Question

What is the name of the group $$\text{C}{\text{H}}_{\text{2}}\text{=CH-C}{\text{H}}_{\text{2}}\text{-}$$?
(A)- Allyl
(B)- Vinyl
(C)- Crotyl
(D) 1 - methylvinyl

Answer 1

Hint: Allyl, vinyl and Crotyl are the functional group of hydrocarbons. In Allyl, vinyl and Crotyl are unsaturated hydrocarbon functional groups with one free valence.

Complete Solution :
(A)- Allyl - Allyl is a three carbon containing hydrocarbon molecule in which a vinyl group is directly associated with a methyl group. Allyl is a functional group with its structural formula $$\text{C}{\text{H}}_{\text{2}}\text{=CH-C}{\text{H}}_{\text{2}}\text{-X}$$ where X represents the free valence of hydrocarbons. An Allyl group is formed when a hydrogen atom is removed from$s{p}^3$hybridized carbon atom in prop-1ene. The IUPAC name of allyl is alkylidene. It contains one $s{p}^3$ hybridized carbon and two $s{p}^2$ hybridized carbon. So this given hydrocarbon is allyl.

(B)- Vinyl - vinyl is a function group of hydrocarbons which is formed after the removal of a hydrogen atom from ethene. Vinyl contains two carbon atoms with $s{p}^2$ hybridization and three hydrogen atoms. The IUPAC name of that vinyl compound is ethylene in which ethene with one free valence. The structural formula of vinyl is $$\text{C}{\text{H}}_{\text{2}}\text{=CH-X}$$ where X represents the free valence of hydrocarbon. Vinyl is used as a monomer in the polymer industry for the production of polyvinyl chloride (PVC).

(C)- Crotyl- Crotyl is a function group of hydrocarbons which IUPAC name is but-2-en- 1yl. It contains two carbon atoms with $s{p}^3$ hybridization and two carbon atoms with $s{p}^2$ hybridization. Crotyl is represented by structural formula $$\text{C}{\text{H}}_3\text{-CH=CH-C}{\text{H}}_2\text{-X}$$ where X represents the free valence of the Crotyl compound. This compound also show geometrical isomerism

(D)- 1 -methylvinyl - In 1 -methyl vinyl a $s{p}^3$ hybridized carbon atom associated with the vinyl group. In this compound it is represented as $$\text{C}{\text{H}}_3\text{-CH=CH-X}$$ where free valence is present on vinylic $s{p}^2$ hybridized carbon atoms. The compound of 1-methylvinyl is flammable, colourless and toxic liquid.

Note: Allyl and 1- methylvinyl show structural and positional isomerism (compound having the same structural formula but different in the position of the function group or free valence).