ALCOHOLS, THIOLS, PHENOLS,
IUG, Fall 2013
Dr. Tarek Zaida
AND ETHERS
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1. ALCOHOLS

Alcohols are derivatives of hydrocarbons in
which 1 or more of the hydrogen atoms has
been replaced by a hydroxyl (-OH) functional
group.

Functional group: a particular arrangement of a
few atoms that imparts certain characteristic
properties to an organic molecule.
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GENERAL STRUCTURAL FORMULAS OF ALCOHOLS,
THIOLS, PHENOLS, AND ETHERS
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NAMING ALCOHOLS
In the IUPAC system, the hydroxyl group in
alcohols is indicated by the ending -ol.
 In common names, the separate word alcohol
is placed after the name of the alkyl group.
 The following examples illustrate the use of
IUPAC rules, with common names given in
parentheses.

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 The
general formula of alcohols is
R-OH
Where R indicates the Alkyl group attached to
an –OH
R could be:
CH3,
CH3CH2CH3CH2CH2-, ect.,
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Alcohols are soluble in H2O because of the –OH
group.
 But as the length of the carbon chain
increases, the solubility decreases
 Alcohols react with acids to give compounds
called esters:

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USES OF ALCOHOLS
1. Methyl
alcohol (methanol) CH3OH
 Commonly Known as wood alcohol
 The U.S. production of methanol is 1.4
billion gallons per year. Most of it is used
to produce formaldehyde and other
chemicals,
 Is also used as an anti-freeze.
 Used as a solvent in many industrial
reactions.
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It should never be applied to the body neither
should the vapors be inhaled because it can be
absorbed both through the skin and through the
respiratory tract.
 Ingestion as little as 15 ml can cause blindness (it
is oxidized to formaldehyde (CH2=O), which binds
to opsin, preventing formation of rhodopsin, the
light-sensitive pigment needed for vision.
 While 30 ml are enough to cause death.

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PREPARATION
1.
2.
By distillation of wood
It is prepared commercially from carbon
monoxide:
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2. ETHANOL (ETHYL ALCOHOL)
Known as grain alcohol
 It has an important property: it denatures
proteins (that’s why it is used as antiseptic in
hospitals).
 As antiseptic, 70% alcohol is preferred to a
stronger solution 100%, why?

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ANSWER
Ethanol causes protein to coagulate on contact,
 a 100% solution coming into contact with a
microorganism creates a hardened protein wall
around the outside of the organism, rather than
permeating into its interior.


Because microorganisms can be very resilient,
this protein shell only causes dormancy rather
than death.
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
This can lead to revival and a continuation of
the cycle of reproduction under the right
circumstances.

At a purity of 70%, however, the alcohol causes
coagulation to occur more gradually, slowing
down the microorganism from the inside out.
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Ethanol is also used as a sponge bath because
it evaporates rapidly (bp: 78 C) by the heat of
the patient’s skin.
 However Water is used instead of ethanol for
sponge bath because it is cheaper.
 Ethanol is also used as a solvent for many
substances.

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PREPARATION OF ETHANOL
1.
From Sucrose (cane sugar)
2.
Synthetically can be prepared from ethene:
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3. 2-PROPANOL (ISOPROPYL ALCOHOL)
Is toxic
 Used as a stringent.
 Used as a rubbing alcohol (can be applied as a
cooling, soothing application for bedridden
patients and athletes.
 It is also widely used for cleansing surgeons'
hands and instruments and for the disinfection of
skin prior to penetration by a hypodermic needle.
 Is manufactured commercially by the acidcatalyzed hydration of propene.

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4. ETHYLENE GLYCOL (1,2-ETHANEDIOL)
Ethylene glycol is used:
- as antifreeze in cooling and heating
systems,
- in hydraulic brake fluids,
- as a solvent in the paint and plastics
industries, in the formulations of
printers' inks.
- As additive in moisturizer of the skin.
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-
-
Ethylene glycol is toxic because it is oxidized in
the lever to oxalic acid, which crystalizes as
calcium oxalate in kidney, causing renal
damage, which can lead to kidney failure.
Antidote for ethylene glycol & methyl alcohol is
the administration of high level of ethanol.
Ethanol will force liver enzymes to oxidize
ethanol instead of poisonous alcohol which is
presented in smaller amounts.
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5. GLYCEROL (GLYCERIN)
• An example of a trihydric alcohol.
• Glycerol is important in terms of body
chemistry; it is a constituent of fats.
• It is a by-product in soap manufacture.
• It is used in preparation of cosmetics
& hand lotions, suppositories.
• Is used in labs as a lubricant for rubber
tubing & stoppers.
•When treated with nitric acid it forms
nitroglycerin.
1,2,3-propanetriol
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MEDICAL USE OF NITROGLYCERIN






Is used to treat angina or heart pain
It causes a dilation of coronary arteries,
Thus increasing the supply of blood to heart muscle.
How does nitroglycerin work?
Liberates nitric oxide from endothelial cells of blood
vessels.
NO binds to heme component of enzyme guanylate
cyclase, which in turn catalyzes the synthesis of cGMP
which acts as a signal that induces muscular relaxation
in the blood vessel.
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OTHER ALCOHOLS
1. Menthol: a cyclic alcohol
 It is used in cosmetics and
shaving lotions, due to it’s
cooling and refreshing feeling
when rubbed on the skin.
 It is also used in cough drops &
nasal sprays

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
2. Cholesterol: A very important steroid in the
human body

3. Retinol (Vitamin A): important in vision

Tocopherol (Vitamin E): a very strong
antioxidant
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TYPES OF ALCOHOLS
1. Primary alcohols
 2. Secondary alcohols
 3. Tertiary alcohols

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REACTIONS OF ALCOHOLS

1. Dehydration of alcohols:
Alcohols can be dehydrated by heating them with a
strong acid.
For example,
When ethanol is heated at 180°C with a small
amount of concentrated sulfuric acid, a good
yield of ethylene is obtained.
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
Write the dehydration reaction of
2 CH3-CH2-CH2-CH(OH)-CH3?
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
2. Formation of Ethers
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3. Oxidation:
 Primary alcohols can be oxidized to form
aldehyde,
 Further oxidation of aldehyde yields an acid.
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
Secondary Alcohols can be oxidized to give
ketones

Tertiary alcohols, having no hydrogen atom on the
hydroxyl-bearing carbon, do not undergo this type
of oxidation
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4. Forming esters:
Alcohols react with organic acids to give esters.
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2. THIOLS

Are sulfur analogs of alcohols and contain an
-SH functional group in place of an –OH group
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NAMING THIOLS ACCORDING TO IUPAC
Just add the ending thiols to the name of the
parent hydrocarbon.
 Note:
 The e is not deleted from the parent alkane.
 Common name of thiols were formed by first
naming the alkyl group and then adding the
word mercaptan.

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Thiols are sometimes called mercaptans, a
name that refers to their reaction with
 mercuric ion to form mercury salts, called
mercaptides.

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PROPERTIES OF THIOLS






Many thiols are found in nature.
They have unpleasant odor.
Onion when cut, releases 1-propanethiol
HS-CH2-CH2-CH3
The odor of garlic is due to thiols.
Skunk when attacked it releases thiols.
Thiols added to heating - & cooking- gas to detect gas
leak.
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PREPARATION OF THIOLS

By heating alkyl halides with NaHS (sodium
hydrogen sulfide).

CH3-CH2-CH2-Cl + NaHS

Thiols are easily oxidized to disulfides:

2 R-CH2-SH
O2
CH3-CH2-CH2-SH + NaCl
R-CH2-S-S-CH2-R
disulfide
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3. PHENOLS

When –OH is attached to benzene ring, phenol
is formed.

Unlike alcohols, phenols are weak acids
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
Phenols react with aqueous solution of sodium
hydroxide to form a soluble salt:
Uses of Phenols:
1. As antiseptic
2. As disinfectant

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4. ETHERS
All ethers are compounds in which two organic
groups are connected to a single oxygen atom.
 The general formula for an ether is
R-O-R’
 where R and R’ may be identical or different,
and they may be alkyl or aryl groups.
 In the common anesthetic, both R and R’ are
ethyl groups.
CH3CH2-O-CH2CH3

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NAMING ETHERS

Ethers are usually named by giving the name of
each alkyl or aryl group, in alphabetical order,
followed by the word ether.
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For ethers with more complex structures, it may
be necessary to name the -OR group as an
alkoxy group.
 In the IUPAC system, the smaller alkoxy group is
named as a substituent.

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PROPERTIES OF ETHERS
Low boiling point
 They are good solvents because they do not
react with solutions.
 Ethyl ether is used to extract organic materials
from naturally occurring substances.

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ETHER AS ANESTHETIC
Used as a general anesthetic
Advantages:
1. Easy to administer
2. Excellent muscular relaxant
3. Little effect on respiration, blood pressure

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Disadventage:
1. Very flammable
2. Irritating to membrane of respiratory tract
Today ether as anesthetic has been replaced
by:
 Halothane
 Nitrous oxide
 Enflurane

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