O-Chem

O-Chem - Abstract The objective of this experiment was to synthesize an alpha-acylated cyclohexanone at relative purity and at a reasonable percent

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Abstract : The objective of this experiment was to synthesize an alpha-acylated cyclohexanone at relative purity and at a reasonable percent yield via the nucleophilic enamine intermediate . This short sequence of reactions included the reaction of a carbonyl compound with a secondary amine to form the enamine, and subsequent acid-catalyzed hydrolysis to form the acylated cyclohexanone. In the first step, pyrrolidine was the cyclic secondary amine added in the presence of toluene solvent and an organic acid catalyst, para-toluenesulfonic acid, for the formation of enamine and water. During this reaction, water was azeotropically distilled with toluene in order that the products were favored. This new technique is fully discussed in the introduction section. Subsequently, acetic anhydride was added to form an intermediate with a formal positive charge on nitrogen. This reaction developed for one week unto completion, after which the synthesis was resumed. The intermediate iminium ion was hydrolyzed with water and hydrochloric acid to yield the final product and regenerate the pyrrolidine used as a reagent. The techniques employed in this experiment included enamine formation, column chromatography, extraction, evaporation, heating under reflux, infrared spectroscopy, and azeotropic distillation. The results of this experiment can be summarized as follows . 0.2793 g of 2-acetylcyclohexanone was synthesized with 32.10% efficiency, based on a theoretical yield of 0.87 g. The purity of the final product can only be discussed in terms of the lack of other characteristic peaks on the infrared spectrum, since no experimental melting point was taken. The textbook, Pavia , 4 th Edition, has provided ideal NMR spectra for analysis of relative keto-enol content of the product, although no experimental spectra were taken. The experimental IR spectrum confirms formation of relatively pure 2-acetylcyclohexanone, as evidenced by the presence of a carbonyl absorption and corresponding C (sp 3 )-H stretches at their proper locations, 1760 cm -1 and slightly below 3000 cm -1 , on an otherwise empty spectrum. In conclusion, the desired product was formed at an acceptable percent yield with no obvious or measurable impurity based on the characterization tests performed (further testing is needed to generate a more specific conclusion) . Figure 43.1—Overall Reaction of Cyclohexanone via Enamine to Form 2-Acetylcyclohexanone + + + 1.) 2.) H 2 O
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Introduction : In this experiment, an enamine was used to acylate a carbonyl compound, cyclohexanone, such that many of the common problems confronted when acylating such a compound in high concentrations of sodium hydroxide were avoided . It is essential that the general principles involved with acylation of a carbonyl compound are examined if this specific reaction is to be understood in all of its rigorousness. Any given carbonyl compound has weakly acidic hydrogen atoms bonded at the alpha carbon position, which can be removed by deprotonation with the addition of a strong base. Pavia , 4 th
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This note was uploaded on 04/02/2008 for the course CHM 232 taught by Professor Gould during the Spring '08 term at ASU.

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O-Chem - Abstract The objective of this experiment was to synthesize an alpha-acylated cyclohexanone at relative purity and at a reasonable percent

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