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ERIC Number: EJ921605
Record Type: Journal
Publication Date: 2011-Jan
Pages: 4
Abstractor: As Provided
Reference Count: 9
ISBN: N/A
ISSN: ISSN-0021-9584
Synthesis of 5,5-Diphenyl-4-penten-2-One: A Variation on a Classic Organic Synthesis Laboratory
Alber, Joshua P.; DeGrand, Michael J.; Cermak, Diana M.
Journal of Chemical Education, v88 n1 p82-85 Jan 2011
The Grignard reaction and the addition of protecting groups are standard reactions in an organic chemistry course. Organic students learn about the "quench" step of the Grignard reaction using acid and water and the acid-catalyzed hydrolysis to remove the protecting group, yet in the lecture students find these two reactions to be confusing in their similarity. Although there are published syntheses that explore multistep synthesis utilizing a Grignard reaction and protecting groups, we have had limited success with these procedures in the lab. The multistep synthesis of 5,5-diphenyl-4-penten-2-one from ethyl levulinate includes these reactions. Ethyl levulinate, a gamma-ketoester, undergoes protection with ethylene glycol to provide an acetal ester. The acetal ester is then treated with phenylmagnesium bromide, which is prepared prior to use, followed by an aqueous acid quench to produce a tertiary alcohol that can be purified by recrystallization. Finally, the acetal is removed and the tertiary alcohol undergoes dehydration under acid-catalyzed conditions to provide 5,5-diphenyl-4-penten-2-one. Students characterize their products at each stage of the synthesis using GC-MS, IR, [superscript 1]H NMR, and [superscript 13]C NMR spectroscopy. The three-week experiment teaches students not only about classic reactions in organic chemistry, but also the difference between quench and hydrolysis steps in a hands-on manner. (Contains 2 tables and 3 figures.)
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail: eic@jce.acs.org; Web site: http://pubs.acs.org/jchemeduc
Publication Type: Journal Articles; Reports - Research
Education Level: Higher Education; Postsecondary Education
Audience: Teachers
Language: English
Sponsor: N/A
Authoring Institution: N/A