Peroxycarboxylic acids Baeyer-Villiger reaction

Functional groups that stabilize radicals are expected to increase susceptibility to autoxidation. This is illustrated by two cases that have been relatively well studied. Aldehydes, in which abstraction of the formyl hydrogen is facile, are easily autoxidized. The autoxidation initially forms a peroxycarboxylic acid, but usually the corresponding carboxylic acid is isolated because the peroxy acid oxidizes additional aldehyde in a parallel heterolytic reaction. The final step is an example of the Baeyer-Villiger reaction, which is discussed in Section 12.5.2.1 of Part B. 

Peroxycarboxylic acids oxidize ketones to esters by the Baeyer-Villiger reaction (see Section 6.3). The more electron-rich substituent migrates to the electron-deficient oxygen... 

The final step involving oxidation of a mole of aldehyde by the peroxycarboxylic acid is not a radical reaction, but an example of the Baeyer-Villiger reaction, which will be discussed in Part B, Chapter 10. 

The CL monomer is obtained by the traditional Baeyer-Villiger reaction, starting from cyclohexanone as substrate. However, this synthetic route is not environmentally friendly, which has involved the development of two greener routes (1) use of a peroxycarboxylic acid (such as 3-chloroperbenzoic acid or peracetic acid) in dichloromethane at 40 ° C, and (2) use of hydrogen peroxide as oxidizer and zeolite/tin catalysis.The second process is considered the greenest because the main by-product is exclusively water and the tin-impregnated zeolite is an environmentally friendly catalyst. Nowadays, CL is produced by several manufacturers like BASF (USA), Perstorp (UK), and Daicel Chemical Industries Ltd. (Japan). 

The general equation for the Baeyer-Villiger oxidation (see p. 772) begins with a reaction between a ketone and a peroxycarboxylic acid to form a peroxy analog of a hemiacetal. Formulate a detailed mechanism for this process. 

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