Question

Write structural formula and IUPAC name of the following:
(i) sec-butyl chloride
(ii) isopentyl bromide
(iii) tert-butyl chloride
(iv) isobutyl chloride
(v) neopentyl chloride

Hint:

When naming alkyl halides, remember the IUPAC rule of identifying the longest carbon chain and number it so that the halogen (e.g., chlorine, bromine) is attached to the lowest-numbered carbon.

Answer 1

(i) sec-butyl chloride:
- Structural formula: \(\text{CH}_3\text{CH}_2\text{CHCl}\)
- IUPAC name: Butyl chloride (2-chlorobutane). This is the sec-butyl group, where the chlorine atom is attached to the second carbon of the butane chain.
(ii) isopentyl bromide:
- Structural formula: \(\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{Br}\)
- IUPAC name: Pentyl bromide (3-bromobutane). This is the isopentyl group, where the bromine atom is attached to the third carbon of the pentane chain.
(iii) tert-butyl chloride:
- Structural formula: \(\text{(CH}_3\text{)}_3\text{CCl}\)
- IUPAC name: Butyl chloride (2-chloro-2-methylpropane). This is the tert-butyl group, where the chlorine atom is attached to the central carbon in the isopropyl group.
(iv) isobutyl chloride:
- Structural formula: \(\text{CH}_3\text{CH}_2\text{CHCl}\)
- IUPAC name: Butyl chloride (1-chlorobutane). This is the isobutyl group, where the chlorine atom is attached to the first carbon of the butane chain.
(v) neopentyl chloride:
- Structural formula: \(\text{CH}_2\text{Cl}\text{CH}_2\text{CH}_2\text{CH}_3\)
- IUPAC name: Pentyl chloride (1-chloro-2-methylpropane). This is the neopentyl group, where the chlorine atom is attached to the first carbon of the chain.