Nomenclature of Organic compounds

1. BPHARM 2ND SEM
ORGANIC CHEMISTRY CLASS
By
S. R. Mohanta (contact-srmph05@yahoo.co.in)
COLLEGE-SIPS,Jharpokharia,Odisha
UNIT-I-DAY2 STUDY
Nomenclature of Organic compounds

2. What is IUPAC Nomenclature?
IUPAC nomenclature of organic compounds refers to
the systematic approach taken for the naming of organic
compounds as per the recommendation of the International
Union of Pure and Applied Chemistry (often abbreviated to
IUPAC).
 1st start with naming of saturated hydro carbons.
 Saturated hydrocarbons are those whose all 4 valences of carbon
satisfied with sigma bond or single bond.

3. Primary naming of alkanes

4. Branched Alkanes
When an alkane has a shorter side-chain attached to the continuous-
chain, it is designated as a Branched alkane.
The continuous chain is called the root or parent chain, while the side-
chain is the alkyl group.
 Nomenclature of Alkyl groups
 (alkane—ane+yl=alkyl). Thus CH3-CH3 is ethane and CH3-CH2 is named ethyl group.

5. Branched-chain Alkyl groups having 3, 4, 5 carbon atoms.

6. IUPAC Rules for Naming Branched Alkanes.
 1.Select the longest continuous carbon chain and name the branched
alkane as alkyl derivative of the parent alkane containing this chain. It
is not necessary that the longest chain is a straight line ; it may be
straight or zig-zag.
 Both are 2-methyl butane.

7. 2. The parent-chain carbon atoms are numbered 1, 2, 3, 4, etc.,
beginning with the end nearest to the branch alkyl group. This gives the
lowest number to the carbon to which the alkyl group is attached.
 The position of the alkyl group on the Parent chain is indicated by
the number of the carbon which carries it. It is called Position
number .
 The position number is mentioned before the name of alkyl group
from which it is separated by a hyphen.
 Thus, if a methyl group is on carbon 2, it is written as 2-methyl.

8. 3. The complete name of the branched alkane is written as one word
by prefixing the name of the alkyl group to the name of the parent
aikane.
 4. When two or more different alkyl groups are present on the
parent chain, assign position-number to each and list them
alphabetically with a hyphen in between.

9. 5. When two or more identical groups are present, indicate them by the
use of the prefixes di, tri, tetra, etc., immediately before the alkyl group.
Commas are used to separate position numbers from each other.
 While determining the alphabetic order, the prefixes di, tri. etc., are
ignored. Thus the prefix di is disregarded while determining the
alphabetic order.

10. 6. When there are two longest chains having equal member of carbons,
select the one with the greater member of branches alkyl groups) as the
parent chain.
 7. When branching occurs at an equal distance from either end of the
longest chain, choose the numbering pattern that gives the lower
number at the first point of difference.

11. 8. In case the substituent on the parent chain is a complex one
(containing more than 4 carbons), name it as a substituted alkyl group
whose carbon chain is numbered from the carbon attached to the main
chain.
The name of the complex substituent is given in brackets to avoid
confusion with the numbers of the parent chain.