When naming alcohols, remember that we want the alcohol at the lowest possible
IUPAC name: Z‐hex‐3‐en‐1‐ol
Properties of Alcohols
• Boiling point higher than corresponding hydrocarbon
o H‐bonds between OH groups
• Alcohols are weak acids
o pKa(H O)2= 15.5
o pKa(ROH) = 16‐17
• RO‐ and H+
o RO‐ is called the alcoholate
Preparation of Alcohols
A Markovnikov addition is when the C with the most H gains another H, and the
new group (ex: Br‐) goes to the C with the least H.
• favored because less steric hindrance
An antiMarkovnikov addition is when the C with the most H gains a new group
(ex: Br‐) and the C with the least H gains another group.
1. Hydration of alkenes (acid catalyzed)
This reaction is a Markovnikov addition.
Possible solvents: H+ in 2 O Hg(OAc 2 in H 2, followed by NaBH 4
2. Hydroboration/oxidation of alkene
This reaction is an anti‐Markovnikov addition to alkenes, and proceeds in
two steps: 1) BH ad3s to alkenes; 2) the trialkylborane is oxidized.
For ring compounds, the net effect is the cis addition of H+ and OH‐. This is
because of steric hindrance.
3. Hydrolysis of alkyl halides
This reaction could be complicated by elimination if there are more than 2
4. Grignard reaction of aldehydes, ketones, esters and epoxides
A Grignard reagent will react with most carbonyl functions to give alcohols.
In planning syntheses with the Grignard reagent, care must be exercised to
be sure that other functional groups will not interfere.
Reactions with Alcohols
Reactions with alcohols usually involve adding an H+ to the OH‐ group so that water
dissociates and leaves. OH‐ is a very bad leaving group, so it would not leave on its
own. This is why most reactions with alcohols are carried out under acidic
conditions. 1. OH dissociation (forming of alcoholate)
This reaction is often carried out in NaH, to form RO‐ and Na+, with H 2
leaving as a gas.
pKa ~ 16, which is similar to water
2. Displacing of OH with X
X = I, Br or Cl
X ≠ F
PROS: simple, clean
CONS: harsh acidic conditions