Question

Write structures of the following compounds: (i) 2-chloro-3-methylpentane
(ii) 1,4-dibromobut-2-ene
(iii) 1-chloro-2-methylbenzene
(iv) 1-chloro-4-ethylcyclohexane
(v) 3-bromo-2-methylbut-2-ene

Hint:

Always select the longest chain, number to give lowest locants, and place substituents alphabetically in naming.

Answer 1

(i) 2-chloro-3-methylpentane.
Pentane chain, Cl at C-2, CH\(_3\) at C-3: \[ CH_3-CH(Cl)-CH(CH_3)-CH_2-CH_3 \] (ii) 1,4-dibromobut-2-ene.
4-carbon chain, double bond at C-2, Br at C-1 and C-4: \[ Br-CH_2-CH=CH-CH_2-Br \] (iii) 1-chloro-2-methylbenzene.
Benzene ring with Cl at position 1, CH\(_3\) at position 2 (ortho-chlorotoluene).
(iv) 1-chloro-4-ethylcyclohexane.
Cyclohexane ring with Cl at C-1 and –CH\(_2\)CH\(_3\) at C-4.
(v) 3-bromo-2-methylbut-2-ene.
4-carbon chain with double bond at C-2, CH\(_3\) substituent at C-2, Br at C-3: \[ CH_2=C(CH_3)-CH(Br)-CH_3 \]