WOAHHI

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Dec 28, 2008
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I was wondering if someone could tell me the HNMR pattern that we should expect from Propanal. Kaplan seems to claim the chart would look like this:

http://jasper.kaptest.com/content/media/05/46005.0.ospq09g01.gif

but I was wondering why the H on the carbonyl carbon does not get split since it is adjacent to the 2 H's of the CH2.

Then i found this...

http://www.yteach.co.uk/page.php/resources/view_all?id=nuclear_magnetic_resonance_NMR_spectroscopy_high_resolution_coupling_atom_non_equivalent_oxygen_nitrogen_t_page_10&from=search

-- can't get a clear answer =/ help ! thank you!
 

BTtheman777

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Nov 26, 2008
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I dont think either or those are correct. There are 3 different types of protons thus you should see 3 peaks. The Proton on the aldehyde is extremely deshielded and it will not split any other protons thus it will have ONE peak around 10 ppm. The 2 protons attached to the alpha carbon will have a quartet that is further downfield (since it is closer to the carbonyl carbon) than the protons attached to the beta carbon (triplet).

http://www.chem.ucalgary.ca/courses/351/nmrsketch/13/nmr.html

Try to figure it out and when you are down, hit ""give up" . It will show you the correct HNMR and then why those signals are present.
 

saDDS

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Dec 7, 2008
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the first one is close, except as the previous poster said the one that is farther downfield should be the quartet.
 
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W

WOAHHI

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Dec 28, 2008
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thank you! mmm its weird that kaplan has a mistake..
 

miedvied

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Apr 23, 2009
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