O chem Q

[nixon13]

Advertisement - Members don't see this ad

So i took a kaplan subject test and came across this problem: the product of Br2 addition to 2-pentene would be?

So i know it would add anti but is the explanation it says it would add anti but has the Brs on the same side? I dont get it?

Does anti mean trans or does it mean cis or trans but going in the opposite direction of the molecule?

 

[condoleezarice]

Br should be added to opposite sides. Sometimes, it doesn't even matter since the alkene becomes an alkane with free rotation. The original

i.e. adding Br2 anti or syn to ethene would get the same result.

http://forums.studentdoctor.net/showthread.php?t=545375

 

[akirar]

So i took a kaplan subject test and came across this problem: the product of Br2 addition to 2-pentene would be?

So i know it would add anti but is the explanation it says it would add anti but has the Brs on the same side? I dont get it?

Does anti mean trans or does it mean cis or trans but going in the opposite direction of the molecule?

You are correct Br2 it does add anti. Anti would be Trans. If you think about a cyclic molecule if you want to add Br anti to eachother they have to be on opposite side of the ring, so they would need to be trans.

After the addition of Br2 the double bond is gone, so the molecule is free to rotate (think of newman projections). Did they just rotate the molecule around the C-C bond in the picture?