This chapter discusses the structure, properties, nomenclature and synthesis of alcohols. Alcohols are classified based on whether the carbon bonded to the hydroxyl group is primary, secondary or tertiary. Common methods for synthesizing alcohols include Grignard reactions, reduction of carbonyl groups, and hydration of alkenes. Grignard reagents add across carbonyl groups to form alcohols while reduction uses agents like sodium borohydride or lithium aluminum hydride. Alcohols exhibit hydrogen bonding which affects their physical properties like higher boiling points and solubility.

1. Chapter 10
Structure and Synthesis
of Alcohols
Organic Chemistry

2. Chapter 10 2
Structure of Alcohols
• Hydroxyl (OH) functional group
• Oxygen is sp3
hybridized.
=>

3. Chapter 10 3
Classification
• Primary: carbon with –OH is bonded to
one other carbon.
• Secondary: carbon with –OH is bonded
to two other carbons.
• Tertiary: carbon with –OH is bonded to
three other carbons.
• Aromatic (phenol): -OH is bonded to a
benzene ring.
=>

4. Chapter 10 4
Classify these:
CH3 CH
CH3
CH2OH CH3 C
CH3
CH3
OH
OH
CH3 CH
OH
CH2CH3 =>

5. Chapter 10 5
IUPAC Nomenclature
• Find the longest carbon chain
containing the carbon with the -OH
group.
• Drop the -e from the alkane name, add
-ol.
• Number the chain, starting from the end
closest to the -OH group.
• Number and name all substituents. =>

6. Chapter 10 6
Name these:
CH3 CH
CH3
CH2OH
CH3 C
CH3
CH3
OH
CH3 CH
OH
CH2CH3
2-methyl-1-propanol
2-methyl-2-propanol
2-butanol
OH
Br CH3
3-bromo-3-methylcyclohexanol
=>

7. Chapter 10 7
Unsaturated Alcohols
• Hydroxyl group takes precedence. Assign
that carbon the lowest number.
• Use alkene or alkyne name.
4-penten-2-ol (old)
pent-4-ene-2-ol
(1997 revision of IUPAC rules)
=>
CH2 CHCH2CHCH3
OH

8. Chapter 10 8
Naming Priority
• Acids
• Esters
• Aldehydes
• Ketones
• Alcohols
• Amines
• Alkenes
• Alkynes
• Alkanes
• Ethers
• Halides
=>

9. Chapter 10 9
Hydroxy Substituent
• When -OH is part of a higher priority class of
compound, it is named as hydroxy.
• Example:
CH2CH2CH2COOH
OH
4-hydroxybutanoic acid
also known as GHB
=>

10. Chapter 10 10
Common Names
• Alcohol can be named as alkyl alcohol.
• Useful only for small alkyl groups.
• Examples:
CH3 CH
CH3
CH2OH CH3 CH
OH
CH2CH3
isobutyl alcohol sec-butyl alcohol
=>

11. Chapter 10 11
Naming Diols
• Two numbers are needed to locate the two
-OH groups.
• Use -diol as suffix instead of -ol.
HO OH
1,6-hexanediol
=>

12. Chapter 10 12
Glycols
• 1, 2 diols (vicinal diols) are called glycols.
• Common names for glycols use the name of
the alkene from which they were made.
CH2CH2
OH OH
CH2CH2CH3
OH OH
1,2-ethanediol
ethylene glycol
1,2-propanediol
propylene glycol
=>

13. Chapter 10 13
Naming Phenols
• -OH group is assumed to be on carbon 1.
• For common names of disubstituted phenols,
use ortho- for 1,2; meta- for 1,3; and para- for
1,4.
• Methyl phenols are cresols.
OH
Cl
3-chlorophenol
meta-chlorophenol
OH
H3C
4-methylphenol
para-cresol
=>

14. Chapter 10 14
Physical Properties
• Unusually high boiling points due to
hydrogen bonding between molecules.
• Small alcohols are miscible in water, but
solubility decreases as the size of the
alkyl group increases.
=>

15. Chapter 10 15
Boiling Points
=>

16. Chapter 10 16
Solubility in Water
Solubility decreases as the size
of the alkyl group increases.
=>

17. Chapter 10 17
Methanol
• “Wood alcohol”
• Industrial production from synthesis gas
• Common industrial solvent
• Fuel at Indianapolis 500
Fire can be extinguished with water
High octane rating
Low emissions
But, lower energy content
Invisible flame =>

18. Chapter 10 18
Ethanol
• Fermentation of sugar and starches in grains
• 12-15% alcohol, then yeast cells die.
• Distillation produces “hard” liquors
• Azeotrope: 95% ethanol, constant boiling
• Denatured alcohol used as solvent
• Gasahol: 10% ethanol in gasoline
• Toxic dose: 200 mL ethanol, 100 mL methanol
=>

19. Chapter 10 19
2-Propanol
• “Rubbing alcohol”
• Catalytic hydration of propene
=>
CH2 CH CH2 H2O
100-300 atm, 300°C
catalyst
+ CH3 CH
OH
CH3

20. Chapter 10 20
Acidity of Alcohols
• pKa range: 15.5-18.0 (water: 15.7)
• Acidity decreases as alkyl group
increases.
• Halogens increase the acidity.
• Phenol is 100 million times more acidic
than cyclohexanol!
=>

21. Chapter 10 21
Table of Ka Values
=>
CH3 OH

22. Chapter 10 22
Formation of Alkoxide
Ions
React methanol and ethanol with sodium
metal (redox reaction).
CH3CH2OH + Na CH3CH2O Na +
1
/2
H2
React less acidic alcohols with more
reactive potassium.
+ K (CH3)3CO K +
1
/2
H2)3C OH(CH3
=>

23. Chapter 10 23
Formation of Phenoxide
Ion
Phenol reacts with hydroxide ions to form
phenoxide ions - no redox is necessary.
O H
+ OH
O
+ HOH
pK a = 10
pK a = 15.7
=>

24. Chapter 10 24
Synthesis (Review)
• Nucleophilic substitution of OH-
on alkyl
halide
• Hydration of alkenes
water in acid solution (not very effective)
oxymercuration - demercuration
hydroboration - oxidation
=>

25. Chapter 10 25
Glycols (Review)
• Syn hydroxylation of alkenes
osmium tetroxide, hydrogen peroxide
cold, dilute, basic potassium
permanganate
• Anti hydroxylation of alkenes
peroxyacids, hydrolysis
=>

26. Chapter 10 26
Organometallic
Reagents
• Carbon is bonded to a metal (Mg or Li).
• Carbon is nucleophilic (partially
negative).
• It will attack a partially positive carbon.
C - X
C = O
• A new carbon-carbon bond forms.
=>

27. Chapter 10 27
Grignard Reagents
• Formula R-Mg-X (reacts like R:- +
MgX)
• Stabilized by anhydrous ether
• Iodides most reactive
• May be formed from any halide
primary
secondary
tertiary
vinyl
aryl =>

28. Chapter 10 28
Some Grignard
Reagents
Br
+ Mg
ether MgBr
CH3CHCH2CH3
Cl
ether
+ Mg CH3CHCH2CH3
MgCl
CH3C CH2
Br + Mg
ether
CH3C CH2
MgBr
=>

29. Chapter 10 29
Organolithium Reagents
• Formula R-Li (reacts like R:- +
Li)
• Can be produced from alkyl, vinyl, or
aryl halides, just like Grignard reagents.
• Ether not necessary, wide variety of
solvents can be used.
=>

30. Chapter 10 30
Reaction with Carbonyl
• R:-
attacks the partially positive carbon in the
carbonyl.
• The intermediate is an alkoxide ion.
• Addition of water or dilute acid protonates the
alkoxide to produce an alcohol.
R
C O R C O
HOH
R C OH
OH
=>

31. Chapter 10 31
Synthesis of 1° Alcohols
Grignard + formaldehyde yields a primary
alcohol with one additional carbon.
C O
H
H
C
CH3
H3C CH2 C MgBr
H
HH
CH3 CH
CH3
CH2 CH2 C
H
H
O MgBr
HOH
CH3 CH
CH3
CH2 CH2 C
H
H
O H
=>

32. Chapter 10 32
Synthesis of 2º Alcohols
Grignard + aldehyde yields a secondary
alcohol.
MgBrCH3 CH
CH3
CH2 CH2 C
CH3
H
OC
CH3
H3C CH2 C MgBr
H
HH
C O
H
H3C
CH3 CH
CH3
CH2 CH2 C
CH3
H
O H
HOH
=>

33. Chapter 10 33
Synthesis of 3º Alcohols
Grignard + ketone yields a tertiary alcohol.
MgBrCH3 CH
CH3
CH2 CH2 C
CH3
CH3
OC
CH3
H3C CH2 C MgBr
H
HH
C O
H3C
H3C
CH3 CH
CH3
CH2 CH2 C
CH3
CH3
O H
HOH
=>

34. Chapter 10 34
How would you
synthesize…
CH3CH2CHCH2CH2CH3
OH CH2OH
OH
CH3
C
OH
CH2CH3
CH3
=>

35. Chapter 10 35
Grignard Reactions
with Acid Chlorides
and Esters
• Use two moles of Grignard reagent.
• The product is a tertiary alcohol with
two identical alkyl groups.
• Reaction with one mole of Grignard
reagent produces a ketone
intermediate, which reacts with the
second mole of Grignard reagent.
=>

36. Chapter 10 36
Grignard + Acid
Chloride (1)
C O
Cl
H3C
MgBrR MgBr C
CH3
Cl
OR
C
CH3
Cl
OR MgBr C
CH3
R
O
+ MgBrCl
Ketone intermediate =>
• Grignard attacks the carbonyl.
• Chloride ion leaves.

37. Chapter 10 37
Grignard and Ester (1)
• Grignard attacks the carbonyl.
• Alkoxide ion leaves! ? !
C O
CH3O
H3C
MgBrR MgBr C
CH3
OCH3
OR
C
CH3
OCH3
OR MgBr C
CH3
R
O
+ MgBrOCH3
Ketone intermediate =>

38. Chapter 10 38
Second step of reaction
• Second mole of Grignard reacts with the
ketone intermediate to form an alkoxide ion.
• Alkoxide ion is protonated with dilute acid.
C
CH3
R
O
R MgBr + C
CH3
R
OR MgBr
HOH
C
CH3
R
OHR
=>

39. Chapter 10 39
How would you
synthesize...
CH3CH2CCH3
OH
CH3
C
OH
CH3
Using an acid chloride or ester.
CH3CH2CHCH2CH3
OH
=>

40. Chapter 10 40
Grignard Reagent +
Ethylene Oxide
• Epoxides are unusually reactive ethers.
• Product is a 1º alcohol with 2 additional
carbons.
MgBr + CH2 CH2
O
CH2CH2
O MgBr
HOH
CH2CH2
O H
=>

41. Chapter 10 41
Limitations of Grignard
• No water or other acidic protons like
O-H, N-H, S-H, or -C—C-H. Grignard
reagent is destroyed, becomes an
alkane.
• No other electrophilic multiple bonds,
like C=N, C—N, S=O, or N=O.
=>

42. Chapter 10 42
Reduction of Carbonyl
• Reduction of aldehyde yields 1º alcohol.
• Reduction of ketone yields 2º alcohol.
• Reagents:
Sodium borohydride, NaBH4
Lithium aluminum hydride, LiAlH4
Raney nickel
=>

43. Chapter 10 43
Sodium Borohydride
• Hydride ion, H-
, attacks the carbonyl
carbon, forming an alkoxide ion.
• Then the alkoxide ion is protonated by
dilute acid.
• Only reacts with carbonyl of aldehyde or
ketone, not with carbonyls of esters or
carboxylic acids.
H
C
O
H
C
H
OH
C
H
OH H
H3O+
=>

44. Chapter 10 44
Lithium Aluminum
Hydride
• Stronger reducing agent than sodium
borohydride, but dangerous to work with.
• Converts esters and acids to 1º alcohols.
C
O
OCH3
C
OH H
H
H3O
+
LAH
=>

45. Chapter 10 45
Comparison of
Reducing Agents
• LiAlH4 is stronger.
• LiAlH4 reduces more
stable compounds
which are resistant
to reduction.
=>

46. Chapter 10 46
Catalytic Hydrogenation
• Add H2 with Raney nickel catalyst.
• Also reduces any C=C bonds.
O
H2, Raney Ni
OH
NaBH4
OH
=>

47. Chapter 10 47
Thiols (Mercaptans)
• Sulfur analogues of alcohols, -SH.
• Named by adding -thiol to alkane name.
• The -SH group is called mercapto.
• Complex with heavy metals: Hg, As, Au.
• More acidic than alcohols, react with
NaOH to form thiolate ion.
• Stinks! =>

48. Chapter 10 48
Thiol Synthesis
Use a large excess of sodium
hydrosulfide with unhindered alkyl
halide to prevent dialkylation to R-S-R.
H S
_
R X R SH +
_
X
=>

49. Chapter 10 49
Thiol Oxidation
• Easily oxidized to disulfides, an
important feature of protein structure.
R SH + RHS
Br2
Zn, HCl
R S S R + 2 HBr
• Vigorous oxidation with KMnO4,
HNO3, or NaOCl, produces sulfonic acids.
SH
HNO3
boil
S
O
O
OH
=>

50. Chapter 10 50
End of Chapter 10