Problem Set 3 Answers

Problem Set 3 Answers - (an indole group), but answers...

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Problem Set 3 Answers Chemistry 154A/254A: Quantum Chemistry Professor Song-I Han Teaching Assistant: Wang, Xiqing (Francis) Office: Chemistry 3223 Office: Chem 1126/ Dahlquist Lab (1 th floor) Office hours: Tue, Th 4-5 pm Office hours: Wed 1-2 pm and Fr 4-5pm Email: songi@chem.ucsb.edu Email: xwang@chem.ucsb.edu temporarily Mark Lingwood ( mlingwood@chem.ucsb.edu ) Tryptophan: (pts) Proton (2) 1. No peak visible. Due to rapid exchange (2) 2. 3.533ppm Electric field effect – close to N and COOH (1) 3. 3.326 / 3.3036 Any number of effects: ring current? (2) 4. 7.263 Ring current or anisotropy of double bond were accepted. Both rings are aromatic
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Unformatted text preview: (an indole group), but answers treating the 5-membered ring as non-aromatic were accepted. (3) 5. 11.11 H-bonding effect in addition to the ring current. (2) 6. 7.5-6.9 Ring current Arginine: (pts) Proton (2) 1. No peak visible. Either exchanges too fast for NMR, or exchanges with D 2 O. (1) 2. 3.27 Electric field effect close to N and COOH (1) 3. 1.64 Normal value for a CH 2 proton (1) 4. 1.64 Normal value for a CH 2 proton (1) 5. 3.21 Electric field effect close to N (1) 6. No peak visible. Exchange effects (1) 7. No peak visible. Exchange effects...
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