CHEM 2311 Lecture Notes - Lecture 21: Phenyl Group, Nitro Compound, Spectroscopy
Document Summary
Be able to use nmr, mass spectrometry and c13 for exam 5. The six methyl hydrogens are homotopic and the 2 vinyl hydrogens are homotopic. Multiplicity is 1 for both these types of hydrogens 2 peaks. Spin- spin coupling can be long range: 3. splitting patterns in aromatic groups can be confusing. 7 to 9 ppm usually means aromatic ring occurs. 5 protons = monosubstituted; 4 protons = disubstituted; 3 protons = trisubstituted: ex. 1- nitropropane splitting of hb into 6 peaks. Proton nmr spectra and rate processes: oh doesn"t split since they are too fast at splitting doesn"t contribute to multiplicity, ex. Carbon 13 nmr spectroscopy: c12 is inactive since it has no magnetic spin and produces no nmr signal. Instead we use c13 is good since it occurs little in natural settings: finding 2 adjacent c13 is minuscule will only show singlets. Examples: 1- chloro -2- propanol, broadband decoupled spectrum.
