can be prepared advantageously by the in situ interaction of lead tetraacetate, alcohol, and iodine suggested that acyl hypoiodites might be obtained similarly.6 Our experiments soon provided evidence that this was correct and that in many cases decarboxylation proceeded smoothly on illumination with a tungsten lamp. All the * Part XVI, J., 1964, 2518.

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