91Ó°ÊÓ

For IUPAC nomenclature of organic compounds, first select the longest chain of carbon atom having maximum carbon atom.Once the chain is selected then numbering of carbon atom is done and it is done in such a manner that branching or functional group get the smallest number.

(a) 3-ethyl-4-methylpentane, here numbering of carbon atom is incorrect and if we do the numbering from other side then molecule name becomes3-ethyl-2-methylpentane.

(b) 2-ethyl-3-methylpentane, here selection of longest chain is incorrect. Longest chain is having six carbon atom and therefore the name is 3,4-dimethylhexane.

(c) 3-dimethylhexane, here two methyl groups are present at position 3 and hence correct name of molecule is 3,3-dimethylhexane.

(d) 4-isobutylheptane, while writing IUPAC name prefixes like iso-, neo- and tert- are not used. The correct name is 2-methyl-4-propylheptane.

(e) 2-bromo-3-ethylbutane is incorrect as longest chain is of five carbon atom. Hence, correct name is 2-bromo-3-methylpentane.

(f) 2,3-diethyl-5-isopropylheptane is incorrect as longest carbon chain is having eight carbon atoms. Hence, correct name is 3,5-diethyl-2,6-dimethyloctane.