When would you need to protect an alcohol group? Provide the steps required in protecting alcohols.

Question

When would you need to protect an alcohol group? Provide the steps required in protecting alcohols.

Answer 1

You would need to "protect" an alcoholic -OH group (actually you inactivate the hydrogen) when it would interfere with a reaction at another site on the molecule. An example is with a Grignard reaction. You won't be able to form the Grignard intermediate if there is an acidic hydrogen present, as in the case of an alcohol. So, first react the alcohol group to form an ester or ether. Then form the Grignard reagent. Then carry out the reaction at the other reactive site on the molecule. Then regenerate the original alcohol.