Mercaptans are a group of chemical compounds similar to alcohols,
but with the
oxygen in the
OH group replaced with
sulfur. Because
sulfur is just below oxygen in the periodic table, many alcohols have
sulfur containing analogs. The modern
IUPAC nomenclature for
the older name "mercaptans " is
alkanethiol or simply
thiol. The
-SH
group of these compounds is called a
thiol group or a
sulfhydryl
group.
H
H H H S H
| | | | |
H-C-SH H-C-C-C-C-H
| | | | |
H H H H H
Methanethiol 2-butanethiol
The most characteristic property of thiols are their odor. The human
nose can detect the presence of these compounds at levels of about 0.02
ppb (that is parts per billion!). These compounds are found for
instance in the spray of skunks, or as breakdown products during the
digestion of asparagus. Mercaptans are also added to butane for
domestic applications, so that consumers can smell whenever they have
a gas leak (butane itself is odorless).