[harvester of sorrow]

This is the proton NMR spectrum of butyric acid - http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi

I'm wondering about the chemical shift on the third group of peaks from the right (at 2,33). The one to the right at 0,98 is obviously R-CH₃, and the one to the left at 11,51 is RCOOH. The one at 2,33 I guess is H-C-C=O (shouldn't it be H₂, though?).
I'm thinking the one at 1,68 should be R₂-CH₂, but the chemical shift for R₂-CH₂ is listed only at 1,3 ppm.. (Chemical shift table: http://science.csustan.edu/tutorial/nmr/index.htm)

Also, what does the uppermost part of the table mean (where the scale goes from 0 to 240), and what is QE-300?

Any help would be greatly appreciated  

Edit: Somehow managed to mix up 1,68 and 2,33 in the original question..

[fledarmus]

Not quite.

What does your splitting pattern tell you about how many protons are adjacent to the signals at 2.33 and 1.68?

The QE-300 is the instrument the spectrum was taken on. It is a 300 MHz machine built by General Electric. The spectra at the top is a 13C spectra overlaid on your 1H spectra.

[harvester of sorrow]

What does your splitting pattern tell you about how many protons are adjacent to the signals at 2.33 and 1.68?

If I'm not mistaken the triplet splitting pattern for 2,33 shows two adjacent protons, whereas the sextet at 1,68 shows five protons.
I'm finding this logical because the one at 2,33 has two proton neighbors in the CH₂ to the right, and the one at 1,68 has two in the CH₂ to the left and three in the CH₃ to the right.
HOOC-CH₂-CH₂-CH₃

Is this correct?

[fledarmus]

Yes - the edit helped a lot! 

The reason that your 1.68 methylene is shifted from the 1.3 on the table is that the 1.3 is assuming that the rest of the molecule is a simple alkane. The carboxylic acid is a strongly electron withdrawing group, and can deshield electrons even a couple of carbons awy.  The chart you are using is very simplistic - using something like this http://www.chem.wisc.edu/areas/reich/handouts/nmr-h/hdata.htm will give you much more detail, probably more than you want, and there are all sorts of other forms of tabulated data for anything in between.

[harvester of sorrow]

Thanks a lot! 

One thing I'm still a bit confused about though: How come the one at 2,33 isn't something along the lines of RCH₂COOH? Why is there only one proton in H-C-C=O, when there are two in CH₂?

[stewie griffin]

Why not Creeping Death?

[fledarmus]

Thanks a lot! 

One thing I'm still a bit confused about though: How come the one at 2,33 isn't something along the lines of RCH₂COOH? Why is there only one proton in H-C-C=O, when there are two in CH₂?

They just aren't showing the other substituents on that carbon - this is just an attempt to indicate a hydrogen attached to a carbon attached to a carbonyl group. Frequently, dashes with nothing at the end of them are used to represent other binding sites on the carbons, but not always. This is not an especially informative table; I really would try to find something more useful to work with if you're going to do a lot of these.