1- Butyl-3-methylimidazolium oxidation with

The experimental simplicity of Method 3 has attracted the specialists in modern trends in catalysis. Thus, in Method 3 different authors used RbF (04SC4431), MgO (09EJM3805), KF/AI2O3, mixed magnesium-aluminum carbonate, or mixed magnesium-lanthanum oxide (08TL2730) in methanol. Recently, 2-aminopyran syntheses with acetylacetone 35 and ethyl acetoacetate 36 were carried out in an ionic liquid [(bmim)(BF4), 1-butyl-3-methylimidazolium borofluoride] with 1,1,3,3-tetramethylguanidine as... 

For oxidation with KMn04 on alumina with no solvent, see Hajipour, A.R. Mallakpour, S.E. Imanzadeh, G. Chem. Lett. 1999, 99. For oxidation with silica-supported KMn04, see Takemoto, T. Yasuda, K. Ley, S.V. Synlett 2001, 1555. For oxidation in the ionic liquid bmim BF4, l-butyl-3-methylimidazolium tetrafluoroborate Kumar, A. Jain, N. Chauhan, S.M.S. Synth, Commun. 2004, 34, 2835. 

When the same [NiI (NHC)2] complexes are employed as alkene dimerisation catalysts in ionic liquid (IL) solvent [l-butyl-3-methylimidazolium chloride, AICI3, A-methylpyrrole (0.45 0.55 0.1)] rather than toluene, the catalysts were found to be highly active, with no evidence of decomposition. Furthermore, product distributions for each of the catalyst systems studied was surprisingly similar, indicating a common active species may have been formed in each case. It was proposed that reductive elimination of the NHC-Ni did indeed occur, as outlined in Scheme 13.8, however, the IL solvent oxidatively adds to the Ni(0) thus formed to yield a new Ni-NHC complex, 15, stabilised by the IL solvent, and able to effectively catalyse the dimerisation process (Scheme 13.9) [25-27],... 

The use of Cu in combination with TEMPO also affords an attractive catalyst [200, 201]. The original system however operates in DMF as solvent and is only active for activated alcohols. Knochel et al. [202] showed that CuBr.Me2S with perfluoroalkyl substituted bipyridine as the ligand and TEMPO as cocatalyst was capable of oxidizing a large variety of primary and secondary alcohols in a fluorous biphasic system of chlorobenzene and perfluorooctane (see Fig. 4.69). In the second example Ansari and Gree [203] showed that the combination of CuCl and TEMPO can be used as a catalyst in l-butyl-3-methylimidazolium hexafluorophosphate, an ionic liquid, as the solvent. However in this case turnover frequencies were still rather low even for benzylic alcohol (around 1.3 h 1). 

Jain SL, Sharma VB, Sain B (2006) Methyltrioxorhenium and sodium bromide-catalyzed oxidation of alcohols to carbonyl compounds with using l-butyl-3-methylimidazolium tetrafluo-roborate ionic liquid as a novel recyclable green solvent. Bull Chem Soc Jpn 79 1601-1603... 

In 2002, Ansari and Gree developed a simple and mild TEMPO-CuCl catalyzed aerobic oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones in l-butyl-3-methylimidazolium hexafluor-ophosphate [bmim][PF6] (Fig. 28) 99). Thus, a mixture of alcohol (Immol) and TEMPO (0.05 mmol) was reacted with latm O2 at 65°C in the ionic liquid. The products were simply isolated by extraction with diethyl ether. We note, however, that it is a pity that a more environmentally acceptable solvent was not used for product extraction. 

The oxidation of alcohols to carbonyl compounds is a fundamental reaction that has synthetic and chemical importance. Using chromium-based catalysts, researchers have developed several catalysts that have impacted alcohol oxidation reactions. Recently, homogeneous catalysts have had problems with catalyst/product separation and suffer from poor catalyst recyclability. Therefore, the quest for a resolution to this problem has led researchers to scaffold salen complexes onto a silica-based material such as MCM-41. Zhou et al. used an ion-exchangeable, layered polysiloxane support to immobili.se their sulfonato-(salen)Cr(m) complex. They reacted benzyl alcohol, cyclo-hexanol and -hexanol with hydrogen peroxide as oxidant in an ionic liquid at 40 °C. Several ionic liquids were investigated [BMImX (BMIm = 1-n-butyl-3-methylimidazolium X =PF6, BF4, NOs")] and compared for each substrate. 

Formation of carbonyl compound derivatives Hasan Mehdi et al. [29] reported the use of imidazolium ILs as solvents for organic transformations with tetravalent cerium salts. Urea-hydrogen peroxide in the presence of catalytic amoimt of magnesium bromide efficiently oxidizes primary and secondary benzylic alcohols into the corresponding aromatic aldehydes and ketones [30]. Margarida M. Antrmes et al. [31] reported IL 1-butyl-3-methylimidazolium chloride ([bmim]Cl) as solvent, in the transformation of o-glucose into 5-(hydroxymethyl)-2-furaldehyde at 120 °C. 

Reaction of 3,4-di-ferf-butylthiophene-l-oxide in ionic liquid l-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) with dienophile parasorbic acid afforded the Diels-Alder product 33 in 91% yield. But the resulting oxidation products 34 and 35 showed no significant photoreactivity, rendering it an inappropriate strategy for the synthesis of a two-stage photobase generator (PBG) based on photoinduced aromatization (Scheme 24) [38]. 

Modified graphene oxide was prepared using alkyl imidazol-ium ionic liquids (l-butyl-3-methylimidazolium tetrafluoroborate, l-butyl-3-methylimidazolium hexafluorophosphate and l-hexyl-3-methyhmidazolium bis(trifluoromethylsulfonyl) amide via an epoxide ring-opening reaction, cation-p stacking, or van der Waals interactions, with modified graphene exfoliated from a graphite rod by a moderate electrochemical method as a a comparative material (3). 

The use of metallorganic precursors also allows for a clean route to metal oxide nanoparticles. By employing diethyl zinc as a starting material, Williams and coworkers have shown that ZnO epoxy-resin nanocomposites and ZnO-coated carbon nanotubes may be prepared. The benefit of this method is the lack of undesirable by-products here, only ethane is produced. Given the pyrophoric nature of diethyl zinc, this reaction should be carried out under inert conditions. Ionic liquids too have been used in the low temperature synthesis of ZnO nanoparticles. Li et al. have employed 1-butyl-3-methylimidazolium chloride, in conjunction with zinc acetate and sodium hydroxide, to prepare hexagonal wurtzite ZnO nanoparticles which were formed upon simple grinding at room temperature for under an hour. ... 

---