Acidic and Basic Character of Carboxylic Acids

In Summary The NMR signals for carboxylic acids reveal highly deshielded acid protons and carbonyl carbons and moderately deshielded nuclei next to the functional group. The infrared spectrum shows characteristic bands at about 2500-3300 (0-H) and 1710 (C=0) cm The mass spectra of carboxylic acids reflect three characteristic modes of fragmentation. 

Like alcohols (Section 8-3), carboxylic acids exhibit both acidic and basic character Deprotonation to carboxylate ions is relatively easy, protonation more difficult. 

Carboxylic acids have much lower values than alcohols do, even though the relevant hydrogen in each case is that of a hydroxy group. 

Why do carboxylic acids dissociate to a greater extent than do alcohols The difference is that the hydroxy snbstitnent of a carboxylic acid is attached to a carbonyl gronp, whose positively polarized and -hybridized carbonyl carbon exerts a powerfnl electron-withdrawing indnctive effect. In addition, the carboxylate ion is signihcantly stabilized by resonance, mnch as is the enolate ion formed by deprotonation of the a-carbon in aldehydes and ketones (Section 18-1). 

Electron-withdrawing substituents increase the acidity of carboxylic acids 

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Acidic and Basic Character of Carboxylic Acids CHAPTER 19... 

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