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nmr help

Hey,

I have a question asking:

state the no. of peaks in the proton nmr spectrum of CH30CH2CH2OCH3. Sorry, dont know ho to do subscript. It's an ether with the C-O-C linkage hence it CH30CH2 etc, if that's helpful.

i've got the answer as four, but the mark scheme says its 2, can anyone explain why? Is it because singlets aren't recorded on the spectrum?

Thanks.
Symmetry is the reason the left half is the same as the right - and so is in an identical environment :smile:
Reply 2
Avatar for Dstbgre
Dstbgre
EierVonSatan
Symmetry is the reason the left half is the same as the right - and so is in an identical environment :smile:


Damn - beat me to it!
Reply 3
Avatar for JUSTME1
JUSTME1
It would be 2 one for the CH2 groups and one for the CH3 groups. Its because they are in the same chemical enviroment. They attached to the same atoms on both sides.
Dstbgre
Damn - beat me to it!


:wink:
Reply 5
Avatar for Dstbgre
Dstbgre
EierVonSatan
:wink:


:p:
yep, always watch out for symmetrical molecules
JUSTME1
It would be 2 one for the CH2 groups and one for the CH3 groups. Its because they are in the same chemical enviroment. They attached to the same atoms on both sides.


ok i see... so i you have two of the same adjacent to each other e.g. two triplets adjacent to one another, it actually counts as one? Hence there are two here?
Reply 8
Avatar for JUSTME1
JUSTME1
yep if they in the same chemical enviroment they count as one,regardless of the amount of hydrogens.
So if the two sets of hydrogen are symmetrical, they count as being in the same chemical environment e.g CH2-CH2?
Reply 10
Avatar for Aliaaa
Aliaaa
huh?? please explain it clearly =(
Reply 11
Avatar for JUSTME1
JUSTME1
so CH3CH2CH3.

would have two peaks. one for the CH3 group and one for the CH2 groups as the hydrogens in the CH2 groups are in the same chemical enviroment as the CH2 group hydrogens are attached to a CH3 group.


The only diffrence will be how the two peaks split.


The CH2 peak will split in to 7 following the N plus 1 rule. N being amount of carbons. The CH3 will be split in to three.


correct me anyone if im wrong.


hope it helps.
JUSTME1
so CH3CH2CH3.

would have two peaks. one for the CH3 group and one for the CH2 groups as the hydrogens in the CH2 groups are in the same chemical enviroment as the CH2 group hydrogens are attached to a CH3 group.


The only diffrence will be how the two peaks split.


The CH2 peak will split in to 7 following the N plus 1 rule. N being amount of carbons. The CH3 will be split in to three.quote]
why would CH2 be split into 7 im preety sure its 4 :confused:
Reply 13
Avatar for JUSTME1
JUSTME1
because when the CH2 looks around it sees 6 carbons, three to the left three to the right and according to the N plus one rule you add an extra one. making it 7.

dont want to hijack the thread but does anyone know how to convert cm3 in to dm3 is it divide by 1000.


Thanks
For CH3OCH2CH2OCH3

Singlet - integration 6
Singlet - integration 4

:yep:
Reply 15
Avatar for JUSTME1
JUSTME1
could you explain that please.
Protons (H's) only couple to give splitting when the see other protons on carbons next to them that are in different enviroments...because oxygen separates the two sets of protons H3C-O-CH2 - X they can't couple (give splittings)
Reply 17
Avatar for JUSTME1
JUSTME1
they would be singlets...... sorry i thought u meant the splliting pattern would be 6 and 4 my mistake......
JUSTME1
they would be singlets...... sorry i thought u meant the splliting pattern would be 6 and 4 my mistake......


No worries :smile:

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