C8953 NMR structural analysis - seminar 1D 13C-NMR + APT Ondˇrej Jurˇcek, Martin Novák jurcekondrej@mail.muni.cz, 323460@mail.muni.cz February 28, 2018 1 H vs 13 C NMR 1 H 13 C Spin number 1 H: s=1 2 × 2 H: s=1 13 C: s=1 2 × 12 C: 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 σdia σdia + σpara Integration of signals × T1 relaxation [s] 1-20 1-40 Homonuclear J-interaction × H↔C J-interaction (∼ 100-250 Hz) carbon satellites (n + 1) splitting × decoupling 1 H-13 Cα 1 H-13 Cβ 1 H-12 C ωC-0.51 JHCωC+0.51 JHC 1 JHC 1 JHC 1D 1 H NMR 1D 13 C NMR 1 Hβ-13 C1 Hα-13 C 1 H decoupled 1 H vs 13 C NMR 1 H 13 C Spin number 1 H: s=1 2 × 2 H: s=1 13 C: s=1 2 × 12 C: 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 σdia σdia + σpara Integration of signals × T1 relaxation [s] 1-20 1-40 Homonuclear J-interaction × H↔C J-interaction (∼ 100-250 Hz) carbon satellites (n + 1) splitting × decoupling Important regions of 13 C chemical shifts Aldehydes RCH=O Ketones R1R2C=O Carboxylic acids R-CO2H Esters R-CO2R' Amines R-CONR2' C-NO2 C-F C-Cl C-Br C-I C-H Saturated Hydrocarbons C-NH2 C-OH C-SR C-OR C-Ar C-SO2 R C-CO R C-C=C C CR RC N Heteroaromatics Aromatics R2C=CH2 RHC=CHR R2C=CH2 200 150 100 50 0.0 ppm(δ) Alkenes Alkynes 1 JCH depends on the bond order ( hybridization ⇔ s-character ) -C-H 1JCH ≈ 125 Hz =C-H 1JCH ≈ 160 Hz ≡C-H 1JCH ≈ 250 Hz X-C-H X = N, O, S, F, Cl, . . . 1 JCH ⇑ X = Li, Mg, . . . 1 JCH ⇓ 2 JCH < 0 or close to zero (<3 Hz) often not observable Values of chemical shift of important solvents Abbr. Formula 1 H 13 C ACN CH3CN 1.9 118 Benzene C6H6 7.2 128 CHCl3 7.2 77 DCM CH2Cl2 5.3 54 DMF (CH3)2NCHO 2.9, 8.0 32, 163 DMSO (CH3)2SO 2.5 40 MeOH CH3OH 3.3, 4.8 49 Water H2O 4.8 Effect of solvent on the position of residual 1H water signal: CHCl3 - 1.6, ACN - 2.1, DMSO - 3.3, MeOH - 4.9 How many 13 C signal would you expect in the NMR spectrum? Ru N N N N Cl Cl Cl S CH3 CH3 O N+ - N H 1D 13 C-NMR 1 1D 13 C-NMR 1 Notes: C1+C7 connected to electronegative groups (C1 quaternary) C2 ipso aromatic, C4+C6 shielded by M+ of OH C5+C4 NOE-enhanced in bit larger extend by close H C9→C12: decaying effect of N8 1D 13 C-NMR 2 1D 13 C-NMR 2 Notes: C7 carbonyl, C1 attached to N C3/5 deshielded by MCO, C2/6 shielded by M+ of NH2 C4 last quaternary aromatic signal C9 effect of esteric group, ? C10 affected by NH exchange C12/C14 + C13/C15 decaying effect of N+ 1D 13 C-NMR 3 1D 13 C-NMR 3 Notes: C3/C4 quaternary aromatic deshielded by O, Cβ quaternary coupled by CH3 and CαH Cα deshielded by NO2 C1 last quaternary aromatic signal C2/C6 coupled mutually and with Cα, C5 isolated (contraintuitive) quartets OMe, Cγ APT - Attached Proton Test based on heteronuclear spin echo t1 = 1/1JCH 13 C signals are differentiated according to the number of directly bound 1 H Cq, CH2 positive CH, CH3 negative Evolution of signal governed by the value of 1 JCH =⇒ reflected by the intensity of APT signal 90x 180y 180 H-1 C-13 acq dec t1 -1 -0.5 0 0.5 1 0 0.5 1 1.5 2 Relativeintensity t1 (1/1 JCH) Cq CH CH2 CH3 13 C APT Cinnamic acid 13 C APT Cinnamic acid 9 DMF 7 1 2,6 3,5 4 8 Notes: C9, C4 positive quaternary C7 deshielded by -M effect of carboxyl group + in neighbourhood of aromatic system equivalent C2/6, C3/5 in aromatic region, para C4 less sensitive 13 C APT of Nicotine 13 C APT of Nicotine 11 10 9 127 3 2,6 54 Notes: C2, C6 CH negative connected to N C3 quaternary, C4 more deshielded C7 tertiary carbon, in neighbourhood of aromatic system and N C9 secondary, close to N; C12 primary attached to N C11 connected to tertiary carbon 13 C APT 4 Cq Cq CH2 13 C APT 4 Cq Cq 2 6 4 8 13 12 5 11 15 14 1',2' CH2 Next topic Vector Model