CoCl_2·6H_2O or LaCl_3·7H_2O Catalyzed Biginelli Reaction. One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1 H)-ones

Ｉｎｔｒｏｄｕｃｔｉｏｎ1,4 Ｄｉｈｙｄｒｏｐｙｒｉｄｉｎｅｓｏｆｔｈｅｎｉｆｅｄｉｐｉｎｅｔｙｐｅ (ｅ .ｇ .Ｉ—ＩＩＩ)ａｒｅｔｈｅｍｏｓｔｓｔｕｄｉｅｄｃｌａｓｓｏｆｏｒｇａｎｉｃｃａｌｃｉｕｍｃｈａｎｎｅｌｍｅｄｉｃｉｎｅ ,ｗｈｉｃｈｈａｖｅｂｅｃｏｍｅａｌｍｏｓｔｉｎｄｉｓｐｅｎｓ ａｂｌｅｆｏｒｔｈｅｔｒｅａｔｍｅｎｔｏｆｃａｒｄｉｏｖａｓｃｕｌａｒｄｉｓｅａｓｅｓｓｕｃｈａｓｈｙｐｅｒｔｅｎｓｉｏｎ ,ｃａｒｄｉａｃａｒｒｈｙｔｈｍｉａｓ ,ｏｒａｎｇｉｎａ .1Ｉｎｔｈｅｐａｓｔｄｅｃａｄｅ…     

Synthesis and characterization of Mn-, La-Mn- and La-Ca-Mn-citrates as precursors for LaMnO<Subscript>3</Subscript> and La<Subscript>1−x</Subscript>Ca<Subscript>x</Subscript>MnO<Subscript>3</Subscript>

Mn-, LaMn- and LaCaMn-citrates were synthesized at 60–120°C in ethylene glycol medium using chlorides or nitrates as metal sources. Their composition, IR spectra and thermal decomposition were studied. Equimolar La/Mn ratio has been established in the complex, prepared from chloride solution with the same initial composition of the metals. In the isolated three-metallic complex the molar ratio of the metals deviates from the composition in the initial solution. The final products of the heating of Mn- and mixed-metal LaMn-citrates at 1000°C are phase-homogeneous Mn₃O₄ (hausmannite) and LaMnO₃ respectively. Parasitic phase(s) are observed in La_xCa_1−xMn_yO₃, produced from LaCaMn-citrate.     

Dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes with lanthanum metal

It was found that lanthanum metal caused the dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes to generate the corresponding benzynes and o-quinodimethanes. When o-dihalogen substituted arenes were allowed to react with lanthanum metal in the presence of dienes, the Diels-Alder products between benzyne and dienes were formed in moderate to good yields. Similarly, the Diels-Alder adducts of o-quinodimethane with dienophiles were obtained, in the reaction of α,α′-dibromo-o-xylenes with lanthanum metal in the presence of dienophiles.     

Synthesis of yttrium,lanthanum, neodymium,praseodymium, and lutetium alkoxides and acetylacetonates

A convenient and practical method is proposed for the synthesis of lanthanide and yttrium alkoxides. The method involves dissolving the metals or their hydrides in a solution of dry HCl in the corresponding alcohol, with subsequent dehalogenation of the LnCl₃ solution by an equivalent amount of alkali metal (Na, Li), The rareearth alkoxides are easily converted into acetylacetonates Ln(acac)₃ by the action of acetylacetone.A. N. Nesmeyanov Institute of Elementoorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2490–2493, November, 1992.     

Zur Kristallstruktur von CaLaAl3O7 und CaLaGa3−xAlxO7 (x = 0,66)

On the Crystal Structure of CaLaAl₃O₇ and CaLaGa_3?xAl_xO₇ (x = 0.66) Single crystals of (I): CaLaAl₃O₇ and (II): CaLaGa_2.34Al_0.66O₇ were grown from molten oxide mixtures and investigated by single crystal X-ray technique. Both compounds crystallize with tetragonal symmetry, space group D? P4 2₁m, (I): a = 7.8075; c = 5.1564 Å, (II): a = 7.9130, c = 5.2360 Å, Z = 2 and are isostructural with the Melilites. The crystal structure is discussed.     

模板法合成含镧的层状无机-有机纳米复合材料

以表面活性剂十二烷基磺酸钠为模板制备了含稀土元素La的无机-有机纳米复合材料。通过XRD、SEM、HRTEM、EDX等的表征，证明所得的稀土复合物为层状结构，且十二烷基磺酸钠与La的比例为1∶1。考察了反应温度、反应时间以及原料配比等对复合物结构的影响。     

Crystal Structure and Characterization of a Large Polyoxotungstate (NH4)21{La(H2O)5[Ni(H2O)]2As4W40O140}·53H2O

The heteropolytungstate (NH4)₂₁{La(H₂O)₅[Ni(H₂O)]₂As₄W₄₀O₁₄₀}·53H₂O is obtained by the reaction of Na₂₇[NaAs₄W₄₀O₁₄₀]· 60H₂O with NiCl₂·6H₂O, La(NO₃)₃·6H₂O and NH₄Cl at pH‐4.5. The structure and chemical composition are determined by X‐ray diffraction analysis and elemental analysis. The crystal data and main structure refinement are a = 1.9551(3) nm, b = 2.4156(4) nm, c= 3.7068(6) nm, β = 91.505(3)°, V = 17.500 (5) nm³, monoclinic crystal system with space group P2₁/n, Z = 4, R₁ = 0.0573, wR₂ = 0.0717 [I >2<s?(I)], R₁, = 0.2463 and wR₂ = 0.1199 (all data). [La(H₂O)₅] {Ni(H₂O)}₂AS₄W₄₀O₁₄₀ has C₂, symmetry. IR spectra of the ligand [NaAs₄W₄₀O₁₄₀]^27‐ and its three complexes were discussed.     

Energetics of magnesium, strontium, and barium doped lanthanum gallate perovskites

LaGaO₃ perovskites doped with Sr or Ba at the La site and Mg at the Ga site were prepared by solid-state reaction or sol-gel method and characterized. Enthalpies of formation from constituent oxides at 298 K were determined by high-temperature oxide melt solution calorimetry. Energetic trends are discussed in terms of defect chemistry. As oxygen deficiency increases, formation enthalpies define three trends, LaGa_1−yMg_yO_3−δ (LGM), La_1−xSr_xGa_1−yMg_yO_3−δ (LSGM), and La_1−xBa_xGa_1−yMg_yO_3−δ (LBGM). They become less exothermic with increasing doping, suggesting a dominant destabilization effect from oxygen vacancies. The endothermic enthalpy of vacancy formation is 275±37, 166±18 and 138±12 kJ/mol of V_O^·· for LGM, LBGM and LSGM, respectively. Tolerance factor and ion size mismatch also affect enthalpies. In terms of energetics, Sr is the best dopant for the La site and Mg for the Ga site, supporting earlier studies, including oxygen ion conductivity and computer modeling.     

镧的植物防病效果及其生物学效应

通过灭菌土接种Rhizoctonia solani以及混合接菌Rhizoctonia solani和Fusarium solani进行盆栽试验,分别研究了镧浸种处理对高羊茅及板蓝根出苗、生长发育的影响。结果表明,镧浸种能明显地减少病原菌的侵染,对由其所造成的种腐、芽腐及根腐等有显著的防治效果,提高了板蓝根和高羊茅种子的出苗率。同时,镧浸种在适当的浓度范围内,还能显著地促进植物的生长发育,生物量明显增加。利用盆栽水稻试验研究了稀土镧对水稻纹枯菌(Rhizoctonia solani)的毒力,测定结果表明,镧喷施于水稻植株上对水稻纹枯病有明显的防治效果,且在活体条件下,喷施镧后1和7 d对水稻纹枯菌(Rhizoctonia solani)的有效中浓度分别为128.7和128.1 mg.L-1,均明显低于离体条件下的有效中浓度(171.9 mg.L-1)。     

Complexes of lanthanum with radical anions of 2,2-bipyridyl and 3,6-di-tert-butyl-o-benzoquinone

Complexes of a rare-earth element containing only one radical-anion ligand have been synthesized and isolated in pure states for the first time. The LaI₂(bpy)(THF)₃ complex has been prepared from [LaI₂(THF)₃]₂(C₁₀H₈) and 2,2-bipyridyl in DME. The semiquinone complex LaI₂(SQ)(THF)₃ has been obtained by reaction of lanthanum iodide with 3,6-di-tert-butyl-o-benzoquinone in THF in the presence of lanthanum powder. ESR spectra of the complexes have been studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2278–2280, November, 1995.We thank Mr. A. V. Protchenko for magnetic measurements and Dr. L. G. Abakumova for recording IR spectra and helpful discussion.This work was supported by the Russian Foundation for Basic Research (Project No. 95-03-08443a).