Author Topic: Alkene reaction  (Read 1426 times)

Offline ashwinkandel

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Alkene reaction
« on: October 05, 2010, 02:10:02 pm »
what happens when CH2=COHCH2 reacts with hot concentrated KMNo4. i know the rupturing occurs on the double bond and oxygen is formed on the both sides of the ruptured double bond. there are 2 H on the right right so it changes into CO2+H2O. but what happens to the right side to the alcohol(OH). does it remains the same or changes. one question related to this

The compound hex-3-en-1-ol, P, has a strong ‘leafy’ smell of newly cut grass and is used in
perfumery.
CH3CH2CH=CHCH2CH2OH
P
What is produced when P is treated with an excess of hot concentrated acidic KMnO4?
A CH3CH2CH(OH)CH(OH)CH2CH2OH
B CH3CH2CH=CHCH2CO2H
C CH3CH2CHO and OCHCH2CH2OH
D CH3CH2CO2H and HO2CCH2CO2H

Offline Deadly_king

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Re: Alkene reaction
« Reply #1 on: October 05, 2010, 02:23:57 pm »
what happens when CH2=COHCH2 reacts with hot concentrated KMNo4. i know the rupturing occurs on the double bond and oxygen is formed on the both sides of the ruptured double bond. there are 2 H on the right right so it changes into CO2+H2O. but what happens to the right side to the alcohol(OH). does it remains the same or changes. one question related to this

The compound hex-3-en-1-ol, P, has a strong ‘leafy’ smell of newly cut grass and is used in
perfumery.
CH3CH2CH=CHCH2CH2OH
P
What is produced when P is treated with an excess of hot concentrated acidic KMnO4?
A CH3CH2CH(OH)CH(OH)CH2CH2OH
B CH3CH2CH=CHCH2CO2H
C CH3CH2CHO and OCHCH2CH2OH
D CH3CH2CO2H and HO2CCH2CO2H

Usually the OH group should have been oxidised to a ketone since it was a secondary alcohol. But the methyl group gets detached and form CO2 and H2O.

This leaves a primary alcohol which I believe will get oxidised to a carboxylic acid.

Now the example :

Since hot acidified KMnO4 is being used the compound will be oxidised to two carboxylic acids as the carbon-carbon double bond breaks!

Moreover the OH group on the last carbon will also be oxidised to a carboxylic acid as well.

Answer is D

Offline ashwinkandel

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Re: Alkene reaction
« Reply #2 on: October 05, 2010, 02:37:09 pm »
in the question i gave, you said that OH group will be converted in carboxylic acid. but if the answer is d then whole CH2OH is converted into carboxylic acid , isn't it?

Offline Deadly_king

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Re: Alkene reaction
« Reply #3 on: October 05, 2010, 02:41:45 pm »
in the question i gave, you said that OH group will be converted in carboxylic acid. but if the answer is d then whole CH2OH is converted into carboxylic acid , isn't it?


Yeah.........you got that right!

You will hence obtain a product containing two carboxylic groups (diprotic acid)