thors.lab
Hazard to Others
Posts: 103
Registered: 19-7-2019
Member Is Offline
|
|
H-NMR Multiplicity of aldehyde hydrogen on 3-fluorobenzaldehyde
So I would suspect the aldehyde hydrogen on 3-fluorobenzaldehyde to be a singlet right? The adjacent carbon has no hydrogens attached. But the
ChemAxon chemicalize calculator says that would be a triplet:
Why? Is this something to do with the conjugated system?
|
|
DraconicAcid
International Hazard
Posts: 4337
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
Yes, you can sometimes get what is called "W-coupling".
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
thors.lab
Hazard to Others
Posts: 103
Registered: 19-7-2019
Member Is Offline
|
|
Awesome, thank you!
|
|
AvBaeyer
National Hazard
Posts: 651
Registered: 25-2-2014
Location: CA
Member Is Offline
Mood: No Mood
|
|
The multiplicity is a result of long distance coupling with the fluorine atom. H-F couplings occur through several bonds. Any good NMR text will give
you an explanation with examples.
AvB
|
|
DraconicAcid
International Hazard
Posts: 4337
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
Quote: Originally posted by AvBaeyer | The multiplicity is a result of long distance coupling with the fluorine atom. H-F couplings occur through several bonds. Any good NMR text will give
you an explanation with examples.
AvB |
No, because it's a triplet. If it was coupling to the F, it would be a doublet.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
Sigmatropic
Hazard to Others
Posts: 307
Registered: 29-1-2017
Member Is Offline
Mood: No Mood
|
|
W coupling would be 4J, in this example it is 5J. So no W coupling. Also in reality it is a doublet, see attachment, so I second avbaeyer. Source:Sigma aldrich
Attachment: FNMR010527.PDF (99kB) This file has been downloaded 289 times
|
|