Question

Which one of the alcohols listed below would be soluble in methylene chloride and would not have an issue being deprotonated by a strong base of NaOH? Please explain your reasoning for your choice.

Alcohol Name	Molecular Weight	Literature Melting Point	Phenylurethane Derivative Melting Point
Piperonyl Alcohol	152.15	54	103
1-Octadecanol	270.49	60	79-80
Benzhydrol	184.23	66	140
3,5-Dimethylphenol	122.16	68	151
Benzoin	212.24	135	171
Salicylamide	137.14	142	185

Answer 1

An alcohol can easily lost a proton and form an alkoxide ion if the resulting alkoxide anion is stabilised by different forces. Phenol and phenol derivatves are easily deprotonated to form phenoxide derivatves because the resulting phenoxide anions are stabilized by resoance with the ring electrons. Among the given alcohols, 3,5-dimethylphenol is the only alcohol where the hydroxyl (-OH) group is attached to a sp² hybridized ring carbon. In all the other alcohols. the -OH group is attached to sp³ hybridized carbon atoms.

Hence, 3,5-dimethylphenol can be easily deprotonated by a strong base like NaOH. Moreover, 3.5-dimethylphenol is largely non-polar due to the presence of the aryl and the alkyl groups and hence, poorly soluble in water. Infact, 3.5-dimethylphenol is more soluble in non-polar organic solvents like methylene chloride. Therefore, 3,5-dimethylphenol is the correct answer.