Dear Prof. Nguyen:
Good afternoon. My name is See Arr Oh (a pseudonym), and I write a chemistry blog called Just Like Cooking. I've posted about one of your recent publications in JACS ASAP:
Another chemist at Princeton graciously offered to repeat one of your reactions (Table 2, entry 2), and could not duplicate your group's yield or purity. Further discussion can be found in the comments section of the second post. Additionally several other members of the chemistry community have expressed an interest in running it themselves, with the intention of aggregating data under the Twitter hashtag #RealTimeChem.
Please share some more information - do you have any hints or tips for successful duplication?
Thank you in advance,
See Arr Oh
Unfortunately, my spam filter ate the (prompt) response, and thus I'm posting it a few days later than when I received it back on 1/2/13:
Dear See Arr Oh,
Thank you for your mail. First, you should carry out the reaction in the same scale as described, otherwise, sulfur is comsumed by reacting with methylhetarene before combining with iron. Second, a vigorous stirring is necessary to disperse iron powder into the reaction mixture. At this temperature, the reaction mixture is homogeneous except iron powder. Third, the reaction should be carried out under Ar atmosphere because oxygen is not an innocent impurity. Oxygen in the reaction tube is best removed in vacuo (10 mmHg is ok) then the tube is filled with Ar. This cycle is repeated twice. Before running an NMR spectrum of the crude mixture, paramagnetic iron residue should be removed by syringe filtration to avoid any magnetic pertubation. In most cases, the products were formed as black solid. The prduct is fluorescent with UV lamp.
Sincerely
Interesting tidbits: vigorous stirring, as opposed to a debate in the comments over whether we should stir the reaction at all, scalability issues, and recommendations for NMR analysis - Fe junk really does mess that up!
Methinks this advice might come too late* for anyone trying the reaction today; sorry, B.R.S.M.!
*Addendum - That's a lot of "insider info" in that email, and I'd argue a lot of the online discussion we've had on this reaction could have been avoided by a more complete Supporting Information file. None of that info was available either there or in the paper, nearest I can tell. Readers?
0 nhận xét:
Post a Comment