Chapter 6 Alcohols, Phenols, and Ethers Classification

Chapter 6 Alcohols, Phenols,
and Ethers

Content
 Classification and nomenclature
 Chemical Reactions
 Uses

Structure
 H-O-H R-O-H Ar-O-H
water alcohol phenol
 Alcohols and phenols have a common
functional group, the hydroxyl group, -OH.
 Ether
R-O-R’ Ar-O-R Ar-O-Ar

6.1 Classification of Alcohols
 Alcohols are subdivided into three classes:
primary(10), secondary(20), and tertiary(30).
The classification depends on the number
of alkyl groups bonded to the C bearing the
-OH, the carbinol carbon.
H H R
－C－OH R－C－OH R－C－OH R－C－OH
H R R
Carbinol group 10 20 30

6.1 Nomenclature of Alcohols
 Common names
(simplest alcohols or very complicated ones)
 Simplest alcohls (alkyl group + alcohol)
CH3OH CH3CH2OH CH3CH2CH2OH
Methyl alcohol Ethyl alcohol Propyl alcohol
OH OH OH
CH3CHCH3 CH3－C－CH3
CH3
Isopropyl alcohol Cyclopentyl alcohol t-Butyl alcohol

 Complicated alcohols
OH
Cholesterol

 IUPAC system
1. longest continuous C chain that contains -OH.
Drop the “e” ending of the parent alkane and
replace it by the suffix - ol.
CH3OH CH3CH2OH OH OH
methanol ethanol
Cyclopentanol
Cyclohexanol

2. Give the -OH the lowest possible number.
CH3CH2CH2OH CH3CH2CH2CHCH3
OH
1-Propanol 2-pentanol
3. The substitutent groups are named alphabetically,
and their position are indicated by a number, the
position of -OH is always given the lowest number.
Cl CH3
CH3CH2CHCH2CH2CHCH2OH
5-Chloro-2-methyl-1-heptanol

4. For cyclic alcohols, numbering starts from the
carbon bearing the -OH group.
OH OH
C6H5
CH3
3-Methylcyclohexanol 3-Bromo-2-phenylcyclopentanol
5. If a molecule contains both -OH and C=C or C≡C
bond, the name should include both -OH and the
unsaturated group, and -OH is given the lowest
number.
Br

CH2=CHCHCH3 HO CH2CH3
OH CH3CHC=CH2
3-Buten-2-ol 3-Ethyl-3-buten-2-ol
 Alcohols contain more than one -OH.
OH OH OH OH OH OH OH
CH2－CH2 CH3－CH－CH2 CH2－CH－CH2
1,2-Ethanediol 1,2-Propanediol 1,2,3-Propanetriol
Ethylene glycol Propylene goycol Glycerol or Glycerin

6.2 Nomenclature of Phenols
 Phenols are generally named as derivatives of the
simplest member of the family, phenol.
OH OH OH OH
NH2 Br NO2
Phenol p-Aminophenol 4-Bromo-2-nitrophenol
(Carbolic acid) 2,4,6-Trinitrophenol
(Picric acid)
NO2
NO2
NO2

OH OH OH
o-Cresol m-Cresol p-Cresol
OH OH OH
Catechol Resorcinol
Hydroquinone
CH3
CH3
CH3
OH
OH
OH

 Compounds in which the -OH group is bonded to
the naphthalene ring are called naphthols.
OH
1-Nahthol 2-Nahthol
α-Nahthol β -Nahthol
(insecticide intermediate) (dye intermediate)
OH

6.3 Structure and Nomenclature of Ethers
 The geometry of simple ethers is similar to that of
water.
O O
H H R R
104.5O 110O
 Symmetrical ether
 Unsymmetrical ether

 Common names
(organic group + ether)
CH3-O-CH3 CH3CH2-O-CH2CH3 CH3-O-CH2CH3
Methyl ether Ethyl ether Ethyl methyl ether
 IUPAC system
The ethers are considered as alkoxy (RO-) derivatives
of a parent compound. The position of the RO- is
indicated by a number along the chain of the
parent compound.
6.3 Nomenclature of Ethers

CH3CH2CHCHCH3 CH3CH2CH2CHCH2CH3
OCH3 OCH2CH3
2-Methoxypentane 3-Ethoxyhexane
H3CO-CH2CH2OH
2-Methoxyethanol
6.3 Nomenclature of Ethers

 Reactions of alcohols:
CO H
C OH
 Reactions of phenols:
ArO H
6.4 Reactions of Alcohols and Phenols

6.4 Reactions of Alcohols and Phenols
 As acids
 Oxidation
 C-OH bond breaking
 Specific reaction

6.4.1 Alcohols and phenols as acids
 Alcohols and phenols can act as acids whenever
they donate a proton to a base.
 RO-H + base RO:- + base-H
Alkoxide ion
conjugate base of alcohol
 ArO-H + base ArO:- + base-H
Phenoxide ion
 The base must be stronger than RO:- or ArO:-

 ROH + Na+OH- No reaction
Alcohols are weaker acids than water, it can’t form
the salt of an alcohol in aqueous NaOH solution.
 The salt of an alcohol can be formed by alcohol +
active metals (K, Na).
2RO-H + 2Na 2RO:- Na+ + H2
2CH3CH2OH + 2Na 2CH3CH2O:- Na+ + H2
Ethanol sodium ethoxide
2HO-H + 2Na Na+ OH- + H2

 The liberation of H2, can be used as a test for
alcohols.
 Acids pKa conjugate base
ArOH 10 ArO: -
H2O 14 HO: -
ROH 16 RO:-
Acidity : ArOH > H2O > ROH
Basicity : RO:- > HO: - > ArO: -

OH O:- Na+
+ Na+ OH- + H-OH
Sodium phenoxide
 Phenols are only slightly soluble, while phenoxide
salts are water soluble.
 It is possible to extract phenols from neutral
organic mixtures by treatment with NaoH, the
aqueous extract will contain phenoxide salts.

ArO:- Na+ + HCl ArOH + NaCl
 The free phenol can be regenerated from
the aqueous extract by acidifying it with
acid (HCl).

 Oxidation of Alcohols
Laboratory methods
Biological oxidation
 Oxidation of Phenols
6.4.2 Oxidation

6.4.2 Oxidation
 Oxidation
the removal of H from a compound
the addition of O to a compound
 Reduction
the addition of H to a compound
the removal of O from a compound

Oxidation Change
Removal of 2H
Addition of O
[ O ] : represent the oxidizing agent
6.4.2 Oxidation
H H
R－C－OH R－C=O
H
[O]
O O
R－C－H R－C－OH
[O]

 Reduction Change
Addition of 2H
Addition of 2H and
removal of 2O
[ H ]: reducing agent
6.4.2 Oxidation
O OH
R－C－R R－C－R
H
[ H ]
Ar－NO2 Ar－NH2
[ H ]

 Laboratory methods
The oxidation products of alcohols:
(1) the class of alcohols primary alcohols
secondary alcohols
tertiary alcohols
(2) the kind of oxidizing agent
Cu or CrO3/pyridine （mild）
chromic acid(H2Cr2O7) (stronger)
neutral KMnO4 (stronger)
6.4.2 Oxidation of alcohols

 Primary alcohols
Primary alcohols aldehydes
carboxylic acids
CH3CH2OH
10 alcohol Acetaldehyde
Mild
oxidizing agents
Stronger
oxidizing agents
H
CH3C=O
Cu or CrO3/pyridine
heat

10 alcohol Aldehyde carboxylic acid
(intermediate)
CH3CH2OH + Cr3+
H H OH
R－C－OH R－C=O R－C=O
H
H2Cr2O7
25℃
O
CH3C－OH
H2Cr2O7
25℃
green
orange

 This reaction is the basis of roadside breath test
used by police to detect potential drunken drivers.
Sample of breath Breathalyzer green color
 if a green color develops and persists beyond a
certain point in the apparatus, this is taken as a
probable indication that the motorist’s blood
contains more than the legal level of alcohol
(0.10%) to allow further driving.

 Secondary alcohols
secondary alcohols ketones
20 alcohol Ketone
Any
oxidizing agent
OH O
R－C－R R－C－R
H
[ O ]

+ Cr3+
2-Propanol Acetone
OH O
CH3CCH3 CH3CCH3
H
H2Cr2O7
25℃
green
orange

 Tertiary alcohols
No reaction
 Chromic acid and KMnO4 oxidation is
useful for distinguishing 10 and 20
alcohols from 30 alcohols.
OH
R－C－R
R
[ O ]

 Oxidation of alcohols is an important route
to the synthesis of aldehydes and ketones.

6.4.2 Oxidation of Alcohols
 Biological oxidation of alcohols
The oxidation of alcohols in the laboratory has its
counterpart in living organism .
 The human body don’t require hot copper or
chromic acid to oxidize ethanol (drinking alcohol)
to acetaldehyde, or to acetic acid.
 The oxidative process, which takes place
primarily in the liver, is much more sophisticated
and is mediated by several chemical steps
catalyzed by enzymes.

 The ethanol is transformed by the liver first to
acetaldehyde and immediately thereafter to acetic
acid.
 The acetic acid produced can be utilized by almost
every cell of the body, so it is not surprised that our
bodies can tolerate ethanol up to a certain dose.
Any excess alcohol, the overload that the liver
cannot transform, continues to circulate in the
blood, eventually causing intoxication.

 The treatment of alcoholics with the drug Anta-
buse (disulfiram), can be understood from a
chemical point of view.
 Antabuse inhibits the ability of the liver to
transform acetaldehyde into acetic acid, thereby
quickly causing a toxic pileup of acetaldehyde.
This is why anyone who has taken disulfiram
cannot drink even a single glass of alcohol
without becoming violently ill.

 Methanol, when take internally, is poisonous.
Small doses can cause blindness by degeneration
of the optic nerve. Large amounts may be fatal,
undoubtedly because the products of oxidation,
formaldehyde an formic acid, cannot be
assimilated quickly enough by the body.

 Phenols can be easily oxidized, some phenols are
oxidized slowly by oxygen in the air alone (auto-
xidation). Also, we can oxidize phenols with the
same oxidizing agents that were used to oxidize 10
and 20 alcohols (H2Cr2O7).
HO OH O = = O
Hydroquinone p-Benzoquinone
(colorless) (yellow)
6.4.2 Oxidation of Phenols
[ O ]
[ H ]

OH O
OH O
Caechol o-Benzoquinone
6.4.2 Oxidation of Phenols
[ O ]
[ H ]

6.4.3 Reactions Involving C-OH breaking
 The cleavage of the C OH bond is applicable to
alcohols only.
A. Inorganic esters
R－OH + H－OX R－OX + H2O
Alcohol Oxyacid Inorganic ester
CH2－OH CH2－ONO2
CH －OH + 3H-ONO2 CH2－ONO2
CH2－OH CH2－ONO2
Glycerin Nitroglycerin

B. Alkyl halides
R－OH R－X ( X=Cl, Br, or I )
Alcohol Alkyl halide
Alkyl flrorides, R-F, are not prepared from alcohols.
R－OH + H－X
+ Cl2S=O R-X
+ PX3

 Reaction with H-X: Lucas test
R－OH + H－X R-X + H2O
Reaction rates: 3o > 2o > 1o alcohols
 Distinguish among 3o , 2o, and 1o alcohols
(Lucas test)
R3COH (3o) R3CCl + H2O
R2CHOH (2o) + HCl R2CHCl + H2O
RCH2OH (1o) No visible reaction
ZnCl2
25℃
Immediate
cloudiness
Cloudiness
in 5 min
Solution remains clear

 Reaction with thionyl chloride
Better than the previous one, it is irreversible.
O
ROH + Cl-S-Cl R-Cl + HCl + SO2
thionyl chloride
 Reaction with phosphorus trihalides
3ROH + PX3 3R-X + H3PO3 (PX3= PCl3 ,PBr3 ,PI3)
This reaction goes to completion because the R-X
can be distilled off from the reaction mixture as it
is formed.
heat

C. Dehydration of alcohols:
CH3－CH2－OH CH2=CH2 + H2O (Ⅰ)
CH3CH2-O-CH2CH3 (Ⅱ)
The formation of ethene by route (Ⅰ) is an E1, which
formation of diethylether by route (Ⅱ) is SN1.
H2SO4
170℃
H2SO4
140℃

6.4.4 The specific reaction of phenol
 Phenols are often identified by:
They can dissolve in strong bases;
FeCl3 will change color on treatment with phenols
6ArOH + FeCl3 [Fe(OAr)6]3- + 6H+ + 3Cl-
yellow-orange different color
varying from green to violet to brown

6.5 Uses of Phenols
 Phenol kills many microorganisms and has been
used to disinfect surgical instruments, furniture,
rooms, etc.
 It is also used in the manufacture of dyes and
medicines.
 Large amounts of phenol are used for making
phenol-formaldehyde resins.
 While phenol is a great hazard to animal and plant
world.

6.6 Uses of Ethers
 Ethyl ether is by far the most important ether.
 Despite its flammability and danger of explosion,
ethyl ether has been used safely countless times
in surgery.
 It is a relatively slow inhalation anesthetic that
can be administered over a fairly wide range of
concentrations.
 Because it dissolves many types of organic
compounds, ethyl ether is often used to separate
organic substances from inorganic material.

 In biochemical applications, lipids, which are
soluble in ether, are separated from carbon-
hydrates and proteins, which are usually
insoluble.
 Ethyl ether is also a solvent in many chemical
reactions because of its relative inertness. It is
the preferred solvent in Grignard reactions.
dry ether
CH3CH2Br + Mg CH3CH2MgBr
6.6 Uses of Ethers

Exercise
dry ether
CH3CH2CH2Br + Mg ? ?
 Distinguish the following pair of compounds ?
① CH2 CH2
O
② H2O
OH OH

Chapter 6 Alcohols, Phenols, and Ethers Classification

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