Abstract / Excerpt:

Abstract: The ring opening of coumarins by sodium hydride is reported by several workers. However, no information is available on the species responsible for the ring opening. Hence, a detailed study has been made on the ring opening reactions of coumarins as well as on the hydrogen abstracting and donating abilities of sodium hydride lead to the following conclusions: (i) Depending on the nature of the nucleophilic reagents, coumarin may either undergo a 1,2- or 1,4- addition. (ii) The hydride ions are not directly responsible for the reducing ability of sodium hydride but the electrons originating from the hydride. The oxygenated impurities prsent may also bring about some anomalous reactions. Based on the study, towards the formation of o-methoxycinnamic acids and its esters, two independent pathways involving the intermediacy of aldehydes as well as acids have been considered. To verify this in detail, coumarin as well as various 7-oxygenated-4-methylcoumarins were prepared and the ring opening was attempted with sodium, sodium paroxide and sodium hydroxide, likely impurities present in sodium hydriade, and also a mild base like sodium carbonate.

Info

Source Institution	Ateneo de Davao University
Unit	Natural Science
Authors	Macavinta, Mary Sol E.
Page Count	1
Place of Publication	Manila
Original Publication Date	March 3, 1986
Tags	Chemistry, Dissertations

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