ADA sample test mistakes

[jorasic]

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ADA Sample Test mistakes?

Ochem #83 Isn't choice D also a trans config?
Ochem #99 choice B has a Hydrogen missing from its last methyl group sticking out.

 

[TedyBearSuicide]

Take the time to post the actual question and answers as well.

 

[Valigator00]

ADA Sample Test mistakes?

Ochem #83 Isn't choice D also a trans config?
Ochem #99 choice B has a Hydrogen missing from its last methyl group sticking out.

83: No, Methyl groups have the same priority.
99: You are right about the hydrogen. I think it was just a typo.

 

[jorasic]

So a trans E is talking about the methyl groups?

I thought trans meant the 2 highest priorities went on different sides?

Cl is higher than Carbon.

 

[NumbaOneStunna]

E Z notation isn't needed for D like the above poster said because of the two methyl groups. By your logic the two "smallest" groups a CH3 and H are also on the same side making it cis as well in addition to being trans like you explained. If you broke the double bond twisted the thing and made the double bond again - you'd get the same thing so there's no need for EZ notation.

 

[jorasic]

actually, if the question gives you, which is an E or Z, you can't just break double bonds here and there. If it were a sigma bond you can rotate but I've never heard of any case where you can jsut break a double bond and assume it can re-rotate. Unless a specific reagent was given.

For alkene nomenclature, the 2 highest priorities on the same side should be Z, if the 2 highest are on opposite sides, it should be E.