The purpose of sodium borohydride (NaBH4) in the coboxalamine alkylation process is to reduce cobalt from Co(III) to Co(I), creating a highly nucleophilic intermediate that facilitates the SN2 reaction with ethyl iodide. This reduction leads to the displacement of iodide during the alkylation step. Additionally, the reaction conditions, which include slightly alkaline media, result in the formation of bromide ions as a byproduct, rather than HBr.
PREREQUISITESChemists, particularly those specializing in organic synthesis and coordination chemistry, will benefit from this discussion, as well as students engaged in laboratory work involving alkylation reactions.
Thank you very much. What happens to the bromide substiuent?TeethWhitener said:
I’ve honestly never really thought about it before. I imagine the hydride binds to the bromine, pushing the electron pair from the Co-Br bond onto the cobalt center. So you’ll get HBr out, but these reactions are often done under slightly alkaline conditions, so it’ll probably be bromide ion at the end.Mayhem said:
Yes, the NaBH4 is stabilized in KOH as the solvent is MeOH in this case. I turned in the assignment the other night, so I guess we will just wait and see.TeethWhitener said:
Eh, these were pre-lab safety schemes. I didn't consider it homework in the traditional sense.TeethWhitener said: