| First off, thanks for asking an organic chemistry question. I just love organic! The Baeyer test for unsaturation is for determining the presence of carbon-carbon double bonded compounds, called alkenes or carbon-carbon trible bonded compounds, called alkyne bonds. The Baeyer test uses dilute Pottasium Permanganate to Oxidize the carbon-carbon double or triple bond. It’s called oxidation because the double bond is replaced by a hydroxy group (an OH group). The carbon’s charge goes from being +1 to +2, so it loses an electron (and is thus oxidized) The reaction looks like this: H H OH OH | | | | H-C=C-H + KMnO4 ------> H- C - C-H + Mn02 | | H H An alkene is replaced with a diol (a compound with 2 hydroxy groups). Evidence for the reaction is there because the purple Pottasium permanganate goes colorless. Alkynes work the same way, but a 4 hydroxy quattrol is produced (with 2 hydroxy groups on each carbon). The reaction is important because it doesn’t work on alkanes (compounds with carbon-carbon single bonds) or aromatic compounds. However, the test has a few drawbacks. Aldehydes (terminal carbonyls...carbon double bonded to Oxygen) will also be oxidized (to carboxylic acids) and formic acid (ethanoic acid) and its esters are known to give positive tests. I hope that explains it sufficiently. Jason |
(published on 10/22/2007)
(published on 08/13/2009)
(published on 12/22/2010)
