Selenophenes of practical importance

Compounds of the selenophene series are effective high-temperature antioxidants for silicone liquids.132 /9-Diketones, bis-/S-diketones, and azomethines of the selenophene series have been studied as stabilizers 

Selenienyl azomethines are also highly active as oxidation inhibitors. 

Selenophene /3-diketones can be used as extractants for the separation and isolation of metals. The advantages of selenophene /3-dike-tones were revealed by comparison of their dissociation and distribution constants with those of acetylacetone, benzoylacetone, thenoyl-trifluoromethylacetone, etc. Selenophene /3-diketones containing a trifluoromethyl group and a pyridyl radical were of particular interest. 2-Acetoacetylselenophene127 is better for the extraction of thorium from water than acetylacetone, previously extensively used. 

To separate zirconium from hafnium, 2-thenoyltrifluoroacetone is less effective than the selenophene analog, which yields hafnium solutions of 98-99% purity thus, the two similar elements can be efficiently separated.133 

Selenophene /3-diketones containing a-, /3-, or y-pyridyl radicals can be used for extraction of neodymium the extraction percentage is approximately 90%. The most practical is w-picolinoyl-2-aceto-selenophene which gives a high percentage of metal extraction at a 

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