CHEM14C_s07_e02_key

CHEM14C_s07_e02_key - Chemistry 14C Spring 2007 Exam 2...

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Chemistry 14C Spring 2007 Exam 2 Solutions Page 1 Statistics : High score, average and low score will be posted on the course web site after exam grading is complete. The exam is ready to be picked up when these numbers are posted. A note about exam keys : The answers presented here may be significantly longer than expected from a student taking the exam. An exam key serves not only to reveal what was expected, but to instruct you as well. To see the projected course grade cutoffs, consult the grading scale on the Chem 14C course web page. 1. C 15 H 21 NO 6 2. (a) 311 (b) 17% 18% also acceptable, depending upon how many digits you used for the calculation (c) 1% 3. 7 4. m/z for M = 353 Calculation: Formula = C 18 H 27 NO 6 Mass = (18 x 12) + (27 x 1) + (1 x 14) + (6 x 16) = 353 5. N-H ~3400 cm -1 vinyl C-H ~3050 cm -1 alkyl C-H ~2900 cm -1 ester C=O ~1740 cm -1 C=C ~1650 cm -1 6. Difference #1 : The IR spectrum of domoic acid features a carboxylic acid O-H stretch in zone 2, which is absent in the IR spectrum of trimethyldomoate. Difference #2 : The C=O stretch in the IR spectrum of domoic acid occurs 1725-1700 cm -1 whereas in the IR spectrum of trimethyl domoate the C=O stretching frequency is in the range of 1750-1735 cm -1 . Other answers are possible . 7. (a) The spectra are identical 8. Assuming hydrogens of CH 2 N are equivalent: Four singlets, five doublets, no triplets, and seven signals of more than three lines.
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Chemistry 14C Spring 2007 Exam 2 Solutions Page 2 Better answer : Assuming hydrogens of CH 2 N are not equivalent (one cis, other trans to COOH across the ring) then four singlets, four doublets, two triplets, and seven signals of more than three lines. Best answer
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This note was uploaded on 03/02/2010 for the course CHEM CHEM14C taught by Professor Hardinger during the Winter '10 term at UCLA.

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CHEM14C_s07_e02_key - Chemistry 14C Spring 2007 Exam 2...

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