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Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols .
Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes, ketones, carboxylic acids, and esters. The reaction mainly applies to primary and secondary alcohols. Secondary alcohols form ketones, while primary alcohols form aldehydes or carboxylic acids. [1] A variety of oxidants can be used.
The complex can reduce carboxylic acids to alcohols and is a common route for the reduction of amino acids to amino alcohols [3] (e.g. valinol). It adds across alkenes to give organoboron compounds that are useful intermediates. [4]
Like esters, most carboxylic acids can be reduced to alcohols by hydrogenation, or using hydride transferring agents such as lithium aluminium hydride. Strong alkyl transferring agents, such as organolithium compounds but not Grignard reagents, will reduce carboxylic acids to ketones along with transfer of the alkyl group.
The direct oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate (R−CH(OH) 2) by reaction with water before it can be further oxidized to the carboxylic acid. Mechanism of oxidation of primary alcohols to carboxylic acids via aldehydes and aldehyde hydrates
For oxidations to the aldehydes and ketones, two equivalents of chromic acid oxidize three equivalents of the alcohol: 2 HCrO 4 − + 3 RR'C(OH)H + 8 H + + 4 H 2 O → 2 [Cr(H 2 O) 6] 3+ + 3 RR'CO. For oxidation of primary alcohols to carboxylic acids, 4 equivalents of chromic acid oxidize 3 equivalents of the alcohol. The aldehyde is an ...
Chiral diamines and amino alcohols have also been used to modify LAH for enantioselective reductions. (4) Chirally modified borohydrides are also useful for enantioselective ketone reductions. Economical ligands derived from amino acids have been used to modify borohydrides, affording highly selective reducing agents. [7] (5)
Most carboxylic acids are suitable for the reaction, but the alcohol should generally be primary or secondary. Tertiary alcohols are prone to elimination. Contrary to common misconception found in organic chemistry textbooks, phenols can also be esterified to give good to near quantitative yield of products.