Chemistry

WSU NMR Project

Organic Chemistry Survey - Dr. Nalli

Presentation given at 229th National ACS Meeting in San Diego, March 17, 2005. An NMR Intensive Organic Curriculum

13C NMR of Alkanes – Class Project: Each team prepared an NMR sample using an assigned alkane from among the following; pentane, hexane, heptane, cycloheptane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, and dodecane. Non-alkanes, cyclohexene and 1-bromopropane were also assigned in certain cases. The instructor provided initial training in operating the spectrometer by talking the students through the procedures need to obtain the spectra. Approximately 30 min of spectrometer time for each group was allotted, so teams of three were used in this experiment. Time away from the spectrometer was used to finish up the previous experiment (melting point determinations). Students were asked to write a lab report which used all of the spectra obtained by the class, which were posted in printable format on the course website (links are below). The lab report included making peak assignments, labeling spectra, tabulating the results, and identifying and explaining chemical shift trends.

Proton NMR of Aromatics – Class Project: Each team prepared an NMR sample using an assigned arene from among the following; tert-butylbenzene, nitrobenzene, 2,2'-diiodobiphenyl, 1-iodo-2-nitrobenzene, 1-iodo-3-nitrobenzene, 1-iodo-4-nitrobenzene, 4-bromoanisole, 1-bromo-4-fluorobenzene, mesitylene, 4-bromotoluene, 2,6-di-tert-butyl-4-methylphenol (BHT), acetylsalicylic acid, and benzophenone. The instructor assisted and instructed as students obtained their spectrum, integrated it, and printed it out. The spectra were posted in a printable format on the course website. The spectra obtained ranged from very simple with no spin-spin splitting present (BHT, mesitylene) to fairly complex with splitting patterns due to meta and fluorine coupling evident. Students were asked to write a report that included peak assignments, labeling spectra, measuring J values, tabulating the results, discussing the chemical shifts found for aromatic protons, generalizing o, m and p splitting patterns, and predicting spectra for other compounds