The Student Room Group

Chemistry question help

Hi. I have a question that I really can't understand. It's about drawing a possible structure for each species asked for in the question. I've completed what F is, but can't figure out what E is. Any help would be appreciated.

Question: c) Compounds E and F are esters with the molecular formula C5H10O2. The proton NMR spectrum of E consists of two singlets only whereas that of F consists of two quartets and two triplets.
Original post by KMarC
Hi. I have a question that I really can't understand. It's about drawing a possible structure for each species asked for in the question. I've completed what F is, but can't figure out what E is. Any help would be appreciated.

Question: c) Compounds E and F are esters with the molecular formula C5H10O2. The proton NMR spectrum of E consists of two singlets only whereas that of F consists of two quartets and two triplets.

I’d start by using the fact that there is an ester functional group in E. Do you know what the structure of an ester functional group looks like?

Singlet peaks imply no adjacent non-equivalent hydrogen environments. That simply means that any atoms which hydrogen atoms are bonded to are not bound to other atoms which are also bonded to hydrogen atoms that are considered to be in a different hydrogen environment.
(edited 1 year ago)
Reply 2
Original post by TypicalNerd
I’d start by using the fact that there is an ester functional group in E. Do you know what the structure of an ester functional group looks like?

Singlet peaks imply no adjacent non-equivalent hydrogen environments. That simply means that any atoms which hydrogen atoms are bonded to are not bound to other atoms which are also bonded to hydrogen atoms that are considered to be in a different hydrogen environment.

Hi, yes I do know what the structure looks like, but I'm struggling to figure out how there'd only be singlet peaks if it's a 5 carbon molecule. Thanks
Original post by KMarC
Hi, yes I do know what the structure looks like, but I'm struggling to figure out how there'd only be singlet peaks if it's a 5 carbon molecule. Thanks

If you have multiple CH3- groups bonded to the same carbon atom, they all constitute one hydrogen environment. If that carbon atom that the several CH3- groups are bonded to has no hydrogens on it, the signal due to the CH3- groups will be a singlet. Considering that the carbon bound to all the CH3- groups will form part of the ester group, how many CH3- groups fit on it?

Hint: the molecule contains an ester functional group, so it has -(C=O)-O-C- as part of its structure. This may be a useful starting point.
(edited 1 year ago)
Reply 4
Original post by TypicalNerd
If you have multiple CH3- groups bonded to the same carbon atom, they all constitute one hydrogen environment. If that carbon atom that the several CH3- groups are bonded to has no hydrogens on it, the signal due to the CH3- groups will be a singlet. Considering that the carbon bound to all the CH3- groups will form part of the ester group, how many CH3- groups fit on it?

Hint: the molecule contains an ester functional group, so it has -(C=O)-O-C- as part of its structure. This may be a useful starting point.

Good morning. This helps a lot, I think the answer would be dimethyl ethyl methanoate. Thank you so much!

Quick Reply

Latest