Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Just for fun, you might like to try and work out just how many diastereoisomers hexachlorocyclohexane has and how many of them are meso compounds.
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Solution:
Ans. 1,2,3,4,5,6-Hexachlorocyclohexane has 9 stereoisomers in all : 8 diastereomeric forms, of which 7 are achiral (meso) and one is chiral, existing as a pair of enantiomers.
Sol. Start with all the Cl atoms on one side and gradually move them over. Moving one Cl down gives a single five-up isomer; two down gives three isomers (1,2- 1,3- and 1,4-down); three down gives three isomers (1,2,3- 1,2,4- and 1,3,5-down); four down is equivalent to two up, and so on by the up/down symmetry of the molecule : 1 + 1 + 3 + 3 + 1 = 9 distinct configurations. Checking each for a plane of symmetry: 7 are meso and the all-trans-1,2 form is the single chiral pair.
