Question

Why is EtOH not ideal for the Williamson ether synthesis? What would be a better solvent choice? Why isn't the better solvent choice used on a large industrial scale? Consider the cost and waste disposal.

Answer 1

The reaction of RO^– with an alkyl halide is always going to be much faster than the reaction of ROH because of the higher electron density on the nucleophile (oxygen). That’s why we use RO^–

our normal choice of solvent is the conjugate acid of the alkoxide..

to undersand consider that if for ethoxide ion you use propanol as solvent. then that ethoxide ion will react to form propanoxide ion, now there are two alkoxide that can react will alkyl halide and can form two different products, possibility of side reaction increases.

and the inorganic salt as the side product also have problem of disposal and the cost of ethanol also increases the cost of reaction.

The alcohol that supplies the electron rich alkoxide can be used as the solvent, as well as dimethyl sulfoxide (DMSO) or hexamethylphosphoric triamide (HMPA).