Carboxylic acid derivative interconversions

Using the three principles of logic and the four possible mechanistic steps presented here, you should be able to write a reasonable mechanism for all the carboxylic acid and carboxylic acid derivative interconversions discussed in the next chapter, as well as many other mechanisms in other chapters. 

Figure 21.2 Interconversions of carboxylic acid derivatives. A more reactive acid derivative can be converted into a less reactive one, but not vice versa.

When a multistep synthesis is being undertaken with other sensitive functional groups present in the molecule, milder reagents and reaction conditions may be necessary. As a result, many alternative methods for effecting interconversion of the carboxylic acid derivatives have been developed and some of the most useful reactions are considered... 

The realisable and synthetically useful interconversions between these carboxylic acid derivatives are summarised below. 

Fig. 7.1 Survey of the mutual interconversion of carboxylic acid derivatives, especially primary amides of carboxylic acids, and nitriles.

Structure and Nomenclature of Acid Derivatives 982 21-3 Physical Properties of Carboxylic Acid Derivatives 988 21-4 Spectroscopy of Carboxylic Acid Derivatives 991 21-5 Interconversion of Acid Derivatives by Nucleophilic Acyl Substitution 997... 

We have looked at a whole series of interconversions between carboxylic acid derivatives and, after this next section, we shall summarize what you should have learned. We said that it is always easy to move down the series of arid derivatives we listed early in the chapter and, so far, that is all we have... 

Modification of substituents in purines generally follows patterns which are similar to substituent modification in typicfd aromatic S5rstems. These include interconversion of hydroxyl, thiol, halogeno, amino and similar groups, and Sandmeyer type reactions involving primary amines although isolation of stable diazonium salts is rarely possible. In addition, transformations and reactions of carboxylic acid derivatives follow standard patterns. 

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