http://books.google.com/books?id=ZCXPte7PL0EC&pg=RA1-PA4...
Thiols are stronger acids than alcohols. Compare, for example, the pKa values of ethanol and ethanethiol in dilute aqueous solution:
Ch3CH2OH + H2O <=> CH3CH2O- + H3O pKa = 15.9
Ch3CH2SH + H2O <=> CH3CH2S- + H3O pKa = 8.5
The greater acidity of thiols compared to alcohols is a combination of two factors. First, S-H bonds are generally weaker than O-H bonds, which
facilitates removal of the S-H proton by a base. Second, sulfur (a third-period element) is larger than oxygen (a second-period element), which means
that the negative charge on an alkylsulfide ion (RS-) is delocalized over a larger area and is, therefore, more stable than the negative charge on an
alkoxide ion (RO-).
Thiols are sufficiently strong acids that when dissolved in aqeuous sodium hydroxide, they are converted completely to alkylsulfide salts:
CH3CH2SH + Na+OH- --> CH3CH2S-Na+ + H2O
pKa = 8.5 pKa = 15.7
(Stronger acid) (Stronger Base) (Weaker Base) (Weaker Acid)
To name salts of thiols, give the name of the cation first, followed by the name of the alkyl group to which is attached the suffice -sulfide. For
example, the sodium salt derived from ethanethiol is names sodium ethylsulfide.
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