Organic Chemistry II - Midterm 2008

A what is the structure of the unknown compound whose

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a. What is the structure of the unknown compound whose molecular formula is C 6 H 12 O 2 ? The 1 H NMR spectrum of this compound is below. (2 points) b. Justify your answer by accounting for all information given. (10 points) Note : the infrared spectrum showed a number of absorbances from 2879 – 2960 cm -1 , and a strong absorbance at 1734 cm -1 . 0 1 2 3 4 5 PPM A B C D Peak Chemical shift Integra- tion Multi- Plicity Comments/Ideas A ~ 4.3 1H m (n=many) CH —O B ~2.3 2H q (n=3) CH 3 –CH 2 —C=O C ~1.4 6H d (n=1) 2 × CH 3 -CH D ~1.1 3H t (n=2) CH 3 —CH 2 DU = 1 (1 point) From infrared : sp3 CH’s, and Carbonyl group (responsible for the 1 DU) (1 point) Integration: 2 points Multiplicity: 1 point Identifying number of non-equivalent neighbors (n): 1 point Associating each chemical shift with an appropriate functional group: 1 point each—total 4 points O O 2 points
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Midterm Answers 10 of 11 BONUS: (2 points) Provide a detailed mechanism for the following transformation: Cl N O H N H Cl O Cl N O H Cl N O H C O N H Cl N H Cl O H :B N H Cl O N H Cl O 1/2: Electrophilic aromatic substitution mechanism with an activated electrophile shown 2/2: complete mechanism
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