Dear colleagues!
At the moment we are looking for "nice" reactions employing BuLi solutions for our practical training at the university. We aim to expand our five standard BuLi reactions to a broader field.
Therefor if you know suitable reactions for that purpose please write a short answer. Links or literature citations are also welcome!
"Didactically valuable" reactions with simple starting materials would be of special importance.
Thank you very much!
Eric Täuscher
BuLi stands for Butyllithium a metal organic compound.
Sorry, it is my first question and I somehow forgot to add the keywords.
In my opinion the titration of BuLi using diphenylacetic acid in THF is a nice one. Its an instructive experiment in which, in addition to the color change, students also will learn how to use the syringe and other protective equipment. You can find the working instruction on http://www.chem.rochester.edu/notvoodoo/pages/how_to.php?page=titrate_alkyllithiums
I belive there is even a video of the titration reaction somewhere.
Diphenylacetic acid is the reagent of choice for the titrations (concentration estimation) most students have no problems spotting the equivalent point.
OK here are four reactions we use:
1. alpha-alkylation of p-methoxyphenylacetic acid
2. substitution of Br against I using 9-Bromoanthracene
3. DOM like Reaction starting from 2,5-dibromopyridine using LDA than DMF
4. synthesis of 2-[(trimethylsilyl)methyl]-pyridine (Orgsyn)
I agree with T Werner. For "nice " n-BuLi", 1.5M or less in hexane will not be very pyrophoric. Although I would never recommend it I have seen a colleague pour 1.5N n-BuLi directly into an addition funnel from the bottle without any problem. The formation of 2- pyridyllithium in THF must be done at dry ice temp under N2 or Ar and if the orange solution warms above -65 oC the ring opens up and a dark purple mess is obtained. Metalation of other heterocycles by halogen exchange is interesting such as the formation of 2-thienyllithium which is reasonably stable and could lead to interesting reaction products.
I suggest Interesting BuLi reactions involving umpolung i.e. use of dithiane for the synthesis of cyclic four , five menbered ketones , alpha hydroxy and Beta hydroxy ketones etc. Another reaction is Sonogashira coupling involving reaction of sub- acetylene with alkyl or aryl halides forming C -C bond.
I would recommend the Negishi reaction Cp2ZrCl2+2nBuLi (Uwe Rosenthal, ChemistryOPEN Reviews, 2019, 8(8), 1036-1041). It leads to several interesting derivatives through beta-hydrogen elimination of the product.
A nice research project would be the reaction of BuLi with 2-phenyl indole ZrCl2 (see download) prepared by myself. It is easy to prepare. If interested please ask for the procedure.
Dear Eric Täuscher the titration of n-butyllithium with diphenylditelluride involves nice color changes. It is also a good method to determine the concehtration of your n-butyllithium solution. The attached article is freely available on the internet.
Hi Eric Täuscher , if you think to include some organic reactions in your practical training, I would suggest a very nice formylation reaction type by formation of Lithiated aryles and subsequent addition of DMF (N,N-dimethylformamide) under low temperature and highly dried medium.
Dear Eric Täuscher here is another interesting paper by the famous Henry Gilman entitled "Color Tests for Some Organolithium Compounds"
Article Color Tests for Some Organolithium Compounds
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