A Dehydration

A Dehydration - A Dehydration/ Htdrogenation Reaction...

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A Dehydration/ Htdrogenation Reaction Performed 7/21/10 Results: R-carvone (0.141mL) was reacted with Pd/C (.026g) at 180°C with samples of the reaction mixture and carvone spotted on a TLC plate every 15 minutes. Four TLC plates were run, all were run in 95:5 hexane:ethyl acetate twice, and all showed an incomplete reaction until the fourth plate. This mixture was then reacted with sodium hydroxide (2mL) giving a product with an initial pH of 11 which later turned to pH 2 after addition of hydrochloric acid (1mL). This was then reacted with diethyl ether (3mL) after which the product was collected and dried. The product smelled of herbs and the final weight of the product was .05g giving a 38.5% yield overall. Discussion: To determine the structure of the final product the properties of Pd/C were taken into consideration. Pd/c is capable of using molecular hydrogen to hydrogenate double bonds, as well as creating hydrogen transfer reactions. It was expected that the carvone tautomerized to the enol form before it was dehydrogenated to create the benzene ring. These extra hydrogen’s would then hydrogenate the 5’ alkyl double bond to create our desired product. This reaction was not as successful as expected with only a 38.5% yield as calculated below: The TLC plates taken displayed the movement of product away from the original material carvone and although the Rf values can not be taken due to the second development of all the plates, the distinct shift of the product could be seen. TO determine the overall energies of the reaction the ∆H was calculated with the equation ∆H total= (∆H new bonds formed)+( ∆H old
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bonds broken). Using the data of the reaction this is found to be ∆H=(dehydrogenate 1,3-
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This note was uploaded on 10/08/2010 for the course CHEM 3BL taught by Professor Chunmei during the Spring '08 term at Berkeley.

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A Dehydration - A Dehydration/ Htdrogenation Reaction...

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