Taking Them a Step Further Reactions of Aldehydes and Ketones

Taking Them a Step Further Reactions of Aldehydes and Ketones 

Importa nt features to keep in mind when considering the reaction of carbonyl groups. 

Strong reducing agents like sodium borohydride and lithium aluminum hydride are capable of reducing aldehydes to primary alcohols and ketones to secondary alcohols. The general reaction is the reverse of the reactions used to form aldehydes and ketones by the oxidation of primary and secondary alcohols, respectively (to review, see the earlier section Oxidation reactions ). However, the mechanisms for reduction are different. 

The general mechanism forforming a hemiac-etal and an acetal. 

If you look in older texts, you may still see the terms hemiketal and ketal. At one time, four terms were used for the products of alcohols with carbonyl groups hemiacetal, acetal, hemiketal, and ketal. A hemiketal is now a type of hemiacetal and a ketal is now a type of acetal. Originally, acetals and hemiacetals came from aldehydes and ketals and hemiketals came from ketones. The structures of hemiacetals and acetals contained a C-H bond, but ketals and hemiketals did not. 

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