Some Basic Principles and Techniques
Organic compounds are the hydrocarbons
and their derivatives and
organic
chemistry is that branch of chemistry that deals with the study of these compounds
Tetravalency of carbon
The atomic number of Carbon is 6 and
its electronic
configuration is 2,4 i.e. it has 4
valence electrons. Thus carbon is always tetracovalent, i.e. it forms 4 covalent
bonds with other atoms
C
Due to tetravalency of carbon it has a tetrahedron sh
ape.
Catenation
-
The self linking property of carbon is known as catenation. This is the
main reason of existence of such large number of compounds
Classification of organic compounds
Organic compounds
Acyclic Cyclic
Homocyclic heterocyclic
Alicyclic aromatic
Benzenoid non benzenoid
Functional groups:
A functional group may be defined as an atom or a group of
atoms present in a molecule which largely determines the chemical properties.
CLASS OF ORGANIC
NAME OF FUNCTIONAL
STRUCTURE
COMPOUNDS GROUP
Alkenes double bond
=C=C=
Alkynes triple bond
-
C
Ξ C
-
Halogens halogen
-
X ( F,Cl,Br,I )
Alcohols
hydroxyl
-
OH
Aldehydes aldehydic(formyl)
-
CHO
Carboxylic acids
carboxyl
-
COOH
Acid amides amides
-
CONH
2
Primary amines amino
-
NH
2
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HOMOLOGOUS SERIES
Homologous series is defined as a family or group of structurally similar organic
compounds all members of which contain the same functional group, show a
gradation in physical and similarity in chemical properties and any two adjacent
members of which dif
fer by
-
CH
2
group. The individual members of this group are
called homologues and the phenomenon is called homology.
NOMENCLATURE OF ORGANIC COMPOUNDS
Organic chemistry deals with millions of compounds. In order to clearly identify
them, a systematic
method of naming known as IUPAC system of nomenclature is
adopted.
T
he names are such that the listener can deduce the structure from it. The
IUPAC name consists of three parts:
Prefix Word root Suff
ix
EX: 3 methlyoctane
NOMENCLATURE OF ALKANES
Straight chain alkanes:
The names of such compounds is based on their chain structure,and end with suffix
‘
-
ane’ and carry a prefix indicating the number of carbon atoms present in the chain
.
Branched chain hydrocarbons:
1.)
The longest carbon chain in the molecule is identified.
2.)
The numbering is done in such a way that the branched carbon atoms get the
lowest possible value.
3.)
The names of the alkyl groups attached as a branch are then prefixed to
the
name of the parent alkane and its position is indicated by numbers.
4.)
The lower number is given to the first in alphabetical order.
5.)
The carbon atom of the branch that attaches to the root alkane is numbered 1.
Organic compounds having Functional Groups
:
The longest chain of carbon atoms containing the functional groups is numbered in
such a way that the functional group attached to the carbon atom gets the lowest
possible number in the chain.
When there are more functional groups then a priority orde
r is followed as:
-
COOH,
-
SO
3
H,
-
COOR, COCl,
-
CONH
2
,
-
CN,
-
HC=O, =C=O,
-
OH,
-
NH
2
, =C=C=,
-
C
Ξ
C
-
.
ISOMERISM
Two or more compounds having the same molecular formula but different physical
and chemical properties are called isomers and this phenomenon is
called isomerism.
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