Class notes ICSE

THE CAREER NR Classes


ALCOHOL (ETHANOL)
Alcohols are formed when a hydrogen atom in aliphatic hydrocarbon is
replaced by hydroxyl group (−OH group).
Hence alcohols are the compounds containing hydroxyl group attached to
alkyl group. Therefore, these are regarded as hydroxy derivative of
hydrocarbon.

CLASSIFICATION OF ALCOHOLS
Alcohols may be classified as
i) Monohydric alcohol : Alcohol which contain only one – OH group.
𝐂𝐇𝟑 𝐎𝐇 − 𝑴𝒆𝒕𝒉𝒂𝒏𝒐𝒍 (𝑴𝒆𝒕𝒉𝒚𝒍 𝒂𝒍𝒄𝒐𝒉𝒐𝒍)
𝐂𝐇𝟑 𝐂𝐇𝟐 𝐎𝐇 − 𝑬𝒕𝒉𝒂𝒏𝒐𝒍 (𝑬𝒕𝒉𝒚𝒍 𝒂𝒍𝒄𝒐𝒉𝒐𝒍)
ii) Dihydric alcohol : Alcohol which contain two – OH groups.
𝑪𝑯𝟐 − 𝑶𝑯
|
𝑪𝑯𝟐 − 𝑶𝑯
𝑬𝒕𝒉𝒂𝒏 − 𝟏, 𝟐 − 𝒅𝒊𝒐𝒍
(Ethylene glycol)
iii) Polyhydric alcohol : Alcohol which contain three or more −OH
groups.
𝐂𝐇𝟐 − 𝐎𝐇
|
𝐂𝐇 − 𝐎𝐇
|
𝐂𝐇𝟐 − 𝐎𝐇
𝑷𝒓𝒐𝒑𝒂𝒏𝒆 − 𝟏, 𝟐, 𝟑 − 𝒕𝒓𝒊𝒐𝒍
(Glycerol)
N.B : Monohydric alcohols have the general formula CnH2n+1OH or ROH.

ETHANOL (ETHYL ALCOHOL)
Molecular formula: C2H5OH
Molecular mass: 46
Ethyl alcohol is also called grain alcohol as
it is obtained from starchy grains by
fermentation. As it is the constituent of all
wines, it is also called spirit of wine or
drinking alcohol.

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PREPARATION OF ETHANOL (ETHYL ALCOHOL)
By hydrolysis of alkyl halides (haloalkanes)
When chloroethane (ethyl chloride) or bromoethane (ethyl bromide) or
iodoethane (ethyl iodide) is treated with hot dilute aqueous solution of alkali,
like potassium hydroxide (KOH), ethyl alcohol obtained.
∆
𝑪𝟐 𝑯𝟓 𝑪𝒍 + 𝒂𝒒 𝑲𝑶𝑯 → 𝑪𝟐 𝑯𝟓 𝑶𝑯 + 𝑲𝑪𝒍
Chloroethane Ethanol
∆
𝑪𝟐 𝑯𝟓 𝑩𝒓 + 𝒂𝒒 𝑲𝑶𝑯 → 𝑪𝟐 𝑯𝟓 𝑶𝑯 + 𝑲𝑩𝒓
Bromoethane Ethanol
∆
𝑪𝟐 𝑯𝟓 𝑰 + 𝒂𝒒 𝑲𝑶𝑯 → 𝑪𝟐 𝑯𝟓 𝑶𝑯 + 𝑲𝑰
Iodoethane Ethanol
DIFFERENCE BETWEEN aq. KOH AND alc. KOH

aq. KOH alc. KOH
When alkyl halide react with hot aq. When alkyl halide react with hot alc.
KOH(dil) solution, alcohol is KOH solution, alkene is the main
obtained. product. This reaction is called
dehydrohalogenation reaction.
∆ 𝑪𝑯𝟑 𝑪𝑯𝟐 𝑩𝒓 + 𝒂𝒍𝒄. 𝑲𝑶𝑯
𝑪𝟐 𝑯𝟓 𝑩𝒓 + 𝒂𝒒 𝑲𝑶𝑯 → 𝑪𝟐 𝑯𝟓 𝑶𝑯 + 𝑲𝑩𝒓
Ethyl bromide Ethanol Ethyl bromide
𝑯𝟐 𝑪 = 𝑪𝑯𝟐 + 𝑲𝑩𝒓 + 𝑯𝟐 𝑶
Ethene


PHYSICAL PROPERTIES OF ETHANOL
1) Nature: It is inflammable and highly volatile liquids.
2) Boiling point: Ethanol, like Ethane, have Van Der Waals' intermolecular
attractive forces. But it also have an additional intermolecular hydrogen
bonding between two ethanol molecules. Due to which more amount of
heat is required to overcome the forces than corresponding hydrocarbons.




Organic Ethane Ethene Ethyne Ethanol
compound
Boiling point – 𝟖𝟗°𝑪 −𝟏𝟎𝟑. 𝟕°𝐂 −𝟖𝟒°𝐂 𝟕𝟖. 𝟑 °𝑪
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