[omegasynthesis999]

Suppose you have ethene molecule where one of the Hs is replaced by a benzene ring. When you use the following steps: 1)KMnO4, OH-, heat followed by 2) H3O+ for oxidation, does the KMnO4 cleave the double bond or the bond between the benzene and alkene carbon or both?

Thanks

[sjb]

Suppose you have ethene molecule where one of the Hs is replaced by a benzene ring.

Vinylbenzene, styrene, or even phenylethylene.

When you use the following steps: 1)KMnO₄, OH^-, heat followed by 2) H₃O⁺ for oxidation, does the KMnO₄ cleave the double bond or the bond between the benzene and alkene carbon or both?

I think it only attacks the C=C bond to initially form benzaldehyde, then benzoic acid.

c.f. part 5A at http://www.cem.msu.edu/~reusch/VirtTxtJml/benzrx2.htm and the oxidation of indene.

S

[Delerium]

The KMnO4 will cleave the C=C giving benzoic acid, especially in this case since the styrene (or analogs of styrene) C=C bond is quite activated.