Nucleophilic acyl substitution carbonyl compound

Both in the laboratory and in living organisms, the reactions of carbonyl compounds take place by one of four general mechanisms nucleophilic addition, nucleophilic acyl substitution, alpha substitution, and carbonyl condensation. These... 

The second fundamental reaction of carbonyl compounds, nucleophilic acyl substitution, is related to the nucleophilic addition reaction just discussed but occurs only with carboxylic acid derivatives rather than with aldehydes and ketones. When the carbonyl group of a carboxylic acid derivative reacts with a nucleophile, addition occurs in the usual way, but the initially formed tetra-... 

As a general rule, nucleophilic addition reactions are characteristic only of aldehydes and ketones, not of carboxylic acid derivatives. The reason for the difference is structural. As discussed previously in A Preview of Carbonyl Compounds and shown in Figure 19.14, the tetrahedral intermediate produced by addition of a nucleophile to a carboxylic acid derivative can eliminate a leaving group, leading to a net nucleophilic acyl substitution reaction. The tetrahedral intermediate... 

We said in A Preview ofCnrbonyl Compounds that much of the chemistry of carbonyl compounds can be explained by just four fundamental reaction types nucleophilic additions, nucleophilic acyl substitutions, o substitutions, and carbonyl condensations. Having studied the first two of these reactions in the past three chapters, let s now look in more detail at the third major carbonyl-group process—the a-substitution reaction. 

We ve now studied three of the four general kinds of carbonyl-group reactions and have seen two general kinds of behavior. In nucleophilic addition and nucleophilic acyl substitution reactions, a carbonyl compound behaves as an electrophile. In -substitution reactions, however, a carbonyl compound behaves as a nucleophile when it is converted into its enol or enolate ion. In the carbonyl condensation reaction that we ll study in this chapter, the carbonyl compound behaves both as an electrophile and as a nucleophile. 

Nucleophilic acyl substitution reaction (Section 21.2) A reaction in which a nucleophile attacks a carbonyl compound and substitutes for a leaving group bonded to the carbonyl carbon. 

Chapter 22 continues the study of carbonyl compounds with a detailed look at nucleophilic acyl substitution, a key reaction of carboxylic acids and their derivatives. Substitution at sp hybridized carbon atoms was introduced in Chapter 20 with reactions involving carbon and hydrogen nucleophiles. In Chapter 22, we learn that nucleophilic acyl substitution is a general reaction that occurs with a variety of heteroatomic nucleophiles. This reaction allows the conversion of one carboxylic acid derivative into another. Every reaction in Chapter 22 that begins with a carbonyl compound involves nucleophilic substitution. Chapter 22 also discusses the properties and chemical reactions of nitriles, compounds that contain a carbon-nitrogen triple bond. Nitriles are in the same carbon oxidation state as carboxylic acids, and they undergo reactions that form related products. 

We are in a strange, complex chemical environment here, but in it we recognize familiar kinds of compounds—hemiacetals, esters, anhydrides, carboxylic acids—and familiar kinds of reactions—nucleophilic carbonyl addition, hydride transfer, nucleophilic acyl substitution. 

The chemistry of all acid derivatives is similar and is dominated by single reaction—the nucleophilic acyl substitution reaction that saw briefly in A Preview of Carbonyl Compounds ... 

Class I carbonyl compounds undergo nucleophilic acyl substitution reactions. These reactions are discussed in Chapter 17, where you will see that all Class I carbonyl compounds react with nucleophiles in the same way— they form an unstable tetrahedral intermediate that collapses by eliminating the weakest base. So all you need to know to determine the product of a reaction—or even whether a reaction will occur—is the relative basicity of the groups in the tetrahedral intermediate. 

Carbonyl Compounds II Nucleophilic Acyl Addition, Nucleophilic Acyl Substitution, and Nucleophilic Addition-Elimination Reactions of a, 6-Unsaturated Carbonyl Compounds... 

Nucleophiles form nucleophilic acyl substitution products with a,j8-unsaturated Class I carbonyl compounds that have reactive carbonyl groups and conjugate addition products with compounds with less reactive carbonyl groups. 

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