The Foundations of Chemistry

Representing alkyl groups as R, we can illustrate the three classes of alcohols. The R

groups may be the same or different.

Nomenclature

The systematic name of an alcohol consists of the root name plus an -olending. A numeric

prefix indicates the position of the XOH group on a chain of three or more carbon atoms.

EXAMPLE 27-11 Formulas of Alcohols

There are four constitutional isomers of the saturated acyclic four-carbon alcohols with one

XOH per molecule. Write the structural formula of each, and identify each as primary,

secondary, or tertiary. Name each isomer.

Plan

The carbon skeleton can be either a straight chain, CXCXCXC, or branched, CXCXC.

A

C

Each skeleton has two different types of carbons to which the XOH group can be attached.

Solution

You should now work Exercise 46.

The polyhydric alcoholscontain more than one XOH group per molecule. Those

containing two OH groups per molecule are called glycols.Important examples of poly-

hydric alcohols include

CH 3 C

CH 3

CH 3

OH

2-methyl-2-propanol

tertiary butyl alcohol

3 
:

CH 3 CH 2 CHCH 3

OH

2-butanol

secondary butyl alcohol

2 
:

CH 3 CH

CH 3

CH 2 OH

2-methyl-1-propanol

isobutyl alcohol

CH 3 CH 2 CH 2 CH 2 OH 1 
:

1-butanol

butyl alcohol

1 
:

R

R

H

C OH

a secondary (2) alcohol

R

H

H

C OH

a primary (1) alcohol

R

R

R

C OH

a tertiary (3) alcohol

In writing organic structures, we often

use primes when we wish to specify

that the alkyl groups might be

different, for example, R, R, R.

27-9 Alcohols and Phenols 1069

CH 3 OH

methanol
methyl alcohol
(wood alcohol)

CH 3 CH 2 CH 2 OH

1-propanol

propyl alcohol

(a primary alcohol)

CH 3 CH CH 3

OH

2-propanol

isopropyl alcohol

(a secondary alcohol)

CH 3 C CH 2 CH 3

CH 3

OH

2-methyl-2-butanol

t-pentyl alcohol

(a tertiary alcohol)

Acycliccompounds contain no rings.

Polyhydric alcohols are used in

permanent antifreeze and in

cosmetics.