A-Hydroxyoximes

There is considerable interest in amino derivatives of chroman and hydrogen bromide has been found to promote a stereoselective hydrogenation of an a-hydroxyoxime enabling the 5,5-aminochromanol 53 to be obtained in over 30% yield from chroman-4-one on a multi-kilo scale (Scheme 31) <00TL8021>. 

Two commercial flow sheets (Figs. 11.10 and 11.11) use either di- -octyl sulfide or a hydroxyoxime as selective extractants to remove the palladium, followed by tri- -butylphosphate (TBP INCO) and an amine... 

The second selective extractant route (that of MRR) uses a hydroxy-oxime to remove palladium. The actual compound used has not been specified, but publications refer to both an aliphatic a-hydroxyoxime and an aromatic S-hydroxyoxime. The a-hydroxyoxime LIX63 has the faster extraction kinetics, but suffers from problems with stripping. For the (i-hydroxyoxime, a kinetic accelerator in the form of an amine (Primene JMT ) has been proposed. The precise mode of operation of this accelerator is unknown, but it may be a similar process to that proposed for the sulfide... 

Benzisoxazoles and isoxazoles are also accessible in excellent yields by intramolecular Mitsunobu reaction or related reactions of o-hydroxy- or a-hydroxyoximes ° . Thus, treatment of oxime 208 in the presence of diethyl azodicarboxylate (DEAD) and PPhs in THE leads to benzisoxazoles 209 (equation 91). ... 

Reactions of a-hydroxyoxime 366 with NaH/i-Pr0H/ClC02Et or CS2 afforded 1,5,2-dioxazines 367 and 368 in 79 or 76% yields, respectively (equation 160) . ... 

The kinetics of the extraction of metals, especially copper(II), by ort/io-hydroxyoximes (HA) has been widely studied in recent years.146 Of particular interest is the observation that the rate of extraction can be considerably increased by the incorporation of small amounts of aliphatic a-hydroxyoximes (H2B) into the organic phase.168 An even more marked effect has been noted with a-dioximes.169 170 Accelerator compounds of the former type are used in Henkel s commercial extractant LIX 64N, whereas those of the latter type are used in the Shell reagent SME 530. 

Note TBP = tributyl phosphate DEHPA = diethylhexyl phosphoric acid STTA = monothio-thenolytrifluoroacetone DMABR = 5-(4-dimethylaminobenzylidene)-rhodanine TPTZ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine LIX 63 = aliphatic a-hydroxyoxime LIX 65N = 2-hydroxy-5-nonylbenzophenoneoxime LIX 64N = a mixture of LIX 65N with approximately 1% (v/v) of LIX-63. 

Komasawa, I., Otake, T., and Yamashita, T., Mechanism and kinetics of copper permeation through a supported Uquid membrane containing a hydroxyoxime as a mobile carrier. Ind. Eng. Chem. Fund., 1983, 22 127-131. 

Usually, the composition of commercial extractants is proprietary information, but a typical example is an a-hydroxyoxime carried in a hydrocarbon solvent such as kerosene. 

Phosphorus oxide chloride pyridine Ketones from a>hydroxyoximes Degradation by Beckmann rearrangement... 

LIX 63, an aliphatic a-hydroxyoxime, was the first commercial reagent developed for copper. Although it was very selective for copper, it operated at pH values of 5 to 8. Since most leach solutions have pH values between 0.7 and 2.2, it was necessary to optimise the pH dependence of the extractants for use under more acidic conditions. The first reagent used in a full-scale plant was LIX 64N, a P-hydroxybenzophe-none oxime developed by General Mills (now Cognis) and comprising a mixture of LIX 63 (2% by mass) and LIX 65N (40%) (Arbiter and Fletcher 1994 House 1985 Dasher and Power 1971). 

Oximes, a-oximinoketones, and a-hydroxyoximes react with phenylacetic acid in the presence of dicyclohexylcarbodiimide to form the oximino ester. At pH 5 and room temperature, H20-soluble carbodiimides convert hydroxamic acids to amines 7, Cyanooldehydes and -ketones are attainable by conversion of olefins to a-dimethylamino oximes and subjecting these to a Beckmann fragmentation ... 

Barnard KR, Nealon GI, Qgden MI, Skelton BW (2010) Crystallographic determination of three Ni-a-hydroxyoxime-carboxylic acid synergist complexes. Solvent Extr Ion Exch... 

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