1. Lecture 5c

2. Introduction 1 H-NMR spectroscopy is used to determine the structure of the epoxide based on characteristic splitting patterns in the aromatic range and the epoxide range When analyzing the spectrum, it will become much more difficult if the submitted sample is a mixture of many compounds i.e., epoxide, aldehyde, water (  =1.56 ppm), ethyl acetate (  =1.26 ppm, 2.05 ppm and 4.12 ppm), hexane (  =0.88 ppm, 1.26 ppm), etc. (see SKR, p. 284) The proton spectrum will exhibit a singlet at  =7.26 ppm due to the presence of CDCl 3 if the concentration of the epoxide is very low The carbon spectrum will show a “triplet” at  =77 ppm due to the presence of CDCl 3

3. 4-Methylstyrene oxide 1 H-NMR spectrum (integration in blue) H 1, dd H 2, ddH 3, dd 4 111 3 CH 3 H1-H2H1-H3H2-H3 J3J3 3.31 Hz3.30 Hz5.68 Hz

4. 4-Methylstyrene oxide 13 C{ 1 H}-NMR spectrum Seven signals total Epoxide carbons at ~ 50-60 ppm Four signals in the aromatic range The size of the peak for CDCl 3 depends on the concentration of the sample CDCl 3

5. 1 H-NMR spectrum (J 3(CH 2 -CHO) = 2.56 Hz) 4-Methylbenzacetaldehyde CH 2, “s” CHO, “s” 4 1 2 3 CH 3

6. 4-Methylbenzacetaldehyde 13 C{ 1 H}-NMR spectrum Aldehyde: ~200 ppm Methylene: 45-50 ppm Methyl group: ~30 ppm CHOCH 2 CDCl 3 CH 3

7. 4-Methylacetophenone 1 H-NMR spectrum Two doublets in the aromatic range, one of then significantly shifted downfield due to the adjacent carbonyl function Two singlets in the  2-2.5 ppm range due to the two methyl groups 22 3 3

8. 4-Methylacetophenone 13 C{ 1 H}-NMR spectrum Carbonyl: ~195 ppm (small) Methyl groups: 20-30 ppm CO CDCl 3 CH 3

9. What is that? Interpret the following 1 H-NMR spectrum

10. How about that one? Interpret the following 13 C{ 1 H}-NMR spectrum