2
$\begingroup$

The key tells me these are enantiomers.

enter image description here

I however don't think they are; their chiral carbons' configurations aren't inverted - i.e. only one chiral carbon's R/S configuration changes! This suggests diastereomers to me! Plus the Sawhorse projections I draw don't seem to be mirror images.

enter image description here

enter image description here

Improve this question
$\endgroup$
4
$\begingroup$

They are diastereomers. Both of the "front" chiral carbons (the one with the bromine attached) are "S". Rotate the one on the right 120 degrees CCW and it is identical to the one on the left. But the "back" carbon (the one with the hydroxyl attached) is "S" on the left figure and "R" on the right figure - diastereomers.

Improve this answer
$\endgroup$
15
  • $\begingroup$ I get the opposite of what you get for the back carbon for both images. $\endgroup$ – Dissenter Jun 20 '14 at 1:35
  • $\begingroup$ Are you "holding" the hydrogen such that the "steering wheel" is between your eye and the hydrogen? $\endgroup$ – ron Jun 20 '14 at 1:37
  • $\begingroup$ I'm not holding the hydrogen; I'm holding the group with priority 2 and rotating the molecule so the hydrogen is pointing away. ETA: And so I am holding the hydrogen so that the steering wheel is between my eye in the hydrogen. $\endgroup$ – Dissenter Jun 20 '14 at 1:39
  • $\begingroup$ Try holding the lowest priority group, in this case hydrogen, so that the 3 remaining groups form a circle (steering wheel) between your eye and hand. When you travel around the circle going from the highest priority group (1) to the next to lowest priority group (3) by way of (2), if you travel CW then your chiral center has the "R" configuration, if you travel CCW, then the "S" configuration. $\endgroup$ – ron Jun 20 '14 at 1:44
  • $\begingroup$ I'm still traveling clockwise for the left figure. Will insert picture of model in OP. $\endgroup$ – Dissenter Jun 20 '14 at 1:46

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.