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Topic: Aldehydes and Ketones  (Read 3780 times)

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4mylGL6

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Aldehydes and Ketones
« on: January 30, 2006, 09:44:37 AM »
Why is it that when KMnO4 is added to a primary alcohol it creates an aldehyde, and then an organic acid, and when it is added to a secondary alcohol, it creates a ketone?
Why does the oxygen atom create these particular bonds in these alcohols?

Offline Alberto_Kravina

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Re:Aldehydes and Ketones
« Reply #1 on: January 30, 2006, 11:04:59 AM »
In a secondary alcohol the OH group is between 2 alkyl groups. The oxidizing agent oxidizes the OH group to a carbonyl group C=O. Since the carbonyl group is between two alkyl groups the end product is a ketone. R-CO-R

In a primary alcohol the OH group is attached to an alkyl group and a H-atom. Again, the oxidizing agent dehydrogenates the OH group to a carbonyl group, but since the C=O functional group is't between 2 alkyl groups but between an alkyl group and a hydrogen atom the product is an aldehyde. The aldehyde is partially oxidized to an acid with excess oxidizing agent.

This are the differences between a primary and a secondary alcohol:

H3C-CH2-OH => Example for a primary alcohol (Ethanol)
H3C-CH-CH3 => Example for a secondary alcohol
        |
         OH  

By the way, I would suggest to move this topic in the organic chemistry forum :coffee1:
« Last Edit: January 30, 2006, 11:27:47 AM by Alberto_Kravina »

forislam20

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Re:Aldehydes and Ketones
« Reply #2 on: January 30, 2006, 11:08:14 AM »
hydrogen atoms are the most important thing to care for on the oxidation of carbonyl compounds ;D!!!!!!!!!!!1

Offline qlabel

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Re:Aldehydes and Ketones
« Reply #3 on: February 01, 2006, 10:18:20 AM »
Aldehydes are more reactive than ketones, just to say it.

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