destroyer o.chem # 37

[604boo]

The answer should be a) 2?
the solution says that III is meso so it doesn't have optical activity.
Therefore only I and II are isomers? right?

One more.. it says it should have 4 isomers according to the 2^n rule, but it only shows three compounds. I guess fourth one is the same as the third one?

Confused...Help

Thank You.

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[burgler09]

I think it would be better to somehow give an example of the question, if you can do that I can see if I can get you an answer and a reason behind it.

Btw, do you think you could maybe take a look at my O-chem thread just below it? I am kind of confused by that question.

 

[fifi1314]

The answer should be a) 2?
the solution says that III is meso so it doesn't have optical activity.
Therefore only I and II are isomers? right?

One more.. it says it should have 4 isomers according to the 2^n rule, but it only shows three compounds. I guess fourth one is the same as the third one?

Confused...Help

Thank You.

I, II and III are isomers! not only I and II.

1. count chiral Cs. According to the pic, there is 2 chiral Cs.
2. using 2^n rule, 2^2=4 Isomers, because this compound can be trans, trans, cis, cis.
3. Trans not equal to Trans, but Cis = Cis, therefore, you only have 3 isomers, they are 2 Trans, 1 Cis.

Hope it helps.

 

[604boo]

Thanks