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Class 10, Science, Chapter-4, Lecture-4, IUPAC Nomenclature of Hydrocarbons-Part-2 (Notes)

B) IUPAC System of Naming for Branched-chain:

B-1. Saturated Hydrocarbons

Case: III – Two Or More Different Alkyl Groups are Present: (For Case I and Case II go to the previous page)

(i) Search for the longest chain (parent chain)

(ii) Number the carbon atom so that the locant of the first branch is MINIMUM (Locant is minimum at the first point of difference)

(iii) Search for the ALKYL GROUPS present. (in ALPHABETICAL order)

(iv)

Locant + Hyphen + alkyl group + Hyphen + Locant . . . + alkyl grop + parent alkane (in ALPHABETICAL ORDER)

B-2. Unsaturated Hydrocarbons

(i) Search for the longest chain CONTAINING MULTIPLE BOND.

(ii) Number the carbon atoms so that MULTIPLE BOND gets LOWEST NUMBER.

(iii) Search for the alkyl groups.

(iv)

Locant of alkyl + Hyphen + alkyl group + word-root + Hyphen + Locant of bond + Hypen + ene/yne

C) IUPAC System of Naming for Hydrocarbons with Cyclic chain as Parent chain:

C.1)Saturated Cyclic Hydrocarbons

Case: I – No Branch is Present:

(i) Use prefix “cyclo” and stem as per number of carbon atoms

(ii)

cycloalkane

Case: II – Branches are Present:

(i) Start numbering the carbon atoms from one of the substituent such that the sum of the locants is minimum

 

(ii) Search for the ALKYL GROUPS present. (in ALPHABETICAL order)

(iii)

Locant + comma + Locant + comma . . . (n-time) + Hyphen + di/tri/tetra . . . + alkyl group + cycloalkane

C.2)Unsaturated Cyclic Hydrocarbons

(i) Start numbering the carbon atoms from the multiple bond such that the sum of the locants (of branches) is minimum

(ii) Search for the ALKYL GROUPS present. (in ALPHABETICAL order)

(iii)

Locant of alkyl + Hyphen + alkyl group + word-root + Hyphen + Locant of bond + Hypen + cycloalkene/yne

PRIORITY SERIES For Functional Groups:

This is only for reference, not for CBSE exam. For more on this you may visit this page

Functional
Group

Prefix

Suffix

Carboxylic
Acids

carboxy-

-oic acid

Esters

alkoxycarbonyl-
carbalkoxy-

alkyl -oate

Aldehydes

alkanoyl-

-al

Ketones

-oxo-

-one

Alcohols

hydroxy-

-ol

Alkenes

alkenyl-

-ene

Alkynes

alkynyl-

-yne

Halides

halo-

-halide

Nitro

nitro-

-----

Alkanes

alkyl

-ane