Which three of the following names are incorrect according to the IUPAC rules?
(i) 2-methyl-4-ethylheptane
(ii) 2-Isopropyl-3-methylhexane
(iii) 3-ethyl-2, 2-dimethylhexane
(iv) 4-isopropyl-3-ethylheptane?
What is the correct name in each case ?
Explain it
Answers
Answer:
Rules for Naming Hydrocarbons:-
Rule-I Selection of the longest carbon chain.
Rule-II Numbering the longest chain: Longest chain is numbered starting from a terminal carbon. Numbering is done is such a way that the lowest possible number is given to the side chain or a functional group.
Rule-III Writing names of branched, saturated hydrocarbons, locants are written first in alphabetical order followed by name of parent chain.
Rule-IV Some common names are retained in IUPAC system for unsubstituted hydrocarbon only.
(i) 2-Ethylbutane ⟶ 2-ethyl-butane
(ii) 4-Methylpentane ⟶4-methyl-pentane
(iii) 3,5-Dimethylhexane ⟶ 3,5,-dimethyl-hexane
(iv) 5-Ethyl-4-methylheptane ⟶ 5-ethyl-4-methyl-heptane
(v) 2,3-Dimethyl-3-ethylpentane⟶ 3-ethyl-2,3-dimethyl-pentane
(vi) 3-Methyl-4-isopropylheptane ⟶ 4-isopropyl-3-methyl-heptane
(vii) 4-Ethyl-5-sec-butylnonane ⟶ 5-sec-butyl-4-ethyl-nonane