How do primary secondary and tertiary alcohols differ?

1 Answer
May 10, 2016


#RCH_2OH, 1^@; R_2CHOH, 2^@, R_3COH, 3^@#


How many hydrogens are attached to the ipso carbon (which is the carbon to which the oxygen is directly bound)? If there are 2 hydrogens, then this is a primary, #1^@#, alcohol. Ethanol is a primary alcohol by necessity. If there is only the one hydrogen bound to the ipso carbon, then this is a secondary alcohol, an example of which is isopropanol. And should there NO hydrogens attached, a tertiary, #3^@# alcohol is specified, for example tert-butyl alcohol, #(H_3C)_3C-OH#.

Some texts make the distiction between #1^@# alcohols and methanol, the which tends to be more reactive than primary alcohols, but this is something we can tolerate. Under oxidative conditions, primary alcohols can be oxidized to aldehydes, then to carboxylic acids (it is in fact hard to stop at the aldehyde). Secondary alcohols can be oxidized up to ketones; and tertiary alcohols are usually inert to oxidation.

For reference see this site.