2013 FINAL Q6A

[Hung_Sabrina_3N]

Why is the compound 1,5,5,6-tetramethylcyclohex-1-ene not named 2,3,4,4-tetramethylcyclohex-1-ene? Wouldn't the overall numbering of the second one be lower than the first except for the the first substituent?

[Susanne_Taavitsa_2J]

Since one of the methyl substituents is on the carbon carbon double bond, it gets numbered as 1. And since the double bonds in cycloalkenes are given the number 1 and 2 when numbering the carbons in the ring, the numbers are given in a counterclockwise order.

[giareyes_2B]

For this same problem, why is the 1 Carbon identified as being sp2? I thought sp2 meant 3 areas of electron density, but by this reasoning shouldn't carbons 2 and 3 be circled since they both have 3 bonds?

[sboutros2B]

I have the same exact question. If someone could explain to me why carbon 2 and 3 isn't circled it would be greatly appreciated (:

[regina_ho_3A]

Carbon 2 is circled, if you check the solutions in the book. Carbon 3 is not sp2 hybridized, since it is bonded to 2 other carbon atoms and 2 hydrogen atoms.