ALCOHOLS AND PHENOL

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  • Created on: 24-09-13 09:37
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CH4 Ffion Griffiths
ALCOHOLS AND PHENOL
CLASSIFYING ALCOHOLS
Alcohols have the functional group OH and the general formula CnH2n+1OH (apart from in phenol
where ­OH is attached directly to the Benzene ring.) They are classified according to the environment
of the ­OH group.
Primary alcohols 1 : the Carbon atom attached to -OH is only attached to one alkyl
group
Secondary alcohols 2 : the Carbon atom attached to -OH is directly joined to two
alkyl groups (which may be the same or diff.)
Tertiary alcohols 3 : the Carbon atom attached to -OH is directly attached to 3
alkyl groups (which may be any combination same or diff.)
AROMATIC ALCOHOLS
Have a ­OH group bonded directly to the benzene ring
NAMING ALCOHOLS
1. Select the longest chain containing ­OH group
2. Remove the `e' and add `ol' at the end of the name
3. Number the chain starting with the end nearer the ­OH group
4. The number of the Carbon attatched to the ­OH is placed after the `an' and before
the `ol' e.g butan-2-ol
5. As in alkanes prefix with alkyl substituents
6. Side chain positions are based on the number allocated to the ­OH group
STRUCTURAL ISOMERISM
Possible due to branching
BOILING POINTS
High due to presence of intermolecular Hydrogen
Bonding
Increases with molecular size due to increased VDW
forces
More energy is required to separate the molecules
Greater branching = lower inter-molecular forces
and lower boiling points
SOLUBILTY
Alcohols with low Mr are soluble due to H bonding between the two molecules
As the hydrocarbon chain increases solubility decreases
SOLVENT PROPERTIES
Alcohols are very good solvents that can dissolve a large number of organic molecules

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CH4 Ffion Griffiths
INDUSTRIAL PREPARATION
FERMENTATION
Reagent: Glucose (produced by hydrolysis
of starch)
Conditions: Yeast, Warm but not above 37
Equation: CHO 2CHOH + 2CO
HYDRATION OF ETHENE
Reagent: Ethene (from cracking of fractions
from distilled crude oil)
Conditions: Phosphoric acid catalyst, High
temperature, High pressure
Equation: CH + HO CHOH
REACTIONS OF ALCOHOLS
WITH HYDROGEN HALIDES
Reaction: Basis of the Lucas Test to distinguish 1°
, 2°and 3°alcohols (test is based on the relative
stabilities of carbocations)
General:
Conditons: Catalyst Zinc Chloride in Concentrated…read more

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CH4 Ffion Griffiths
REACTIONS WITH CARBOXYLLIC
ACIDS
Reaction: Esterification
Conditions: Acid Catalyst, for
example concentrated sulphuric
acid
Equation: Carboxylic acid + Alcohol
Ester + Water
RCOOH + ROH
RCOOH + HO
The conc. Sulphuric acid protonates the carboxylic acid and the resulting positive species undergoes
nucleophillic attack by the alcohol. Elimination of a proton results in the formation of the ester
(sweet
smelling.)
DEHYDRATION REACTION
Reaction: Elimination Reaction
Conditions: Acid Catalyst (e.…read more

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CH4 Ffion Griffiths
By heating and distilling the product immediately, oxidation can be stopped at the aldehyde
stage. CHCHOH + [O] CHCHO + HO
By refluxing with an excess of the oxidising agent , further oxidation takes place to form
carboxylic acid CHCHOH + 2[O] CHCOOH + HO
OXIDATION OF SECONDARY ALCOHOLS
Conditions: Heating with oxidising agent.
Equation: Oxidation of Propan-2-ol:
CH(CHOH)CH + [O] CHCOCH + HO
ETHANOL AS A BIOFUEL
·The principle fuel used as a petrol substitute for
road transport vehicles is bioethanol.…read more

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CH4 Ffion Griffiths
Phenol will react with sodium hydroxide solution but not with weak alkalis such as sodium
carbonate. (Test to distinguish between a carboxylic acid and a phenol, carboxylic acids will
react with sodium carbonate.)
Phenol can lose a hydrogen ion because the phenoxide ion formed is stabilised to some
extent. 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.…read more

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CH4 Ffion Griffiths
Slow reaction, but faster if the sodium has been converted to sodium phenoxide.
WITH IRON (III) CHLORIDE
Test to detect the presence of phenolic ­OH groups
By adding a crystal of phenol to iron (III) chloride you get an intense violet-purple solution
formed.…read more

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