Question

Consider the molecule shown below. ch_2ohchohchohch_3, Indicate chiral centers and predict the total number of stereoisomers. Draw them out in the Fischer projection. Build a model of one of them (orient it in the Fischer projection) so you can visualize the shape and how the chain curves. Sketch it to the best of your ability. Which of the molecules are enantiomers of each other? Are there any meso compounds? Justify your answers and draw them out. Take a pair of the enantiomers and designate the chiral centers as R or S. Do the enantiomers have opposite designations? Show how you arrived at the answer by illustrating with the two-exchange rule.

Answer 1

a) The molecule has two chiral carbons.

The total number of isomers = 4

As the molecule is not symmetric number of optical isomers = 2 ⁿ where n = number of chiral carbons.

b) compounds I and II are an enantiomeric pair and III and IV are other pair of enantiomers.

As the molcule has no plane of symmetry, it has no meso isomers.

c)given the scheme: