CHEM 3331 1nd Edition Lecture 28Outline of Last Lecture I. NMR SpectroscopyII. Number of different peaksIII. Position of peaksIV. Peak areaV. Peak splittingOutline of Current Lecture I. NMR C13Current LectureI. NMR C13C12 is NMR inactive and accounts for 98.9% of a carbon molecule.C13 is NMR active and accounts for 1.1% of a carbon molecule.C14 is NMR inactive and is only in trace amounts since it is radioactive.There is a 100 fold lower sensitivity then in proton NMR. Takes over an hour to get results. ƔC=1/4ƔH sensitivity is 400 times lower in C NMR.C13 will feel electronic disturbances easier. The range for C NMR is 0-250 ppm.Alkanes= 0-40 C-O=55-90 C=C=100-150 C=O=160-210 C≡C= 75-100Spectra are recorded in D2O, CDCl3, and CD2Cl2. H is replaced with deuterium so we don’t get peaks from H in the solvent. CDCl3 is the most common and is indicated by three lines around 77ppm with a 1:1:1 ratio. Peak areas mean nothing in C NMR. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Peak splitting: H-H= common= splitting C-H= 100x less common= splitting= intentionally suppressed with continuous irradiation C-C= 10000x less common= negligibleTherefore peaks are
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