ACS Stereochemistry question
Started by alanan84
The chiral center given in the aldehyde is already fixed (ie the absolute configuration is already given).
Once Ph-Li is added, a new chiral center results, and with respect to the newly formed chiral center...R or S is possible.
Thus, treatment of the aldehyde with the carbanion results in two diastereomers.
Once Ph-Li is added, a new chiral center results, and with respect to the newly formed chiral center...R or S is possible.
Thus, treatment of the aldehyde with the carbanion results in two diastereomers.
Ok I think I've got it. Does the Ph add to the carbonyl carbon?
Yeah...it's an organometallic reagent.
It helps to understand that Li is similar in chemical behavior to Mg (diagonal relationship). Mg++ and Li+ are similar in size and thus coordinate effectively with lewis bases; in the case of organometallic reagents, carbanions.
Ok, thanks, that makes sense.
Geez, I didn't think I was bad at stereochemistry until I started working through this book. Did you find the questions on the DAT to be similar in difficulty to this ACS study guide? I'm assuming you used it to study...
Yeah, I used both ACS guides to study from. The level of difficulty is harder than the real DAT (as is the case with most practice material).
However, the key benefit of the ACS guides is that they cover a wide range of problems.
It may be on the difficult side, but I would invest a lot of time in those guides. I think they are probably one of the best chemistry study tools out there and the best bang for your buck.
