Generally nothing would happen to an alkene in the presence of PCC. It is mildly acidic, however, so in rare cases when there is a highly substituted electron-rich alkene, protonation can occur.

Hi Roman – no useful compound would likely be obtained from treating 4-methylphenol with PCC. You are right in saying that the carbon attached to the OH has no hydrogen to be removed.

However….

One thing that could happen is formation of something called a “p-quinone methide” which is a very strong electrophile, which would then be easily attacked by another equivalent of phenol (via EAS). The reaction can be hard to control and very easily leads to mixtures since phenols are such great nucleophiles in EAS reactions.

I haven’t looked up whether this happens or not with phenols and PCC but it is one possibility.

Great source of organic chemistry knowledge. Thank you! I want to ask, what product will be gained if we oxidise 4-methylphenol with PCC? As far as I know, PCC will not be able to oxidise methyl group and -OH group will not be oxidised either, because C atom with -OH group doesn’t have bond with hydrogen. Please correct me, if I am wrong.

Silica role is just to mop up the chromate esters and gunk that form in the process of running the reaction. Can also use Celite or alumina or molecular sieves. Makes cleanup easier.

The trick here is to try to extract your product from the chromate ester sludge. During filtration the silica is rinsed with a solvent. Using dichloromethane as a rinse solvent will make more of the highly colored sludge pass through the silica. If you use a non-chlorinated rinse solvent like diethyl ether you will pass your product through the silica but carry less of the chromate ester sludge. There’s nothing magical about diethyl ether, but it’s a solid choice.

I have no idea of what your substrate is, but there are plenty of alternatives to PCC – Dess Martin, Swern, Parikh Doering, the list goes on and on. If you told me what your substrate is, that would help.