The number of optical isomers possible for the given organic molecule is? $\ce{CH_3-C^*H(OH)-CHCl-CH_2Cl}$ (the configuration is fixed at $\ce{C^*}$)

The given answer is 2. The carbon marked with an asterisk is chiral, and the carbon to the right of it is also chiral. Doesn't that give 4 isomers? What does "configuration is fixed" mean?


1 Answer 1


The carbon marked with the asterisk cannot change its configuration, for it to be counted as a stereocentre, it must be able to. hence 2 isomers only

  • $\begingroup$ So we're considering the optical rotation of the carbon which lies next to the one marked with an asterisk? $\endgroup$
    – Tapi
    Commented Dec 30, 2019 at 15:51
  • $\begingroup$ Yes. The only chiral atom here is the third C, which is part of the CHCl group. $\endgroup$
    – Maurice
    Commented Dec 30, 2019 at 16:23
  • $\begingroup$ Yes, thats exactly what i meant $\endgroup$ Commented Dec 30, 2019 at 16:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.