Sciencemadness Discussion Board

Na(Ac)3BH

chemrox - 8-2-2007 at 20:16

Sodium cyanoborohydrie is a mild reducing agent useful for many reductive amination reactions but having the disadvantage of toxicity and a bit of bother to prepare. I found the following:

Preparation of Sodium Triacetoxyborohydride. Preparation
from sodium borohydride in situ prior to reduction is
our preferred method. To NaBH4 (74 mg), suspended in ethyl
acetate (15 mL) and cooled with an ice-water bath, was added
glacial acetic acid (3.05 equiv) by syringe over _5 min. Stirring
was continued for another 5 min until a clear solution was
formed. The solution is the ready-to-use reducing agent. For
large scale (3.5 g), the addition of acetic acid was performed
dropwise over _30 min and stirring continued for a further
30 min.

[Edited on 10-2-2007 by chemrox]

Sergei_Eisenstein - 9-2-2007 at 12:33

Sodium triacetoxyborohydride is NaBH(OAc)3.

chemrox - 9-2-2007 at 21:54

Thanks for straightening that out. I was careless. I changed it accordingly

[Edited on 10-2-2007 by chemrox]

Sergei_Eisenstein - 10-2-2007 at 06:25

I think you're ignorant rather then just careless. Sodium triacetoxyborohydride is NaBH(OAc)3 and not Na(Ac)3BH. Acetoxy is AcO while Ac is acyl. As far as I know, acetic acid sometimes is written as AcOH and not AcH. The compound you're currently referring to is sodium triacetylborohydride.

panziandi - 11-2-2007 at 18:52

sorry just like to point out to Sergi_Eisentein that Ac is not acyl but acetyl! yeah AcO is acetoxy! in theory AcH is infact acetaldehyde if one draws it out! :)

chemrox - 12-2-2007 at 21:33

sometimes these boards get visted by arrogant jerks.. so what? if I cared a lot about conventions I wouldn't come here but I try to use a shorthand others can follow and if I make mistakes I don't mind a polite reminder. I do so dislike rudenss don't you?

Sergei_Eisenstein - 13-2-2007 at 11:24

Quote:
sorry just like to point out to Sergi_Eisentein that Ac is not acyl but acetyl! yeah AcO is acetoxy! in theory AcH is infact acetaldehyde if one draws it out!


Sorry to tell you, but I'm not Sergi :P But you're right that Ac is acetyl and not acyl. Let's blame my old teacher ;)
Quote:
sometimes these boards get visted by arrogant jerks.. so what? if I cared a lot about conventions I wouldn't come here but I try to use a shorthand others can follow and if I make mistakes I don't mind a polite reminder. I do so dislike rudenss don't you?


Conventions are necessary in chemistry, so in case you'd like to keep on practicing it as a hobby, I'd suggest you try to follow them up to a certain level. Nobody here wants to hear about your distillation setup exploding at 1496° Mendelsohn at a pressure of 96.3 picogrignard.

Considering rudeness, I don't dislike it when I consider it justified. Dogmatized religion, IMHO, is the only thing more disguisting than political correctness.

JT07 - 20-3-2007 at 20:55

The method described here was rather dilute. Anyone tried to make NaH(OAc)4 at higher concentration?