The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

Organic chemistry help

I've been confused on this question, the answer is A but I don't understand why ? :

A compound, Q, gives an orange precipitate with 2,4dinitrophenylhydrazine.
Compound Q is resistant to oxidation.On reduction, Q gives a product made up of a pair of optical isomers.
Which of the following compounds could be compound Q?

A) CH3CH2CH2COCH3

B) CH3CH=CHCH(OH)CH3

C) CH3CH2CH2CH2CHO

D) CH3CH2COCH2CH3

All help would be greatly appreciated
Go through it one by one...

orange precipitate with 2,4dinitrophenylhydrazine.


What does this test for? Which, if any, of the compounds can you rule out as a result?

Compound Q is resistant to oxidation


Which functional groups can be oxidised? A is a ketone, B has an alcohol + alkene, C is an aldehyde and D is a ketone.

Can any more be ruled out, now?
As it reacts 2,4 dnp so is an aldehyde or ketone.
As wont oxidises further, must be a ketone or 3rd alcohol.
So is A, as A is a ketone.


Posted from TSR Mobile
Reply 3
Avatar for yousefshah77
yousefshah77
OP
Original post by EierVonSatan
Go through it one by one...



What does this test for? Which, if any, of the compounds can you rule out as a result?



Which functional groups can be oxidised? A is a ketone, B has an alcohol + alkene, C is an aldehyde and D is a ketone.

Can any more be ruled out, now?


I understand it now ! Thanks mate
Reply 4
Avatar for yousefshah77
yousefshah77
OP
Original post by Girling1996
As it reacts 2,4 dnp so is an aldehyde or ketone.
As wont oxidises further, must be a ketone or 3rd alcohol.
So is A, as A is a ketone.


Posted from TSR Mobile


Thanks for the help , appreciate it !
Original post by yousefshah77
Thanks for the help , appreciate it !

This answer wouldn't get all the marks though. Compound D is also a ketone and wouldn't oxidise further, you would need to say that as the reduced version of compound D would not form optical isomers as no carbon has 4 distinct groups, and therefore are no chiral centres, whereas in the reduced version of compound A, there are 4 distinct groups attached to a carbon atom, therefore there is a chiral centre

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you