Final 2013 Q6A

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Douglas Dean
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Joined: Fri Sep 25, 2015 3:00 am

Final 2013 Q6A

Postby Douglas Dean » Tue Mar 08, 2016 11:10 pm

The question asks to name the molecule given. It is a cyclohexene, so it is a hexagon with one double bond, and then it has 4 methyl groups attached.

The answer given is 1,5,5,6-tetramethylcyclohexene. Why are the methyls numbered 1,5,5,6 instead of 2,3,4,4? In both cases the double bond is on carbons 1 and 2, but the second set of numbering is lower. Thanks so much!

Cindy Chen_2I
Posts: 43
Joined: Wed Nov 18, 2015 3:00 am

Re: Final 2013 Q6A

Postby Cindy Chen_2I » Tue Mar 08, 2016 11:20 pm

Because we want the lowest single number possible, not the lowest sum. That's why we want the 1 in 1556 as opposed to the 2 in 2344.

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