Chemical Properties
white crystalline powder
Uses
ALPHA-BENZOIN OXIME can be used to test and determine copper, molybdenum and tungsten. It can form insoluble precipitates with copper, molybdenum and tungsten ions, and is used as a precipitant for gravimetric determination or for extraction and separation by dissolving in organic solvents. It is also used as a chelating agent for extracting tantalum, vanadium, tungsten and other metals. It can also be used for spectrophotometric determination of Pd(II), Pt(VI), Rh(III) and for the determination of trace metal elements in physiological studies.
Safety Profile
Poison by intraperitoneal route.Mildly toxic by ingestion. An eye irritant. When heated todecomposition it emits toxic fumes of NOx.
Synthesis
General procedure for the synthesis of α-benzoin oxime (copper reagent) from benzene diphosgene: benzene diphosgene (21.2 g, 0.1 mol) was dissolved with NH4OH-HCl (21 g, 0.3 mol) in 300 mL of ethanol. 41.5 mL of triethylamine was added slowly and dropwise to the reaction system, warmed to 75 °C and refluxed for 24 hours. The progress of the reaction was monitored by thin layer chromatography (TLC), and after the disappearance of the raw material point, 300 mL of water was added and extracted three times with dichloromethane. The organic phases were combined, dried over anhydrous sodium sulfate and filtered, and the solvent was removed by rotary evaporation to give about 18 g of the benzene diphenoxime compound in 79% yield.
2.4 g of 10% Pd/C catalyst with a small amount of 3% hydrochloric acid-ethanol solution (10 mL HCl-EtOH) was added to the reaction flask and activated by passing hydrogen gas. Benzene coupling oxime (12.0 g, 52.5 mmol) obtained in the previous step was dissolved in 80 mL of ethanol and slowly added dropwise to the reaction flask and reacted overnight, the system was observed to become viscous. After adding 300 mL of water and filtering, the pH of the filtrate was adjusted to 8 with concentrated ammonia and 9.2 g of 1,2-diphenylamino alcohol solid was precipitated in 82% yield.
Purification Methods
Crystallise the oxime from diethyl ether. It is used for the spectroscopic determination of Cu2+, Pd2+, Pt4+, Rh3+ and V5+ [Singh et al. Talanta 26 425 1979, Beilstein 8 IV 1282.]
References
[1] Patent: CN104945345, 2017, B. Location in patent: Paragraph 0105; 0107-0109
[2] Journal of the Chemical Society, 1909, vol. 95, p. 1597
[3] Heterocycles, 2000, vol. 52, # 3, p. 1359 - 1370
[4] Oriental Journal of Chemistry, 2014, vol. 30, # 3, p. 1343 - 1348
