48 Properties

48.1 Naming alcohols

Follow these rules to name alcohols the IUPAC way:

1.find the longest carbon chain containing at least one OH group, this is the parent

a)if there are multiple OH groups, look for the chain with the most of them, and

the way to count as many carbons in that chain

b)name as an alcohol, alkane diol, triol, etc.

2.number the OH groups, giving each group the lowest number possible when different

numbering possibilities exist

3.treat all other groups as lower priority substituents (alcohol / hydroxy groups are the

highest priority group for naming)

48.1.1 Example alcohols

IUPAC name Common name

CH 3 CH 2 OH Ethanol Ethyl alcohol

CH 3 CH 2 CH 2 -OH 1-Propanol n-Propyl alcohol

(CH 3 ) 2 CH-OH 2-Propanol Isopropyl alcohol (Note: Isopropanol

would be incorrect. Cannot mixand match

between systems.)

2-Ethylbutan-1-ol 2-Ethylbutanol

3-Methyl-3-pentanol

2,2-Dimethylcyclopropanol

Multiple OH functional groups

1,2-Ethanediol Ethylene glycol

1,1-Ethanediol Acetaldehyde hydrate

1,4-Cyclohexanediol

(form that body fat is stored as)- 1,2,3-Propanetriol Glycerol

OH can be named as a substituent hy-

droxyl group (hydroxyalkanes)

1,2-Di(hydroxymethyl)cyclohexane

2-(hydroxymethyl)-1,3-propanediol

Find the longest chain of carbons contain-

ing the maximum number of-OH groups

1-(1-hydroxyethyl)-1-methylcyclopropane

2-(1-methylcyclopropyl)ethanol

2-(2-hydroxyethyl)-2-methylcyclopropanol

3-(2-hydroxyethyl)-3-methyl-1,2-

cyclopropanediol

48.2 Acidity

In an O-H bond, the O steals the H’s electron due to its electronegativity, and O can carry
a negative charge (R-O-). This leads todeprotonationin which the nucleus of the H,
a proton, leaves completely. This makes the -OH group (and alcohols) Bronsted acids.