Transcript Click on image to content

CARBON
COMPOUNDS
ORGANIC COMPOUNDS
 The
compounds of carbon( except the
oxides of carbon, carbonates, hydrogen
carbonates and carbides) are called
organic compounds.
 The study of organic compounds is called
organic chemistry.
FUNCTIONAL GROUPS
 A functional
group in an organic compound is
an atom or a group of atoms bonded together in
a unique fashion, which is usually the site of
chemical reactivity in an organic molecule.
 For Example - The hydroxyl group in ethanol
(C2H5–OH) is known as a functional group. The
functional group in ethene is , and in ethyne, it
is – C ≡ C – .
 Thus, we see that the properties of a compound
depend on the functional group.
ALCOHOLS





Alcohols are carbon compounds containing – OH
group attached to a carbon atom.
The general formula of alcohols is R-OH, where R is
an alkyl group and –OH is a functional group.
An alcohol may also be considered as derived by
replacing a hydrogen atom of an alkane by a hydroxyl
group.
The name of the alcohol is derived by replacing –e in
the name of alkane (from which it is derived) by the
ending –ol.
For example, methanol (CH3OH), an alcohol, is
derived by substituting one H in methane (CH4) by a
hydroxyl (-OH) group.
ETHANOL
Ethanol,
commonly known as
alcohol, is a constituent of all
alcoholic beverages, namely beer,
wine, whisky, some cough syrups,
digestive syrups, etc. In industries,
alcohol is produced by the
fermentation of sugar.
FERMENTATION
 The
slow decomposition of organic matter into
simpler substances in presence of enzymes is
known as fermentation.
 Fermentation was used for the preparation of
alcoholic beverages from grape juice and other
fruit juices in presence of yeast, which contains
proper enzymes. This process is called
fermentation, as the liquid appears as boiling
(fervour – to boil) due to the liberation of carbon
dioxide gas.
 In
this process, the sugar from molasses or
sugarcane, or fruits, or starch from various
grains, is first converted to glucose and
fructose, (isomers) both of them have the
formula C6H12O6, in presence of an enzyme,
invertase.
Invertase
C12H22O11+ H2O------C6H12O6+ C6H12O6
Sugar
Glucose Fructose

Glucose and fructose are both converted to ethanol
and carbon dioxide in presence of another enzyme,
zymase. Both the enzymes, invertase and zymase,
are present in yeast.
Zymase
C6H12O6 ----------- 2C2H5OH + 2CO2
Glucose and Fructose
Ethanol
Nowadays, a large amount of ethanol used for
commercial purposes is produced by hydration of
ethene, that is, by reacting ethene with water in
presence of sulphuric acid.
H2SO4
 H2C = CH2 + H2O ---------H3C - CH2 -OH
Ethene
Ethanol
PROPERTIES OF ETHANOL
 Pure
ethanol is a colourless liquid with a boiling
point of 351 K. It is miscible with water in all
proportions.
(i) Combustion: Ethanol is a highly inflammable
liquid, i.e., it catches fire easily. It burns with a
blue flame to form carbon dioxide and water.
C2H5OH + 3O2 ----------2 CO2+ 3H2O
 The reactions of ethanol with other reagents are
due to the presence of hydroxyl (–OH) group.
(ii) Reaction with Sodium: Ethanol reacts with
sodium to produce sodium ethoxide and
hydrogen.
2 C2H5OH + 2Na ---- 2 C2H5ONa + H2
Ethanol
Sodium
Sodium ethoxide
(iii) Oxidation :
a) With chromic anhydride (CrO3):
Chromic anhydride oxidises ethanol to ethanal.
CrO3 in
CH3CH2OH ----------
CH3CHO
Ethanol
CH3COOH
Ethanal
(b) With potassium permanganate :
Alkaline KMnO4 oxidises ethanol to ethanoic
acid.
Alk. KMnO4
CH3CH2OH ----------- CH3COOH
Ethanoic acid
ESTERIFICATION
(iv) Reaction with ethanoic acid : Ethanol
reacts with ethanoic acid in presence of
concentrated sulphuric acid to form ethyl
ethanoate and water.
The compound formed by the reaction of
an alcohol with a carboxylic acid is known
as ester, and the reaction as
esterification.
 Esters are sweet smelling compounds
used for making perfumes.
H2SO4
C2H5OH+ CH3COOH-----CH3COOC2H5+H2O
 On
treating with an alkali solution, sodium
hydroxide, the ester is converted back to the
constituent alcohol and sodium salt of the acid.
CH3COOC2H5+NaOH----H3COONa+C2H5OH
 This reaction is hydrolysis of an ester. It takes
place in presence of alkali, and is known as
USES OF ALCOHOL
 Ethanol
is one of the most important organic
chemical.
 In industries, ethanol is used as a solvent for
lacquers, varnishes, perfumes, medicines, etc.
 It is used for sterilising wounds, as it is a good
antiseptic.
 Ethanol is an important industrial chemical.
Therefore, it is subjected to very small excise
duty.
DENATURED ALCOHOL
 To
prevent its misuse for drinking purposes, the
alcohol supplied for industrial purpose is
rendered unfit by mixing it with some poisonous
substances, such as methanol, pyridine, copper
sulphate, etc.
 It is known as denatured alcohol.
 Ethanol
containing 5 per cent water is known as
rectified spirit.
HARMFUL EFFECTS OF
ALCOHOL
 Alcohol
is an intoxicant, so under the influence
of alcohol, a person loses his sense of
discrimination. He can’t distinguish between
good and bad, right or wrong.
 The consumption of alcohol in large quantities
may even cause death by damaging the liver.
 If methanol is consumed in small quantities, it
causes serious poisoning resulting in the loss of
eyesight.
ALDEHYDES AND KETONES
 Aldehydes
and ketones are carbon compounds
containing carbonyl ( C=O) group.
 In aldehydes, carbon of carbonyl group is
attached to a carbon atom and a hydrogen
atom in addition to oxygen.
 In ketones, carbon of carbonyl group is
attached to two carbon atoms.
 However, formaldehyde is an exception. It is an
aldehyde in which the carbon atom of –CHO
group is attached to a hydrogen atom instead of
another carbon atom.