CHEM 6371/4511 Name: The exam consists of interpretation of spectral data for compounds A-C. The analysis of each structure is worth 33.33 points. Compound A (a) How many carbon atoms are in the molecular formula of compound A? [Consider the molecular ion cluster and 13 C NMR spectrum] (b) How many hydrogen atoms are in the molecular formula of compound A? [Consider the 1 H NMR] (c) Does the compound contain any of the following bonds: C=O C-O O-H [Circle all that apply] (d) What is the molecular formula of compound A? [Consider your answers to (a)-(c), and the molecular weight] (e) What is the value of SODAR? (f) How many of the following are present? sp 3 CH 3 C=O sp 3 CH 2 sp 2 CH 2 sp 3 C with no attached H sp 3 CH sp and sp 2 CH sp and sp 2 C with no attached H (excluding C=O) [These should sum to the number of signals in the 13 C NMR spectrum] (g) What is the substitution pattern of the benzene ring in this compound (e.g., monosubstituted, para (1,4-) disubstituted; 1,2,4-trisubstituted, etc)? [Consider the 1 H and 13 C NMR spectra] substitution pattern: (h) What feature (a fragment of the molecular structure) is consistent with the set of three multiplets (A, B and C) that appear between 2.0 and 3.0 in the 1 H NMR spectrum? (i) [8 points] Structure of compound A with letters next to each hydrogen atoms corresponding to the 1 H NMR signal (A-G).
Compound B, C 9 H 10 O (a) What is the value of SODAR? (b) Does the compound contain any of the following bonds: C=O C-O O-H [Circle all that apply] (c) How many of the following are present? sp 3 CH 3 C=O sp 3 CH 2 sp 2 CH 2 sp 3 C with no attached H sp 3 CH sp and sp 2 CH sp and sp 2 C with no attached H (excluding C=O) [These should sum to the number of signals in the 13 C NMR spectrum] (d) What is the substitution pattern of the benzene ring in this compound (e.g., monosubstituted, para (1,4-) disubstituted; 1,2,4-trisubstituted, etc)? [Consider the 1 H and 13 C NMR spectra] substitution pattern: (e) Determine the multiplicity and coupling constants of signals A ( 4.69), B ( 5.31) and C ( 5.43) in the 1 H NMR spectrum. [Remember that a multiplet of multplets has two coupling constants.] multiplicity J / Hz int. [e.g., q, dt, ddq, etc] [e.g., 10,3] A 4.69 2 B 5.31 1 C 5.43 1 (h) Which 13 C signals (t-z) correspond to: [i] vinylic carbon atoms: _ [ii] carbon atoms in the benzene ring (f) The protons giving rise to signals A, B and C all couple to one another. Which other signal corresponds to a hydrogen that couples to all of the hydrogen atoms that give rise to signals A, B and C? (g) Describe the multiplicity and provide the coupling constants of signal D ( 6.). Multiplicity: Coupling constants (Hz): (i) [8 points] Structure of compound B with letters next to each hydrogen atoms corresponding to the 1 H NMR signal (A-F).
Compound C (a) Does the compound contain any of the following bonds: C=O C-O O-H [Circle all that apply] (b) What is the formula of the molecule? (consider the molecular ion cluster, NMR spectra and your response to (a)) (c) What is the value of SODAR? (d) What specific combination of features gives rise to this value of SODAR in this compound (i.e., specific functional groups, and number of rings)? (e) How many of the following are present? sp 3 CH 3 C=O sp 3 CH 2 sp 2 CH 2 sp 3 C with no attached H sp 3 CH sp and sp 2 CH sp and sp 2 C with no attached H (excluding C=O) [These should sum to the number of signals in the 13 C NMR spectrum] (f) Consider signal G ( 4.36) in the 1 H NMR spectrum. It looks like a pentet. [i] Which 13 C signal (u-z) corresponds to the carbon atom to which the hydrogen giving rise to signal G is attached? [ii] Which 1 H signals (A-G) correspond to the hydrogen atoms that give rise to splitting of signal G? [iii] Which 13 C signals (u-z) correspond to the carbon atoms that are attached to the hydrogen atoms which give rise to the signals you identified in [ii]? [iv] Which 1 H signals (A-G) correspond to hydrogen atoms that give rise to splitting of the 1 H NMR peak for the methyl group in this compound? (g) Propose a fragment of the molecule that is fully consistent with the information in part (f) about the appearance of 1 H NMR signal G and about the methyl group. (h) [8 points] Structure of compound C with letters next to each carbon atoms corresponding to the 13 C NMR signal (u-z)
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compound A _ mass spectrum molecular ion cluster 146: % 147: 11.1% 148: 0.75%
Exercise 5.5 1 H NMR 0 MHz 40 47 Hz 44 4400 Hz 43 4300 Hz 17 10 Hz 15 10 Hz 12 1200 Hz 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 13 C/DEPT 1.9 MHz 200 1 1 140 120 40
Exercise 5.5 8 7 6 5 4 3 2 COSY 0 MHz 2 2 3 3 4 7.0 8.0 7.5 7.0 4 F1 5 7.5 5 6 8.0 6 7 7 8 8 HMQC 0 MHz 40 40 125 130 F1 135 8.2 8.0 7.8 7.6 7.4 7.2 120 120 140 140 9 8 7 6 5 4 3 2
Problem 8.31A MASS 134 % of Base Peak 41 65 77 94 91 105 119 IR 40 m/z 90 110 120 130 %Transmittance 2866 2916 3032 3066 1496 11 4000 3000 2000 0 1 H NMR 0 MHz Wavenumber (cm-1) 1242 690 752 36 36 Hz 3300 32 Hz 3220 3200 Hz 27 2740 Hz 7.4 7.2 7.0 6.8 6.6 6.4 6.2 6.0 5.8 5.6 5.4 5.2 5.0 4.8 13 C/DEPT NMR 1.9 0 MHz 1 1 140 130 120 110 90
Problem 8.31B 7.5 7.0 6.5 6.0 5.5 5.0 4.5 COSY 0 MHz 4.5 4.5 5.0 5.0 5.5 5.5 F1 6.0 6.0 6.5 6.5 7.0 7.0 HMQC 0 MHz 90 90 F1 110 110 120 120 130 130 140 140 1 1 7.5 7.0 6.5 6.0 5.5 5.0 4.5
Problem 8.33A MASS 85 % of Base Peak 57 114 IR m/z 90 110 656 %Transmittance 2885 29 1774 1358 1466 11 972 4000 3000 2000 0 1 H NMR 0 MHz Wavenumber (cm-1) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 13 C/DEPT NMR 1.9 0 MHz 29 28 1 1 140 120 40 20
Problem 8.33B 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 COSY 0 MHz 1.0 1.0 1.5 1.5 2.0 2.0 F1 2.5 2.5 3.0 3.0 3.5 3.5 4.0 4.0 HMQC 0 MHz 10 10 20 20 30 30 40 40 F1 28 30 2.5 2.0 1.5 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0