help plz!!

[shal3]

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Could someone plz tell me how many chiral center will cyclopentene have when you add Br2, Ch2Br2 to it? (add 2 bromine groups to it) and why does it only an enantiomer? this is from dat destroyer ochem #33.

thank you

 

[DROCKINDAHOUSE]

There will be two chiral centers on the newly formed 1,2-dibromocyclohexane....but as for the second part of your question....maybe you should reword that

 

[water88]

You get enantiomers (RR and SS) because it's anti-addition.

 

[shal3]

I menat why does is only have a pair of enantiomers? sorry about that.
We want the carbon to be bound to 4 different groups, so it's bound to an H group, to a Br, to the carbon nextdoor (an alkyl group) and to the other carbon next door which is bound to another Br. so I thought because of that we get 3 different groups instead of 4! I understand that we get a pair of enant. once I draw it but assuming we get 2 chiral centers that would give us a 2^2= 4 enantiomers but b/c this is meso we get 3 enantiomers!? But still if you draw it out it's like you don't have any chiral centers b/c 2 of the carbons have a Br group (these carbons are right next to each other) so they are boud to the same group. Or would it count as different groups since they are anti? Ah man it's hard to explain this without a pic. hope that's clear enough and I'd appreciate your help.

Thanks

 

[doc3232]

I menat why does is only have a pair of enantiomers? sorry about that.
We want the carbon to be bound to 4 different groups, so it's bound to an H group, to a Br, to the carbon nextdoor (an alkyl group) and to the other carbon next door which is bound to another Br. so I thought because of that we get 3 different groups instead of 4! I understand that we get a pair of enant. once I draw it but assuming we get 2 chiral centers that would give us a 2^2= 4 enantiomers but b/c this is meso we get 3 enantiomers!? But still if you draw it out it's like you don't have any chiral centers b/c 2 of the carbons have a Br group (these carbons are right next to each other) so they are boud to the same group. Or would it count as different groups since they are anti? Ah man it's hard to explain this without a pic. hope that's clear enough and I'd appreciate your help.

Thanks

just trying to help, but a lot of what you said is not true.
It is 4 different groups: one in a Hydrogen, one is a Bromine, one is a CH2CH2..., and one is a CHBr. That is 4, the last two are different because there is a bromine there rather than another carbon. The 2 to the power of how many chiral centers you have applies to the number of enantiomers and diasteromers...not just enantiomers. So as everyone else said, you will have rr and ss
Hope this helps