Winthrop CHEM 304 - Preparation of N,N-Diethyl-m-toluamide (DEET) and its Identification by IR and NMR Spectroscopy (12 pages)

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Preparation of N,N-Diethyl-m-toluamide (DEET) and its Identification by IR and NMR Spectroscopy



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Preparation of N,N-Diethyl-m-toluamide (DEET) and its Identification by IR and NMR Spectroscopy

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12
School:
Winthrop University
Course:
Chem 304 - Organic Chemistry Laboratory

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Preparation of N N Diethyl m toluamide DEET and its Identification by IR and NMR Spectroscopy Eim A Chemist CHEM 304 July 10 2005 INTRODUCTION N N Diethyl m toluamide DEET is the active ingredient in many insect repellants 1 In this experiment DEET will be prepared from m toluic acid through the intermediate acid chloride and then identified by its IR and proton NMR spectra The overall reaction is a series of two acyl substitutions and is shown in Scheme 1 below Scheme 1 Carboxylic acids can be converted to acid chlorides by treatment with a compound such as phosphorus trichloride PCl3 or thionyl chloride SOCl2 2 The reactive acid chloride can then be treated with a primary or secondary amine to give the amide along with HCl which reacts with the excess amine to give an alkylammonium chloride salt The mechanism of this process is shown on the following page in Scheme 22 Page 1 Scheme 2 Page 2 To carry out this reaction the apparatus shown in Figure 1 will be assembled The apparatus must be dry since thionyl chloride will react with water to give sulfur dioxide and hydrogen chloride 4 Figure 13 m Toluic acid and thionyl chloride will be charged into the reaction flask USE A HOOD then boiled gently to effect the formation of the acid chloride The acid chloride will then be cooled to room temperature and dissolved in anhydrous ether Ice cold diethylamine will be added as a solution in anhydrous ether to form the amide The resulting ether mixture will washed with aqueous sodium hydroxide to remove any excess acid chloride then washed with hydrochloric acid to remove any excess diethylamine The resulting ether solution of DEET will be dried and evaporated to yield the crude product which will then be purified by column chromatography to afford pure DEET The percent yield from m toluic acid will be determined and the product will be analyzed by transmission infrared spectroscopy IR as a neat sample using NaCl plates5 to confirm its structure by 1 looking at the major



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