Addition reactions of aldehydes and ketones

Nucleophilic Addition Reactions of Aldehydes and Ketones (Chapter 19)... 

Nucleophilic addition reactions of aldehydes and ketones (a) Addition of hydride alcohols (Section 19.7)... 

A summary of nucleophilic addition reactions of aldehydes and ketones. 

Nucleophilic addition is the characteristic mechanism for addition reactions of aldehydes and ketones. It can be base-initiated in which a negative or neutral nucleophile attacks the carbonyl carbon generating a negative carbonyl oxygen that is subsequently neutralized. In the acid-initiated mechanism, hydrogen ion bonds to the carbonyl oxygen a carbocation results which is neutralized by the nucleophile. 

The nucleophilic addition reactions of aldehydes and ketones occurring at the carbonyl carbon atom that we have studied so far are summarized below. In Chapters 18 and 19 we shall see other examples. 

Other reactions of carbohydrates include those of alcohols, carboxylic acids, and their derivatives. Alkylation of carbohydrate hydroxyl groups leads to ethers. Acylation of their hydroxyl groups produces esters. Alkylation and acylation reactions are sometimes used to protect carbohydrate hydroxyl groups from reaction while a transformation occurs elsewhere. Hydrolysis reactions are involved in converting ester and lactone derivatives of carbohydrates back to their polyhydroxy form. Enolization of aldehydes and ketones leads to epimerization and interconversion of aldoses and ketoses. Addition reactions of aldehydes and ketones are useful, too, such as the addition of ammonia derivatives in osazone formation, and of cyanide in the Kiliani-Fischer synthesis. Hydrolysis of nitriles from the Kiliani-Fischer synthesis leads to carboxylic acids. 

In this section, we examine nucleophilic acyl addition reactions of aldehydes and ketones with the following types of carbon nucleophiles. 

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