Are the following two compounds isomers or not? I feel they are enantiomers(non-superimposable mirror images) however my book states that they are not isomers? I cannot understand why?

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  • 6
    $\begingroup$ Probably a typo. You are correct that they are enantiomers. $\endgroup$
    – Dan Burden
    Aug 23, 2016 at 0:28
  • $\begingroup$ This is an example of a compound with no chiral center, but it is chiral. Compare 1,1-diethyl 3-methyl propa-1,2-diene (did I get the substituents in the right order?). $\endgroup$ Aug 23, 2016 at 1:19
  • $\begingroup$ chemistry.stackexchange.com/q/42999/16683 #3 $\endgroup$ Aug 23, 2016 at 4:47

1 Answer 1


You are right, these two molecules are enantiomers. If you rotate the bottom molecule 180 degrees, you can see that it is the mirror image of the top molecule. Enantiomers are stereoisomers, so the only reason your book would say they are not isomers is that it (unfortunately) contains a typo.

  • $\begingroup$ Or possibly they missed the concept that a molecule can have not a (single atom) chiral center and yet be chiral. $\endgroup$ Aug 23, 2016 at 22:48

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