[sonya36]

I'm given the molecule attached in the file.

The question is: If the compound above was halogenated with Cl2 which of the following statements would be true?
a) Four stereoisomers would result and they would be diastereomers
b) Two stereoisomers would result and they would be enantiomers
c) Two stereoisomers would result and they would be meso compounds
d) Four stereoisomers would result and there would be two enantiomers and two
diastereomers
e) Two stereoisomers would result and they would be diastereomers

I'm looking at the double bond at the lower right-hand corner of the molecule. I thought it was choice B since when chlorinum ion forms during halogenation at the double bond, chlorine anion can attack both Re and Si faces, resulting in two anti-additions. When I actually tried to add chlorines on the molecule, I got SS and RR enantiomers. But the answer is supposed to be choice E. Where am i going wrong here?

I think this is a similar type of question:
If the compound above was hydrated with mercury acetate (Hg(OAc)2) followed by treatment with sodium borohydride (NaBH4), which of the following statements would be true?
a) a tertiary alcohol would result
b) two compounds with the same boiling point would result
c) a mixture of enantiomers would result
d) A and C
e) A and B

I got D because again, OH can be added to both Re and Si faces at the most substituted carbon, resulting in two enantiomers.But the answer says it's A. Am I doing something wrong here as well?

[sjb]

I'm given the molecule attached in the file.

The question is: If the compound above was halogenated with Cl2 which of the following statements would be true?
a) Four stereoisomers would result and they would be diastereomers
b) Two stereoisomers would result and they would be enantiomers
c) Two stereoisomers would result and they would be meso compounds
d) Four stereoisomers would result and there would be two enantiomers and two
diastereomers
e) Two stereoisomers would result and they would be diastereomers

I'm looking at the double bond at the lower right-hand corner of the molecule. I thought it was choice B since when chlorinum ion forms during halogenation at the double bond, chlorine anion can attack both Re and Si faces, resulting in two anti-additions. When I actually tried to add chlorines on the molecule, I got SS and RR enantiomers. But the answer is supposed to be choice E. Where am i going wrong here?

I think this is a similar type of question:
If the compound above was hydrated with mercury acetate (Hg(OAc)2) followed by treatment with sodium borohydride (NaBH4), which of the following statements would be true?
a) a tertiary alcohol would result
b) two compounds with the same boiling point would result
c) a mixture of enantiomers would result
d) A and C
e) A and B

I got D because again, OH can be added to both Re and Si faces at the most substituted carbon, resulting in two enantiomers.But the answer says it's A. Am I doing something wrong here as well?

What is the definition of enantiomerism and diastereomerism?

[sonya36]

I'm given the molecule attached in the file.

The question is: If the compound above was halogenated with Cl2 which of the following statements would be true?
a) Four stereoisomers would result and they would be diastereomers
b) Two stereoisomers would result and they would be enantiomers
c) Two stereoisomers would result and they would be meso compounds
d) Four stereoisomers would result and there would be two enantiomers and two
diastereomers
e) Two stereoisomers would result and they would be diastereomers

I'm looking at the double bond at the lower right-hand corner of the molecule. I thought it was choice B since when chlorinum ion forms during halogenation at the double bond, chlorine anion can attack both Re and Si faces, resulting in two anti-additions. When I actually tried to add chlorines on the molecule, I got SS and RR enantiomers. But the answer is supposed to be choice E. Where am i going wrong here?

I think this is a similar type of question:
If the compound above was hydrated with mercury acetate (Hg(OAc)2) followed by treatment with sodium borohydride (NaBH4), which of the following statements would be true?
a) a tertiary alcohol would result
b) two compounds with the same boiling point would result
c) a mixture of enantiomers would result
d) A and C
e) A and B

I got D because again, OH can be added to both Re and Si faces at the most substituted carbon, resulting in two enantiomers.But the answer says it's A. Am I doing something wrong here as well?

What is the definition of enantiomerism and diastereomerism?

Enantiomerism when two molecules are mirror images of one another? And have SS/RR or SR/RS configuration to one another.
Disastereomerism is when they are not mirror images and have configurations such as SR/RR or SS/RS.

[sjb]

What is the definition of enantiomerism and diastereomerism?

Enantiomerism when two molecules are mirror images of one another? And have SS/RR or SR/RS configuration to one another.
Disastereomerism is when they are not mirror images and have configurations such as SR/RR or SS/RS.

Right, are you forming any new stereocentres? Are any stereocentres being destroyed? Are any staying the same?

[sonya36]

What is the definition of enantiomerism and diastereomerism?

Enantiomerism when two molecules are mirror images of one another? And have SS/RR or SR/RS configuration to one another.
Disastereomerism is when they are not mirror images and have configurations such as SR/RR or SS/RS.

Right, are you forming any new stereocentres? Are any stereocentres being destroyed? Are any staying the same?

Ohhh I think I get it now. I'm only forming new stereocentres at the double bond area but that's not affecting other stereocentres of the molecule. So even if the ones at the double bond are SS/RR are to one another, other ones stay the same which means the entire molecule itself is not an enantiomer to one another.. Am I right?

[sjb]

Right, are you forming any new stereocentres? Are any stereocentres being destroyed? Are any staying the same?

Ohhh I think I get it now. I'm only forming new stereocentres at the double bond area but that's not affecting other stereocentres of the molecule. So even if the ones at the double bond are SS/RR are to one another, other ones stay the same which means the entire molecule itself is not an enantiomer to one another.. Am I right?

Makes sense to me. So you can say that the dichloride is relatively cis trans but the rest of the molecule is unspecified relative to that, for instance (and the saccharide acid also has a defined stereochemistry that is not related to the dichloride)

(edit, tea before typing)