20. The Variety of Organic         Compounds   Previous PageNext Page

-Butyl alcohol becomes 1-butanol and sec-butyl alcohol is 2-butanol, but for isobutyl and tert-butyl alcohols a shorter carbon skeleton than four atoms must be used. Isobutyl alcohol has the systematic name of 2-methyl-1-propanol, or 2-methyl propanol, and tert-butyl alcohol is 1,1-dimethyl ethanol.

Common names usually are employed for these small molecules because they are simpler to write. But with more than four or five carbon atoms, the systematic name becomes easier to remember, or to work out from the molecular structure.

Alcohols are classified as primary, secondary, or tertiary, depending on whether the carbon bearing the OH group is connected to one, two, or three other carbons.

Of the alcohols illustrated on the previous page, all are primary except isopropyl alcohol and sec-butyl alcohol, which are secondary, and tert-butyl alcohol, which is tertiary.


Alcohols can be prepared synthetically by the hydrolysis of chlorides and bromides of hydrocarbons:

RCl + ROH + HCl

Since this reaction liberates HCl, it proceeds best in basic solution where the acid can be neutralised as fast as it is made.

Many of the lower-molecular-weight alcohols are produced by yeasts, bacteria, and other microorganisms as by-products in their energy-extracting metabolism. Yeasts burn sugars to and water (as we do) if given enough oxygen, but under anaerobic conditions they stop halfway and give off ethyl alcohol. as a waste product.

The ancient art of brewing has given ethyl alcohol (ethanol) the name of "grain alcohol" because of its easiest and cheapest source.

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