Alkynes

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Basic IUPAC Organic Nomenclature

Alkynes

Nomenclature

Formula

3D structure

Functional group suffix = -yne

Substituent prefix = alkynyl

Structural unit : alkynes contain C≡C bonds.

The root name is based on the longest chain containing both ends of the alkyne unit, the C≡C.
The chain is numbered so as to give the alkyne unit the lowest possible number.

Functional group is an alkyne, therefore suffix = -yne The longest continuous chain is C4 therefore root = but The first point of difference rule requires numbering from the right as drawn, the substituent locant is 1- but-1-yne or 1-butyne	CH₃CH₂C≡CH
Functional group is an alkyne, therefore suffix = -yne The longest continuous chain is C4 therefore root = but The substituent is a C2 alkyl group i.e. a ethyl group The first point of difference rule requires numbering from the right as drawn, the substituent locant is 2- but-2-yne or 2-butyne	CH₃C≡CCH₃

©Dr. Ian Hunt, Department of Chemistry