How is it possible for m-cresol (3-methylphenol) to be synthesized?
The methylation of phenol would lead to the ortho- and para-isomers instead.
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Here is a synthesis of m-cresol starting from benzene. It achieves the desired meta orientation of the final substituents by introducing a meta-directing substituent (the aldehyde group) early-on in the synthetic scheme. In the nitration step, the meta isomer is by far the major product (o:m:p 19:72:9), but a distillation or recrystallization would be needed (or you could carry all the isomers along and separate later, but you'd probably have the widest range in boiling points at this stage with the nitro group present). The only novel step is the double Wolff-Kishner used to reduce both the aldehyde and nitro groups in a single reaction.
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$\begingroup$ +1, thanks for the link to that article. Very interesting. I wasn't aware of that use for the Wolff-Kishner reduction. Previously I would've chosen Clemmensen reduction, which should also reduce both groups in one step, but Wolff-Kishner seems eminently preferable given the option. $\endgroup$ – Greg E. Aug 6 '14 at 20:08
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From the comments above, its clear you are asking how m-cresol is prepared. I know one method, which involves diazotization of m-toluidine.
In this way we should make m-toluidine first but it making m-toluidine is more difficult than m-cresol.
m-toluidine is prepared by m-nitrotoluene but unfortunately m-nitro toulene is minor isomer in nitration of toluene and this is really so difficult to separate it. But you can prepare M-cresol thorugh this process, though the yield of the reaction will be small.
Though I will be looking for more answers on this question if someone knows another way of preparing this particular compound. Hope this helps.
