NY Regents Chemistry Exam August 2023 Question 42
42 Given the formula representing a compound:
What is a chemical name of this compound?
(1) 2,3,3-trimethylbutane
(2) 2-methyl-2-ethylbutane
(3) 2,3-dimethylpentane
(4) 2,3-ethylpentane
Solution: First, we find the longest carbon chain. In this case, it is the horizontal chain with five carbons. Table P on the reference table shows that the prefix for five carbons is pent, making the parent chain pentane. This eliminates choices 1 and 2. Next we number the carbons from the end closest to the first substituent, (CH3 group in this case). We must number from the left. We have two CH3 groups, one on carbon number 2 and another on carbon number 3. 2,3 dimethyl pentane, Choice 3 is correct.
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