Chapter 18 alcohol, phenols and ethers

Dr. Hashim Ali
Post-Doc Uppsala University, Sweden.
PhD Computational Biology, KTH, Stockholm, Sweden.
Chapter 18 - Alcohol, phenols and ethers
Federal Board of Intermediate and Secondary
Education (FBISE)

• Explain nomenclature, structure and acidity of alcohols as exemplified by ethanol.
• Describe the preparation of alcohols by reduction of aldehydes.
• Explain reactivity of alcohols.
• Describe the chemistry of alcohols by preparation of ethers and esters, oxidative
cleavage of 1,2-diols.
• Discuss thiols RSH.
• Explain the nomenclature, structure and acidity of phenols.
• Describe the preparation of phenols from benzene sulphonic acid, chlorobenzene,
acidic oxidation of cumene and hydrolysis of diamozonium salts.
• Discuss the reactivity of phenol and their chemistry by electrophonic aromatic
substitution, reaction with sodium metal and oxidation.
• Differentiate between alcohols and phenol.
• Describe isomerism in alcohols and phenols.
• Identify ethers from their formula.
After completing this lesson, you will be able to

Chapter Overview - Sections
• Alcohols
• Phenols
• Ethers
Chapter Overview - Sections

Dr. Hashim Ali
18.0 – Introduction to alcohols, phenols and ethers
Education (FBISE)
Chemistry F.Sc
II

S
O
C
X
Hydrogen atom
Carbon atom
Oxygen atom
Sulphur atom
Halogens atom
Single bond
R
Double bond
Triple bond
Hydrocarbon chain
(alkyl chain)
N Nitrogen atom
H
15.7.3 – Color scheme for elements

Aldehyde
Ethanol/Ethyl Alcohol
CH3CH2OH  C2H6O
Ethanal/Acetaldehyde
CH3CHO  C2H4O
C OR
H
Hydroxyl/Alcohol
15.7.5 – Functional groups - Common functional groups

Benzeldehyde (C6H5COH)
Phenol
(C6H5OH)
OH
C
O
H
15.7.6.3 – Functional groups - Example - Some common arenes

Carboxylic acid
Ether linkage
Ethanoic acid/Acetic acid
CH3COOH C2H4O2
Dimethyl ether/methoxymethane
CH3OCH3  C2H6O
OR R
15.7.5 – Functional groups - Common functional groups

• Used as disinfectant / antiseptic.
• Solvent - ethanol is relatively safe, and can
dissolve many organic compounds which are
insoluble in water. Therefore used in
perfumes and cosmetics.
• Liquor - the alcohol in alcoholic drinks is
simply ethanol.
• High efficiency fuels - ethanol burns to give
carbon dioxide and water, and can be used
as a fuel on its own right or in mixtures with
petrol.
• Used to synthesize other organic
compounds, e.g., acetone.
• Fungicides
• Used to make vinegar
• Used in the manufacture of plastics.
18.0.1 - Introduction - Alcohols in daily life

• Rubbing alcohol on skin:
o Sterilizer.
o Removes nail fungus.
o Muscle and joint pain reliever.
o Ear wax removal.
o Helps cure swimmers ear.
o Helps avoid athletes feet.
o Hand sanitizer.
o Remove ticks.
o Relieves itch and help aid in healing
mosquito bites.
o Heals cold sore.
o Window cleaner.
o Removes windshield frost.
o Wipes floor scuffs
18.0.1 - Introduction - Alcohols in daily life

• Methanol (wood alcohol): CH3OH
o Useful as a solvent and industrial starting material.
o Highly toxic, if taken internally causes blindness and/or
death.
• Ethanol (ethyl alcohol, grain alcohol): CH3CH2OH
o Produced commercially from ethylenes and through
biological (yeast) fermentation of carbohydrates.
o Useful as a solvent, industrial starting material, fuel
(gasohol), and found in alcoholic beverages.
o Moderately toxic.
• 2-Propanol (isopropyl alcohol) is the main
component of rubbing alcohol.
• 1,2,3-propanetriol (glycerol) is used as a food
moistening agent (nontoxic) and for its soothing
qualities (soaps).
• Cholesterol is a waxy steroid found in cell
membranes and transported in blood stream. High
level can lead to heart disease.
• Antifreezes - 1,2-ethanediol (ethylene glycol) and
1,2-propanediol
18.0.1 - Introduction - Important alcohols

• The major uses of phenol, consuming two
thirds of its production, involve its
conversion to plastics or related
materials.
• Is used in production of useful organic
compounds like bisphenol, bakelite,
cyclohexane (for nylon) and alkylphenols.
• A versatile precursor to a large collection
of drugs, most notably aspirin but also
many herbicides and pharmaceuticals.
• Used as an oral anesthetic/pain killer for
treating sore throat.
• Derivatives are used as antioxidants in
food.
• Diluted solution and derivatives are used
as a disinfectant.
• Used in preparation of cosmetics
including sunscreens, hair dyes and skin
lightning preparations.
18.0.2 - Introduction - Famous Phenols

• The use of ether specifically as an anesthetic
in dental and surgical procedures began in
1840.
• Some commonly used ethers are
o ethylene oxide (simplest epoxide),
o dimethyl ether (aerosol spray propellant,
potential renewable alternative fuel for diesel
engines).
o Diethyl ether (a common low boiling solvent,
refrigerant, used in manufacture of smokeless
gun powder, perfumery and an early anesthetic)
o Dimethoxyethane (a high boiling solvent)
o Dioxane (a cyclic ether and high boiling solvent)
o Tetrahydrofuran (a cyclic ether used as solvent)
o Anisole (aryl ether and a major constituent of
the essential oil of anise seed).
o Polyethylene glycol (linear polyether used in
cosmetics and pharmaceuticals).
18.0.3 - Introduction - Ethers in daily life

18.0 - Introduction to alcohol, phenols and ethers

Dr. Hashim Ali
18.1 – Alcohols
Education (FBISE)
Chemistry F.Sc
II

• The structure of alcohols, phenols and ethers are much closer to water.
• Alcohols and phenols both contain hydroxyl (–OH) group attached to alkyl and phenyl
groups, respectively.
• In ether, both hydrogen atoms of water are replaced by alkyl or phenyl groups.
• The aliphatic organic compounds containing hydroxyl group –OH, as functional group are
called alcohols.
18.1.0 – Alcohols - Introduction
Water Alcohol
Phenol
Ether

• Alcohols containing one –OH group are
called monohydric alcohols and those
containing two or more hydroxyl groups
are known as polyhydric alcohol.
• The monohydric alcohols are classified
into the following three families,
depending on which carbon the
hydroxyl group is attached.
o Primary alcohol.
o Secondary alcohol.
o Tertiary alcohol.
18.1.1 – Alcohols - Classification
Monohydride
alcohol
CH3–CH2–OH
Dihydride
alcohol
CH2–CH2
OH OH
Ethyl alcohol
(Primary alcohol)
CH3–CH2–OH
Isopropyl alcohol
(Secondary alcohol)
CH–OH
H3C
H3C
Ter-butyl alcohol
(Tertiary alcohol)
H3C C–OH
H3C
H3C

18.1.1 – Alcohols - Classification

18.1.1 – Alcohols - Classification - Follow up
a. CH3CH2CHCH3
OH
b. CH3CH2CH2–C–CH3
OH
CH3
c. CH3CH2–OH
d. CH2–CH2–OH
CH2–CH2
Carbinol atom (C atom attached with OH
group) has 2 other alkyls attached.

• In common system, the alcohols are named by adding the word alcohol after the
name of the alkyl group to which the –OH group is attached.
18.1.2.1 – Alcohols - Nomenclature - Common system rules
Ethyl alcohol Benzyl alcohol
C2H5OH C6H5CH2OH

• The longest chain of carbon atoms
containing the hydroxyl group is selected as
the parent hydrocarbon.
• The ending ‘e’ of the parent hydrocarbon
(alkane) is replaced by ‘ol’.
• The position of the –OH group is indicated
by placing the number of carbon, to which –
OH is attached, before the name of alcohol.
• The carbon chain bearing –OH group is
numbered, beginning from that end which
would assign the lowest possible number to
carbon atom linked to the –OH group.
• The presence of more than one –OH groups
is indicated by suffixes -diol, –triol, etc., and
repeating the number of carbon atoms on
which –OH groups are attached.
18.1.2.2 – Alcohols - Nomenclature - IUPAC System rules
1,2-ethanediol or
ethane-1,2-diol
(glycol)
1,2,3-propane triol or
propane-1,2,3-triol
(glycerol)
CH2–CH2
OH OH
CH2–CH2–CH2
OH OH OH

• In unsaturated alcohol, the hydroxyl group gets the lower number rather
than the unsaturation.
18.1.2.2 – Alcohols - Nomenclature - IUPAC System rules
But-2-en-1-ol
(crotyl
alcohol)
CH3–CH CH–CH2–OH
3-methyl-but-3-en-1-ol
(iso-prenol)
H2C C–CH2–CH2–OH
CH3

• Alcohols upto butanol are generally colorless
liquids with characteristic sweet smell and
burning taste.
• Smaller alcohols are readily soluble in water
but as molecular weight increases, alcohols
become insoluble in water.
o Still polar but ratio of hydroxyl groups to carbons
in the chain determines solubility.
o Diols and triols are more soluble than those with
only a single hydroxyl group.
• The solubility of alcohols is due to hydrogen
bonding which is significant in lower alcohols
but decreases in higher alcohols.
• Melting and boiling points of alcohols are
higher than corresponding alkanes.
• This is due to hydrogen bonding which is
present in alcohols but absent in alkanes.
18.1.3 – Alcohols - Physical properties
Hydrogen bonding
in alcohol
Hydrogen bonding
in water
Formula Name Boiling
point
CH3–CH2–CH3 Propane -42°C
CH3–O–CH3 Di-methyl ether -23°C
CH3–CH2–OH Ethyl alcohol +78.5°C

18.1.3 – Alcohols - Physical properties

• The alcohol functional group consists of the O atom bonded to a C atom and an H atom via
sigma bonds.
• The measured C–O–H bond angle in methanol is 108.9°, very close to the perfectly tetrahedral
bond angle of 109.5°.
• The oxygen atom of an alcohol is also sp3 hybridized.
• Two sp3 hybridized orbitals of oxygen form sigma bonds with atoms of carbon and hydrogen,
and the remaining two sp3 hybrid orbitals each contain an unshared pair of electrons.
• Both the C–O and O–H bonds are polar due to the high electronegativity of the O atom.
18.1.4 – Alcohols - Structure
108.9
109.5
Methanol

• Hydration of alkenes is carried
out in the following two steps.
o Preparation of alkyl hydrogen
sulphate.
o Hydrolysis of alkyl hydrogen
sulphate.
• In the first step, alkenes are
dissolved in concentrated
H2SO4 to form alkyl hydrogen
sulfate.
• In the second step, on dilution
with water followed by heating,
alkyl hydrogen sulfates are
hydrolyzed to form alcohols.
18.1.5.1 – Alcohols - Preparation - Hydration of alkenes
Ethene Ethyl hydrogen sulphate
CH2 CH2 + HOSO3H CH3CH2OSO3H
Ethyl hydrogen sulphate Ethanol
CH3CH2OSO3H + H–OH CH3CH2OH + H2SO4
Ethene Ethanol
CH2 CH2 + H2O CH3CH2OH
H2SO4

• Alkyl halides can be converted to
alcohols using water or hydroxide
as the nucleophile.
• The mechanism is a simple
nucleophilic substitution.
18.1.5.2 – Alcohols - Preparation - Nucleophilic substitution of
alkyl halide
Alkyl
halide
Alkyl
alcohol
C X C OH
H2O or HO-

• Primary, secondary and tertiary alcohols can be prepared by the use of
Grignard’s reagent.
• The Grignard’s reagent adds to a carbonyl molecule and the resulting
compounds form alcohol on hydrolysis.
18.1.5.3 – Alcohols - Preparation - Reaction of RLi or RMgX with
aldehydes and ketones

• Formaldehyde(methanal CH2O) gives primary alcohol with Grignard’s reagent.
18.1.5.3.1 – Alcohols - Preparation - Reaction of RLi or RMgX
with aldehydes and ketones - Primary alcohol
Methanal
(formaldehyde)
Grignard’s
reagent
Ethanol (Primary
alcohol)
ethoxy magnesium
bromide complex
H–Cδ+ Oδ- + CH3
δ-–Mgδ+–Br CH3–C–O-MgBr CH3–C–OH + Mg
H H
H
Hδ+–OHδ-
H+
OH
BrH
H
Methanal
(formaldehyde)
Grignard’s
reagent
Propanol
(Primary alcohol)
H–C O + CH3–CH2–Mg–Br CH3–CH2–CH2–OH + Mg
H
Ether
H3O+
OH
Br

• All other aldehydes give secondary alcohol with Grignard’s reagent.
with aldehydes and ketones - Secondary alcohol
ethanal
(acetaldehyde)
Grignard’s
reagent
Propan-2-ol
(Secondary alcohol)
Prop-2-oxy magnesium
bromide complex
CH3–Cδ+ Oδ- + CH3
δ-–Mgδ+–Br CH3–C–O-MgBr CH3–C–CH3 + Mg
H CH3
H
Hδ+–OHδ-
H+
OH
BrOH
H
ethanal
(acetaldehyde)
Grignard’s
reagent
Butan-2-ol
(Secondary alcohol)
H–C O + CH3–CH2–Mg–Br CH3–CH2–CH2–CH3 + Mg
CH3
Ether
H3O+
OH
Br
OH

• Ketones form tertiary alcohol with Grignard’s reagent under similar
conditions.
with aldehydes and ketones - Tertiary alcohol
Propanone
(acetone)
Grignard’s
reagent
2-methyl-propan-2-
ol (Tertiary alcohol)
2-methyl-prop-2-oxy
magnesium bromide complex
CH3–Cδ+ Oδ- + CH3
δ-–Mgδ+–Br CH3–C–O-MgBr CH3–C–CH3 + Mg
CH3 CH3
CH3
Hδ+–OHδ-
H+
OH
BrOH
CH3
Propanone
(acetone)
Grignard’s
reagent
2-methyl-butan-2-ol
(Tertiary alcohol)
CH3–C O + CH3–CH2–Mg–Br CH3–CH2–CH2–CH3 + Mg
CH3
Ether
H3O+
OH
Br
OH
CH3

18.1.5.4 – Alcohols - Preparation - Reduction (hydrogenation) of
aldehydes, ketones and carboxylic acid
• Reduction (Hydrogenation) of aldehydes, ketones and carboxylic acid (esters
in the presence of Ni, Pd or Pt) gives alcohols.
Aldehyde Hydrogen
Primary
alcohol
R–C –H + H2 RCH2OH
Pt, Pd, Ni, or Ru
O
Ketone Hydrogen
Secondary
alcohol
R–C –R’ + H2 RCHR’
Pt, Pd, Ni, or Ru
O OH

18.1.5.4 – Alcohols - Preparation - Reduction (hydration) of
aldehydes, ketones and carboxylic acid
• Besides reducing aldehydes, ketones and ester, Lithium tetrahydroaluminate (LiAlH4) also reduces carboxylic
acids in the presence of water to produce alcohols.
• The reduction of carboxylic acid happens in two stages - first to form an aldehyde and then a primary alcohol.
Because lithium tetrahydridoaluminate reacts rapidly with aldehydes, it is impossible to stop at the halfway
stage.
• Due to violent reaction of LiAlH4 with water, the reactions are carried out in solution in ether!

18.1.5.4 – Alcohols - Preparation - Reduction (hydrogenation) of
aldehydes and ketones
• Another strong reducing agent but which does not violently react with water, is sodium
borohydride NaBH4, which is often used as a safer alternative to LiAlH4.
• It can not be used with carboxylic acids since it isn't reactive enough to reduce carboxylic acids.

• Esters react with Grignard’s reagent to form aldehyde.
• The aldehyde so form reacts with another molecule of Grignard’s reagent to
form alcohol.
18.1.5.4.1 – Alcohols - Preparation - Reaction of RMgX with ester
Ethyl formate
Grignard’s
reagent
Ethyl
alcohol
Ethanal
(aldehyde)
H–Cδ+ Oδ- + CH3
δ-–Mgδ+–Br CH3–C–H + Mg C2H5OH + Mg
OC2H5
CH3
Hδ+–OHδ-
-MgBr(OC2H5)
OH
Br
O
Br
Hδ+–OHδ-

• In reality the carboxylic acids and esters are reduced to produce alcohols.
• Elaboration of mechanism:
o Carboxylic acids and esters are less reactive to Nu than aldehydes or ketones.
o As a result, they can only be reduced by LiAlH4 and NOT by the less reactive sodium
borohydride NaBH4.
o Each reaction requires that 2 hydrides be added to the carbonyl carbon of acids or
esters.
18.1.5.4.2 – Alcohols - Preparation - Reduction of carboxylic acid
and esters

18.1.5.4.3 – Alcohols - Preparation - Reduction of carbonyl
functional groups

• Alcohols react with other reagents due to the breaking of C–O and O–H
bonds in R–O–H molecules.
• Which bond breaks, depends upon the nature of attacking reagent.
o If a nucleophile attacks, C–O bond breaks.
o If an electrophile attacks, O–H bond breaks.
• The order of reactivity of alcohols with respect to cleavage of C–O bond is
tertiary alcohol > secondary alcohol > primary alcohol.
• The order of reactivity of alcohols with respect to cleavage of O–H bond is
CH3OH > Primary alcohol > Secondary alcohol > tertiary alcohol
18.1.6 – Alcohols - Reactivity
CH3CH2
δ+–Oδ–H CH3CH2
+ + OH–
Nucleophile
CH3CH2Oδ––Hδ+ CH3CH2O– +H+
Electrophile

• The reactions of alcohols may be divided into four types.
o Reactions in which C–O bond is broken (reaction # 1,2,3,4).
o Reactions in which O–H bond is broken (reaction # 5).
o Reactions in which oxygen of an alcohol acts as a base (reaction # 5).
o Oxidation of alcohols (reaction # 6).
18.1.7 – Alcohols - Reactions

• Due to the presence of unshared electron pairs on the oxygen atoms of alcohols, they act as
bases and react with halogen acids to form their respective alkyl halides.
• The C–O bond in an alcohol is very slightly polarized, which means the –OH group can not be
substituted by an alkyl.
• In fact the alcohol acting as a base first forms an alkyl oxonium ion.
• Then, the C–O bond becomes highly polarized and the electrophile carbon is easily attached by
a nucleophile.
18.1.7.1 – Alcohols - Reactions - With acid halides
R–O–H + H–Br R–Br + H2O
Rδ+–Oδ-H + Hδ+–Brδ– R–Br + H2O
Rδ+–Oδ-H + Hδ+–Brδ– R–O+–H + Br–
H
::
Rδ+–O+–H + Br– R–Br + H2O
H

• The orders of reactivity of halogen acids and alcohols are
o HI> HBr > HCl
o ter-alcohol > sec-alcohol > prim-alcohol.
• HCl and prim-alcohol are the least reactive amongst halogen acids and
alcohols respectively.
• Therefore, they react only in the presence of a catalyst.
• A solution of ZnCl2 in concentrated HCl is used as a catalyst.
18.1.7.1 – Alcohols - Reactions - With acid halides
CH3OH + HCl CH3Cl + H2O
ZnCl2(in HCl)

• It is a test for identification of primary, secondary and tertiary alcohols.
• The difference of chemical reactivity of alcohols with halogen acids is used for their
identification.
• For this purpose, alcohol is treated with an equimolar solution of ZnCl2 in concentrated
HCl.
o Tertiary alcohol immediately forms an insoluble layer of a ter-alkyl chloride.
o Secondary alkyl forms an insoluble sec-alkyl chloride in 5-10 min.
o Primary alcohol forms an insoluble prim-alkyl chloride on heating.
18.1.7.1.1 – Alcohols - Reactions - With hydrogen halides - Lucas
Test
Alkyl halideAlcohol

• Ethanol gives iodoform (CHI3) with iodine (I2) in the presence of Sodium
hydroxide (NaOH).
• Formation of yellow crystals indicates that the alcohol is ethanol.
• Methanol does not give the iodoform test.
18.1.7.2 – Alcohols - Reactions - Distinction between methanol
and ethanol
Ethyl
alcohol
Iodine
CH3CH2OH + 4I2 + 6NaOH CHI3+HCOONa + 5NaI + 5H2O
Triiodomethane
(Iodoform)

• Alcohols react with thionylchloride (SOCl2) to give alkyl chlorides.
• Alcohols react with tri-alkides e.g., with phosphorus tribromide (PBr3) and
triodide (PI3) to give alkyl bromides and alkyl iodides.
18.1.7.3 – Alcohols - Reactions - With SOCl2, ZnCl2 and PX3
Rδ+–O:δ- + Sδ+–Clδ– R–O+–S + Cl–
Cl
:
Cl
O O
HH
Rδ+–O:δ- – Sδ+ + Cl– R–Cl + SO2 + HCl
:
Cl
O
H
3ROH + PBr3 3RBr + H3PO3
3ROH + PI3 3RI + H3PO3HOZnCl2 + H+ H2O + ZnCl2
R–O+– Zn–Cl2 R+ + HO–ZnCl2
H

• Synthesis of ethers via acid-catalyzed condensation of
alcohols.
• Typical requirements are H2SO4 and heat.
• In general, typically limited to symmetric ethers of primary
alcohols.
• The method is not suitable for unsymmetrical ethers.
• The substitution involves the O nucleophile of one alcohol
attacking the electrophilic O of the other alcohol,
displacing a water molecule.
18.1.7.4 – Alcohols - Reactions - Acid catalyzed dehydration

• An acid/base reaction.
• Protonation of the alcoholic oxygen to make better leaving group.
• This step is very fast and reversible.
• The lone electron pair on the oxygen makes it a good Lewis base.
18.1.7.4.1.1 – Alcohols - Reactions - Acid catalyzed dehydration -
Mechanism - Step 1 Protonation of alcohol

• The O of the second alcohol molecule functions as the nuleophile and attacks
to displace the good leaving group, a neutral water molecule, by cleaving the
C–O bond.
• This creates an carbocation intermediate.
Mechanism - Step 2 Formation of carbocation and water

• Another acid/base reaction.
• The proton is removed by a suitable base (here a water molecule, ROH is
another alternative) to give the ether product.
Mechanism - Step 3 Formation of ether

• Alcohols react with organic as well as inorganic acid to form their respective esters.
• The reaction of an alcohol and a carboxylic acid yields an ester and water, and is known as
Fischer esterification.
18.1.7.5.1 – Alcohols - Reactions - Preparation of esters - Alcohols
with acids

• Write the structure of the ester formed in each of the following reactions.
18.1.7.5.1 – Alcohols - Reactions - Preparation of esters - Alcohols
with acids - Activity

• Glycerine reacts with a mixture of concentrated HNO3 and H2SO4 to give an
ester called Nitroglycerine or Glycerylnitrate.
• Nitroglycerine is highly explosive liquid and is mixed with fine sand and
molded into sticks called dynamite.
18.1.7.5.2 – Alcohols - Reactions - Preparation of esters -
Glycerine with nitric acid and sulfuric acid
Glycerine Nitroglycerine

• Esters are also formed by treating acid chlorides with sodium alkoxides.
18.1.7.5.3 – Alcohols - Reactions - Preparation of esters - Acid
chloride with sodium alkoxide
acetylchloride
sodium
ethoxide
sodium
chloride
ethyl acetate
CH3–C + C2H5ONa CH3C–O–C2H5 + NaCl
H
OO

• Alcohols are easily oxidized by alkaline KMnO4 or K2Cr2O7 + H2SO4
solutions to give different products.
• A primary alcohol is first oxidized to an aldehyde, which is further oxidized
to a carboxylic acid.
18.1.7.6.1 – Alcohols - Reactions - Oxidation - Primary alcohol
CH3COH CH3COOH
K2Cr2O7 + H2SO4
50°C
Acetic acid
CH3–CH2–OH CH3COH + H2O
K2Cr2O7 + H2SO4
50°C
acetaldehydeEthyl alcohol

• A secondary alcohol is oxidized under similar condition to give a ketone
which is not further oxidized.
18.1.7.6.2 – Alcohols - Reactions - Oxidation - Secondary alcohol
Sec-propyl
alcohol
propanone
CH3– COH CH3C–CH3 + H2
CH3
O
K2Cr2O7 + H2SO4
50°C
H

• A tertiary alcohol is not oxidized by alkaline KMnO4.
• When heated with a mixture of K2Cr2O7 and H2SO4, it is first dehydrated to an alkene in
the presence of acid.
• Then alkene is oxidized to a ketone and a carboxylic acid by K2Cr2O7 and H2SO4.
• Each of the products contain lesser number of carbon atoms than the parent alcohol
molecule.
18.1.7.6.3 – Alcohols - Reactions - Oxidation - Tertiary alcohol
ter-pentyl
alcohol
2-methyl-
but-2-ene
CH3– CH2–C–OH CH3–CH C + H2O
CH3
H2SO4
CH3
CH3
CH3
2-methyl-but-
2-ene
acetic acid
CH3– CH C CH3–COH + CH3–C–CH3
CH3
K2Cr2O7 + H2SO4
CH3 O O
acetone
50°C

• Predict the principal organic product of each of the following reactions.
18.1.7.6.3 – Alcohols - Reactions - Oxidation - Activity

18.1.7.6.3 – Alcohols - Reactions - Oxidation - Examples

• 1,2- or vicinal diols are cleaved by per-iodic acid, HIO4, into two carbonyl
compounds.
• The reaction is selective for 1,2-diols.
• The reaction occurs via the formation of a cyclic per-iodate ester.
• This can be used as a functional group test for 1,2-diols.
• The products are determined by the substituents on the diol.
18.1.7.7 – Alcohols - Reactions - Oxidative cleavage of 1,2-diols

• Predict the products formed on oxidation of each of the following with per-
iodic acid
18.1.7.7 – Alcohols - Reactions - Oxidative cleavage of 1,2-diols-
Activity

• Two alcohol molecules react with each other to produce ether via dehydration.
• The reaction is a 3 step process as shown below.
18.1.7.8 – Alcohols - Reactions - Alcohol with alcohol
(dehydration)

• An alcohol is converted into an alkene by dehydration: elimination of a molecule of water.
• Dehydration requires the presence of an acid and the application of heat.
• It is generally carried out in either of two ways, heating the alcohol with sulfuric or phosphoric acid to temperatures as
high as 200, or passing the alcohol vapor over alumina, Al2O3 , at 350-400, alumina here serving as a Lewis acid.
• Ease of dehydration of alcohols : 3° > 2° > 1°
• Where isomeric alkenes can be formed, we again find the tendency for one isomer to predominate. Thus, sec-butyl
alcohol, which might yield both 2-butene and 1-butene, actually yields almost exclusively the 2-isomer.
• The formation of 2-butene from n-butyl alcohol illustrates a characteristic of dehydration that is not shared by
dehydrohalogenalion: the double bond can be formed at a position remote from the carbon originally holding the -OH
group.
• It is chiefly because of the greater certainty as to where the double bond will appear that dehydrohalogeation is often
preferred over dehydration as a method of making alkenes.
18.1.7.9 – Alcohols - Reactions – Dehydration of alcohol
butan-1-ol but-2-ene
CH3– CH2–CH–CH2–OH CH3–CH CH–CH3 + H2O
H2SO4
heat

• Thiols are sulfur analogs of alcohols.
• These are named by adding the suffix –thiol to the name of the
corresponding alkanes.
18.1.8.1 – Alcohols - Sulfur analogues (Thiols, RSH) -
Nomenclature
4-Methyl-1-
pentanethiol
2-Methyl-1-
propanethiol
5-chloro-3-methyl-2-
hexanethiol

• Thiols show little association by hydrogen
bonding, both with water molecules and among
themselves as compared to alcohols of similar
molecular weight.
• Hence, they have lower boiling points and are
less soluble in water and other polar solvents
than alcohols of similar molecular weight.
• Many thiols have strong odors resembling that
of garlic or rotten eggs.
• Thiols are used as odorants to assist in the
detection of natural gas (which in pure form is
odorless), and the “smell of natural gas” is due
to the smell of the thiol used as the odorant.
• Thiols are sometimes referred to as mercaptans
“capturing mercury”.
18.1.8.2 – Alcohols - Sulfur analogues (Thiols, RSH) - Physical
properties

• Structure is generally similar to alcohols but bonds to S are longer and
weaker than those to O.
• The thiol functional group consists of an S atom bonded to a C atom and a H
atom via sigma bonds.
• The S–H bond is less polar than that in alcohols since S is less
electronegative than O.
18.1.8.2 – Alcohols - Sulfur analogues (Thiols, RSH) - Structure

• Thiols are weak acids but more
acidic than similar alcohols, e.g, R–
S–H (pKa = 10) versus R–O–H
(pKa≈16 to 19).
• Thiols are also much more
nucleophilic than similar alcohols. In
fact, R–S–H is about as nucleophilic
as RO-.
• Thiols are readily oxidized but to S–
O systems rather than C=S systems.
• Thiols are commonly oxidized to
disulfides, R–S–S–R, a biologically
important reaction.
18.1.8.3 – Alcohols - Sulfur analogues (Thiols, RSH) - Reactivity

• What are monohydric and polyhydric alcohols?
• Why some alcohols are readily soluble in water?
• Write the structures of water and methyl alcohol.
• Write the formulas of primary, secondary and tertiary alcohols.
• How Grignard’s reagent is used for the preparation of alcohols?
18.1.9 - Quick quiz

Dr. Hashim Ali
18.2 – Phenols
Education (FBISE)
Chemistry F.Sc
II

• Aromatic compounds containing one or more –OH groups, directly attached
with a carbon of benzene ring are called phenols.
• The simplest example is phenol, which is also known as carbolic acid, i.e.,
C6H5OH.
• It was first obtained from coal tar by Runge in 1834.
• Phenol is derived from the old name for benzene (phene), to include the suffix
‘ol’ indicates the presence of a hydroxyl group.
• Caution: The word ‘phenol’ (C6H5–OH) is often confused with ‘phenyl’ (C6H5).
• Phenols can be obtained via substitution reactions, with the hydrolysis of
diazonium salts, being the most important laboratory method.
• Phenols are acidic and are important intermediates in the preparation of aryl
ethers C6H5–O–R.
18.2.0 – Phenols - Introduction

• Phenols are named just like other derivatives of benzene.
• Most of the members of aromatic family have special names.
• In IUPAC system, –OH group is represented by name hydroxyl and used as a prefix, while the benzene part of
the molecule is used as a suffix.
18.2.1 – Phenols - Nomenclature
OH
Hydroxyl-
benzene
(Phenol)
OH
Hydroxyl-2-nitro-
benzene (2-nitrophenol
o-nitrophenol)
NO2
OH
Hydroxyl-3-nitro-
benzene (3-nitrophenol
m-nitrophenol)
NO2
OH
Hydroxy-2,4,6-trinitro-
benzene (2,4,6-
trinitrophenol (Picric acid))
NO2
NO2NO2

• The alcohol functional group consists of an O atom bonded to an sp2-
hybridized around C atom and a H atom via sigma bonds.
• Both the C–O and the O–H bonds are polar due to the high electronegativity
of the O atom.
• Conjugation exists between the unshared electron pair on the oxygen and
the carbon atom of ring.
• As compared to simple alcohols, this results in
o A shorter carbon-oxygen bond distance.
o A more basic hydroxyl oxygen.
o A more acidic hydroxyl proton (–OH).
18.2.2 – Phenols - Structure

• Phenol is a colorless, crystalline, poisonous solid with characteristic phenolic
odor having melting point 41°C and boiling point 182°C.
• It is sparingly soluble in water forming pink solution at room temperature
but completely soluble above 68.5°C.
• It is poisonous and causes blisters on the skin.
• It is used as a disinfectant and in washrooms.
• It has distinctive odor.
• It is a polar compound due to hydroxyl group.
• Component of flavoring and fragrances.
18.2.3 – Phenols - Physical properties

• Phenol exists as a resonance hybrid of 5 structures.
• Due to resonance, oxygen atom of the –OH group acquires a positive charge (as in structures III to V) and hence attracts electron pair of O–H bond
leading to the release of hydrogen atom as proton.
• Carbon atom of the C–OH group in phenol being sp2 hybridized is more electron attracting than the sp3 hybridized carbon atom in alcohols.
• Thus in phenols, there is greater I-effect which facilitates proton release, which means that phenols are more acidic than alcohols.
• Phenol is a weak acid and the position of equilibrium lies well to the left. Phenol can lose a hydrogen ion because the phenoxide ion formed is stabilised to
some extent.
o The negative charge on the oxygen atom is delocalised around the ring. The more stable the ion is, the more likely it is to form.
o One of the lone pairs on the oxygen atom overlaps with the delocalised electrons on the benzene ring.
o This overlap leads to a delocalization which extends from the ring out over the oxygen atom.
o As a result, the negative charge is no longer entirely localized on the oxygen, but is spread out around the whole ion.
• Since resonance is impossible in alcohols (due to the absence of conjugation of the lone pair of oxygen with a double bond), the hydrogen atom is more
firmly held to the oxygen atom. Hence alcohols are neutral in nature.
18.2.4.1 – Phenols - Acidity - Comparison of phenols and alcohols
Phenolate/Phenoxide
ion

• The negative phenoxide ion formed
after the release of hydrogen atom is
more resonance stabilized than
phenol.
• Since there is no possibility for the
delocalization of negative charge in
the alkoxide ion, the latter is not
stable.
• Hence alcohols have no tendency to
form alkoxide ion and hydrogen ion.
• Phenol behaves as a weak acid in
water.
• Phenol can react with bases to form
salts.
18.2.4.1 – Phenols - Acidity - Comparison of phenols and alcohols
Phenol (a
weak acid)
+ H2O
O–OH
+ H3O+
Phenol (a
weak acid)
+ KOH
O–K+OH
+ H2O

• The resonating structures I and II of carboxylic acid are non-equivalent and
hence much less stable than the equivalent resonating structures III and IV
for the carboxylate ion.
• The carboxylic acids have a tendency to undergo ionization to form more
stable carboxylate ion and protons.
18.2.4.2 – Phenols - Acidity - Comparison of phenols and
carboxylic acids
Carboxylic
acid
Caboxylate
ion
R– COOH RCOO– + H+

• Now let us compare the acidic strengths of carboxylic acids and phenols.
• The resonating structures of phenoxides are not equivalent.
• Since the resonating structures III and IV of carboxylate anions are equivalent, carboxylate
anion is relatively more resonance stabilized than the phenoxide ion.
• Thus a carboxylic acid is more acidic than a phenol.
• The relative acidity of some common compounds follow the order.
R–COOH > H2CO3 > C6H5OH > HOH > R–OH
18.2.4.2 – Phenols - Acidity - Comparison of phenols and
carboxylic acids
:Ö:–
V
:Ö:–
VI
:Ö
VII
:–
VIII
:Ö
:–
IX
:Ö
:–

• Electron attracting substituents tend to disperse the negative charge of the
phenoxide ion, thus stabilize the ion and increase the acidity of phenols.
• Electron releasing substituents tend to intensify the charge, destabilize the
ion, diminish the resonance and decrease its acidity.
18.2.4.3 – Phenols - Acidity - Effect of substituents

• Phenol can be industrially prepared by the following three reactions while the
fourth reaction (hydrolysis of diazonium salt) is the most important laboratory
method.
• A fifth more recent method is also touched briefly.
18.2.5 – Phenols - Preparation

• Sodium benzene sulphonate on reaction with strong alkali like NaOH at
300°C give sodium phenoxide.
• Sodium phenoxide on treatment with HCl gives phenol.
18.2.5.1 – Phenols - Preparation - Reaction of sodium salt of
benzene sulfonic acid with sodium hydroxide
SO3Na
Sodium benzene
sulphonate
O–Na+
Sodium
phenoxide
10%NaOH
300°C
phenol
HCl
OH
+ NaCl

• Chlorobenzene is hydrolyzed by heating 10% NaOH at 360°C under high
pressure to form sodium phenoxide.
• Sodium phenoxide on treatment with HCl gives phenol.
18.2.5.2 – Phenols - Preparation - Base hydrolysis of
chlorobenzene (Dow’s method)
Cl
chlorobenzene
O–Na+
Sodium
phenoxide
10%NaOH
360°C
phenol
HCl
OH
+ NaCl

• It is a recently developed commercial method for the preparation of phenol.
• Cumene is oxidized by atmospheric oxygen in presence of metal catalyst,
into cumene hydroperoxide.
• The hydroperoxide is converted into phenol through an acid catalyzed
rearrangement.
18.2.5.3 – Phenols - Preparation - Acidic oxidation of cumene
CH3–C–CH3
cumene
+ O2
H
CH3–C–CH3
Cumene
hyperoxide
O–O–H
60°C-80°C
OH
phenol
H2SO4
+ CH3–C–CH3
O
acetone

• Aryl diazonium salts are prepared by reaction of aryl amines with nitrous
acid, HNO3.
• Aryl diazonium salts can be converted into phenols using H2O/H2SO4/heat.
18.2.5.4 – Phenols - Preparation - Aryl diazonium salts
aniline
+ HNO3
N+ NNH2
10°C
Aryl diazonium
salt
NaNO2 + HCl
+ H2O
OH
100°C
phenol
H2SO4

18.2.5.5 – Phenols - Preparation - From aryl ethers
Ethoxy benzene
+ HBr + CH3CH2Br
OH
phenol
O
CH2CH3
H2O
Ethyl
bromide

• Phenols are very reactive towards electrophilic aromatic substitution.
• This is because the hydroxy group, –OH, is a strongly activating, ortho-
/para- directing substituent.
• Phenols are acidic but not as acidic as carboxylic acids.
• They react with NaOH to give salt and water.
18.2.6 – Phenols - Reactivity
OH
phenol
+ NaOH + H2O
ONa
Sodium
phenoxide

• Phenols are potentially very reactive
towards electrophilic aromatic
substitution.
• This is because the hydroxy group, –OH,
is a strongly activating, ortho-/para-
directing substituent.
• Substitution typically occurs para to the
hydroxy group unless the para position
is blocked, then ortho substitution
occurs.
• The strong activation often means that
milder reaction conditions than those
used for benzene itself can be used (see
table for comparison).
• Phenols are so activated that poly
substitution can be a problem.
18.2.7.1 – Phenols - Reactions - Electrophilic aromatic
substitution
Reaction Phenol Benzene
Nitration Dil. HNO3 in H2O or CH3CO2H Conc. HNO3/H2SO4
Sulfonation Conc. H2SO4 H2SO4 or SO3/H2SO4
Halogenation X2 X2/Fe or FeX3
Alkylation ROH/H+ or RCl/AlCl3 RCl/AlCl3
Acylation RCOCl/AlCl3 RCOCl/AlCl3
Nitrosation Aq. NaNO2/H+
OH
phenol
+ +
H+
OH
Ortho-
OH
Para-
E
E
E+

• Acids react with the more reactive metals to give hydrogen gas.
• Phenol is no exception - the only difference is the slow reaction because
phenol is such a weak acid.
• Phenol is warmed in a dry tube until it is molten, and a small piece of
sodium added.
• There is some fizzing as hydrogen gas is given off. The mixture left in the
tube will contain sodium phenoxide.
18.2.7.2 – Phenols - Reactions - Sodium metal
OH
phenol
2 + 2Na + H2
ONa
Sodium
phenoxide

• Carboxylation of sodium salt of phenols occurs through Kolbe-Schmitt (or simply
Kolbe) reaction, which is an intermediate step in the preparation of aspirin!
• At low temperature, sodium salicylate (sodium-o-hydroxy benzoate) is produced, whereas
at higher temperature, o-product isomerizes to p-isomer.
• Carbon of CO2 acts as electrophilic center in this reaction.
• Acidification of the salt gives corresponding hydroxyl acid.
18.2.7.3 – Phenols - Reactions - Carboxylation of sodium salt of
phenol
OH
phenol
+ NaOH + CO2
ONa
Sodium
phenoxide
OH
Sodium
salicylate
COONa
OH
Sodium;4-
hydroxybenzoate
COONa
125°C
100atm-H2O

• Phenol isn't acidic enough to react with either of these.
• Or, looked at another way, the carbonate (CO3
-2) and hydrogen carbonate (HCO3
-
1) ions aren't strong enough bases to take a hydrogen ion from the phenol.
• Unlike the majority of acids, phenol does not give carbon dioxide when you mix
it with one of these.
• This lack of reaction is actually useful.
• You can recognize phenol because:
o It is fairly insoluble in water.
o It reacts with sodium hydroxide solution to give a colorless solution (and therefore must
be acidic).
o It does not react with sodium carbonate or hydrogen carbonate solutions (and so must
be only very weakly acidic).
18.2.7.4 – Phenols - Reactions - With sodium carbonate or
sodium hydrogen carbonate

• Phenols are very reactive towards oxidizing agents.
• The oxidation takes place through several steps eventually destroying the
ring.
18.2.7.5 – Phenols - Reactions - Oxidation of phenols

• The compounds in which hydroxyl group is attached to
an alkyl group.
• Alcohols are derivatives of alkanes.
• The compounds in which one hydrogen of water is
replaced by an alkyl group.
• The general formula of phenol is R–OH.
• Alcohols may be monohydric or polyhydric depending
on the number of –OH groups attached.
• Lower alcohols are generally colorless liquids.
• Alcohols have a characteristic sweet smell and bumming
taste.
• They are readily soluble in water but solubility decreases
in higher alcohols.
• Alcohols react with other reagents in two ways, either in
which C–O bond breaks or in which O–H bond breaks.
18.2.8.1 – Phenols - Difference between alcohols and phenols -
Alcohols

• The compounds in which hydroxyl group is attached to an aryl group.
• Phenols are derivatives of benzene.
• The compounds in which one hydrogen of water is replaced by an aryl group.
• The general formula of phenol is C6H5OH. It is also known as carbolic acid.
• Phenols are not monohydric or polyhydric.
• They are colorless, crystalline, deliquescent solids.
• They have characteristic phenolic odor.
• Its melting point is 41°C.
• Phenols are more acidic (pKa≈10) than alcohols (pKa≈16–20).
o Ferric chloride test is specific for determination of phenol presence.
o As mentioned earlier, phenol forms phenoxide anions but alcohols being weakly acidic do not form the
alkoxide ions .
o Phenol can thus form complex with Fe(III) in FeCl3, which has a blue/green/red color depending on the
nature of the phenol but alcohols do not even form the alkoxide or the complex.
• Phenols are sparingly soluble in water forming pink solution at room temperature but
completely soluble above 68.5°C.
• Phenolate ions have resonance structures but alcohols do not have such type of structures.
18.2.8.2 – Phenols - Difference between alcohols and phenols -
Phenols

• How negative charge of phenolate ion is stable?
• What is acidity order of phenols?
• Why phenols are very reactive towards electrophilic aromatic
substitution?
• Explain carbonation of phenols.
• Alcohols and phenols both contain –OH group. What is the difference
between them?
• Why phenol is more acidic than ethyl alcohol.
• What happens when phenol is heated with zinc dust?
• What happens when phenol is treated with bromine water?
18.2.9 - Quick quiz

Dr. Hashim Ali
18.3 – Ethers
Education (FBISE)
Chemistry F.Sc
II

• Ethers can be classified into symmetrical and unsymmetrical ethers.
• Symmetrical (simple) ethers have identical alkyl groups on both sides of O atom.
• Unsymmetrical (mixed) ethers have a different alkyl group on both sides of O
atoms.
18.3.0 – Ethers - Classification

• In common system of naming, simple and mixed (or unsymmetrical) ethers
are named by naming the two groups bonded to oxygen alphabetically
followed by the word ether.
18.3.1.1 – Ethers - Nomenclature - Common system rules
methyl ethyl
ether
ethyl benzyl
etherEthyl methyl
ether Benzyl ethyl
ether (Anisole)
ethyl Iso-propyl
ether
Ethyl iso-propyl
ether
CH3–CH2–O–C–CH3
CH3
H

• In IUPAC system of naming, simple ethers are named by naming the smaller of the two R
groups as an alkoxy group attached to the parent chain by replacing the -yl ending of the R
group with -oxy.
• Mixed ether are named as alkyl derivatives of hydrocarbons.
18.3.1.2 – Ethers - Nomenclature - IUPAC system rules
Methoxy ethane
CH3–CH2–O–CH3
2-methoxy butane
(sec-butyl methyl
ether)
CH3–CH2–CH–CH3
O–CH3
2-ethoxy butane
CH3–CH2–CH–CH3
O–CH2–CH3
furan
pyran

• Ethers can be prepared in the laboratory by the following methods.
o Williamson synthesis
o From alkyl halides with dry silver oxide
o From alcohols with alcohols
18.3.2 – Ethers - Preparation

• When alkyl halides are heated with sodium or potassium alkoxide, then
ethers are produced.
• This is one of the most important laboratory method.
18.3.2.1 – Ethers - Preparation - Williamson synthesis
R–O–Na + R–X R–O–R + NaX
Methoxy
methane
CH3–O–Na + CH3–I CH3–O–CH3 + NaI
Sodium
methoxide
Methyl
iodide

• When alkyl halides are heated with silver oxide (Ag2O), then ethers are
produced.
18.3.2.2 – Ethers - Preparation - Reaction of alkyl halides with
dry silver oxide
2R–X + Ag2O R–O–R + 2AgX
Ethoxy
ethane
Ethyl
chloride
2CH3–CH2–Cl + Ag2O CH3–CH2–O–CH2–CH3 + 2AgCl
Silver
oxide

• Two different primary alcohols give three ethers when treated with H2SO4.
• Ter-butyl and ethyl alcohol give one ether.
• Dehydration of two alcohol molecules in the presence of heat and acid
catalyst produces symmetrical as well as unsymmetrical ethers.
18.3.2.3 – Ethers - Preparation - Reactions of alcohols with
alcohols
R1–OH + R2–OH R1–O–R2 + H2O
EtherAlcohol Alcohol
H+
heat
CH3CH2–OH + CH3–OH CH3CH2–O–CH3 + CH3–O–CH3 + CH3CH2–O–CH2CH3 + H2O
Methoxy
ethane
Ethyl
alcohol
Methyl
alcohol
H2SO4
heat
Methoxy
methane
Ethoxy
ethane

• Ethers are colorless, low boiling (due to lack of hydrogen bonding), highly flammable compounds.
• Their chemical inactivity and their ability to dissolve fats, oil, gum and many other organic compounds make
them very good solvent.
• They are rather non-polar due to the presence of an alkyl group on either side of the central oxygen.
• Ethers are more polar than alkenes, but less polar than esters, alcohols and amides.
• Ethers are soluble in concentrated sulfuric acid, a characteristic of oxygen containing compounds. This
property is used as a test to distinguish between ethers and saturated hydrocarbons.
• Lower ethers act as anesthetics.
• Ethers are lighter than water.
18.3.3 – Ethers - Physical properties

• Much less polar than alcohols
• More soluble in water than alkanes, but less soluble than alcohols.
• Low boiling and melting points because of the inability to hydrogen bond
between molecules.
• Inert and do not react with most reagents (like alkanes)
• Highly flammable (like alkanes)
• Hydrogen bonding of dimethyl ether:
o (a) with water and
o (b) no hydrogen bonding in the pure state.
18.3.3 – Ethers - Physical properties

• Chemically, ethers are moderately inert.
o Do not react with reducing agents or bases.
o Extremely volatile.
o Highly flammable = easily oxidized in air.
• The image shows the electrostatic potential for
dimethyl ether.
• The more red an area is, the higher the electron
density and the more blue an area, the lower the
electron density.
• The ethereal O atom is a region of high electron
density (red) due to the lone electron pair.
• Ether oxygen atoms are Lewis bases.
• Like an alcohol –OH group, the –OR group is a
poor leaving group and needs to be converted to
a better leaving group before substitution can
occur.
18.3.4 – Ethers - Reactivity

• The most important reaction of ethers is their cleavage by strong acids such
as HI and HBr.
• Ethers are resistant to attack by the usual chemical oxidizing agents.
• Moreover reagents like NH3, Na, alkali and acids have no reactions with
ether.
18.3.4.1 – Ethers - Reactivity - How ethers show resistance to
oxidation?

• The oxygen atom of an ether molecule possesses unshared electron pair,
which accepts a proton of H–Br to form oxonium ion.
• No further reaction takes place.
18.3.5.1 – Ethers - Reactions - With HBr
R–O–R + H–Br R–O+–R + Br–
Oxonium
ion
Ether Akyl
halide
H
::

• The Oxygen atoms of an ether molecule possesses unshared electron pair,
which accepts a proton of H–I to form oxonium ion.
• This oxonium ion reacts with I- to form R–OH and RI.
• Diethyl ether reacts with HI to form C2H5–OH and C2H5I.
18.3.5.2 – Ethers - Reactions - With HI
R–O–R + H–I R–O+–R + I–
Oxonium
ion
Ether Hydrogen
iodide
H
::
:
R–O–R + I– R–OH + RI
AlcoholOxonium
ion
Akyl
halide
H
:
C2H5–O–C2H5 + H–I C2H5–OH + C2H5–I
Ethyl
alcohol
Diethyl
ether
Hydrogen
iodide
Ethyl
iodide

• How is diethyl ether prepared in the laboratory?
• What are symmetrical and unsymmetrical ethers?
• What is Williamson’s synthesis?
18.3.6 - Quick quiz

• Antiseptics and disinfectants
o Antiseptics and disinfectants are an essential part of infection control practices.
o They are extensively used in hospitals and other health care settings.
o A wide variety of active organic agents or biocides are found in these products
many of which have been used for hundreds of years for antiseptics,
disinfection and preservation.
o In general, biocides have a broader scope of activity than antibiotics.
o The widespread use of antiseptic and disinfectant products promoted some
speculation on the development of microbial resistance, in particular, resistance
to antibiotics.
o Anti-microbial activity of antiseptics and disinfectants can be induced by many
factors, e.g., formulation effects, presence of an organic load, temperature etc.
Society, Technology and Science

• Antispetics
o An antiseptic is a substance which inhibits the growth and development of micro-organisms.
o For practical purposes, antiseptics are thought of as topical agents for application to skin,
mucous membrane and inanimate objects.
o They can be either bactericidal or bacteriostatic.
o Their uses include cleansing of skin and wound, surfaces after injury, preparation of skin surface
prior to medical or surgical procedure and routine disinfection.
• Disinfectants
o Disinfectants were introduced by Listen who introduced carbolic acid (phenol) as the first
disinfectant.
o Today, disinfectants are widely used in the health care, food and pharmaceutical places to
prevent unwanted micro-organisms from cuisine diseases.
o Disinfectant chemicals stop specific chemical structures or processes in order to kill or eliminate
micro-organism.

• Ether - an effective anesthetic
o Before the advent of anesthetics, surgery was a savage and primitive affair.
o It was agony for the patient and surgeons were, therefore, only prepared to operate if
it was absolutely essential, for example, the amputation of a damaged limb that
would otherwise become gangrenous.
o Anesthetics enabled surgery to develop from crude carpentry to its present day
sophisticated forms.
o Three of the most important early anesthetics were nitrous oxide (dinitrogen oxide
NO2), ether (ethoxy ethane, CH3CH2OCH2CH3) and chloroform (trichloromethane
CHCl3).
o Nitrous oxide is non-toxic and non-flammable but it only produces light anesthesia.
o Chloroform produces deep anesthesia and is non-flammable but it is toxic and
carries the risk of liver damage.

 Alcohols and phenols are hydroxyl derivatives of aliphatic and aromatic hydrocarbons.
 General formula for alcohol is ROH, for phenol is ArOH, and for ether is ROR.
 Alcohols are usually named by replacing ‘e’ from the Alkane with ‘ol’.
 Primary alcohols can be oxidized.
 Secondary alcohols can be oxidized to ketones but no further.
 Tertiary alcohols can not be oxidized (no carbinal C–H).
 The thiol functional group consists of an S atom bonded to a C atom and a H atom via
sigma bonds.
 Thiols are much more acidic than similar alcohols, e.g., RSH (pKa = 10) versus ROH
(pKa = 16 to 19).
 Phenols are more acidic (pKa >> 10) than alcohols (pKa >> 16-20) but less acidic than
carboxylic acids (pKa >> 5).
 Epoxides are more reactive than simple ethers.
 In IUPAC system, ethers are named as alkoxy derivatives of alkanes.
 In contrast to alcohol, ethers are fairly unreactive.
Key Points

 Alcohols are soluble in water while phenols are sparingly soluble.
 General formula for alcohol is R–OH while for phenol is Ar–OH.
 Methyl alcohol has proved to be excellent fuel for racing car.
 Ethyl alcohol may be the first organic chemical routinely manufactured by humans.
 Ethyl alcohol is also named as wine, beer and whiskey.
 Fuel oil mainly consists of amyl alcohol (C5H11OH).
 95% ethyl alcohol is known as rectified spirit or commercial alcohol.
 Ethylene glycol is the major component in commercial collants and anti-freeze.
 Glycerol is an excellent moisture retaining agent. It is used in vanishing creams, body
lotions, shaving foams and tooth pastes.
 Bakelite (plastic) is phenol from aldehyde resin.
 Phenol is used as starting material for drugs such as salol, aspirin, phenolphthalein
and several other dyes.
 Diethyl ether has been used in surgery for anesthesia.
 Cyclic ethers are known as epoxides.
Key Points

1. Which compound shows
hydrogen bonding?
a. C2H6
b. C2H5Cl
c. CH3–O–CH3
d. C2H5OH
2. Which compound is called a
universal solvent?
1. H2O
2. CH3OH
3. C2H5OH
a. CH3–O–CH3
1. Select the right answer from the choices given
3. According to Lewis concept,
ethers behave as
a. Acid
b. Base
c. Acid as well as base
d. None of them
4. Ethanol can be converted into
ethanoic acid by
1. Hydrogenation
2. Hydration
3. Oxidation
4. Fermentation

5. Ethanol is denatured by adding
a. Methanol
b. Carbolic acid
c. Acetone
d. Propanol
6. When phenol reacts with
CH3COCl the product formed is
a. Ether
b. Alcohol
c. Aldehyde
d. Ester
7. Williamson’s synthesis of ethers is
superior to alcohols because it
makes
a. Symmetrical ethers
b. Asymmetrical ethers
c. Ether at room temperature
d. Both symmetrical and asymmetrical
ethers.
8. A methyl phenol is also called
a. A cresol
b. Benzyl alcohol
c. Alcohol
d. Formaldehyde

9. Which one of the following
compounds does not contain
carboxylic group?
a. Acetic acid
b. Formic acid
c. Benzoic acid
d. Picric acid
10.Hydrogen bonding is maximum in
a. Diethyl ether
b. Ethanol
c. Ethyl alcohol
d. Triethyl amine
11. Which of the following compounds
have no attraction at all with water?
a. C6H6.
b. C2H5OH
c. CH3CH2CH2OH
d. CH3–O–CH3
12. Phenols are more acidic than alcohols.
Which statement is correct?
a. Phenol turns blue litmus paper red.
b. Alcohol liberates CO2 with carbonate
solution.
c. Phenoxide ion is stabilized due to
resonance.
d. Alkoxide ion is stabilized due to
resonance.

13.Carbolic acid is treated with
dilute nitric acid at 25°C. The
product is
a. o-nitrophenol
b. p-nitrophenol
c. m-nitrophenol
d. Both a and b
14.Oxonium ion is formed when
a. Ethanol reacts with Na metal
b. Phenol reacts with NaOH solution
c. Ether is treated with HI
d. Ethanol is treated with aq. NaOH
and iodine.
15. 2,4,6-trinitrophenol is
commercially called as
a. TNT
b. Picric acid
c. Carbolic acid
d. Fumeric acid

1. What are alcohols? How are they classified? (18.1.1) mono and poly
2. How are monohydric alcohols classified? (18.1.1) primary, secondary and tertiary
3. Compare the acidity of primary, secondary and tertiary alcohols. (18.1.6)
4. 2-butene is the major product when n-butyl alcohol is heated with conc. H2SO4.
Explain? (18.1.7.9)
5. Give the mechanism of dehydration of alcohols. (18.1.7.9)
6. How will you obtain benzene from alcohols? (dehydrate to alkene  halogenate to di
haloalkane  dehydrohalogenate to acetylene  cyclic polymerize to benzene)
7. Alcohols and phenols both have OH group but phenols are more acidic than alcohols.
Why? (18.2.4.1)
8. How will you differentiate between an alcohol and a phenol? (18.2.8.2) Ferric chloride
test)
9. Write the nomenclature of ether by IUPAC system. (18.3.1.2)
10. Why is phenol more soluble in water than toluene? (Hydrogen bonding)
2. Give brief answers to the following questions

1. How will you prepare alcohols on industrial scale? (18.1.5) + fermentation of
molasses
2. Distinguish ethanol from methanol and ethanol from phenol. (18.1.7.2)
Iodoform test + bromine water test
3. How will you distinguish between primary, secondary and tertiary alcohols?
Explain with reactions. (18.1.7.1.1) Lucas test
4. Give IUPAC names and structures of the following compounds.
1. Secondary butyl alcohol (butan-2-ol CH3CH(OH)CH2CH3)
2. Lactic acid (2-hydroxypropanoic acid CH3CH(OH)COOH)
3. Ter-butyl alcohol (2-Methylpropan-2-ol (CH3)3COH)
4. Tartaric acid (2,3-Dihydroxybutanedioic acid)
5. Give the reactivity of ethers. (18.3.4)
6. Give at least two methods for the preparation of phenols. (18.2.5)
3. Give detailed answers to the following questions

7. How does phenol react with
1) HNO3, (18.2.7.1) Electrophilic aromatic substitution, NO2 added to o,p
2) H2SO4, (18.2.7.1) Electrophilic aromatic substitution, HSO3 added to
o,p
3) H2/Pt, (cyclohexanol)
4) NaOH (18.2.6) sodium phenoxide
5) Ag2O? (oxidation reaction) produces double bond with O
8. What is oxonium ion? Describe the chemical reactivity of ether.
(18.3.5.2) (18.3.5.4)

9. Explain the following terms using ethyl alcohol as an example.
1. Oxidation (18.1.7.6)
2. Dehydration (18.1.7.8) and (18.1.7.9)
3. Esterification (18.1.7.5.1) Fischer esterification
4. Ether formation (18.1.7.8)
10. How does ethyl alcohol react with the following reagents?
1. Conc. H2SO4. (18.1.7.8) and (18.1.7.9) depending on temperature
2. Na (sodium ethoxide + hydrogen gas)
3. PCl5 (18.1.7.3) ethyl chloride + HCl + POCl3
4. CH3COOH (18.1.7.5.1 Fischer esterification)
5. SOCl2 (18.1.7.3)
11. How will you distinguish between
1. An alcohol and a phenol. (18.2.8.2) Ferric chloride test
2. An alcohol and an ether. (Reaction with sodium metal)
3. Methanol and ethanol. (18.1.7.2) Iodoform test
4. A tertiary alcohol and a primary alcohol. (18.1.7.1.1) Lucas test
5. 1-propanol and 2-propanol. (18.1.7.1.1) Lucas test

12.Give reason for the following.
1. Ethyl alcohol is a liquid while ethyl chloride is a gas at room temperature.
(Hydrogen bonding in ethyl alcohol gives it higher boiling point)
2. Ethanol has higher boiling point than diethyl ether. (hydrogen bonding vs
dipole moments)
3. Absolute alcohol can not be prepared by fermentation process. (Because of the
poisonous nature of alcohol, kills most yeast and bacteria by 10% but absolute
alcohol is 100%)
4. Ethanol gives different products with conc. H2SO4 under different conditions. .
(18.1.7.8) and (18.1.7.9) dehydration to alkenes or ether
5. Water has higher boiling point than ethanol. (More stronger hydrogen
bonding due to 2 H with O rather than one H with O)

18 – Alcohols, phenols and ethers
Dr. Hashim Ali
Education (FBISE)
Chemistry F.Sc
II

4. Practice questions
4. Fill in the blanks.
1. Primary, secondary and tertiary alcohols can be identified by ___________ test.
2. Oxidation of _______ alcohols gives ketones.
3. Alcohols on heating with _______ give alkenes at high temperature.
4. Alcohols have ______ boiling points than ether due to stronger hydrogen bonding.
5. Williamson’s synthesis is used to prepare ________.
6. _________ is also called wood spirit.
7. Carbolic acid is the other name of ________.
8. Primary, secondary and tertiary alcohols can be prepared by reacting Grignard
reagent with _______.
9. Alcohols and _______ react to produce esters.
10. _______ is used as anti-freezing agent in automobile radiator.
11. The process of conversion of starch into alcohol with the help of micro-organisms is
called _________.
12. Ketones on reduction give ________ alcohols.

5. Indicate true or false.
i. Methylated spirit contains 95% methyl alcohol and 5% ethyl alcohol.
ii. Ethyl alcohol is a very good anti-freezing agent.
iii. Methanol is also called wood spirit.
iv. Only 14% ethyl alcohol can be prepared by fermentation.
v. Ethers do not show hydrogen bonding.
vi. Alcohols are more acidic than phenols.
vii. Phenol is more soluble in water than lower alcohols.
viii. Alcohols are more basic than ethers.
ix. Ethers have higher boiling points than alcohol and phenols.
x. Methanol and ethanol can be distinguished by iodoform test.

i. Which compound shows hydrogen bonding?
a) C2H6 b) C2H5Cl c) CH3–O–CH3 d) C2H5OH
ii. Which compound shows maximum hydrogen bonding with water?
a) CH3OH b) C2H5OH c) CH3–O–CH3 d) C6H5OH
iii. Which compound is more soluble in water?
a) CH3COCH3 b) C2H5OH c) n-hexanol d) C6H5OH
iv. Which compound will have the maximum repulsion with H2O?
a) C6H6 b) C2H5OH c) CH3–O–CH3 d) CH3CH2CH2OH
v. Ethanol can be converted into ethanoic acid by?
a) Hydrogenation b) Hydration c) Oxidation d) Fermentation
vi. Which enzyme is not involved in the fermentation of starch?
a) Diastase b) Zymase c) Urease d) Invertase
vii. Which compound is called a universal solvent?
a) H2O b) CH3OH c) C2H5OH d) CH3–O–CH3

viii. Methyl alcohol is not used
a) As a solvent b) as an anti-freeze agent
c) As a substitute for petrol d) for denaturing of ethyl alcohol.
ix. Rectified spirit contains alcohol about
a) 80% b) 85% c) 90% d) 95%
x. According to Lewis concept ethers behave as
a) Acid b) Base c) Acid as well as base d) None of them

6. What are alcohols? How are they classified? How will you distinguish between primary,
secondary and tertiary alcohols?
7. How is methyl alcohol obtained on large scale? How it may be distinguished from ethyl
alcohol?
8. What is fermentation? Which compound may be obtained on industrial scale by
fermentation?
9. How will you convert:
5. Methanol into ethanol
6. Ethanol into methanol
7. Ethanol into isopropyl alcohol.
8. Formaldehyde into ethyl alcohol.
9. Acetone into ethyl alcohol.
10. Explain the following terms.
5. Absolute alcohol
6. Methylated spirit
7. Rectified spirit
8. Denaturing of alcohols.

11. Arrange the following compounds in order of their increasing acid
strength and give reasons.
12.Give uses of phenols. How is bakelite prepared from it?
13.Write IUPAC names for the following compounds.

Chapter 18 alcohol, phenols and ethers

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