Thiols are characterized by containing the -SH functional group. They are named by ending the main chain name in -thiol, analogous to alcohols whose ending is -ol

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Thiols have a higher acidity than alcohols due to the larger size of sulfur compared to oxygen. The pKa values are around 10-11, compared to alcohols that have values between 16-18.

However, the larger size of sulfur favors its polarizability and consequently its nucleophilicity. Thiols are much better nucleophiles than alcohols, their nucleophilicity being further enhanced by deprotonation.
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S N 2 -type reactions become faster in the presence of a basic medium that generates the l-thiol (thiolate) salt.
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The thiols are prepared from sodium hydrogen sulfide and a primary or secondary haloalkane.
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The excess hydrogen sulfide tries to minimize the side reaction whereby the propanethiol reattacks the propyl bromide to give a thioether.
One way to avoid this side reaction is to use thiourea in combination with a haloalkane.
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Another method of synthesis consists in the reaction of magnesium with elemental sulfur.
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