Direct conversion of furfural to levulinic acid/ester in dimethoxymethane:Understanding the mechanism for polymerization

This study investigated the conversion of furfural to 5-hydroxymethylfurfural(HMF)and further to levulinic acid/ester in dimethoxymethane under acidic conditions,with the particular focus on understanding the mechanism for polymer formation.The results showed that furfural could react with dimethoxymethane via electrophilic substitution reaction to form HMF or the ether/acetal of HMF,which were further converted to levulinic acid and methyl levulinate.The polymerization of furfural and the cross-polymerization between dimethoxymethane and the levulinic acid/ester produced were the main side reactions leading to the decreased yields of levulinic acid/ester.Comparing to the other solvent,methanol as the co-solvent helped to alleviate but not totally inhibited the occurrences of the polymerization,as the polymerization reactions via aldol condensation did not eliminate the C=O functionalities.As a consequence,the polymerization reactions continued to proceed.Other co-solvent used such as guaiacol,dimethyl sulfoxide and acetone interfered with the transformation of furfural to HMF or aided the polymerization reactions.The polymer produced from the reactions between furfural and DMM was different from that produced from levulinic acid/ester.The former had a higher crystallinity,while the latter was more aliphatic.The DRIFTS and TG-MS studies showed that the polymer had the carboxylic group,methyl group and the aliphatic structure in the skeleton.The removal of these functionalities was accompanied by the aromatization of the polymer.The condensation of DMM with levulinic acid/ester was the key reason for the diminished production of levulinic acid/ester.

Solvent effects on infrared spectra of 2—Methyl—4,5—dimethoxy—3—oxo—2H—Pyridizine：Part 2.Binary Solvent SYstems

This research on the solvent effects of 2 methyl 4,5 dimethoxy 3 oxo 2H pyridizine (MDOP) in binary solvent systems on the infrared spectra for MDOP in n hexane/CHCl 3 mixture solvents showed that there were three forms of carbonyl stretching vibration band [ υ (C=O)] of MPOP as the mole fraction of CHCl 3 in the binary solvents changes. In pure n hexane solvent, the υ (C=O) of MDOP appeared at a relatively high wavenumber. With CHCl 3 added, the υ (C=O) shifted to lower wavenumbers. Two new bands were observed over a certain range of mixture solvent compositions. The origin of the bands was discussed in the terms of two kinds of hydrogen bond together with their individual dependence on mixture composition. Comparisons were drawn for the solvent sensitivities of υ (C=O) for propanone.

An Improved Preparation of 2,5-Dimethoxy-tetrahydrofuran

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RESOLUTION OF RACEMIC DIMETHYL 4,4′-DIMETHOXY-5, 6, 5′, 6′-BISMETHYLENEDIOXYBIPHENYL-2, 2′-DICARBOXYLATE (BIPHENYL DIESTER) ——A NEW ANTIHEPATITIC DRUG

Synthetic biphenyl diester, dimethyl 4, 4’-dimethoxy-5, 6, 5′, 6′-bismethylenedioxybi-phenyl-2, 2′-dicarboxylate is a new antihepatitic drug. Pharmacological studies showed that biphenyl diester has relatively strong SGPT lowering activity. It has been used clinically for the treatment of chronic hepatitis and lowering the elevated SGPT caused by certain chemicals and medicaments. Owing to the presence of four ortho substituents on the 2, 2′ and 6, 6′position in the biphenyl skeleton, the molecule can exist in two atropisomers.

Therapeutic Effect of Dimethyl Dimethoxy Biphenyl Dicarboxylate on Collagen-Induced Arthritis in Rats

Objective： To study the effect of oral administration of dimethyl dimethoxy biphenyl dicarboxylate （DDB） on adjusting angiogeneic/inflammatory mediators and ameliorating the pathology of bones in rats with collagen-induced arthritis （CIA）. Methods： Wistar rat model of CIA was set up using bovine collagen type H. Fifty rats were divided into five groups randomly： normal, CIA model, DDB treatment, methotrexate （MTX） treatment, and combined DDB＋MTX treatment. Ankle joints of rats were imaged with digital X-ray machine to show the destruction of joints. Fore and hind paw and knee joints were removed above the ankle joint then processed for haematoxylin and eosin staining. Plasma levels of vascular endothelial growth factor （VEGF）, platelet derived growth factor, interleukin-8 （IL-8）, IL-4, tumor necrosis factor α （TNF-α）, and cyclooxygenase-2 （COX-2） were quantified by enzyme-linked immunosorbent assay. Nitric oxide levels were detected by Griess reagent. Results： Compared with the CIA model group, a remarkable reduction in various angiogenic （VEGF and IL-8） and inflammatory mediators （TNF-α, IL-4 and COX-2） after treatment with DDB either alone or combined with MTX （P〈0.05 or P〈0.01）. Histopathological and X-ray findings were confirmatory to the observed DDB anti-arthritic effect. The DDB-treated group showed amelioration in signs of arthritis which appeared essentially similar to normal. Conclusion： Our data shed light on the therapeutic efficacy of DDB in experimental rheumatoid arthritis （RA） compared with a choice drug （MTX） and it may be offered as a second-line drug in the treatment of RA.

New Chiral Ligand N-Toluenesulfonyl-2,2′-dimethoxy-6,6′-diaminobiphenyl for Catalytic Asymmetric Transfer Hydrogenation of Ketones

A new chiral ligand N p toluenesulfonyl 2,2′ dimethoxy 6,6′ diaminobiphenyl (Ts DMBDPPA) was prepared from 2,2′ dimethoxy 6,6′ diaminobiphenyl via N tosylation. Its Ru(II) complex was effective catalysts for catalytic asymmetric transfer hydrogenation of aromatic ketones (with ee 's up to 69.3%).

曲昔匹特体内代谢过程及种属差异性研究

日本入仑 勉等1979年报告了新药曲昔匹持(KU—54)在大鼠、小鼠、豚鼠、犬及人体内的代谢过程.结果如下: 1、尿和胆汁的代谢物包括有M—1为原形药,M—2为5—(3,4,5—trimethoxy—benzamido)-2-piperidine,M-3为3—(4.5—dimethoxy-3-hydroxybenzamido)piperidine,和M—4为3—(3,4—dimethoxy—4—hydroxybenzamido)piperidine。是经过β—醛糖酸酶/芳基硫酸酶的水解后,用物理化学方法分析、鉴定(包括熔点、红外(IR)、质谱(Mass)、顺磁共震(PMR)等法),并用薄层层析密度计(TLC—densitometry)加以估量。

副凋亡:肿瘤细胞克服凋亡抵抗的途径(英文)

Since inherent or acquired cellular resistance to various pro-apoptotic treatments often leads to therapeutic failure,a better understanding of alternative non-apoptotic pathways may facilitate the design of novel therapeutics against malignant cancer cells.Paraptosis is a cell death mode characterized by extensive vacuolization that arises via dilation of the endoplasmic reticulum(ER)and mitochondria,without any apoptotic characteristics.We found that curcumin,dimethoxycurcumin(a more stable analog of curcumin),and celastol kill malignant cancer cells via induction of paraptosis as a main cell death mode.Study on the underlying mechanisms of paraptosis revealed that simultaneous proteasomal inhibition and mitochondrial Ca2+ overload can effectively induce paraptosis in cancer cells.Mitochondrial Ca2+ overload can be achieved not only by inhibition of mitochondrial Na+/Ca2+ exchanger but also by IP3 receptor-or ryanodine receptor-mediated release of Ca2+ from the ER and its subsequent mitochondrial Ca2+ uniporter-mediated Ca2+ influx into mitochondria.Since malignant cancer cells are more vulnerable to oxidative stress and ER stress than normal cells,clarification of the molecular basis of paraptosis that targets mitochondria and the ER at the same time may provide a rational therapeutic strategy for effectively killing resistant cancer cells.

Experimental Investigation of the Influence of Fuel Viscosity on the Spray Characteristics of Diesel Nozzle

This paper presented an investigation of atomization characteristics including the velocity vector field and the mean droplet sizes for different percentages of DMM-diesel blended fuels using a phase doppler anemometry (PDA) analyzer system. Based on the fuel design concept, an oxygenated fuel named dimethoxy methane (DMM), which has lower viscosity, surface tension, and boiling point, was used to blend with diesel. The experiments were carried out under atmospheric conditions on a single-hole type diesel nozzle, liquid conditions comprise a temperature of 298 K under the needle valve opening pressure of 6 MPa. The results show that the sauter mean diameter (SMD) and spray cone angle of blended fuels decrease with the increase of DMM content; the axial mean velocity in the centerline increases with the increase of DMM. However, the spray behavior of blended fuel in which DMM exceeds 75% is virtually identical to that of neat DMM. The measurement also reveals the existence of an "S" shape in the radial mean velocity variations with radial distance.

Two new xanthones from Lomatogonium carinthiacum

AIM: To study the chemical constituents of Lomatogonium carinthiacum(Wulfen) Rchb. METHOD: The CHCl3-soluble fraction was separated by chromatography and the structures of the new compounds were elucidated by spectral experiments. RESULTS: Two new xanthones, 1, 8-dihydroxy-4, 5-dimethoxy-6, 7-methylenedioxyxanthone(1), 1, 4, 8-trimethoxyxanthone-6-O-β-D-glucoronyl-(1→6)O-β-D-glucoside(2) were isolated from the whole plant of Lomatogonium carinthiacum. CONCLUSION: Compounds 1 and 2 are new natural products.