How can I report #""^13"C"# NMR data?

2 Answers
Sep 11, 2015

In a typical lab report, I would expect someone to report the following data:

  • Number of unique carbons in the molecular formula
  • Number of distinct #""^13 C# peaks seen in the spectrum
  • Presence or absence of symmetry (such as in a benzene ring with two identical substituents para or meta to each other)
  • Chemical shifts of each unique carbon in #"ppm"#
  • Proposed carbon types (e.g. #"C sp"^3# (likely alkyl) bonded to carbonyl #"C sp"^2#); this can be an educated guess
  • Your carbon labels (e.g. #"C"_A, "C"_B#, etc.)

This is how I tended to do it when I took O-Chem:

Based on the table, I said that #"C"_A# was the methyl attached to the carbonyl, #"C"_F#, #"C"_E#, and #"C"_D# were the aromatic carbons, starting from the top carbon on the ring going counterclockwise as well as their symmetric counterparts on the opposite side of the symmetry axis, #"C"_C# was the aromatic carbon directly connected to the carbonyl carbon, and #"C"_B# was the carbonyl carbon.

In published research papers though, you should not have any row borders (except those below a heading), nor outermost column borders, at least by ACS convention. Also, you would need a table caption at the top, explaining briefly what the table is showing.

For a lab report, you follow the format specified by your instructor.

Explanation:

If your instructor has not specified a format, Truong-Son N. has provided you with an excellent template in the preceding answer.

Research journals usually have their own formats for the reporting of #""^(13)"C"# NMR data.

These include rules such as:

  • The peak shifts should be rounded off to the nearest 0.1 ppm except when greater precision is needed to distinguish closely spaced peaks.
  • Information about numbers of hydrogen atoms may be included, in order of increasing number of attached hydrogens.
  • Detailed peak assignments should not be included in the Experimental section (they go in the Discussion section).

The usual format is:

#""^(13)"C"# NMR (frequency, solvent) #δ# in decreasing order of frequency.

Thus, you might see spectra reported in formats such as:

#""^(13)"C"# NMR (50 MHz, #"CDCl"""_3#) #δ# 145.4, 129.3, 128.5, 29.1, 16.0

#""^(13)"C"# NMR (50 MHz, #"CDCl"""_3#, DEPT) #δ# 145.4, 129.3, 128.5, 29.1, 16.0

#""^(13)"C"# NMR (50 MHz, #"CDCl"""_3#, DEPT) #δ# #"C"# 145.4, #"CH"# 128.5, 128.9, 129.3, #"CH"_2# 29.1, #"CH"_3# 16.0