Methyl iodide, photooxidation

Reaction (18) was suggested by Bates and Spence in 193111 to occur in the photooxidation of methyl iodide. Formaldehyde was first detected by Hoare68 as a product of the photooxidation of acetone. He showed that addition of formaldehyde resulted in the production of more carbon monoxide and Caldwell and Hoare81 have now shown that the formaldehyde concentration tends to reach a maximum as an experiment is continued for longer periods. It appears that abstraction of a hydrogen atom from formaldehyde may be several hundred times easier than from acetone,67 so only results of experiments with conversions considerably less than 1% may be valid for formaldehyde yields. 

Studying the photooxidation of methyl iodide at room temperature they show that the addition of hydrogen iodide does not give the methanol yields which might be expected from the reaction... 

The photooxidation of alkyl iodides represents one of the early methods by which the oxidation of alkyl radicals was studied. Thus Bates and Spence,11 in 1931, found that the chief products in the photooxidation of methyl iodide were methanol, formaldehyde, water, and iodine. For these products they postulated the following reactions... 

Since that time the increasing sensitivity of analytical techniques (in particular, those of mass spectrography and gas chromatography) has enabled workers to show that The photooxidation of methyl iodide is complicated and a large number of reactions occur. 67 In fact,... 

Christie42 studied the photooxidation of methyl iodide at room temperature and was able to show that the third-order reaction of methyl radicals with oxygen occurred with a rate constant 690 cc. mole-1 times larger than the second-order reaction with iodine molecules. (C02 CHJ = 32.3 1 and C02 had V 10th the efficiency of CH3T as a third... 

Reaction (50) has been supported by Vaughn and co-workers as a four-center reaction, and they confirmed the disproportionation reaction (51). By means of flash spectroscopy (and in systems with a substantial temperature rise), hydroxyl radicals have been observed in the photooxidation of methyl iodide. Thus the second set of reactions is ... 

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