Preparation of Cinnamic Acids from Styryl Ketones

Preparation of Cinnamic Acids from Styryl Ketones 

It is known from Houben-Weyl, Methoden der organischen Chemie, volume 8, pages 415-416, that carboxylic acids can be manufactured by oxidation of methyl ketones with hypohalites in an aqueous medium. The publication recommends dispersing the ketone by means of oxidation-resistant emulsifiers or carrying out the reaction in the presence of dioxane all the examples were carried out in this way. In most cases the reaction only takes place satisfactorily with hypobromite solutions, which are more expensive and less stable than hypochlorite solutions. For this reason alone, industrial utilization of the reaction is confined to special reactions with aromatic ketones. 

It is an object of the present invention to provide a new process for the manufacture of carboxylic acids by a simpler and more economical method and in some cases in better yield and higher purity. 

We have found that carboxylic acids are obtained advantageously from methyl ketones by reaction with hypochlorites in an aqueous medium... 

The catalysts used are bromine, iodine, haloamides I and/or polymerization inhibitors, in general in amounts of from 0.0001 to 0.1 preferably from 0.001 to 0.05, mole of catalyst per mole of methyi ketone. Instead of the above catalysts, it is also possible to usr compounds which form such catalysts under the reaction conditions, e.g to use bromides and iodides in place of bromine or iodine. Water-soluble halides are preferred and are advantageously used in the form of thei alkaline earth metal salts or, especially, their alkali metal salts, e.g calcium bromide, calcium iodide, magnesium bromide, magnesiais iodide, lithium bromide, lithium iodide and especially sodium bromide or iodide or potassium bromide or iodide... 

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