Ionic liquids oxime

The caprolactam based Bronsted acidic ionic liquids such as [NHC][BP4], [NHC][CF3C00] and [NHC][N03] have been used to catalyze the rearrangement of cyclohexanone oxime to caprolactam and was found that with a 3 1 mole ratio of ionic liquid oxime, the conversion increased to... 

To explain the difficulties encountered in the reuse of sulfonyl chloride functionalized ionic liquids during Beckmann rearrangement, Deng and colleagues proposed a mechanism for rearrangement of cyclohexanone oxime (equation 97). 

A -Butylpyridinium tetrafluoroborate, containing dissolved phosphorus pentachloride, allows catalytic Beckmann rearrangement of cyclohexanone oxime giving e-caprolactam with good conversion and selectivity <2001TL403>. The same ionic liquid containing dissolved ytterbium(m) trifluoromethanesulfonate was used to perform Friedel-Crafts acylation of furan and thiophene <2005JIG398>. 

HCl-HOAc-AcjO, POCls, BiCla, neat with FeCls, and polyphosphoric acid. The reaction has been done in supercritical water and in ionic liquids. A polymer-bound Beckman rearrangement has been reported. Sim-ply heating the oxime of benzophenone neat leads to A-phenyl benzamide. The oximes of cyclic ketones give ring enlargement and form the lactam,as in the formation of caprolactam (83) from the oxime of cyclohexanone. Heating an... 

Guo S, Du Z, Zhang S, et al. Clean beckmann rearrangement of cyclohexanone oxime in caprolactambased brpnsted acidic ionic liquids. Green Chem. 2006. 8, 296-300. 

Scheme 5.6-5 Supported ionic liquid catalyzed oxime transformation [84].

Also, in a closely related study, a similar sol-gd synthetic pathvray was used to prepare silica gel supported ionic liquid deoximation catalysts from carboxylic acid-functionalized ionic liquids [85]. Here various aryl and alkyl oximes were converted into the corresponding 0x0 compounds with high conversions (up to 94%) and excellent selectivity (>99%) in aqueous acetone at room-temperature by coproduction of 2-propanone oxime. TONs of up to 200 h obtained with the SILC were about four times higher than the TONs obtained using pure ionic liquids as catalysts. 

In another approach, an oxime carbapalladacycle ionic liquid catalyst was attached to an aluminosilicate support (Al/MCM-41, Si/Al 13) via electrostatic interaction by... 

Scheme 5.6-9 Base-promoted Suzuki cross-coupling of halobenzenes and phenylboronic acid using AI/MCM-41-supported oxime carbapalladacycle ionic liquid catalyst [105],...

Pinto and Neto demonstrated that if the isatin formation was run using an imidazolium based ionic liquid 27 as the solvent, the reaction could be sloped at isatin oxime 26. The choice of acid and ionic liquid counter anion had a substantial influence on this reaction efficiency. ... 

The cited conditions for the preparation and rearrangement of oxime have been selected among many others reported in the literature and patents. For specific oximes, the Beckmann rearrangement is catalyzed by zeolites or nanoporous materials in ionic liquids in the presence of Co(III), Mn(III) or Fe(III) salts [4]. 

A new and efficient microwave induced bismuth trichloride catalyzed Beckmann rearrangement of oximes in the solid state has been achieved by Thakur et al. (2007). Beckmann rearrangement of aryl ketoximes catalyzed by In(OTf)3 gave amides in ionic liquid under microwave irradiation. These aryl ketoximes were converted to corresponding amides in good yields within very short times (10-270 sec). The catalyst and the ionic liquid were easily recovered and reused (Sugamoto et al, 2011). 

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