Question

how alcohols are obtained by reduction of esters

Answer 1

Reduction of Esters  Reactions usually in Et2O or THF followed by H3O+work-ups 
Reaction type:  Nucleophilic Acyl Substitution then NucleophilicAddition

Carboxylic esters are reduced give 2 alcohols, one from the alcohol portion of the ester and a 1o alcohol from the reduction of the carboxylate portion.Esters are less reactive towards Nu than aldehydes or ketones.They can only be reduced by LiAlH4 but NOTby the less reactive NaBH4The reaction requires that 2 hydrides (H-) be added to the carbonyl group of the esterThe mechanism is an example of the reactive system type.The reaction proceeds via a aldehyde intermediate which then reacts with the second equivalent of the hydride reagent (review)Since the aldehyde is more reactive than the ester, the reaction is not normally used as a preparation of aldehydes .

Answer 2

Summary

Carboxylic esters are reduced give 2 alcohols, one from the alcohol portion of the ester and a 1o alcohol from the reduction of the carboxylate portion.Esters are less reactive towards Nu than aldehydes or ketones.They can only be reduced by LiAlH4 but NOT by the less reactive NaBH4The reaction requires that 2 hydrides (H-) be added to the carbonyl group of the esterThe mechanism is an example of the reactive system type.The reaction proceeds via a aldehyde intermediate which then reacts with the second equivalent of the hydride reagent (review)Since the aldehyde is more reactive than the ester, the reaction is not normally used as a preparation of aldehydes .