Question

Br ph H Br prie Br ph Br The enantiomer at Dis: The enantiomer of A is: List letters corresponding to the mes structures if öry which structures, if any, are chiral: Which structures, if any are Achirals

Answer 1

For all cases the priority of the substituents of stereocenter is: -Br > C (attached to Br) > Ph > H. We know configuration of a chiral center is R if 1 to 2 to 3 is clockwise from the opposite of C-4 bond and S if it is anticlockwise from opposite of C-4.

Now, we'll have a look to the configurations,

Molecule	Configuration of left chiral center	Configuration of right chiral center
A	S	R
B	R	S
C	S	S
D	R	R

Now, we know for same connectivity for the same carbon, R configuration is the mirror image of S.

• D has a configuration (R,R). So its enantiomer will be (S,S) which is C.
• The configuration of A is (S,R), so its enantiomer will be (R,S) which is B.
• Now, if we see the Fischer projection of similar compounds, then for B and C it is:
  11
  

Both having a plane of symmetry, so they are meso.

• All the structures are chiral because all of them have chiral centers, so answer is A, B, C, D.
• None of the molecule is achiral.

NOTE: We have shown here the two meso compounds, actually they are same compound. So, there is no meaning of individually representing them. Even, one of them is the homomer of the other, not enantiomer. But for the sake of question, the answer should be written like this.