Alcohols
Alcohols
Contain a hydroxyl group (-OH).
Phenols
Contain a benzene ring with a hydroxyl
group (-OH).
OH
OH + NaOH
Phenol
H2 O
O- Na+
+
S od ium phenoxide
(a w ater-soluble salt)
Naming Alcohols
CH4
methane
CH3─OH
methanol
CH3─CH3
ethane
CH3─CH2─OH
ethanol
Naming Alcohols
Step 1- Identify the root
Select the longest carbon chain
that contains the -OH group. Name the parent alkane.
Step 2 – Identify the suffix
Number from the end nearest -OH group. The suffix of an alcohol
always ends with –Ol. Indicate the position of each hydroxyl group. If
more than one -OH group place a prefix (di, tri, tetra) at the beginning of
the suffix
Step 3- Identify the prefix
Name and number any branches as you would for a hydrocarbon
Step 4- Name the compound
Combine the prefix, root, and suffix to name the compound.
If the suffix begins with a vowel, drop the “e” on the end of the
parent alkane.
Name the following alcohol
•
•
•
•
Parent alkane: heptane
Suffix: -2,3-diol
Prefix: 4-ethyl
Name:4-methylheptane-2,3-diol
Name the following alcohol
•
•
•
•
Root: hexane
Suffix: -1-ol
Prefix:3-methyl
Name: 3-methylhexan-1-ol
Naming Alcohols
3
1
2
CH3─CH2─CH2─OH
propan-1-ol
OH
│
CH3─CH─CH3
propan-2-ol
3
2
1
CH3
OH
│
│
CH3─CH─CH2─CH2─CH─CH3
6
5
4
3
2
1
5-methylhexan-2-ol
Naming Alcohols
OH
│
CH3─CH─CH2─CH3
1
2
3
butan-2-ol
4
CH3
│
CH3─CH─CH ─CH2─OH
Cl
4
3
2
3-chloro-2-methylbutan-1-ol
1
CH3
CH3─C─CH2─OH
CH3
3
2
1
2,2-dimethylpropan-1-ol
Draw the condensed structural formula
for 4-methylpentane-1,2-diol
• Root: 5 carbons
• Suffix: OH groups on
C1 and C2
• Prefix: methyl on C4
Different types of Alcohols
Primary (1º)
Secondary (2º )
H
│
CH3─C─OH
│
H
CH3
│
CH3─C─OH
│
H
1C
2C
attached
to C-OH
attached
to C-OH
Tertiary (3º)
CH3
│
CH3─C─OH
│
CH3
3C
attached
to C-OH
Physical Properties of Alcohols
1. Alcohols are polar molecules (because of O-H and C-O).
C-O: (3.5 – 2.5 = 1.0)
O-H : (3.5 – 2.1 = 1.4)
2. Hydrogen bonding between alcohols molecules.
3. Have higher boiling points than Alkanes, Alkenes, and Alkynes.
4. Molecular weight ↑ : London dispersion forces ↑ : bp ↑
5. More soluble in water than alkanes (Molecular weight ↑ : solubility ↓).
polar
nonpolar
OH
Oxidation of 1° Alcohols
In the oxidation [O] of a primary alcohol 1, one H is
removed from the –OH group and another H from the C
bonded to the –OH.
primary alcohol
OH
│
CH3─C─H
│
H
ethanol
[O]
K2Cr2O7
H2SO4
aldehyde
O
║
CH3─C─H + H2O
ethanal
Oxidation of 2° Alcohols
The oxidation of 2 alcohols is similar to 1°, except that a
ketone is formed.
[O]
secondary alcohol
OH
│
CH3─C─CH3
│
H
2-propanol
K2Cr2O7
H2SO4
ketone
O
║
CH3─C─CH3 + H2O
2-propanone
Oxidation of 3° Alcohols
Tertiary 3 alcohols cannot be oxidized.
[O]
Tertiary alcohol
OH
│
CH3─C─CH3
no reaction
K2Cr2O7
H2SO4
no product
│
CH3
no H on the C-OH to oxidize
2-methylpropan-2-ol