NY Regents Exam June 2022
45 Given the formula for a compound:
What is the IUPAC name of the compound? (1) 2,3-dimethyloctane
(2) 2,3-dimethylhexane
(3) 4,5-dimethyloctane
(4) 4,5-dimethylhexane
Explanation: First we need to find the longest continuous carbon chain (parent chain) . The longest chain of carbons is the horizontal chain and it has 6 carbons. According to Table P on the Reference Table, 6 carbons should have a prefix hex and since it is all single bonds the parent's chain should be named hexane. Choices 1 and 3 can be eliminated.
Next, we count the carbons on the parent chain starting from the end that is closest to the first attachment.
Next, we name the groups attached. Both groups have one carbon and according to Table P should have a prefix meth. We get 2- methyl (CH3 attached to carbon 2) and 3- methyl (CH3 attached to carbon 3). Combining all-together we get 2,3-dimethylhexane .
Answer: 2