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JEE Advanced levelSingle correct optionDifficulty 3 of 3nm050

A cyclohexene ring has a methyl group on each of the two sp2 carbons and an isopropyl group on the sp3 carbon adjacent to one of them. Name it (use the prefix 1-methylethyl for isopropyl).

  1. A2,3-dimethyl-1-(1-methylethyl)cyclohexene
  2. B1,2-dimethyl-3-(1-methylethyl)cyclohexene
  3. C3-(1-methylethyl)-1,2-dimethylcyclohexene
  4. D1,2-dimethyl-6-(1-methylethyl)cyclohexene

Answer: B

The double bond is C1=C2. Whichever way the ring is numbered, the methyls are on C1 and C2. The isopropyl carbon is C3 in one direction and C6 in the other, so {1,2,3} is chosen. The prefixes are cited alphabetically: methyl (from dimethyl) before methylethyl. The name is 1,2-dimethyl-3-(1-methylethyl)cyclohexene.
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