I found a question to determine the number of possible chiral products of monochlorination of 2-chloropentane.So, first the products are (with possible number of enantiomers in the parentheses:

2,2-dichloropentane(no chiral product),

1,2-dichloropentane(4 or 2, I am not sure is there a plane of symmetry here)

2,3-dichloropentane(2 or 4)

2,4-dichloropentane(obviously none for a plane of symmetry)


But my surprisingly the answer says it's only 5. That's even lower than my lower estimate. I am not sure how there are 5 enantiomers.

  • 1
    $\begingroup$ Chlorination at 2°carbon is more probable to happen here if we consider the thermodynamics of the reaction but still I am confused about having just 5 products. $\endgroup$
    – Suraj S
    May 10, 2017 at 17:19
  • $\begingroup$ I am not. Narendra Kumar answer is right. $\endgroup$ May 11, 2017 at 12:34

2 Answers 2


2-chloropentane is optically active compound hence in some cases we will get only diastereomers. For example 1,2-dichloropentane is single product because it is formed by attack at carbon no. 1 hence no change in chirality of carbon no. 2. So product formed by attack at carbon 1 (one chiral product) carbon3 (two chiral product i.e. diastereomers) carbon 4 (one chiral product, i.e. one chiral and one meso) carbon5 (one chiral product)


The answer is 5. See- 1) 1,2 dichloropentane --- 1 chiral 2) 2,3 dichloropentane --- 2 chiral 3) 2,4 dichloropentane --- not chiral as there is plane of symmetry 4) 2,5 dichloropentane -- 2 chiral

Therefore 2+1+2 =5 Chiral Products

  • $\begingroup$ why 2 chiral products when there are 2 stereocenters in 2,3-dichloropentane? $\endgroup$ May 10, 2017 at 11:28
  • $\begingroup$ It would be better if you explain it better. $\endgroup$ May 10, 2017 at 11:31
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    $\begingroup$ Please don't use all caps. $\endgroup$ May 10, 2017 at 12:37
  • $\begingroup$ @pritt Balagopal Are u sure this answer is right? and why 2 chiral products when there are 2 stereocenters in 2,3-dichloropentane? $\endgroup$ May 11, 2017 at 11:16
  • $\begingroup$ I think there won't be 2 enantiomers for 2,5-dichloropropane. only 1. and 2,4-dichloropropane would have 1 enantiomer $\endgroup$ May 11, 2017 at 12:33

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