Properties of Alcohols, Phenols, and Thiols

Alcohols and phenols have nearly the same geometry around the oxygen atom as water. The C-O-H bond angle is approximately tetrahedral (108.5° in methanol, for instance), and the oxygen atom is sp -hybridized. Thiols have a more compressed C-S-H bond angle (96.5° in methanethiol). 

FIGURE 13.1 Hydrogenbonding in alcohols and phenols. Attraction between a positively polarized OH hydrogen and a negatively polarized oxygen holds molecules together. 

Yet another similarity with water is that alcohols and phenols are both weakly basic and weakly acidic. As weak bases, they are reversibly protonated by strong acids to yield oxonium ions, R0H2  

As weak acids, they dissociate slightly in dilute aqueous solution hy donating a proton to water, generating HsO and an alkoxide ion (RO ) or a phenoxide ion (ArO ). 

CHAPTER 13 ALCOHOLS, PHENOLS, AND THIOLS ETHERS AND SULFIDES 

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