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C 13 NUCLEAR MAGNETIC RESONANCE (NMR). 13 C NMR. 13 C occurs naturally as 1.11% of total C and the NMR signal is weaker than 1 H. Fourier Transform NMR is used to collect a spectrum. 13 C resonances occur from 0 to 200 ppm ( δ ) so there is little interference with 1 H δ values.
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13C NMR 13C occurs naturally as 1.11% of total C and the NMR signal is weaker than 1H. Fourier Transform NMR is used to collect a spectrum. 13C resonances occur from 0 to 200 ppm (δ) so there is little interference with 1H δ values. 13C peaks are split by the attached hydrogens. Off-resonance decoupling eliminates interactions of hydrogens on adjacent carbons. Broadband decoupling eliminates splitting of C by Hs attached to that C.
13C NMR Distortionless enhancement by polarization transfer (DEPT) spectra permit identification of CH3, CH2, and CH carbon atoms. DEPT 45 shows 1o, 2o,and 3o carbons. So any broadband peak not in DEPT 45 is 4o. DEPT 90 shows only 3o carbons. DEPT 135 shows 1o and 3o carbons as positive peaks and 2o carbons as negative peaks.
1H & 13C NMR: 1,1,2-trichloropropane Broadband
13C Off-resonance & Broadband decoupled spectra Off-resonance Broadband
13C NMR – n-Hexane Broadband
13C NMR – Acetone Broadband
1H & 13C NMR: 2-methyl-2-butene Broadband
1H & 13C NMR: 2-methyl-1-butene Broadband
13C NMR – 6-methyl-5-hepten-2-ol Broadband All carbons as singlets
13C NMR – 6-methyl-5-hepten-2-ol DEPT 90 Only CH carbons
13C NMR – 6-methyl-5-hepten-2-ol DEPT 135 Methyl and CH positive Methylene negative