Development of Catalyst Technology for Producing Methyl Methacrylate (MMA) by Direct Methyl Esterification

The direct methyl esterification reaction for MMA was commercialized. Precisely synthesized Pd₃Pb₁ catalyst and the catalysis at the proposed reductive oxidation reaction condition (PROC) realized and guaranteed high MMA yield and long catalyst life. Controlled Pd distribution in a catalyst particle drastically decreased Pd loss from the catalyst during reaction. Unit processes are introduced as well.     

1:2 Complexes of chloranilic acid with pyrazole and imidazole,and the aceto­nitrile solvate of a 1:1 complex with imidazole

2,5‐Di­chloro‐3,6‐di­hydroxy‐1,4‐benzo­quinone (chloranilic acid) forms X—H?Y (X, Y = N or O) and C—H?Cl hydrogen bonds with pyrazole and imidazole to afford bis­(pyrazolium) di­chloro­anilate and bis­(imidazolium) di­chloro­anilate, (I) and (II), both 2C₃H₅N₂⁺·C₆Cl₂O₄^2?, and imidazolium chloro­anilate aceto­nitrile solvate, C₃H₅N₂⁺·­C₆HCl₂O₄^?·C₂H₃N, (III). Their crystal structures demonstrate three novel supramolecular architectures based on supramolecular synthons to build a ladder, (I), a two‐dimensional network, (II), and a flat ribbon, (III).     

2:1 Complexes of 2‐chloro‐4‐nitro­benzoic acid and 2‐chloro‐5‐nitro­benzoic acid with pyrazine

2‐Chloro‐4‐nitro­benzoic acid and 2‐chloro‐5‐nitro­benzoic acid form O—H?N hydrogen bonds with pyrazine to afford 2:1 complexes of 2C₇H₄ClNO₄·C₄H₄N₂, (I) and (II), respectively, that are located on inversion centers. The 2C₇H₄ClNO₄·­C₄H₄N₂ units in both complexes are connected by weak C—H?O hydrogen bonds; the units build a three‐dimensional hydrogen‐bond network in (I) and a ribbon structure in (II).     

A new polymorph of barium chloro­anilate trihydrate

Single crystals of a new polymorph of the title compound, barium(II) 3,6-di­chloro-2,5-di­hydroxy-1,4-benzo­quinone tri­hydrate, Ba²⁺·C₆Cl₂O₄²⁻·3H₂O, have been grown in sodium metasilicate gel. Each Ba²⁺ cation is coordinated by eight O atoms. The Ba²⁺ cations are bridged by an O atom of a ligand around the centre of symmetry at Wyckoff position 4a and by the O atom of a water mol­ecule around the centre of symmetry at Wyckoff position 4b, forming a sheet parallel to the (100) plane. Loose contacts are found around one of the water mol­ecules, as observed in the Cmca form.     

Ammonium hydrogen tartronate at 240 and 20 K

The low-temperature structure determination of the title compound, alternatively called ammonium hydrogen hydroxy­propane­dioate, NH₄⁺·C₃H₃O₅⁻, has revealed that the H atom involved in a very short asymmetric O—H⋯O hydrogen bond [O⋯O = 2.448 (2) Å at 240 K and 2.4393 (10) Å at 20 K] is disordered.     

FORMATION OF INTRAMOLECULAR EXCIMER IN ARYL PHOSPHATES AND THEIR REACTIVITIES

The fluorescence spectra of bis(4-methoxyphenyl) hydrogen phosphate and tris(4-meth-oxyphenyl) phosphate showed two emission bands. A longwavelength emission band arose from the intramolecular excimer of two 4-methoxyphenyl groups and a short band arose from a 4-methoxyphenyl group itself. There was a good correlation between the relative intensity of the monomer/excimer emissions and the quantum yield of 4,4′-dimethoxybiphenyl, which was an intramolecular coupling product.     

Photoelectron measurements of naphthacene polycrystal by using NeII and HeII resonance radiation

Photoelectron spectra of naphthacene polycrystals excited with NeII and HeII resonance radiation have been measured. The spectra are compared with that excited with HeI resonance radiation. It is found that the corresponding peak positions of these three spectra are in good agreement with each other, while the peak intensity depends on the energy of the incident photon. The origin of the peak width in the photoelectron spectrum is discussed.