Benzoin oxime from

Benzoin Oxime. 2-Hydroxy-l,2-diphenyiethanone Mime 2-hydroxy -2-phenylacetophenone oxime. C Hts-NOji mol wt 227.25. C 73.99%, H 5.76%, N 6.16%, O 14.08%. Two isomers occor a or anti and /S or syn. Both have been prepd from benzoin and hydroxyl amine hydrochloride. Prepn of a-form Werner, Detscheff, Ber. 38, 69 (1905) F. J. Welcher, Organic Analytical Reagents vol. Ill (Van Nosttand, New York, 1947) pp 239-251. Prepn of 3-form Werner, Detscheff, loc. cit, Configuration of a - and Worms Meisenheimer, Meis, Ber. 57, 289 (1924). 

D. Benzoin-a-oxime (cupron) (VII). This compound yields a green predpitate, CuC14Hu02N, with copper in dilute ammoniacal solution, which may be dried to constant weight at 100 °C. Ions which are predpitated by aqueous ammonia are kept in solution by the addition of tartrate the reagent is then spedfic for copper. Copper may thus be separated from cadmium, lead, nickel, cobalt, zinc, aluminium, and small amounts of iron. 

From strongly addic solutions benzoin-a-oxime precipitates molybdate and tungstate ions quantitatively chromate, vanadate, niobate, tantalate, and palladium) II) are partially predpitated. The molybdate complex is best ignited at 500-525 °C to Mo03 before weighing alternatively, the predpitate may be dissolved in ammonia solution and the molybdenum predpitated as lead molybdate, in which form it is conveniently weighed. 

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