Unknown Mixture Including NMR Spectra Fall 2010

Unknown Mixture Including NMR Spectra Fall 2010 -...

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Identification of an Unknown Acid and Alcohol from a Mixture The purpose of this lab is to test your ability to separate an unknown alcohol from an unknown acid and to successfully purify and characterize each of them using the skills you have developed in lab. The unknown compounds will be assigned to you as a mixture from the list in Table 1. Your task will be fourfold: 1) You must propose a method in the form of a flow chart for separating and purifying your unknowns using the reagents and solvents previously available in lab. 2) You will characterize the acid by melting point and by a neutralization equivalent. 3) You will characterize the alcohol by the melting points of both the purified compound and a phenylurethane derivative that you prepare (reaction highlighted below). 4) You will deduce and analyze the proton NMR spectra that belong to your unknowns from a file containing all twelve unknown spectra. Table 1 . List of possible alcohols and acids. Unknowns MW Lit. mp Phenylurethane mp Alcohols: 1 Piperonyl Alcohol 152.15 54 103 1-Octadecanol 270.49 60 79-80 Benzhydrol 184.23 66 140 3,5-Dimethylphenol 122.16 68 151 Benzoin 212.24 135 171 Salicylamide 137.14 142 185 Acids: 1 4-Hydroxyphenylacetic Acid 152.15 148-150 p-Anisic Acid 152.15 183 Hippuric Acid 179.17 188-190 2-Chlorocinnamic Acid 182.60 210 Azelaic Acid 188.22 110 Sebacic Acid 202.25 135 Handling Precautions: 1 Each of the unknowns is relatively non hazardous, however caution should be used when handling; each may cause eye and skin irritation upon exposure.
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Table 2. Reagents and solvents used for the synthesis of the urethane derivative and for the neutralization equivalent. Compound MW Wt./Vol. mmol density bp( o C) Unknown Alcohol 100 mg Phenyl Isocyanate a 119.13 100 μL 1.64 1.0956 158-168 Dichloromethane b 84.93 0.5-1 mL 40 Pyridine c 79.10 1 drop NaOH (0.10 N) d ~10 mL a Extreme inhalation hazard – dispense and contain under ventilation b Health hazard c Stench hazard – dispense and contain under ventilation d Irritant/ mildly corrosive Techniques You May Need to Review from the Techniques Manual in Preparation for this Lab: Extraction: See technique 11 (see page 117 of the techniques manual for an example of
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This note was uploaded on 03/08/2012 for the course CHEM 353 taught by Professor Bronson during the Fall '11 term at BYU.

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Unknown Mixture Including NMR Spectra Fall 2010 -...

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