Synthesis of fluorine-containing betulin esters

28-O-Fluoroacylbetulins were synthesized via acylation of betulin by fluorocarboxylic (perfluorobutyric, perfluorooctanoic, 3-fluorobenzoic, perfluorobenzoic) acid chlorides in CHCl₃ in the presence of Py. 3,28-Di-O-fluoroacylbetulins were prepared by treatment of betulin with fluorocarboxylic (trifluoroacetic, pentafluoropropionic) acid anhydrides in Py in the presence of 4-dimethylaminopyridine. 3,28-Di-O- (3-fluorobenzoyl)betulin was obtained from acylation of betulin by 3-fluorobenzoic acid in CH₂Cl₂ in the presence of N,N′-dicyclohexylcarbodiimide and 4-dimethylaminopyridine whereas acylation by perfluorobutyric acid under the same conditions gave 28-O-perfluorobutanoylbetulin.     

Synthesis and properties of polyamides from 2,5-furandicarboxylic acid and aromatic and aliphatic diamines

Russian Chemical Bulletin - Polyamides based on the 5-hydroxymethylfurfural derivative (2,5-furandicarboxylic acid dichloroanhydride) and diamines of both aromatic and aliphatic series were...     

Solvent-dependent selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid under neat conditions

An eco-friendly and economical route for the oxidation 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) with atmospheric dioxygen as the sole oxidant under acid-, base-, metal-and external initiator-free conditions in minimal solvent was reported.     

Solvent-dependent selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid under neat conditions

An eco-friendly and economical route for the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) with atmospheric dioxygen as the sole oxidant under acid-, base-, metal-, and external initiator-free conditions in minimal solvent was reported. In the present reaction, the 1,2-diethoxyethylane has a dual role: reaction medium and free-radical initiator. The FDCA easily crystallizes during the reaction and was simple purified via recrystallization to provide the pure FDCA.     

Efficient aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid on Ru/C catalysts

2,5-Furandicarboxylic(FDCA) is a potential substitute for petroleum-derived terephthalic acid, and aerobic oxidation of5-hydroxymethylfurfural(HMF) provides an efficient route to synthesis of FDCA. On an activated carbon supported ruthenium(Ru/C) catalyst(with 5 wt% Ru loading), HMF was readily oxidized to FDCA in a high yield of 97.3% at 383 K and 1.0 MPa O_2 in the presence of Mg(OH)_2 as base additive. Ru/C was superior to Pt/C and Pd/C and also other supported Ru catalysts with similar sizes of metal nanoparticles(1–2 nm). The Ru/C catalysts were stable and recyclable, and their efficiency in the formation of FDCA increased with Ru loadings examined in the range of 0.5 wt%–5.0 wt%. Based on the kinetic studies including the effects of reaction time, reaction temperature, O_2 pressure, on the oxidation of HMF to FDCA on Ru/C, it was confirmed that the oxidation of HMF to FDCA proceeds involving the primary oxidation of HMF to 2,5-diformylfuran(DFF) intermediate, and its sequential oxidation to 5-formyl-2-furancarboxylic acid(FFCA) and ultimately to FDCA, in which the oxidation of FFCA to FDCA is the rate-determining step and dictates the overall formation rate of FDCA. This study provides directions towards efficient synthesis of FDCA from HMF, for example, by designing novel catalysts more efficient for the involved oxidation step of FFCA to FDCA.     

铈改性Ru/HAP催化果糖一步法制备2,5-呋喃二甲酸

采用浸渍法制备稀土元素铈（Ce）改性的Ru/HAP催化剂Ce-Ru/HAP，以实现果糖一步法制备2，5-呋喃二甲酸（2，5-FDCA）。采用XRD、TEM、NH₃-TPD和XPS表征手段对催化剂的理化性质进行分析。结果表明，Ce很好地高度分散到载体HAP上，且并未对HAP的结构造成影响；Ce主要以Ce³⁺和Ce⁴⁺形式存在，前者的存在使催化剂表面产生大量氧空穴，同时两者之间的电子转移有利于氧空穴形成，提高储氧能力，提高催化剂的表面催化活性；催化剂具有丰富的弱酸位，能够抑制反应过程中副反应的发生。优化反应条件后，催化剂Ce（8%，质量分数）-Ru/HAP在温度160℃和氧气压力2 MPa的反应条件下，反应4 h时2，5-呋喃二甲酸的产率为34.2%。因此，Ce的引入能够提高传统贵金属复合型催化剂的催化活性，同时也为果糖一步制备2，5-FDCA提供新思路。     

Synthesis of selenophene-2,5-dicarboxylic acid

Selenophene-2,5-dicarboxylic acid was obtained by liquid-phase oxidation of 2,5-dimethylselenophene with molecular oxygen.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, p. 1605, December, 1972.     

Bio-based copolyesters poly(butylene 2,6-naphthalate-co-butylene furandicarboxylate) derived from 2,5-furandicarboxylic acid (FDCA): Synthesis,characterization, and properties

A series of copolymers poly(butylene 2,6-naphthalate-co-butylene furandicarboxylate) (PBNFs) derived from 2,5-furandicarboxylic acid (FDCA) were synthesized. The molecular weight, microstructures, thermal and mechanical properties were characterized. DSC results show that PBN and PBNF25 can crystallize rapidly. However, the crystallization rates of PBNF50, PBNF75 and PBF are very slow. The T_d,5% and T_d,max values of all polyesters were higher than 360 °C and 390 °C, respectively. Compared with PBN, PBNF25, PBNF50, PBNF75 and PBF exhibited much higher elongation at break (214–295%) and bio-based content (46–100%).     

Synthesis of esters of iminocarbonic acid

The first syntheses of asymmetrical esters of iminocarbonic acid are reported. These syntheses were carried out without the separation of intermediates. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, p. 23, October, 1989.     

The mass spectra of some fluorine-containing dimethyl esters

The mass spectra of esters of the general formula MeO₂C·[CF₂]_n·CO₂Me, n = 6 to 9, are reported and briefly discussed. Common features of the mass spectra are prominent peaks at [M ? CO₂], [M ? CO₂ ? C₂F₄] and [M ? CO₂ ? 2C₂F₄].     

Reactions of fluorine-containing 3-oxo esters with aldehydes

Fluoroalkylcontaining 3-oxo esters react with aldehydes to form 2-benzylidene-3-fluoroacyl-esters or 4-aryl(alkyl)-3,5-dialkoxycarbonyl-2,6-dihydroxy-2,6-di(fluoroalkyl)tetrahydropyranes depending on the conditions. Ethyl pentafluorobenzoylacetoacetate with benzaldehyde affords 3,5-diethoxy-carbonyl-4-phenyl-2-pentafluorophenyl-7,8,9,10-tetrafluoro-4,5-dihydrobenzo[b]oxacin-6-one.     

直接合成Beta沸石封装Pt纳米粒子用于5-羟甲基糠醛合成2,5-呋喃二甲酸

生物质是唯一的碳基可再生资源,具有种类丰富、廉价易得、来源广泛等特点,将生物质资源转化为高附加值化学品对于可持续生产,缓解全球性能源和环境危机具有重要意义.5-羟甲基糠醛(HMF)是广泛研究的生物质平台分子,可以转化为多种高附加值化学品,其中氧化产物2,5-呋喃二甲酸(FDCA)有望作为对苯二甲酸的潜在替代物生产聚酯,...     

Liquid-phase polymerization of fluorine-containing esters of acrylic and methacrylic acid in a gamma radiation field

Basic kinetic characteristics of the process of radiation liquid-phase polymerization of fluorine-containing methacrylates and their hydrocarbon analogs have been compiled. The kinetics of the polymerization of fluorine-containing methacrylates is described well by a kinetic mechanism with quadratic termination of growing macromolecules and clearly expressed gel effect. The insertion of perfluorinated substituents into the methacrylate molecule evidently leads to a decrease of the rate constant of termination of the polymer chains. The kinetics of the polymerization of fluorine-containing acrylates, like their hydrocarbon analogs, differ significantly from the polymerization of maethacrylates by the absence of a quasisteady-state regime — the rate increases sharply from the very beginning of the process because of the diffusion character of termination.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1330–1334, June, 1991.     

Synthesis and selective carbocupration reaction of fluorine-containing enynic esters, enynylphosphine oxides, and enynylphosphates

Some new fluorine-containing enynic esters, enynylphosphine oxides, and enynylphosphates were synthesized stereoselectively in good yields by the dehydrohalogenation reaction of fluoroalkylated 3-iodoacrylates, 2-iodovinylphosphonates, and 2-iodovinylphosphine oxides under basic conditions. These fluorine-containing enynic compounds could undergo carbocupration reaction with organocopper reagents and the vinylcopper intermediates formed in situ could further react with some electrophiles such as allyl bromide, phenylselenyl bromide, and iodine to give the corresponding polysubstituted fluorine-containing dienoic esters, phosphates, and phosphine oxides with high regio- and stereoselectivity.     

大环胂酸酯的合成

二氯烷基胂与二甲胺反应得到双(二甲胺基)烷基胂(1)。双(二甲胺基)烷基胂与α,ω-二醇化合物进行环缩合反应得到大环胂酸酯(2a～2e),与α,ω-二硫醇化合物进行环缩合反应得到了相应的大环硫代砷酸酯(2f～2h)。化合物2a～2h均经元素分析、IR、^1HNMR、MS等证实了它们的组成和结构。     

桂皮酸糖酯类衍生物的合成

桂皮酸作为常用的食用香料、新鲜水果和蔬菜等的防腐剂,是一种来源广泛,对人体安全的物质,被美国列为GPAS范围.有报道把它称为一种调节植物分化和生长的激素,还具有抗微生物、抗炎、抗血小板凝聚的作用[1].此外,一系列研究表明桂皮酸及其衍生物对黑色素瘤细胞、结肠癌细胞、流感病毒等多种肿瘤细胞和病毒具有抑制作用[2-6].但由于桂皮酸分子中含有羧基,对胃肠道有较强的刺激作用,因此,对桂皮酸的结构修饰已有研究报道[7].     

Synthesis and characterization of polymers derived from 2,5-dimethoxy-terephthaldehyde and 2,5-dimethoxy-terephthalic acid

Polyamides were synthesized from 2,5-dimethoxyterephthaloyl dichloride and diamines. Also, polyimines and polyaldoles were prepared from 2,5-dimethoxy-terephthaldehyde with diamines and ketones. The polymers were characterized by elemental analysis and infrared and NMR spectroscopy. Their intrinsic viscosity, glass transition temperature, and thermaldecomposition temperatures were determined.     

Base-free aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over Pt/C catalysts synthesized by pulse alternating current technique

The Pt/C catalysts with various Pt content (5-30 wt%) synthesized via electrochemical pulse alternating current technique have been evaluated for the base-free aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid. The higher Pt content in the catalyst (30 wt%) provides the product yield up to 65% upon performing the process in concentrated (～0.1 M) aqueous solutions of the substrate.