C8953 NMR structural analysis - seminar 1D 13C-NMR Matúš Durec 211166@mail.muni.cz March 6, 2017 Diastereotopicity1 http://www.chem.wisc.edu/areas/reich/chem605/ □ Determine the number of nonequivalent 1H signals o o vs 13C NMR 1H 13q Spin number 1H:s=| x 2H:s=1 13C:s=| x 12C:s=0 Abundance [%] 99.98 1.1 Gyromagnetic ratio [107 rad.T-1 .s~1] 26.8 6.7 Chemical shift range [ppm] 0-15 0-200 Nuclear shielding Odia Cdia + Cpara Integration of signals / X 7i relaxation [s] 1-20 1-40 Homonuclear J-interaction / X H^C J-interaction (~ 100-250 Hz) carbon satellites (A7 + 1) splitting x decoupling 1D 1H NMR i 1D 13C NMR U)C+0.51JHC U)c-0.51Jhc 1H-13Ca 1H-13C(3 1Ha-13 1 UQ 13 Hp- 1u 1H decoupled vs 13C NMR H 13C Spin number 1H:s=| x 2H:s=1 13C:s=| x 12C:s=0 Abundance [%] 99.98 1.1 Gyromagnetic ratio [107 rad.T-1 .s~1] 26.8 6.7 Chemical shift range [ppm] 0-15 0-200 Nuclear shielding Odia Cdia + Cpara Integration of signals X 7i relaxation [s] 1-20 1-40 Homonuclear J-interaction X H^C J-interaction (~ 100-250 Hz) carbon satellites (A7 + 1) splitting x decoupling Important regions of 13C chemical shifts _L Aldehydes RCH= 0 RoC—CH5 Ketones R1R2C=0 I-1 RHC=CHR h Alkenes R2C=CH21-1 h Aromatics h Carboxylic acids R-C02H I-1 Esters R-C02R' I-1 Amides R-CONR2' I-1 Heteroaromatics I RC=N ! C-l h C-Br C-NO, C-H Saturated Hydrocarbons C-NH, ^ h C-OH C-SR C-OR H ^Ar^ C-S02 R C-C=C I-HI —I Alkynes C=CR I-1 h H C-CO R ~T~ 150 ~I- 100 ppm(5) 50 200 0.0 □ - = = -o o 1 Jch depends on the bond order ( hybridization o s-character) ► -C-H 1JCH « 125 Hz ► =C-H 1JCH ~ 160 Hz ► =C-H 1JCH « 250 Hz ► X-C-H - X = N,0,S,F,CI,...1JCh^ ► X = Li, Mg, ...1JCH^ 2 Jch < 0 or close to zero (<3 Hz) ► often not observable □ ► < = ► Values of chemical shift of important solvents Abbr. Formula 1H 13C ACN CHgCN 1.9 118 Benzene 7.2 128 CHCI3 7.2 77 DCM CH2CI2 5.3 54 DMF (CH3)2NCHO 2.9,8.0 32, 163 DMSO (CH3)2S0 2.5 40 MeOH CHgOH 3.3,4.8 49 Water H20 4.8 - Effect of solvent on the position of residual1H water signal CHCI3 -1.6, ACN - 2.1, DMSO - 3.3, MeOH - 4.9 Assign correct value of chemical shift to labelled NMR active atoms1: 97 http://www.chem.wisc.edu/areas/reich/chem605/ □ Draw the estimate of 13C NMR spectrum (with and without 1H decoupling): 4 □ ►