NMR SPECTROSCOPY DR. M. KANJIA. Copyright reserved NMRS. Application to reproduce to Dr M Kanjia

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1 NMR SPECTROSCOPY DR. M. KANJIA Copyright reserved NMRS Application to reproduce to Dr M Kanjia

2 13 C NMR Spectra of Butan-2-ol CH 3 CHOH CH 2 CH DEPT 13 C NMR CH 3 CHOH CH 2 CH 3 D = Doublet T = Triplet Q = Quartet 1 H coupled 13 C NMR D T Q Q CDCl 3 Decoupled 13 C NMR

3 1 H coupling to 13 C in 13 C NMR Spectra No. of peaks = 2nI + 1 n is No of spin active nuclei ( 1 H ) [ Neighbours ] I is Spin number of the active nucleus ( 1 H = ½ ) H H H H C C C C H H Methyl 13 C Methylene 13 C Methine 13 C Quaternary 13 C Quartet Triplet Doublet Singlet

4 Notation For Coupling Constant ( 1 J 2 J, 3 J, 4 J & so on ) In 1 H NMR spectra, the most common coupling constant is encountered 1 H three bonds apart 3 J. This is also called as Vicinal Coupling. The angle alpha factor in vicinal coupling. When angle alpha = 0 0 and The coupling constant is maximum = 90 0 The coupling constant is minimum 3 J Doublet Doublet

5 Analysis and Interpretation of 1 H NMR Spectrum of Ethyl-2-Fluoropropionate CH 3 -CHF-CO-O-CH 2 CH 3 F CH 3 -C-CO-O-CH 2 -CH 3 H CH 2 Quartet CH 3 D of D CH 3 Triplet CH D of Q

6 Analysis and Interpretation of 1 H NMR Spectrum of Ethyl-2-Fluoropropionate CH 3 -CHF-CO-O-CH 2 CH 3 F CH 3 C CO O CH 2 CH 3 H CH 4.98 PPM Doublet of Quartet JCH CH 3 = 6.87 Hz JCH F = Hz CH PPM Quartet JCH 2 CH 3 = 7.12 Hz CH PPM Triplet JCH 3 CH 2 = 7.12 Hz CH PPM Doublet of Doublet JCH 3 CH = 6.87 Hz JCH 3 CF = Hz

7 Analysis and Interpretation of 13 C NMR Spectrum of Ethyl-2-Fluoropropionate CH 3 -CHF-CO-O-CH 2 CH 3 CH PPM Singlet CH PPM Doublet JCH 3 F = Hz CH PPM Singlet CHF PPM Doublet JC F = Hz CO PPM Doublet JCO CF = Hz CH 3 CHF CO O CH 2 CH 3 CDCL 3

8 Analysis and Interpretation of 13 C NMR Spectrum of Ethyl-2-Fluoropropionate ( Expansion ) CH 3 -CHF-CO-O-CH 2 CH 3 19 F spin I = ½ CO CF Doublet PPM 2 J = Hz No. Peak = 2nI + 1 = n + 1 = = 2 ( Doublet ) Here n=1 F nucleus Hence all are doublets 13 C is coupling to 19 F CH 3 CHF CO O CH 2 CH 3 C F Doublet PPM 1 J = Hz CH 3 CF doublet PPM 2 J = HZ CO C-F CH 3

9 Analysis and Interpretation of 13 C NMR Spectrum of Ethyl-2-Fluoropropionate ( Dept 135 ) CH 3 -CHF-CO-O-CH 2 CH 3 CH 3 CHF CO O CH 2 CH 3 Quaternary Carbon gives no peak hence CO no signal CHF CH 3 CH 3 CH 2

10 1 H NMR Spectrum Of Sodium Borohydride in D2 O NaBH to 2.00 PPM Range Coupling from the same atom of different spin Isotope % Spin No. SF MHz I D 2 O Quartet And Septet 10 B B / For 1 H No. of peaks = 2 x n x I + 1 ( n = 1 ) Spin active nucleus neighbour ( Boron ) 10 B interaction to 1 H No. of Peaks = 2 x 1 x 3 +1 = 7 septet 11 B interaction to 1 H No. of Peaks = 2 x 1 x3 /2 +1 = = 4 Quartet Intensity Ratio of NMR Signal from 10 B & 11 B will be 1 : 4 reflecting its Isotopic concentration in the atom. CopyRight Reserved NMR Spectroscopy 2007 Application to reproduce Hence to Dr M Quartet Kanjia is four times taller than Septet.

11 Expansion of 1 H NMR Spectrum Of Sodium Borohydride in D 2 O NaBH 4 11 B gives Quartet Intensity 4 times 10 B gives Septet Intensity 1 /4

12 Expansion of 1 H NMR Spectrum Of Sodium Borohydride in D 2 O NaBH 4 J 11 B H = Hz J 10 B H = Hz

13 10 B & 11 B NMR Spectra Of Sodium Borohydride in D 2 O NaBH 4 10 B NMR -710 To PPM Quintet 11 B NMR -10 To - 90 PPM Quintet

14 10 B & 11 B NMR Spectra Of Sodium Borohydride in D 2 O NaBH 4 10 B NMR Quintet J 10 B H = Hz 11 B NMR Quintet J 11 B H = Hz

15 19 F NMR of Sodium tetrafluoroborate In D2 O NaBF 4 Septet Isotopic Shift Quartet Coupling from the same atom of different spin Isotope % Spin No. SF MHz I 10B B / For 19F No. of peaks = 2 x n x I + 1 ( n = 1 ) Spin active nucleus neighbour ( Boron ) 10B interaction to 19F No. of Peaks = 2 x 1 x 3 +1 = 7 septet 11B interaction to 19F No. of Peaks = 2 x 1 x3 /2 +1 = = 4 Quartet Intensity Ratio of NMR Signal from 10B & 11B will be 1 : 4 reflecting its Isotopic concentration in the atom. Hence Quartet is four times taller than CopyRight Reserved NMR Spectroscopy 2007 Application to reproduce to Dr M Septet. Kanjia

16 2D COSY 1 H NMR Spectrum of n-butyl salicylate n-butyl Aromatic

17 13 C NMR Spectrum of n-butyl Salicylate INEPT 13 C NMR Spectrum DEPT C NMR Spectrum 13 C NMR Spectrum C5 C6 C4 C3 -CO-O-CH 2 -CH 2- CH 2 -CH 3 Notice the effect of shielding & deshielding on C1 & C2 C1 C2

18 1 H 13 C COR Spectrum n-butyl Salicylate Aromatic H4 -CO-O-CH 2 -CH 2 -CH 2 -CH 3 H3 H6 H5 Note the shielding effect on 13 C Signal positions with respect to aromatic 1 H. The quaternary 13 C have no correlated peaks hence no foot print in 2D Spectrum ( -CO-, 1H & 2H )

19 13 C NMR Spectrum of Trans FARNESOL In CDCl3 C 15 H 26 O Six 13C from CH= & -C- CDCl 3 Nine 13C from CH2 & CH3

20 13 C & DEPT 135 NMR Spectra of Trans Farnesol In CDCl3 C 15 H 26 O D C B A 2 1 E CH 3 (Four) CH ( Three) DEPT 135 NMR A B C D CH 2 ( Five) Quaternary 13 C CDCl