Chemistry 30A3 Fall 2011 Labs Dr. Troendle 49

Chemistry 30A3 Fall 2011 Labs Dr. Troendle 49 -...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Chemical Biology 3OA3, September 2009 Page 49 What gave Breslow's study broader significance was his recognition that thiamine (vitamin B 1 ) contains a thiazole unit and that a number of important biochemical reactions requiring it as a coenzyme could be understood as analogs of the benzoin condensation. Oxidation of Benzoin to Benzil Benzoin can be oxidized to the diketone benzil in a number of ways, of which the most interesting is by a "coupled oxidation" that uses Cu 2+ as the catalytic-transfer oxidant. In a coupled oxidation the overall oxidation proceeds in two distinct stages. In the present procedure, cupric acetate is used in catalytic amount (less than 1% of the stoichiometric requirement) and is
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: continuously reoxidized from the reduced (cuprous) state by ammonium nitrate, which is present in excess. The latter is reduced to ammonium nitrite, which decomposes in the reaction mixture into nitrogen and water. It is convenient to represent this two-stage oxidation in the manner used by biochemists, who commonly deal with multiple coupled reactions. Cupric salts are mild oxidizing agents that do not attack the diketone product. In the absence of Cu 2+ , ammonium nitrate will not oxidize benzoin (or benzil) at a significant rate. The reaction is general for α-hydroxyketones (acyloins) and is the basis for the Fehling's test for reducing sugars....
View Full Document

This note was uploaded on 01/08/2012 for the course CHM 30A3 taught by Professor Ricktroendle during the Fall '11 term at UNF.

Ask a homework question - tutors are online