以吡啶-2,5-二羧酸或噻吩-2,5-二羧酸为配体的过渡金属配合物的合成、晶体结构及性质

以吡啶-2,5-二羧酸(2,5-pyridinedicarboxylic acid,H_2L_1)、噻吩-2,5-二羧酸(Thiophene 2,5-dicarboxylic acid,H_2L_2)为主要配体,4,4′-联吡啶(4,4′-bipy)、菲咯啉(phen)为辅助配体,采用溶剂热法成功合成了3个过渡金属配合物:[Co_2(L_1)_2(bipy)(H_2O)_6]·bipy·H_2O (1)、[Cu(L_2)_2(bipy)_2]n(2)、[Ni_2(L_2)(phen)_2(H_2O)_4](3),并利用X射线单晶衍射法、红外光谱(IR)、荧光光谱(FL)和热重分析(TG/DTG)等测试手段对其进行了表征。单晶结构分析表明:配合物1、配合物2为P1空间群,配合物3为P2/n空间群;配合物1和配合物3为零维双核小分子结构,配合物2为二维层状结构。     

高效液相色谱法测定饮料中的呋喃-2,5-二甲酸

建立了饮料中呋喃-2,5-二甲酸含量的高效液相色谱(HPLC)分析方法,采用Venusil HILIC(4.6 mm×250 mm,5μm)色谱柱;柱温40℃;流动相为0.02 mol/L乙酸铵(冰乙酸调至p H 3.5)-乙腈(50∶50);流速1.0 m L/min;检测波长265 nm。呋喃-2,5-二甲酸在0.5~100 mg/L浓度范围内线性良好,检出限(LOD)和定量下限(LOQ)分别为0.15 mg/kg和0.5 mg/kg,回收率为93.2%~109.0%,相对标准偏差(RSD,n=6)为0.9%~4.2%。该方法快速、操作简便、灵敏度高,适用于饮料中呋喃-2,5-二甲酸含量的测定。     

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.     

Diprotodecarboxylation Reactions of 3,4-Dialkoxythiophene-2,5-dicarboxylic Acids Mediated by Ag2CO3 and Microwaves

An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag₂CO₃/AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12–18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150 °C.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Synthesis, Structural Characterization and Luminescence of Lanthanide Coordination Polymers with Pyridine-2,5-dicarboxylic Acid

The complexes of formulas [Ln₂(pydc)₂(Hpydc)₂(H₂O)₄]·2H₂O [Ln=Ce ( 1 ), Pr ( 2 ), H₂pydc=pyridine‐2,5‐di‐carboxylic acid] have been hydrothermally synthesized and characterized by elemental analysis, IR, TG and single‐crystal X‐ray diffraction. The structure analyses for 1 and 2 indicate that one‐dimensional metal helical chains are linked through carboxylate groups, and the helical chains are connected with the bridging pydc^2? anion, forming two‐dimensional layered polymeric structures. The luminescent properties of complexes were also discussed.     

The Friedel-Crafts Acylation of Substituted Benzene with 2 - Phenylfuran-3, 4-dicarboxylic Acid Anhydride

TheFriedel-Craftsacylationreactions'-2areofparticularvalueowingt0theselectivityandeasewithwhichtheyareusuallyacc0mPlished,thusprovidingusefulroutestohighlyfimctionalinedar0maticringsystems.Sincesesamin-grouPlignanshavetW0aro-maticmoieties,theaPplicationoftheFriedel-CraftsacylationreactioninourstratCgyforsynthesisofsuchlignansseemedprondsing.Hence,titlecomPoundlwaschosenastheacylatingagenttoexaminesuchfeasibility.Ourresearchw0rkwasstartedfrom2,4-diphenyloxazole2,theprepaxation0fwhichwasgrea…     

Pseudodimorphism of the Trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic Acid Clathrates with Acetic and Propionic Acids

The versatile host compound trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid (1) forms under ambient conditions isostructural complexes with acetic and propionic acids being true clathrates without host-guest type H-bonds. A new modification of the clathrate between 1 and acetic acid (1a) is obtained at sub-room temperature (5 °C) while for preparation of the new crystal form of the clathrate with propionic acid (1b) crystallization temperature should be increased up to 50 °C. Crystal structures of the pseudodimorphs show that homo carboxylic acid dimers existing in the conventional phases are also observed here, demonstrating the new compounds to be of same clathrate type. Crystal data: for 1a: triclinic P-1, a = 8.626(2) Å, b = 9.073(2) Å, c = 12.042(2) Å, α = 76.34(3)°, β = 77.41(3)°, γ = 84.13(3)°, V = 892.5(4) ų, Z = 2, R = 0.0446 for 3171 reflections; for 1b: monoclinic C2/c, a = 13.268(3) Å, b = 12.636(3) Å, c = 21.786(4) Å, β = 90.56(3)°, V = 3652.3(14) ų, Z = 8, R = 0.0618 for 2365 reflections.     

Condensation polymers from 1,2,5-thiadiazole-3,4-dicarboxylic acid

A series of polyamides was prepared by interfacial polymerization of diamines with 1,2,5-thiadiazole-3,4-dicarbonyl chloride. Polyamides from secondary cycloaliphatic diamines and aromatic diamines have high softening points, high glass transition temperatures, and good thermal stability. Secondary amines, in particular cycloaliphatic secondary amines, form very high molecular weight polyamides. The polyamide from trans-2,5-dimethylpiperazine and 1,2,5-thiadiazole-3,4-dicarbonyl chloride is soluble in chloroform and 1,1,2-trichloroethane and has been cast into films and spun into fibers from those solvents. Fibers of this polymer are strong and have very high work recovery from small strains. In addition, these fibers show good retention of strength and work recovery over a range of temperatures and humidities.     

Symmetric 3,4-Diacetyl-2,5-dimethoxypyrroles. Heterocyclization of 3,4-Diacetylhexane-2,5-dione with Primary Amines

Russian Journal of General Chemistry -     

The synthesis of 6-methyl-5-hydroxypyridine-3,4-dicarboxylic acid

Summary We have worked out a new method for a three-stage synthesis of 5-hydroxy-6-methylpyridine-3,4-dicarboxylic acid, starting from 4-acetyl-5-methyloxazofe.     

Reaction of functionally substituted vinyl ethers with 3,4-diaminofurazan and furazan-3,4-dicarboxylic acid dihydrazide

Enaminofurazans were obtained by reaction of vinyl ethers with 3,4-diaminofurazan. It was established by IR and PMR spectroscopy that enaminofurazans exist in the form of a chelate complex. The structure of the chelate complex is discussed. Enehydrazides were obtained by reaction with furazan-3,4-dicarboxylic acid dihydrazide. When there is a cyano group in the ether molecule, the reaction does not stop with the formation of the enehydrazide but continues with its cyclization to give a pyrazole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 319–323, March, 1979.