Chapter 6 hydroxyl compounds

1. ORGANIC CHEMISTRY
CHM 207
CHAPTER 6:
HYDROXYL COMPOUNDS
(ALCOHOLS AND PHENOL)

2. SUBTOPICS
Nomenclature of alcohols, phenols.
Classification of alcohols.
Physical properties of alcohols:
- Physical state
- Boiling points
- Solubility of alcohols in water
 Acidity of alcohols and phenols
Reactions of alcohols:
- Reaction with sodium
- Oxidation
- Esterification
- Halogenation and haloform reactions
- Dehydration
- Formation of ether (Williamson ether synthesis)

3.  Reactions of phenols:
- Reaction with sodium
- Esterification
- Halogenation of the ring
- Nitration of the ring
 Tests to distinguish classes of alcohols:
i) Lucas test
ii) Oxidation
 Haloform test to identify methyl alcohol group
- Iodoform
- Bromoform
 Uses of alcohols and phenols.

4. ALCOHOLS
Alcohols: Organic compounds containing
hydroxyl (-OH) functional groups.
ROH
Phenols: Compounds with hydroxyl group bonded
directly to an aromatic (benzene) ring.
OH

5. NOMENCLATURE OF
ALCOHOLS

6. IUPAC RULES
1.Select the longest continuous chain of carbon atoms
containing the hydroxyl group.
2.Number the carbon atoms in this chain so that the
one bonded to the –OH group has the lowest
possible number.
3.Form the parent alcohol name by replacing the final
–e of the corresponding alkane name by –ol. When
isomers are possible, locate the position of the –OH
by placing the number (hyphenated) of the carbon
atom to which the –OH is bonded immediately before
the parent alcohol name.
4.Name each alkyl branch chain (or other group) and
designate its position by number.

7. Select this chain as the parent compound.
This is the longest continuous chain that
contains an hydroxyl group.

8. 4
3
2 1
This end of the chain is closest to the
OH. Begin numbering here.

9. 4
3
2 1
3-methyl-2-butanol

10. Select this chain as the parent compound.
This is the longest continuous chain that
contains an hydroxyl group.

11. 4 3
21
5
This end of the chain is closest to the
OH. Begin numbering here.

12. 3-methyl-2-pentanol
4 3
21
5 3
2

13. NOMENCLATURE OF CYCLIC
ALCOHOLS
Using the prefix cyclo-
The hydroxyl group is assumed to be on C1.
IUPAC name:
new IUPAC name:
trans-2-bromocyclohexanol
trans-2-bromocyclohexan-1-ol
H
Br
OH
H
1
2
3
4
5
6 HOCH
2CH
3
1-ethylcyclopropanol
1-ethylcyclopropan-1-ol
1
23

14. NOMENCLATURE OF ALCOHOLS
CONTAINING TWO DIFFERENT
FUNCTIONAL GROUPS
Alcohol containing double and triple bonds:
- use the –ol suffix after the alkene or alkyne name.
The alcohol functional group takes precedence over
double and triple bonds, so the chain is numbered in
order to give the lowest possible number to the carbon
atom bonded to the hydroxyl group.
The position of the –OH group is given by putting its
number before the –ol suffix.
Numbers for the multiple bonds were once given early in
the name.

15. 1234
CH
2CHCH
2CHCH
3
OH
5
1) Longest carbon chain that contains –OH group
- 5 carbon
2) Position of –OH group
- Carbon-2
3) Position of C=C
- Carbon-4
COMPLETE NAME = 4-penten-2-ol
EXAMPLE

16. Some consideration:
- OH functional group is named as a hydroxy
substituent when it appears on a structure with a
higher priority functional group such as acids, esters,
aldehydes and ketones.
- Examples:
1234
O
6
OH
CH
3CH
OH
CH
2C
O
OH
3-hydroxybutanoic acid 2-hydroxycyclohexanone
1
2
3
4
5

17. MAIN GROUPS
Acids
Esters
Aldehydes
Ketones
Alcohols
Amines
Alkenes
Alkynes
Alkanes
Ethers
Halides
decreasing priority

18. Alcohols with two –OH groups are called diols or
glycols.
Naming of diols is like other alcohols except that the
suffix diol is used and two numbers are needed to
tell where the two hydroxyl groups are located.
NOMENCLATURE OF DIOLS
123
CH
3CH
OH
CH
2OH
propane-1,2-diol trans-cyclopentane-1,2-diol
OH
OH
IUPAC name
1
2
3
5
4

19. NOMENCLATURE OF
PHENOLS
The terms ortho (1,2-disubstituted), meta (1,3-
disubstituted) and para (1,4-disubstituted) are often
used in the common names.
OH
Br
OHO
2N
OH
CH
3CH
2
IUPAC name:
common name:
2-bromophenol
ortho-bromophenol
3-nitrophenol
meta-nitrophenol
4-ethylphenol
para-ethylphenol

20. Phenols may be monohydric, dihydric or
trihydric according to the number of hydroxyl
groups present in the benzene ring.
benzene-1,3-diol benzene-1,4-diol benzene-1,2,3-triol
OH
OH
OH
OH
OH
OH
OH

21. According to the type of carbinol carbon atom (C bonded
to the –OH group).
CLASSIFICATION
COH
Classes:
i) Primary alcohol
- -OH group attached to a primary carbon atom
ii) Secondary alcohol
- -OH group attached to a secondary carbon atom
iii) Tertiary alcohol
- -OH group attached to a tertiary carbon atom

22. TYPE STRUCTURE EXAMPLESTYPE STRUCTURE EXAMPLES
i)Primary (1°)
ii)Secondary (2°)
iii)Tertiary (3°)
CR
H
OH
H
CR
H
OH
R'
CR
R''
OH
R'
CH
3CH
2-OH CH
3CHCH
2
CH
3
OH
ethanol 2-methyl-1-propanol
H
3CCH
OH
CH
2CH
3
OH
2-butanol cyclohexanol
2-methyl-2-propanol
C
CH
3
OH
CH
3
H
3C

23. •Alcohols that contain more than one OH group
attached to different carbons are called polyhydroxy
alcohols.
•Monohydroxy: one OH group per molecule.
•Dihydroxy: two OH groups per molecule.
•Trihydroxy: three OH groups per molecule.
Polyhydroxy Alcohols

25. PHYSICAL PROPERTIESPHYSICAL PROPERTIES
PHYSICAL STATES OF ALCOHOLS
- simple aliphatic alcohols and lower aromatic
alcohols (such as phenylmethanol, C
6
H
5
CH
2
OH)
→ liquids at room temperature.
- highly branched alcohols and alcohols with twelve
or more carbon atoms → solids.

26. BOILING POINTS
- The boiling points of alcohols are higher than those of
alkanes and chloroalkanes of similar relative molecular mass.
- For example:
C
2
H
5
OH CH
3
CH
2
CH
3
CH
3
Cl
Relative molecular mass: 46 44 50.5
Boiling point: 78°C -42°C -24°C
- Reason:
intermolecular hydrogen bonds exist between the –OH
groups in the alcohol molecules.
R
O
H
O
H R
Ar
O
H
O
H Ar
hydrogen bonding
hydrogen bonding
δ+
δ-
δ+δ-
δ-
δ-
- Branched chain alcohols boils at a lower temperature (more
volatile) than the straight chain alcohols with the same number of
carbon atoms.

27. SOLUBILITY OF ALCOHOLS IN WATER
i) alcohols with short carbon chains (such as methanol,
ethanol, and propanol) dissolve in water.
- when alcohols dissolve in water, hydrogen bonds are formed
between the –OH group of the alcohol molecule and the –OH
group of the water molecule.
ii) the solubility of alcohols in water decreases sharply with the
increasing length of the carbon chain. Higher alcohols are
insoluble in water.
- alcohol contains a polar end (-OH group) called ‘hydrophilic’
and a non-polar end (the alkyl group) called ‘hydrophobic’.
- the water solubility decreases as the alkyl group becomes
larger.

28. iii) alcohols with more than one hydroxyl group (polyhydroxy
alcohols) are more soluble than monohydroxy alcohols with
the same number of carbon atoms. This is because they
can form more hydrogen bonds with water molecule.
iv) branched hydrocarbon increases the solubility of alcohol in
water.
- reason: branched hydrocarbon cause the hydrophobic
region becomes compact so decrease surface area. As the
surface area of the non-polar part in the molecule
decreases, the solubility increases.
* Phenol is sparingly soluble (9.3%) because of its compact
shape and the particularly strong hydrogen bonds formed
between phenolic –OH groups and water molecules.

29. Alcohol is weakly acidic.
In aqueous solution, alcohol will donated its proton to
water molecule to give an alkoxide ion (R-O
-
).
ACIDITY OF ALCOHOLS AND PHENOLSACIDITY OF ALCOHOLS AND PHENOLS
R-OH + H
2
O R-O
-
+ H
3
O
+
K
a
= ~ 10
-16
to 10
-18
alkoxide ion
Example
CH
3
CH
2
-OH + H
2
O CH
3
CH
2
-O
-
+ H
3
O
+
The acid-dissociation constant, Ka, of an alcohol is defined
by the equilibrium
R-OH + H
2
O R-O
-
+ H
3
O
+Ka
Ka = [H
3
O
+
] [RO
-
]
[ROH]
pK
a
= - log (K
a
)
* More smaller the pK
a

value, the alcohol is
more acidic

30. Acidity OF PHENOLS
Phenol is a stronger acid than alcohols and water.
R-OH + H
2
O R-O
-
+ H
3
O
+
K
a
= ~ 10
-16
to 10
-18
alcohol
alkoxide ion
OH H
2O O
-
H
3O
+
phenol phenoxide ion
K
a
= 1.2 x 10
-10
H
2
O + H
2
O HO
-
+ H
3
O
+
K
a
= 1.8 x 10
-16
hydroxide ion

31. Phenol is more acidic than alcohols by considering
the resonance effect.
i) The alkoxide ion (RO
-
)
- the negative charge is confined to the oxygen and
is not spread over the alkyl group.
- this makes the RO
-
ion less stable and more
susceptible to attack by positive ions such as H
+

ions.

32. ii) The phenoxide ion
- one of the lone pairs of electrons on the oxygen atom is
delocalised into the benzene ring.
- the phenoxide ion is more stable than the alkoxide ion
because the negative charge is not confined to the
oxygen atom but delocalised into the benzene ring.
- the phenoxide ion is resonance stabilised by the
benzene ring and this decreases the tendency for the
phenoxide ion to react with H
3
O
+
.
O O O O

33. The acidity decreases as the substitution on the alkyl group increase.
- Reason: a more highly substituted alkyl group inhibits solvation of
the alkoxide ion and drives the dissociation equilibrium to the left.
- For example: methanol is more acidic than t-butyl alcohol.
The present of electron-withdrawing atoms enhances the acidity of
alcohols.
- Reason: the electron withdrawing atom helps to stabilize the
alkoxide ion.
- For example: 2-chloroethanol is more acidic than ethanol because
the electron-withdrawing chlorine atom helps to stabilize the 2-
chloroethoxide ion.
- alcohol with more than one electron withdrawing atoms are more
acidic. For example, 2,2,-dichloroethanol is more acidic than 2-
chloroethanol.
- Example of electron-withdrawing atom/groups:

Halogen atoms and NO
2
.
EFFECTS OF Acidity

34. Reaction with sodium
Oxidation
Esterification
Halogenation and haloform reactions
Dehydration
Formation of ether (Williamson ether
synthesis)
REACTIONS OF ALCOHOLSREACTIONS OF ALCOHOLS

35. Reaction with sodium
Alcohols reacts with Na at room temperature to
form salts (sodium alkoxides) and hydrogen.
2R-O-H + 2Na → 2R-O
-
Na
+
+ H
2
For example:
CH
3
CH
2
OH + Na → CH
3
CH
2
O
-
Na
+
+ 1/2H
2

alcohol sodium ethoxide
Reactivity of alcohols towards the reactions
with sodium:
CH
3
> 1° > 2° > 3°

36. Oxidation
RCOH
H
H
RCOH
H
H
RCOH
H
H
H
H
R-C=O
R-C=O
O
R-C-OH
Pyridinium chlorochromate (PCC)
CH
2Cl
2, 25
o
C
1
o
alcohol aldehyde
Cu or Cr
3O/pyridine
1
o
alcohol aldehyde
KMnO
4/H
+
or K
2Cr
2O
7/H
+
1
o
alcohol carboxylic acid
or CrO
3/H
+
Cr
3O/pyridine = Collins reagent
1° alcohol

37. KMnO
4/H
+
or K
2Cr
2O
7/H
+
or CrO
3/H
+
CH
3(CH
2)
4-CH
2-OH CH
3(CH
2)
4-C-OH
O
CH
3(CH
2)
4-CH
2-OH CH
3(CH
2)
4-C-H
O
1-hexanol hexanal
1-hexanol hexanoic acid
PCC
Examples:
1° alcohol

38. RCOH
H
R'
O
R-C-R'
KMnO
4/H
+
or K
2Cr
2O
7/H
+
2
o
alcohol
ketone
or CrO
3/H
+
RCOH
R"
R'
KMnO
4/H
+
or K
2Cr
2O
7/H
+
3
o
alcohol
or CrO
3/H
+
no reaction
2° alcohol
3° alcohol
CH
3CH
OH
CH
2CH
3 CH
3C
O
CH
2CH
3
KMnO
4/H
+
or K
2Cr
2O
7/H
+
or CrO
3/H
+
2-butanol 2-butanone
Example:

39. Esterification:
- the reaction between an alcohol and a carboxylic acid to
form an ester and H
2
O.
Esterification
RC
O
OH OR'H
H
+
CH
3CH
2-O-H CH
3C
O
OH
CH
3-O-H C
O
OH
H
+
H
+
RC
O
OR'
C
O
OCH
3
CH
3C
O
OCH
2CH
3
H
2O
H
2O
H
2O
carboxylic acid alcohol ester
EXAMPLES
ethanol
ethanoic acid ethyl ethanoate
methanol benzoic acid methyl benzoate
H
+
= catalyst

40. CH
3-O-H CCH
3
O
Cl CCH
3
O
OCH
3
HCl
methanol ethanoyl chloride methyl ethanoate
Esterification also occurs when alcohols
react with derivatives of carboxylic acids
such as acid chlorides

41. Halogenation and haloform reactions
1) Hydrogen halides (HBr or HCl or HI)
R-OH + H-X → R-X + H
2
O
Example:
C
2
H
5
-OH + H-Br C
2
H
5
-Br + H
2
O
•Reactivity of hydrogen halides decreases in order HI >
HBr > HCl
•Reactivity of alcohols with hydrogen halides:
3° > 2° > 1°
H
+

42. 2) Phosphorus trihalides, PX
3
3R-OH + PX
3
3R-X + H
3
PO
3
(PX
3
= PCl
3
or PBr
3
or PI
3
)
Example:
(CH
3
)
2
CHCH
2
-OH + PBr
3
→ (CH
3
)
2
CHCH
2
-Br
isobutyl alcohol isobutyl bromide
3) Phosphorus pentahalides (PX
5
)
R-OH + PX
5
→ R-Cl + POCl
3
+ HCl
phosphorus trichloride oxide
(phosphorus oxychloride)
Example:
CH
3
CH
2
-OH + PCl
5
→ CH
3
CH
2
-Cl + POCl
3
+ HCl
ethanol chloroethane (white fumes of HCl)
RT

43. 4) Thionyl chloride (SOCl
2
)
R-OH + SOCl
2
→ R-Cl + SO
2
+ HCl
Example:
CH
3
(CH
2
)
5
CH
2
-OH + SOCl
2
→ CH
3
(CH
2
)
5
CH
2
-Cl + SO
2
+ HCl
1-heptanol 1-chloroheptane

44. Dehydration of alcohols will formed alkenes and the
products will followed Saytzeff rules.
Dehydration
conc. H
2
SO
4
R-CH
2
-CH
2
-OH R-CH=CH
2
+ H
2
O
Saytzeff rule:
- A reaction that produces an alkene would favour the
formation of an alkene that has the greatest number of
substituents attached to the C=C group.
CH
3CH
2-CH-CH
3
OH
H
+
H
+
CH
3CH=CH-CH
3 + H
2O
CH
3CH
2-CH=CH
2 + H
2O
2-butanol
2-butene
major product
1-butene

45. Reactivity of alcohols towards dehydration:
3° > 2° > 1°
Reagents for dehydration:
i) Concentrated H
2
SO
4
conc. H
2
SO
4
CH
3
-CH
2
-OH CH
2
=CH
2
+ H
2
O
ii) With phosphoric (v) acid
OH
85% H
3PO
4, 165-170
o
C H
2O
iii) Vapour phase dehydration of alcohols
CH
3
CH
2
OH CH
2
=CH
2
+ H
2
O
Al
2
O
3
heat

46. Involves the S
N
2 attack of an alkoxide ion on an
unhindered primary alkyl halides.
The alkoxide is made by adding Na, K or NaH to the
alcohol.
R-O
-
+ R’-X → R-O-R’ + X
-
alkoxide
(R’ must be primary)
Formation of ether (Williamson ether
synthesis)
The alkyl halides (or tosylate) must be primary, so that
a back-side attack is not hindered.
If the alkyl halides is not primary, elimination usually
occurs to form alkenes.

47. CH
3CH
2-OH
CH
3CH
2-OHNa
CH
3I
OH
CH
3CH
2-OTs
CH
3CH
2-O
CH
3CH
2-O-CH
3
Na
+
CH
3CH
2-O-CH
3
OCH
2CH
3
NaI
CH
3I
NaI
EXAMPLES
or
1) Na
2)
1) Na
2)
cyclohexanol ethoxycyclohexane

48. Question:
Alcohol W is a secondary alcohol with a molecular formula
of C
4
H
10
O.
Compound M
C
4
H
10
O
Alcohol W
Step 1
CrO
3
/
pyrridine
Step 2
H+ / heat
Compound N
(major)
+
Compound O
(minor)
Reagent A
C
4
H
10
ONa
a)Draw and give the IUPAC name for alcohol W.
b)Draw the structural formula for the following
compounds:
i) Compound M
ii)Compound N
iii)Compound O

49. c) Give the correct name for the following:
i) Step 1
ii) Step 2
iii)Reagent A

50. Answers
a) Alcohol W
OH
name: butan-2-ol
b) i) compound M ii) compound N iii) Compound O
O
c) i) Step 1: Oxidation
ii) Step 2: Dehydration (of alcohol)
iii) Reagent A: Na Metal

51. Reaction with sodium
Esterification
Halogenation of the ring
Nitration of the ring
REACTIONS OF PHENOLSREACTIONS OF PHENOLS

52. REACTION WITH SODIUM
OHNa O
-
Na
+
1/2 H
2(g)
sodium phenoxide
OHNaOH O
-
Na
+
sodium phenoxide
H
2O
REACTION WITH AQUEOUS SODIUM HYDROXIDE
ROH + NaOH no reaction

53. ESTERIFICATION
OH
OH
H
2O
NaOH
C
O
OH
ONa
CH
3CCl
O
NaOH
OC
O
OCCH
3
O
H
2O
NaCl
sodium phenoxide
phenyl benzoate
EXAMPLES
H
+

54. More reactive towards electrophilic substitution than benzene.
ortho-para director.
1) Halogenation of phenol:
If liquid bromine or bromine water is added to an aqueous solution of phenol
at room temperature, decolorisation occurs and a white precipitate of 2,4,6-
tribromophenol is formed (bromination).
No catalyst (halogen carrier) is needed.
This reaction is used to test the presence of phenol and determine the mass
of phenol in an aqueous solution.
HALOGENATION
OH
3X
2 (aq)
OH
3Br
2(aq)
OH
X
XX
OH
Br
BrBr
3HX
3HBr
room
temperature
EXAMPLE
room
temperature
2,4,6-tribromophenol (white precipitate)

55. OH
3Cl
2
OH
Cl
ClCl
3HCl
room
temperature
2,4,6-trichlorophenol (white precipitate)
Phenol reacts similarly with chlorine or chlorine water to form
white precipitate of 2,4,6-trichlorophenol.
This reaction is called chlorination of phenol.
OH
2Br
2 (CCl
4)
OH
Br
OH
Br
2HBr
2
Monobromophenols are obtained if the bromine is dissolved in
a non-polar solvent such as CCl
4.

56. NITRATION
Dilute nitric (v) acids reacts with phenol at room
temperature to give a mixture of 2- and 4-nitrophenols.
OH
2HNO
3
OH
NO
2
OH
NO
2
2H
2O
2 < 20
o
C
2-nitrophenol4-nitrophenol

57. By using concentrated nitric (v) acid, the nitration of
phenol yields 2,4,6-trinitrophenol (picric acid).
Picric acid is a bright yellow crystalline solid. It is used
in the dyeing industry and in manufacture of explosives.
OH
3HNO
3
OH
NO
2
NO
2
O
2N
3H
2O
2,4,6-trinitrophenol
(picric acid)

58. Aqueous iron (III) chloride and aqueous bromine are used to
test phenols.
i)Complex formation with iron (III) chloride
- when two or three drops of iron (III) chloride solution is
added to a very dilute solution of phenol, a violet-blue
coloration is produced.
- methylphenol (toluene) produce a blue colour.
CHEMICAL TESTS FOR PHENOLSCHEMICAL TESTS FOR PHENOLS
OH
FeCl
3 (neutral)6
H
3[Fe
3+
( )
6]
O
3HCl
violet complexphenoxide ligand

59. Phenol
compound
Colour of
complex with
FeCl
3
(aq)
Phenol
compound
Colour of
complex with
FeCl
3
(aq)
Violet Green
Violet Red
Blue Violet
Violet
OH
OH
CH
3
OH
CH
3
OH
COOH
OH
R
O
OH
OH
OH
OCH
3
O

60. ii)Bromine water
- when bromine water is added gradually to a concentrated
solution of phenol, the bromine water is decolorised.
- when excess bromine water is added, a white precipitate
of 2,4,6-tribromophenol is obtained.

61. 1)Lucas Test
- The alcohol is shaken with Lucas reagent (a solution
of ZnCl
2
in concentrated HCl).
- Tertiary alcohol - Immediate cloudiness (due to the
formation of alkyl chloride).
- Secondary alcohol - Solution turns cloudy within
about 5 minutes.
- Primary alcohol - No cloudiness at room temperature.
TESTS TO DISTINGUISH CLASSES OF TESTS TO DISTINGUISH CLASSES OF
ALCOHOLSALCOHOLS

62. CCH
3CH
3
CH
3
OH
CHCH
3
OH
CH
2CH
3
CH
3CH
2CH
2CH
2OH
CCH
3CH
3
CH
3
Cl
CHCH
3
Cl
CH
2CH
3
HCl/ZnCl
2
room temperature
3
o
alcohol (cloudy solution almost immediately)
HCl/ZnCl
2
room temperature
2
o
alcohol (cloudy solution within 5 minutes)
HCl/ZnCl
2
room temperature
no reaction
1
o
alcohol

63. 2)Oxidation of alcohols
- only primary and secondary alcohols are oxidised by
hot acidified KMnO
4
or hot acidified K
2
Cr
2
O
7
solution.
- the alcohol is heated with KMnO
4
or K
2
Cr
2
O
7
in the
presence of dilute H
2
SO
4
.
- 1
o
or 2
o
alcohol:
→ the purple colour of KMnO
4
solution disappears.
→ the colour of the K
2
Cr
2
O
7
solution changes from
orange to green.
- 3
o
alcohol do not react with KMnO
4
or K
2
Cr
2
O
7
.

64. 3RCHO
RCH
R'
OH RC
R'
O
3RCH
2OH + Cr
2O
2-
7 + 8H
+
3RCHO + 2Cr
3+
+ 7H
2O
1
o
alcohol (orange) aldehyde (green)
+ Cr
2O
2-
7 + 8H
+
aldehyde(orange)
3RCOOH + 2Cr
3+
+ 7H
2O
carboxylic acid(green)
3
+ Cr
2O
2-
7 + 8H
+
(orange)2
o
alcohol
3 + 2Cr
3+
+ 7H
2O
(green)ketone

65. HALOFORM TEST TO IDENTIFY METHYL HALOFORM TEST TO IDENTIFY METHYL
ALCOHOL GROUPALCOHOL GROUP
1) Iodoform:
Ethanol and secondary alcohols containing the group
methyl alcohol group which react with alkaline
solutions of iodine to form triiodomethane (iodoform,
CHI
3
).
Triiodomethane – a pale yellow solid with a
characteristic smell.
CCH
3
H
OH
(methyl alcohol group)

66. CRCH
3
H
OH
+ 4I
2 + 6NaOH CHI
3 (s) + RCOONa + 5NaI + 5H
2O
triiodomethane
(iodoform)
yellow precipitate
where R = hydrogen, alkyl or aryl group
CHCH
3
H
OH
+ 4I
2 + 6OH CHI
3 (s) + 5I
-
+ 5H
2O
iodoform
COH
O
ethanol
methanoate
• The iodoform test can distinguish ethanol from methanol
CHH
H
OH
+ 4I
2 + 6OH
methanol
no reaction
positive iodoform test
negative iodoform test

67. CHCH
3
CH
3
OH
+ 4I
2 + 6OH CHI
3 (s) + 5I
-
+ 5H
2O
iodoform
COCH
3
O
2-propanol
ethanoate
• The iodoform test can distinguish 2-propanol from 1-propanol
positive iodoform test
CHC
H
OH
+ 4I
2 + 6OH
1-propanol
no reactionCH
HH
HH
negative iodoform test
* TERTIARY ALCOHOLS DO NOT GIVE POSITIVE
IODOFORM TEST

68. CRCH
3
H
OH
+ 4Br
2 + 6NaOH CHBr
3 (s) + RCOONa + 5NaBr + 5H
2O
bromoform
where R = hydrogen, alkyl or aryl group
2) BROMOFORM
sample
iodoform
reagent

69. Question:
a) Classify each of the following alcohols as
primary, secondary or tertiary.
i) 2-Propanol
ii) 4-methylpentanol
iii)2,3-dimethylbutan-2-ol
b) Name a simple test to distinguish 1°, 2°, 3°
alcohol. State the reagents and conditions
required for the test and write down the
expected observations.

70. Answer:
a) i) 2°
ii) 1°
iii) 3°
b) Test: Lucas test
Reagent and conditions : Lucas reagent /
Mixture of HCl and ZnCl2
Observatios:
- Clear homogenous solution change into 2
layers or cloudiness
- Rate of reaction: 3° > 2° > 1° alcohol

71. As solvents:
- examples: the lower alcohols such as methanol,
ethanol and propanol.
- methanol is used as a solvent for varnish and paints.
As fuels:
- biofuel (fuel derived from a biological source).
- ethanol can be produced from sugars such as sucrose
from sugar cane, through fermentation and distillation.
It can be blended with petrol and used as fuel in motor
vehicles.
- methylated spirit is ethanol made undrinkable by the
addition of a little methanol. It is used as a fuel in
camping stoves.
USES OF ALCOHOLSUSES OF ALCOHOLS

72. In alcoholic drinks:
- ethanol is used for making wine, beer and etc.
As intermediates:
- methanol can be oxidised to methanal (HCHO), a
chemical feedstock (starting material) for the
manufacture of thermosetting plastics such as bakelite.
- methanol is used to make methyl methacrylate which
is used in the manufacture of another plastic called
perspex.
In cosmetics:
- ethanol is used as solvent for fragrances in perfumes
and after-shave lotions.
- polyhydroxyl alcohols (for example, glycerol) are used
in moisturising creams.

73. Making plastics such as bakelite (phenol-
methanal plastic).
The synthesis of cyclohexanol and
hexanedioic acid to make nylon 6,6.
Making dyes.
Making antiseptics such as 4-chloro-3,5-
dimethylphenol which is active ingredient in
‘Dettol’.
USES OF PHENOLSUSES OF PHENOLS