Acidity of Alcohols and Phenols

The factors affecting the stability of a negative charge were first discussed in Section 3.4. 

Recall that a strong acid will have a low pKg value. To review the relationship between pK and acidity, see SkillBuilder 3.2. 

As we learned in Chapter 3, the acidity of a compound can be qualitatively evaluated by analyzing the stabihty of its conjugate base  

The relative acidity of alkanes, amines, alcohols, and hydrogen halides. 

There are two common ways to deprotonate an alcohol, forming an alkoxide ion. 

2-Propanol is about as toxic as methanol when taken orally, but it is safer for use on the skin because it does not pass through skin as easily as methanol. 

Like the hydroxyl proton of water, the hydroxyl proton of an alcohol is weakly acidic. 10-6 A strong base can remove the hydroxyl proton to give an alkoxide ion. Acid Ity Of AlCOholS 

The acidities of alcohols vary widely, from alcohols that are about as acidic as water to some that are much less acidic. The acid-dissociation constant, K, of an alcohol is defined by the equilibrium 

The acid-dissociation constants for alcohols vary according to their structure, from about 10 for methanol down to about 10 for most tertiary alcohols. The acidity decreases as the substitution on the alkyl group increases, because a more highly sub- 

TABLE 10-4 Acid-Dissociation Constants of Representative Alcohols  

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Structure and Classification of Alcohols 425 10-3 Nomenclature of Alcohols and Phenols 427 10-4 Physical Properties of Alcohols 430 10-5 Commercially Important Alcohols 433 10-6 Acidity of Alcohols and Phenols 435 10-7 Synthesis of Alcohols Introduction and Review 438 Summary Previous Alcohol Syntheses 438 10-8 Organometallic Reagents for Alcohol Synthesis 440 10-9 Addition of Organometallic Reagents to Carbonyl Compounds 443... 

Reactions Involving the O-H Bond of Alcohols and Phenols A. Relative Acidities of Alcohols and Phenols... 

To compare the acidity of alcohols and phenols with that of other organic compounds, see Table C in the Appendix. 

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