11-13 - 11/13/2009 The methyl group (D) is responsible for...

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Unformatted text preview: 11/13/2009 The methyl group (D) is responsible for the absorption at 1.88. HA is more deshielded than HB because of inductive effects. A. A. Very sure this is true B. B. Somewhat sure this is true C. Maybe this is true D. Maybe this is false E. Somewhat sure this is false F. Very sure this is false A. A. Very sure this is true B. B. Somewhat sure this is true C. Maybe this is true D. Maybe this is false E. Somewhat sure this is false F. Very sure this is false Electronegativities: O = 3.5, C = 2.5, H = 2.1 (A) (D) (C) (B) (A) methyl group absorptions 3.67 1.88 (C) (B) (D) HD = 3.67 HC = 1.88 HA = 6.90 8 7 6 5 4 PPM 3 2 1 0 8 7 6 HB = 5.76 5 4 PPM 3 2 1 0 HA is more deshielded than HB because of inductive effects. Why aren't the NMR absorptions, such as HB at 5.76, single lines? H H3C H (A) O O CH3 H3C H O O H CH3 complete 1H NMR spectrum HD = 3.67 HD = 3.67 (B) HC = 1.88 HA = 6.90 HB = 5.76 HC = 1.88 HA = 6.90 HB = 5.76 8 7 6 5 4 PPM 3 2 1 0 8 7 6 5 4 PPM 3 2 1 0 How many absorptions would you expect for equivalent protons next to one proton? H C H CH3 How many absorptions would you expect for equivalent protons next to three protons? C H CH3 A. 1 B. 2 C. 3 D. 4 E. 5 E. 6 C H 2 CH3 actual field applied field 1 0 A. 1 B. 2 C. 3 D. 4 E. 5 5 2 ppm 1 0 C H CH3 applied field 2 1 0 6 2 1 0 ppm E. 6 ppm 1 11/13/2009 How many absorptions would you expect for equivalent protons next to three protons? H C C H H C H CH3 How many absorptions would you expect for equivalent protons next to three protons? H C C H H applied field H applied field 2 H A. 1 B. 2 C. 3 D. 4 E. 5 E. 6 C H ppm 1 0 A. 1 B. 2 C. 3 D. 4 E. 5 7 2 ppm 1 0 CH3 C H CH3 2 1 0 2 1 0 8 ppm E. 6 ppm ppm Propose a structure for a compound with the formula C5H10O2 and the following spectra. ir nmr 3 2 2 3 Propose a structure for a compound with the formula C5H10O2 and the following spectra. formula = one double bond or one ring ir 1. no OH 2. C=O 3. no rings nmr 4000 Propose a structure for a compound with the formula C5H10O2 and the following spectra. formula = one double bond or one ring ir 1. no OH 2. C=O 3. no rings H H H H O O C H C C H O C H H H C-H-C-H =C-H O-H N-H 3000 CC C=C C=O 1742 cm-1 1500 1000 600 CO2H CN C H 2000 cm-1 O C CH nmr 3 2 2 3 3 2 2 3 2 11/13/2009 Propose a structure for a compound with the formula C5H10O2 and the following spectra. formula = one double bond or one ring ir 1. no OH 2. C=O 3. no rings nmr Propose a structure for a compound with the formula C5H10O2 and the following spectra. A B 3 2 2 3 3 Propose a structure for a compound with the formula C5H8O2 and the following spectra. Hydrogen deficiency = 2 C-H -C-H =C-H O-H N-H 4000 3000 Propose a structure for a compound with the formula C5H8O2 and the following spectra. Hydrogen deficiency = 2 1. no OH 2. C=O 3. C=C? CC C=C C=O CO2H CN 2000 cm-1 1500 1000 600 4000 3000 2000 cm-1 1500 1000 600 3 3 3 1 8 8 7 7 6 6 3 1 1 6 6 5 5 4 4 PPM 1 5 5 4 4 PPM PPM ( ) 3 3 2 2 1 1 0 0 8 8 7 7 PPM ( ) 3 3 2 2 1 1 0 0 Propose a structure for a compound with the formula C5H8O2 and the following spectra. Hydrogen deficiency = 2 1. no OH 2. C=O 3. C=C 4000 3000 -1 2000 OcmH Propose a structure for a compound with the formula C5H8O2 and the following spectra. Hydrogen deficiency = 2 1. no OH 2. C=O 3. C=C C O N 1500 H 1000 C O C CH CH C H 600 H C 3 3 H C 3 1 8 8 7 7 6 6 3 1 5 5 4 4 PPM ? PPM ( ) 3 3 2 2 1 1 0 0 1 7 6 1 5 4 PPM PPM ( ) 3 3 2 2 1 1 0 0 8 3 11/13/2009 Propose a structure for a compound with the formula C5H8O2 and the following spectra. Hydrogen deficiency = 2 1. no OH 2. C=O 3. C=C Propose a structure for a compound with the formula C5H8O2 and the following spectra. C O 3 3 ? 8 7 1 6 1 5 5 4 4 PPM PPM ( ) 3 3 2 2 1 1 0 0 8 8 7 7 6 6 5 5 4 4 PPM 3 PPM ( ) 3 2 2 1 1 0 0 Can this spectrum be thoroughly analyzed? How many lines would be predicted for Hb if both Jab and Jbc were observed? A. 2 B. 3 C. 4 D. 5 E. 6 F. 8 Jbc = 1.67 Hz b c c b c c Jab a Jab a Jac Ha Hb Ha Hb Jab = 15.5 Hz Jac = 6.85 Hz Jab Jab = 15.5 Hz Jac = 6.85 Hz Jab ? 8 ? 7 8 7 6 6 5 5 4 4 PPM 3 PPM ( ) 3 2 2 1 1 0 0 8 8 7 7 6 6 5 5 4 4 PPM 3 PPM ( ) 3 2 2 1 1 0 0 How many lines would be predicted for Hb if both Jab and Jbc were observed? A. 2 B. 3 C. 4 Ha Review: The addition of H-Br to alkenes. Jbc c b c c D. 5 E. 6 F. 8 H H Br Br H Br H Br H Br Jab a Hb Jab = 15.5 Hz Jac = 6.85 Hz Jab Jbc 8 8 7 7 6 6 5 5 4 4 PPM 3 PPM ( ) 3 2 2 1 1 0 0 4 11/13/2009 Choose the major product of the following reaction. Choose the major product of the following reaction. H O 1 H O O H Br Br H H O H O H H H H or H H H H O Br O H H H H H O O H O Br Br H Br H H O H O H H H H or H H H H O Br O H H H H H A H B H O C H H C H H H C H H C H H C H H C H H 2 O H O A H B Br 5 4 3 PPM ( ) 2 1 0 Predict the 1H NMR spectrum for compound B. s = singlet, d = doublet, t = triplet, q = quartet singlet, H Br O H O H H H Predict the 1H NMR spectrum for compound B. A 1H s 3H q B 1H d 3H q C 1H q 3H d D 3H q 1H s E 3H d 3H s F 3H s 3H s 5 4 3 PPM 2 H H H H H H H H Br O O H H H H B B H 1 0 5 4 3 PPM 2 1 0 5 ...
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This note was uploaded on 12/25/2009 for the course CHE 320 taught by Professor Ff during the Spring '09 term at SUNY Stony Brook.

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