I think my prof made a mistake. Shouldn't the answer be 1, 4 and 5 instead of 2 and 3?

enter image description here


If the programmers did not make a mistake it seems that you are right - ChemDraw is on your side.

$\hskip.5in$Bildbeschreibung und so

  • $\begingroup$ I got 2 and 3 as the (R) isomer. 2 and 3 are the same isomer and I got a clockwise rotation, hence R, when numbering the priority of groups where H (the lowest priority) is facing away, or dashed line. I thought the order of priority would be NH2>COOH>CH2SH. Any ideas? $\endgroup$ – LiamH Jul 28 '15 at 14:45
  • 1
    $\begingroup$ @LiamH It's NH2>COOH>CH2OH but S is more important than O because of it's higher atomic number and that's why NH2>CH2SH>COOH. $\endgroup$ – pH13 - Yet another Philipp Jul 28 '15 at 14:59
  • $\begingroup$ You beat me to my own correction PH13 haha >> Ah looks like I was wrong. Priority is NH2>CH2SH>COOH>H. Therefore I would have to agree with the above answer and 2/3 are actually an S configuration. Got confused for a minute there! $\endgroup$ – LiamH Jul 28 '15 at 15:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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