1. ALCOHOL
• OBECTIVE STUDY:

2. INTRODUCTION OF ALCOHOL
Functional Group: -OH
General Formula:
• CnH2n+1OH
• OH attached to alkyl group, R (R-OH)
• IUPAC nomenclature
• -e (alkane) change -ol (alcohol)

3. CLASSIFICATION OF ALCOHOL
• 1°,2° & 3° alcohols
• primary alcohol (1°) – OH group attached to
1° carbon (eg: CH3CH2OH -ethanol)
• secondary alcohol (2°) – OH group attached
to 2° carbon (eg: 2-butanol)
• tertiary alcohol (3°) – OH group attached to
3° carbon (2-methyl-2-propanol)

4. TYPES OF HYDROXY COMPOUND
2 TYPES:
• Aliphatic alcohol
• Aromatic alcohol (phenols)

5. NOMENCALTURE OF ALCOHOL
Common Naming of alcohols:
Number the-longest carbon chain so that the -OH group is
attached to the carbon atom with the lowest possible
number.
Name the parent compound by using the alkane name and
replacing the -e ending with an -ol ending.
Indicate the position of the hydroxyl group with a number
in any alcohol containing three or more carbon atoms.

6. 1. Aliphatic alcohol
i.  The parent alcohol - the longest C chain
with OH group attached to it
 OH group is given the lowest number in
the chain.
 prefix & suffix used if alkyl groups are
exist more than one times

7. OH
CH3CH2CHCH3 2- butanol
CH3 OH
CH3CCH2CHCH3
CH3 4,4-dimethyl-2-pentanol

8. OH
CH3CH2CHCHCH3 3-pentanol
OH
cyclopentanol

9. ii. When there are two or more –OH
groups present, the name ends with
diol, triol and so on.
OH OH
CH3CHCH2CHCH3 2,4-pentanediol
OH
CH3CCH2OH 1,2,2-propanetriol
OH

10. 2. Aromatic alcohol (phenols)
In most cases, the name phenol is used
as the parent’s name.
OH OH
NO2
CH3
4-methylphenols 3-nitrophenols
(4-methyl hydroxybenzene)

11. Physical Properties of Alcohol:
As the alkane-like alkyl group (hydrophobic @
water hating) becomes larger, water solubility
decrease.
H O H
hydrogen bond
R OH

12. (i) Boiling point
 The boiling point of an alcohol is always much higher than
that of the alkane with the same number of carbon atoms.
 Intermolecular foces:
 Between alkanes, the presence of van der Waals forces.
 Between alcohols, the presence of hydrogen bonding
 Hydrogen bonding are much stronger than VdW forces
and therefore it takes more energy to separate alcohol
molecules than it does to separate alkane molecules.
 Therefore, boiling point of alcohols is higher than
alkanes.

13. • The boiling points of the alcohols increase as the
number of carbon atoms increases.
– Alcohols with lower number of carbons has
smaller size compared to alcohols with higher
number of carbons.
– Alcohols with smaller size will have weaker van
der Waals forces instead of hydrogen bonding that
is formed between OH group.
– Therefore, alcohols with lower number of carbons
have lower boiling points.

14. Volatility
• But they also cause alcohols to have a lower volatility than
alkanes of a similar molecular mass
Solubility
• Alcohols dissolve in water because hydrogen bonds form
between the polar –O-H groups of the alcohols and water
molecules
• The first three members of the homologous series are
soluble in water
• Solubility decreases as the chain length increases; the
larger part of the alcohol molecule is made up of a non-
polar hydrocarbon chain. Also the hydrocarbon part of the
chain doesn’t form hydrogen bonds with water

15. Chemical properties of Alcohols
• As an acid and as a base
- Alcohol can donate or accept a proton
1. Reaction with Sodium (alcohol as acid)
2. Dehydration of alcohols to yield alkenes
(alcohol as basic)

16. 1.Reaction with Sodium (alcohol as acid)
As an acid
R-OH + H2O RO- + H3O+
• Alcohol reacts with Sodium to form sodium
alkoxide and hydrogen gas.
• This reaction shows the acidic properties of
alcohol.
eg: RO-H + Na RO-Na+ + 1/2H2
CH3CH2OH + Na CH3CH2O-Na+ + 1/2H2
(sodium alkoxide)

17. 2.Dehydration of alcohols to yield alkenes
As a base
R-CH2-OH + HA RCH2-OH2 + A-
eg:
CH3-CH2-OH + H2SO4 conc CH2=CH2 + H2O
Refer to the Saytzeff Rule to predict major
alkene product.

18. Saytzeff Rule
• major product is the more stable alkene.
• Which is the more stable alkene?
– the most number of alkyl groups
attached to the C = C

19. Preparation of Alcohol:
(a) Fermentation of Carbohydrates : by yeast
eg:
C6H12O6 2CH3CH2OH + 2CO2
sugar ethanol
This process still widely used to prepare
alcohol

20. (b) Hydration of Alkenes
- Alkenes was added by H2O and H2SO4 / H3PO4.
This reaction follows Markovnikov’s Rule
eg:
R-C=CH2 + H2O / H+ R-C-CH3
Alkene Alcohol

21. Markovnikov Rule:
• In addition of electrophilic to an
alkene, the more positives reagent adds
to the carbon double bond that have
largest number of hydrogen bonded to
it.

22. (c) Hydrolysis of Haloalkanes
- Alkyl Halide react with strong bases (NaOH)
to produce alcohols and Sodium Halides (NaX)
eg:
R-X + OH- R-OH + X-
H2O/reflux
CH3-Br + NaOH CH3-OH + NaBr

23. (d) Addition of Grignard Reagents to Carbonyl
Compounds
- We can use aryl, alkyl and vinylic halides
react with magnesium in ether solution to
generate Grignard reagents, RMgX.
ether
- R-X + Mg RMgX
where R = alkyl/aryl/vinyl

24. • These Grignard reagents react with carbonyl
compounds to yield alcohol.
hydrolysis / H3O+
RMgX + RCHO R2CHOH
Grignard alcohol
reagent

25. Mg / ether
CH3CH2 X CH3CH2 MgBr
O
H2O / H+
H C CH3
carbonyl
OH
CH3CH2CCH3
H

26. (e) Reaction with carboxylic acid to form
an ester (esterification)
general equation: H+
RCOOH + R’OH RCOOR’ + H2O
eg:
CH3COOH + CH3CH2OH CH3COOCH2CH3 + H2O
carboxylic acid alcohol ester water
(etanoic acid) (ethanol)

27. (f) Hydrogenation of Alcohol
• Dehydrate with conc. H2SO4,
• then add H2 - Hydrogenation
OH
H2SO4 H2
CH3CHCH3 CH2 CHCH3 CH3CH2CH3
Pt
alcohol alkene alkane

28. (g) Reaction with Hydrogen Halides, Phosphorus
Halides (PX3 /PX5) and Thionyl Chloride (SOCl2)
- When alcohol react with a hydrogen halide, a
substitution takes place producing alkyl halide and
water.
General reaction:
(i) R - OH + H X R - X + H2O
(ii) 3ROH + PX3 3RX + H3PO3
(iii) ROH + PCl5 RCl + POCl3 + HCl
(iv) ROH + SOCl2 RCl + SO2 + HCl

29. eg:
3C(CH3)3-OH + PBr3 3C(CH3)3-Br + H3PO3
CH3CH2-OH + PCl5 CH3CH2-Cl
CH3CH2CH2-OH + SOCl2 CH3CH2CH2-Cl
+ SO2 + HCl

30. (h) Formation of Tosylate
• Typical acids used for alcohol dehydration are H2SO4
or p-toluenesulfonic acid (TsOH).
• More substituted alcohols dehydrate more
easily, giving rise to the following order of reactivity.

31. Tosylate: A Good Leaving Group
• Alcohols are converted to tosylates by treatment with
p-toluenesulfonyl chloride (TsCl) in the presence of
pyridine.
• This process converts a poor leaving group (¯OH) into a
good one (¯OTs).
• Tosylate is a good leaving group because its conjugate
acid, p-toluenesulfonic acid (CH3C6H4SO3H, TsOH) is a
strong acid (pKa = -7).

32. Tosylate: A Good Leaving Group
• (S)-2-Butanol is converted to its tosylate with
retention of configuration at the stereogenic center.
Thus, the C—O bond of the alcohol is not broken
when tosylate is formed.

33. Tosylate: A Good Leaving Group
• Because alkyl tosylates have good leaving groups, they
undergo both nucleophilic substitution and 
elimination, exactly as alkyl halides do.
• Generally, alkyl tosylates are treated with strong nucleophiles
and bases, so the mechanism of substitution is SN2, and the
mechanism of elimination is E2.

34. Tosylate: A Good Leaving Group
• Because substitution occurs via an SN2 mechanism, inversion
of configuration results when the leaving group is bonded to
a stereogenic center.
• We now have another two-step method to convert an alcohol
to a substitution product: reaction of an alcohol with TsCl
and pyridine to form a tosylate (step 1), followed by
nucleophilic attack on the tosylate (step 2).
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35. Tosylate: A Good Leaving Group
• Step 1, formation of the tosylate, proceeds with retention of
configuration at a stereogenic center.
• Step 2 is an SN2 reaction, so it proceeds with inversion of
configuration because the nucleophile attacks from the backside.
• Overall there is a net inversion of configuration at a stereogenic
center.
Example:
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