Chem 143B Spring 09 Exam 1 Key

Chem 143B Spring 09 Exam 1 Key - Chemistry 143B Spring,...

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Chemistry 143B Spring, 2009 Exam #1 (4-20-09) Total Points: 100 NAME: Ima Key USE INK FOR RECORDING ANSWERS (if using pencil, no re-grades will be allowed) 1. (20 points) The following questions refer to the TLC depicted below. The image to the right of the TLC plate is a simulated ruler divided in centimeters. 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 solvent front sm rx co 50% EtOAc/hexanes 4 points each correct answer-sig figs must be adhered to! A) (4 points) The R f for the starting material is: 0.50 B) (4 points) The R f for the product is: 0.75 C) (4 points) The key piece of information missing from this TLC rendering is: visualization method (UV, stain, etc.) D) (4 points) If we were to purify the product mixture by column chromatography, would it be best to use a solvent system of higher or lower polarity? E) (4 points) If we wished to adjust the polarity of the solvent mixture to increase the Rf values, which component of the solvent system would be increased in concentration? ethyl acetate
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2. (12 points) In the synthesis of 4-bromo-2-nitroaniline, you employed a protecting group strategy utilizing an acetyl group attached to the aromatic nitrogen. List the four advantages for using this particular protecting group. Be brief but specific. 3 points each complete reason
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This note was uploaded on 03/04/2012 for the course CHEM 143b taught by Professor Staff during the Spring '08 term at UCSD.

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Chem 143B Spring 09 Exam 1 Key - Chemistry 143B Spring,...

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