oxidation of menthol to menthone

bunya Mon, 09/10/2007 - 21:54

Hi,

Just wondering if anyone could help me out with some questions im struggling to answer.

In relation to the topic:

1) How can I explain the colour changes during oxidation, in relation to oxidation-reduction?

2) Why was it important that temp remained low and that a large excess of ox agent was avoided?

3) If citronellol was oxidised the same way what product would come about and why?

4) Finally, the (+) and (-) signs in front of menthol and menthone, does that just represent the fact there is a 50/50 mixture of enantiomers?

I need this info ASAP!!!!

Thanks

1) Color change can be due to pi-bonding.  The more delocalized electrons you have, the different colors you can get b/c of the various energies

2)  Kinetics is related to temperature.  The hotter things are, the faster they react.  Keeping the temp low can prevent some side reactions.  If menthol has a primary alcohol, over oxidation can result in going from an alcohol --> aldehyde --> carboxylic acid.  You might only want the aldehyde.

3)  I don't know the structure of citronellol

4)  They are racemic.

Thanks so much!

Citronellol has the same molecular formular as menthol but it is not a cyclo. any ideas what its product might be if it was oxidised under the same conditions of menthol? and why this would be?

Thanks again :)

Menthol has a secondary alcohol which can only be converted to a ketone

Citronellol has a primary alcohol which can be converted to an aldehyde or a carboxyclic acid if it gets over oxidized