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The oxidative reactions using the alkyl nitrites (RONO) as an oxidant have been developed by Ube Industries, Ltd. In the alkyl nitrite reactions, substrates such as CO andyor unsaturated- andyor carbonyl-compounds are oxidized over the palladium catalysts in no direct contact with molecular oxygen. The dimethyl carbonate (DMC), dialkyl oxalates and other useful chemicals are synthesized efficiently under moderate conditions by the alkyl nitrite reactions.

The transesterification of diethyl oxalate (DEO) with phenol to form diphenyl oxalate (DPO) has been carried out in the liquid phase over very efficient MoO(3)/TiO(2) solid-acid sol-gel catalysts. A selectivity of 100 % with a remarkable maximum yield of 88 % were obtained, which opens the route to downstream phosgene-free processes for the synthesis of polycarbonates. Interpretation of the results of various acidity measurements (NH(3) and pyridine desorption, methanol oxidation as a probe reaction) allowed us to identify the catalytic sites as Lewis acid sites.

The kinetics of the hydrolysis of bis(2,4-dinitrophenyl) oxalate (DNPO) were studied by infrared spectroscopy. The changes in the carbonyl region showed that neither 2,4-dinitrophenyl hydrogen oxalate nor oxalic acid could be detected. Simultaneously, the rate of evolution of carbon dioxide was measured in the reaction mixture and found to be equal to the disappearance of DNPO. Analysis of gaseous products confirmed the liberation of carbon dioxide and carbon monoxide but their ratio did not match that from known reaction pathways. With diphenyl oxalate and phenyl 2,4,6-trichlorophenyl oxalate, hydrolysis to phenyl hydrogen oxalate was detected. On the basis of these observations a new reaction scheme is suggested that describes both hydrolysis and decomposition of the oxalates.

Acid amount of mordenites and dealuminated mordenites with framework aluminum contents of 0.28–2.33 mmol g−1 was measured by temperature-programmed desorption of ammonia. Framework Al content was distinguished from nonframework Al based on 27Al MAS n.m.r. measurements. The relationship between the acid amount and the framework Al content represented a volcano relationship with the maximum acid amount at 1.65 mmol g−1 framework Al content. Below 1.65 mmol g−1 framework Al content, the acid amount was approximately proportional to the framework Al content, whereas the amount decreased as the framework Al content increased above 1.65 mmol g−1. The decrease of acid amount of mordenite with the framework Al content above 1.65 mmol g−1 seems to be due to the generation of nonacidic framework Al atoms owing to paired Al atoms in 4-rings.

Use of bis-aryloxalate neat solid samples to investigate ferromagnetic phenoxy-phenoxy geminate coupling is described. The title compounds (described in Technical Report 16) form good crystals, which up cooling to 77K or below and irradiation with a Xenon arc lamp give ESR spectra indicating both monoradical signals and radical-radical triplet pair interactions. The size of the interaction may be qualitatively determined by the spectral extent of the triplet spectrum (80-120 Gauss), which at this preliminary stage suggests that the radicals are 6.0-7.0 angstroms apart. The spectra are shown and compared to spectra with similar features for solid state photolysis of diphenyl oxalate. Tert-butylated bis-aryloxalates show good radical pair stability, with triplet ESR signals surviving days at room temperature in some cases. (JES)

In this work, a series of MoO3/TiO2−SiO2 catalysts were tested in the transesterification of dimethyl oxalate (DMO) with phenol to produce methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO). The evaluation results showed that MoO3/TiO2−SiO2 catalysts were more active and selective than both MoO3/SiO2 and TiO2/SiO2 catalysts in the transesterification reaction. Moreover, the catalytic activities of MoO3/TiO2−SiO2 linearly increased with increased TiO2 content up to a dispersion threshold and then decreased. To explore the influence of TiO2 modified silica support on the dispersion and acidic properties of molybdenum oxide species, a series of characterization approaches were performed. The results of XRD, XPS, and BET measurements indicated that the incorporation of dispersed TiO2 could not only enhance the interaction between MoO3 and SiO2 but also promote the dispersion state of MoO3 on the surface of composite support, and further increase the specific surface areas of the catalysts. NH3-TPD measure...

This paper presents results of a comparative investigation of the transesterification of dimethyl oxalate (DMO) with phenol to produce methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO) over MoO 3 /SiO 2 and MoO 3 /TiO 2 –SiO 2 catalysts. The evaluation results show that MoO 3 /TiO 2 –SiO 2 is much more active and selective than MoO 3 /SiO 2 . The surface structure and acidity of MoO 3 /SiO 2 and MoO 3 /TiO 2 –SiO 2 were investigated by a series of characterization approaches. XRD and FT-IR demonstrated that the incorporation of amorphous TiO 2 could not only enhance the interaction between MoO 3 and SiO 2 , but also improve the dispersion state of MoO 3 on the surface of SiO 2 . NH 3 -TPD and FT-IR of adsorbed pyridine measurements indicated that amorphous TiO 2 incorporation into and further interaction with MoO 3 and SiO 2 formed more weak acid sites on the surface of the catalysts. However, Bronsted acid sites were also detected on the surface of the MoO 3 /TiO 2 –SiO 2 catalysts, which further motivated us to study the nature of Bronsted acid sites in detail. Several conventional Bronsted acids were also tested in the transesterification. The results unexpectedly showed that conventional Bronsted acids have better reactivities than those of conventional Lewis acids from selective point of view. In addition, the combination of reactivity tests, NH 3 -TPD spectra, and FT-IR measurements of adsorbed pyridine strongly suggest that the strong Lewis acid is more responsible for the production of the by-product anisole than the strong Bronsted acid. The results indicated that the improvement of catalytic efficiency of MoO 3 /TiO 2 –SiO 2 , compared to MoO 3 /SiO 2 , could be ascribed to the increased dispersion capacity of MoO 3 and the dominant weak acid sites (including the synergistic effect of the weak Lewis acid sites with the weak Bronsted acid sites). A tentative mechanism for the transesterification reaction over Bronsted acid was proposed.

Silica-supported MoO3 catalyst prepared by slurry impregnation method exhibits higher activity and dispersion capacity compared to the MoO3/SiO2 prepared conventionally. Slurry MoO3/water is used instead of the solution ammonium heptamolybdate. Highly dispersed amorphous Mo catalysts are obtained, which is closely related the catalytic activities, without calcination, waste solutions, and calcining nitrogeous gases. The dependence of catalytic activity on Mo loading for the slurry prepared catalysts was similar to the samples prepared by the conventional impregnation method, indicating the slurry method is a simple and clean alternative to the conventional one.

The standard enthalpies of combustion of diphenyl oxalate and benzoic anhydride have been measured by static combustion calorimetry. The results have been used to derive the standard enthalpies of formation: ΔHf°(diphenyl oxlate, c)=–129·0 ± 0·8 and ΔHf°(benzoic anhydride, c)=–99·3 ± 0·4 kcal mol–1. The thermochemistry of these and related oxygenated compounds is discussed. Values for bond dissociation energies have been derived and are discussed in the context of possible decomposition pathways.