How can you identify primary alcohol?

1 Answer
Apr 7, 2016

Answer:

By the presence of the #CH_2OH# group.

Explanation:

The alcoholic derivative of a primary methyl group is a so-called primary alcohol. Ethyl alcohol, #H_3C-CH_2OH# is certainly a primary alcohol. So if you see 2 hydrogens on the alcoholic ipso carbon, you know you have a primary alcohol. Other examples include #1-"propanol"# and #1-"butanol"#

On the other hand, if there is only the one hydrogen on the ipso carbon, then you have a secondary alcohol: isopropyl alcohol #(H_3C)_2CHOH# is the examplar.

No prizes for guessing that for the tertiary alcohol, the ipso carbon has no hydrogens. Tertiary butanol, #(H_3C)_3C-OH# is an example.

Note that methyl alcohol, #H_3COH# is to all intents and purposes a primary alcohol. Some texts place methyl alcohols, and methyl derivatives, in a special class (which they are because the ipso carbon bears 3 hydrogens!) because they are more reactive than even ethyl alcohol.