(More) NMR practice problems Sources: Ch14C, Spring 2012 Prof.

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Presentation transcript:

(More) NMR practice problems Sources: Ch14C, Spring 2012 Prof. Dong

Rough 13 C-NMR guidelines ketone210 ppm aldehyde200 (this is a nice even number to remember) carboxylic acid180 ester/amide170 C=C120 C≡C80 C-O60 (note that CHCl 3 appears at 77 ppm) C-C0-30 – CH – Neobutane25.0 TMS Si(CH 3 ) 4 0 ppm (set as reference)

For each structure: 1. Calculate the number of peaks you would expect on 13 C-NMR for each of these structures. 2. Using the molecular formula, calculate the number of DBEs expected and compare it to the actual structure Answers. Number of equivalent carbons (from left to right): 5, 6, 9, 3, 1, 5

Beginner #7, C 14 H 14 Solvent: CHCl 3

Beginner #10, C 10 H 10 O Solvent: CHCl 3

Beginner #12 C 6 H 12 O 2 Solvent: CHCl 3

Beginner #27, C 3 H 7 OCl Solvent: CHCl 3

Beginner #25, C 4 H 8 O Solvent: CHCl 3

Int1 #1, C 3 H 4 O Solvent: CHCl 3

Int1 #16, C 6 H 10 O Solvent: CHCl 3

3H, s 2H, t 2H,p 2H,sextet 3H,t 2H, t 2H,p 2H,sextet3H,t 1 H-NMR 13 C-NMR Int1 #2, C 8 H 12 O 2 Solvent: CHCl 3

Int2 #13, C 10 H 15 N The normal, “standard” 13 C-NMR Up: CH, CH 2, CH 3 Up: CH Up: CH and CH 3 Down: CH 2 Example of a DEPT 13C-NMR spectra (four 13 C-NMR spectra) Solvent: CHCl 3

Int#12, C 7 H 9 NO The normal, standard 13 C-NMR Up: CH, CH 2, CH 3 Up: CH Up: CH and CH 3 Down: CH 2 Solvent: CHCl 3