22.2.5 Selenocarboxylic Acids and Derivatives (Update 2024)

Abstract

Selenocarboxylic acids and their derivatives are the selenium isologues of carboxylic, thioic, carbamic, and carbonic acids, and the corresponding esters, amides, and ureas, and are distinguished by the presence of a C=Se bond. The synthesis of these selenium analogues primarily involves incorporating selenium atoms into precursor molecules. This can be achieved by reducing elemental selenium to produce Se2– species, which are then introduced into electrophilic species. Alternatively, carbon nucleophiles can directly bond with elemental selenium, forming carbon–selenium bonds. Compounds containing a P=Se bond, such as Woollins’ reagent, are used to substitute the oxygen in a C=O bond with selenium, creating a C=Se bond. Carbon diselenide (CSe2) is another agent used in synthesizing these derivatives. However, extreme caution is required when handling CSe2 due to its potent odor and toxicity.