In a lab the following synthesis was performed: [(tBu)H3N]Cl + NaBH4 (tBu)H2NBH3

Question

In a lab the following synthesis was performed: [(tBu)H3N]Cl + NaBH4 (tBu)H2NBH3 + NaCl + H2 (the reaction occured in THF)

It says the BH3 was created in situ (in reaction mixture), and used in the above reaction as it is generated. How is the BH3 prepared? It says to consider the  [(tBu)H3N]+ as an acid and the BH4- as a base.

Im not totaly sure about the process, but I think the BH4 must some how attack [(tBu)H3N]+ stripping it of its hydrogen, and in the process remove one of the hydrogens from the B complex.

Or since it says to consider the  [(tBu)H3N]+ as an acid, is a proton given off, and the BH4- will use a pair electrons from one of the BH bonds, and attack the H+ making H-H?

I would like to try and understand it on my own if possible, so can someone please just point me in the right direction.

Explanation / Answer

Lewis Acid-Base Adduct:

Based on the Lewis theory, acids one is the acceptance of electron pairs and bases is the donation of electron pairs.

Lewis’s definition give for a ready description of the formation of adducts between two stable compounds in terms of acid-base pairs. In mechanisim one need only place a compound containing a free lone pair of electrons in the presence of a compound that is electron deficient and has an open site in its coordination sphere to produce an Lewis acid-base adduct.

same as above above example applicable for this adduct.

in the tert-butylamine hydrochloride acts a base donate a electron pair to acid (sodium tetraorohydride) so in the process the H- ion will leave form as H2 (this H-abstrats H+ from HCl) other side form NaCl the Cl- will react with Na+.

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