Oxalic acids epoxidations

The insertion of Ti in the zeolite framework was accompanied by a significant decrease in A1 content (Table 1). However, there was no stoichiometric process between A1 removal and Ti insertion. Moreover, it was found that the treatment of Ig of an aluminum containing beta zeolite with a 75 ml of 3 x 10 M oxalic acid solution decreased the Si/Al ratio from its original value of 30 to 85 due to A1 extraction. Attempts to incorporate Ti into other zeolites like ZSM-12 and mordenite were not successful. Interestingly, the extraction of A1 from these zeolite structures was also unsuccessful with oxalic acid solutions with comparable concentrations. However, preliminary data show that siliceous mesoporous molecular sieves (MCM-41 and HMS) treated similarly with ammonium titanyl oxalate solutions exhibit good epoxidation activity. It is inferred that the presence of framework cations that can be extracted by oxalate species and/or the presence of defect sites in the parent zeolite is a requisite for the subsequent incorporation of titanium. 

The group of Jacobs reports a Mn complex with a tridentate nitrogen (N3) ligand (trimethyltriazacyclonane) catalyst that can be used for the epoxidation with H2O2 of various terminal olefins [167] and cyclohexene [168] (Table 1.6). It was found that cocatalysts such as oxalic acid suppressed solvent oxidation and the ensuing generation of radicals. 

Succinimides can also be post-treated to provide additional performance properties one of the most commonly used reagents is boric acid which delivers anti wear properties to a formulation [41], Post-treatments with other maleic anhydride-containing co-polymers, such as polyoctadecene succinic anhydride, yield dispersants with enhanced viscosity credit [42], Uses of other reagents, such as carbonates, lactones, sulphur dioxide, epoxides, oxalic acid and carbon disulphide, have also been disclosed [43],... 

Scheme 6 Transformation of Carvone (71) to methyl ketone (74) was achieved by the use of known reagents. It was converted to a mixture of diasteromers(75) and separarated. Hydration of each isomer with dilute methanolic oxalic acid yielded the corresponding lactone (76), each of which was converted into the same lactone (77). Epoxidation followed by reduction gave a mixture of epimeric diols whose diacetate was subjected to pyrolysis to phytuberin (55).

A catalytic amount of an oxalate/oxalic acid buffer strongly enhances the catalytic properties of the Mn-Mestacn complexes and yields for the epoxides of allyl acetate or 1-hexene reach up to 99 % and 65 % on olefin and peroxide basis, respectively 153). It has been suggested that the addition of a catalytic... 

Hydrogen peroxide decomposition by Mn-tmtacn complexes in CH3CN was shown to be suppressed effectively by addition of oxalate [94d] or ascorbic acid [94a] as coepoxidation activity of the in situ prepared Mn-tmtacn complex [94d]. In general, fidl conversion was reached with less than 1 mol% of catalyst within 1 h. In addition to oxalic acid, several other bi- or polydentate additives, for example, diketones or diacids, in combination with Mn-tmtacn and H2O2 were found to favor alkene epoxidation over oxidant decomposition [94d]. Employing this mixed catalytic system, allylic alkenes (e.g., allyl... 

In the case of oxalic acid an even more complex picture emerged [123]. Initially only epoxidation is observed. However, after a certain period of time, cts-dihydrox-ylation begins. This is in stark contrast to the other carboxyUc add-based systems where epoxidation and ds-dihydroxylation proceed concurrently. Furthermore, the reaction mixture does not contain EPR-active spedes at 77 K, and the UV-vis absorption spectra are unstructured. Concurrently with the initiation of cis-dihy-... 

The ENR was prepared by two step reactions. The first step was involved in the formation of novolac resin through condensation of phenol and formaldehyde under oxalic acid catalyzed with the molar ratio of phenol to formaldehyde was 1 0.8. In the second step, the epoxidation of previously prepared novolac resin was carried out by reacting novolac with excess of epichlorohydrin with 1 8 molar ratio under 40 % sodium hydroxide catalyst (Saw et al. 2011b, 2012). The schematics of synthesis are shown in Fig. 1. 

Common stabilizers for organic cellulose molding compounds include epoxides, especially epoxidized soybean oil, alkaline and alkaline-earth salts of acetic and carbonic acid as well as tartaric acid, oxalic acid and citric acid. Effective antioxidants include substituted phenols, such as t-butylphenol, or preferably sterically hindered phenols, such as 2,6-di-tert-butyl-p-cresol. Diphenylamine or esters of thiopropionic acid exhibit an effect similar to that of antioxidants [501]. 

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