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HW Question: 1.21

Posted: Mon Feb 29, 2016 6:28 pm
by Steph S 2F
The answer given states that the name of the cycloalkene is 5-methycyclopenta-1,3-diene. However if we want to number the carbon atoms so that the sum is the smallest possible sum, shouldn't the name be 2-methylcyclopenta-1,3-diene?

Re: HW Question: 1.21

Posted: Mon Feb 29, 2016 7:20 pm
by Michelle Pham 1G
I believe that in lecture we learned that there is not such thing as a sum rule. Rather, we just want the lowest numbering possible.

Each tip of the pentagon represents a C. Double bonds get priority in naming versus the substituent so you want to start with the double bond. It does not matter which double bond you start with. From there, count to the next double bond, so that would be 3. Since you have to number it in the same direction, the methyl would be a 5.

Re: HW Question: 1.21

Posted: Tue Mar 01, 2016 5:44 pm
by Hannah Ship 2H
For this question, why would it not be 5-methyl-1,3 cyclopentadiene?