From alkenes:
Alcohols can be prepared from alkenes by addition of concentrated sulfuric acid across the double bond followed by reaction of the intermediate sulfate with water.
This reaction may give rise to two products for alkenes that have different groups at the double bond. The major product is the more substituted alcohol (the one with the larger number of carbons bonded to the carbon bearing OH).
Therefore secondary and tertiary alcohols can be prepared in good yield, but not primary alcohols. An example of this is the reaction shown where the primary alcohol is the minor (not the major) product.
From haloalkanes:
Haloalkanes react by substitution with hydroxide ion to give alcohols.
Haloalkanes may also react with hydroxide ion to give alkenes (elimination). Substitution is favoured if the alcohol is primary.
From esters:
Hydrolysis of esters gives alcohols and carboxylic acids. This reaction is more strongly product favoured in the presence of OH– which reacts with the carboxylic acid to give the carboxylate which is nonreactive toward the alcohol product. If acid is added when reaction is complete, the carboxylate anion is protonated to give the carboxylic acid.
Alcohols can be prepared from alkenes by addition of concentrated sulfuric acid across the double bond followed by reaction of the intermediate sulfate with water.
 | 1. conc H2SO4 2. H2O |
This reaction may give rise to two products for alkenes that have different groups at the double bond. The major product is the more substituted alcohol (the one with the larger number of carbons bonded to the carbon bearing OH).
Therefore secondary and tertiary alcohols can be prepared in good yield, but not primary alcohols. An example of this is the reaction shown where the primary alcohol is the minor (not the major) product.
 | 1. conc H2SO4 2. H2O |
 major product | + |  minor product |
From haloalkanes:
Haloalkanes react by substitution with hydroxide ion to give alcohols.
 | KOH(aq) |
 |
Haloalkanes may also react with hydroxide ion to give alkenes (elimination). Substitution is favoured if the alcohol is primary.
From esters:
Hydrolysis of esters gives alcohols and carboxylic acids. This reaction is more strongly product favoured in the presence of OH– which reacts with the carboxylic acid to give the carboxylate which is nonreactive toward the alcohol product. If acid is added when reaction is complete, the carboxylate anion is protonated to give the carboxylic acid.
 | 1. KOH(aq) 2. H3O+ |
 | + |  |