Question

The IUPAC name of the compound is?

• A. 3,4-dimethyl-5-(1-methylethyl)-heptane
• B. 2-sec-butyl-3-isopropylpentane
• C. 3-(1-methylethyl)-4,5-dimethylheptane
• D. None of the above

Answer 1

The correct option is D None of the above

First let us choose the longest chain

III is the better chain than I & II as there are more substituents with the same number of carbon atoms.

If III is numbered in the reverse order ,i.e.,

The locant set of III is lower than IV

Hence III is the MOST appropriate way to do the numbering

Root word = hept

Primary suffix = ane

Prefix = 3-ethyl-2,4,5-trimethyl

Alphabetically 3-ethyl precedes 2,4,5-trimethyl

Hence, the IUPAC name is

3-ethyl-2,4,5-trimethylheptane