Skunk scent

The mam components of a skunks scent fluid are 3 methyl 1 butanethiol and as- and trans-2 butene 1 thiol Write structural formulas for each of these compounds... 

A historical account of the analysis of skunk scent and a modern determination of its composition appear in the March 1978 issue of the Jour nal of Chemical Education... 

The most striking characteristic of thiols is their appalling odor. Skunk scent, for instance, is caused primarily by the simple thiols 3-methyl-1-butanethiol and 2-butene-l-thiol. Volatile thiols such as ethanethiol are also added to natural gas and liquefied propane to serve as an easily detectable warning in case of leaks. 

A thiol contains an —SH group covalently bonded to carbon. Sulfur is just below oxygen in the periodic table, so a thiol is somewhat similar to an alcohol. Still, the chemical and physical properties of thiols differ significantly from those of alcohols. For example, whereas alcohols have inoffensive odors, thiols smell bad. The stench of skunk scent is due to thiols, including 3-methylbutanethiol. Thiols are important in proteins because of their abilities to form S—S linkages, which we describe in Section 13-1. 

The odor of thiols is their strongest characteristic. Skunk scent is composed mainly of 3-methylbutane-l-thiol and but-2-ene-l-thiol, with small amounts of other thiols. Ethanethiol is added to natural gas (odorless methane) to give it the characteristic gassy odor for detecting leaks. 

Beckmann studied the scent of the Phillipine teledu and reported In 1896 that It contained 1-butanethlol. Aldrich reported In the same year that striped skunk scent contained "one of the butyl mercaptans" and, most likely 3-methylbutanethiol. With the passage of time, the actual facts were mixed up and most North American chemists were erroneously taught that skunk scent owed Its odor to 1-butanethlol. Elemental analysis of steam distilled zorrino scent... 

Of the twenty-two or more compounds indicated by the glc recordings, nine were identified. Three were Identified in our initial work and six more by the glc-ms analysis. 3-Methyl-butanethiol (6) was identified by comparison to an authentic mass spectrum. Also, its spectrijon did not correspond to the spectra of isomers. 1-Butanethiol (8) was identified in a similar way. Its presence in skunk scent is less than one-percent of the total and any earlier reports of its presence must still be considered erroneous. The remaining five compounds, 9 to 13, were identified by analysis of their fragmentation patterns. Their structural formulas numbered in the relative elution order are shown below. 

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