Alkene oxidation by a platinum oxo complex and isolation of a platinaoxetane

Oxo complex [(1,5-COD)4Pt4(mu3-O)2Cl2](BF4)2 (1) reacts readily with ethylene and norbornylene. The ethylene reaction yields acetaldehyde and a 1:1 mixture of (1,5-COD)Pt(Cl)(CH2CH3) (2) and [(1,5-COD)Pt4(eta3-CH2CHCH(CH3))](BF4) (3), while the norbornylene reaction yields a platinaoxetane complex, the first metallaoxetane to be obtained from the reaction of an oxo complex and an alkene.     

Atomic alignment effect in the dissociative energy transfer reaction of metal carbonyls (Fe(CO)5, Ni(CO)4) with oriented Ar (3P2, M(J) = 2)

The atomic alignment effect has been studied for the dissociative energy transfer reaction of metal carbonyls (Fe(CO)(5), Ni(CO)(4)) with the oriented Ar ((3)P(2), M(J) = 2). The emission intensity from the excited metal products (Fe*, Ni*) has been measured as a function of the atomic alignment in the collision frame. The selectivity of the atomic orbital alignment of Ar ((3)P(2), M(J) = 2) (rank 2 moment, a(2)) is found to be opposite for the two reaction systems; the Fe(CO)(5) reaction is favorable at the Π configuration (positive a(2)), while the Ni(CO)(4) reaction is favorable at the Σ configuration (negative a(2)). Moreover, a significant spin alignment effect (rank 4 moment, a(4)) is recognized only in the Ni(CO)(4) reaction. The atomic alignment effect turns out to be essentially different between the two reaction systems; the Fe(CO)(5) reaction is controlled by the configuration of the half-filled 3p atomic orbital of Ar ((3)P(2)) in the collision frame (L dependence), whereas the Ni(CO)(4) reaction is controlled by the configuration of the total angular moment J (including spin) of Ar ((3)P(2)) in the collision frame (J dependence). As the origin of J dependence observed only in the Ni(CO)(4) reaction, the correlation (and/or the interference) between two electron exchange processes via the electron rearrangements is proposed.     

Preparation of bis-pyrylium salts

Six methods are described for the preparation of bis-pyrylium salts: (1) treatment of 4,4′-bi-2-flavene or 4-(4H-flav-2-en-4-yl)flavylium perchlorate with triphenylmethyl perehlorate; (2) reaction of an aromatic o-hydroxyaldehyde and 1,4-deacetylbenzene under acidic conditions; (3) reaction of o-hydroxyacetophenone, 1,4-diacetylbenzene, perchloric acid and acetic acid; (4) reaction of a 2- or 4-methylpyrylium salt with 2- or 4-pyrone in the presence of phosphorus oxychloride; (5) oxidation of a 1,2-ethanediylidenebis-flavene or -thiaflavene, a bis-flavenylidene or -thiaflavenylidene, and a bis-pyranylidene or -thiapyranylidene by means of cupric perchlorate; and (6) reaction of 4-methylflavylium and -thiaflavylium perchlorate with bromine in acetic acid.     

高碘酸盐氧化硫脲的非线性动力学行为和机理

在酸性介质中,高碘酸盐氧化硫脲的非线性反应呈现多种不同的化学计量方程 式。当[KIO_4]_0/[SC(NH_2)_2]_0 > 4时,计量方程为4IO_4~- + SC(NH_2)_2 + 3H_2O = 4IO_3~- + SO_4~(2-) + CO_3~(2-) + 2H~+ + 2NH_4~+;当[KIO_4]_0/ [SC(NH_2)_2]_0 = 8:7时,计量方程为8IO_4~- + 7SC(NH_2)_2 + 17H_2O = 4I_2 + 7SO_4~(2-) + 7CO_3~(2-) + 6H~+ + 14NH_4~+;而当[KIO_4]_0/[SC(NH_2)_2] _0 < 1时,反应的主要计量方程为IO_4~- + 4SC(NH_2)_2 + 8H_2O = I~- + 4S + 4CO_3~(2-) + 8NH_4~+。同时反应体系在氧化剂过量的条件下碘钟产生的诱导期 与1/[H~+]~2成正比;而当还原剂过量时,体系I_2逐渐累积至极值的诱导期与体系 初始pH呈线性关系。运用包含质子平衡反应、碘化合物自身反应、碘化合物-硫化 合物反应以及硫-硫反应的15步反应机理较好地模拟出封闭体系中pH,[I~-]以及 [I_2]的准振荡行为。     

2-取代吲哚的染料敏化光氧化反应

2-苯基吲哚 (1a) 在甲醇中的染料敏化光氧化反应给出2-苯基-2-(2'-苯基-3'-吲哚基)二氢吲哚-3-酮 (2a) 和2-甲氧基-2-苯基二氢吲哚-3-酮 (4a), 相应N-甲基取代产物由1-甲基-2-苯基吲哚 (1b) 的类似反应获得。发现反应产物分布随吲哚 (1) 的浓度和介质酸度的变化而变化。对反应机理进行了推测, 其中当1a的反应在乙腈中进行时, 分离到了相应的反应中间体: 2-苯基-3H-吲哚-3-酮 (3a)。     

Synthesis of new 1-substituted 4-(2-phenylquinazolin-4-yl)-and 4-(2-phenylquinazolin-4-ylidene) thiosemicarbazides

Two new 1-substituted 4-(2-phenylquinazolin-4-yl)-and 4-(2-phenylquinazolin-4-ylidene) thio-semicarbazides were formed by a multistep domino reaction of imidoyl isothiocyanate derivative with 1,1-di-R-hydrazine in acetone solution. Application of hydrazine hydrate under the same reaction conditions afforded 4-(2-phenylquinazolin-4(3H)-ylidene)-2-(propen-2-yl)-1-(propan-2-ylidene) thio-semicarbazide via a six-step triple-component domino reaction. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1688–1693, November, 2008.     

A 1D Schiff base zinc polymer as a versatile metallo-ligand for the synthesis of polynuclear zinc cages

The 1D polymeric Schiff base zinc complex, [LZn(2)Et(2)](n), where LH(2) = (NN'-ethylene-bis(4-iminopentan-2-one)) has been demonstrated as a useful synthetic metallo building block for the synthesis of homo and heteronuclear zinc cages. The reaction of [LZn(2)Et(2)](n) with CdI(2) afforded the hetero-nuclear cage, 1, [L(2)Zn(4)(Et)(2)CdI(4)], while reaction with HgI(2) afforded a hexanuclear zinc cage, [L(2)Zn(6)(Et)(4)(μ(4)O)(μ(3)OEt)I], 2. The versatility of [LZn(2)Et(2)](n) as a metallo building block is demonstrated through the reaction with ferrocenyl carboxylic acid, affording the ferrocenyl supported zinc cage, [L(2)Zn(8)(FcCO(2))(4)(Et)(2)(OEt)(2)(μ(4)O)(2)], 3, while the reaction with Er(III) acetate afforded the decanuclear zinc cage, [L(3)Zn(10)(μ(4)O)(4)(Et)(6)], 4.     

Sulfated mesoporous alumina: a highly effective solid strong base catalyst for the Tishchenko reaction in supercritical carbon dioxide

Heterogeneous strong base catalysis for the intramolecular Tishchenko reaction of aromatic 1,2-dicarbaldehydes to the corresponding phthalides in supercritical CO2CscCO2 has been realized with mesoporous alumina containing SO4(2-) ions in the alumina framework (mesoAl2O3/SO4(2-)). Infrared spectroscopy of pyrrole adsorbed on the alumina and strong poisoning by a weak Br?nsted acid of methanol revealed that the SO4(2-) ions in the framework slightly suppressed the average strength of base sites (O2-) on mesoAl2O3/SO4(2-), but there exists a small number of strong base sites that promote the Tishchenko reaction in scCO2. Although the intramolecular Tishchenko reaction of phthalaldehyde to phthalide in scCO2 was somewhat slower than those in organic solvents such as tetrahydrofuran (THF) and benzene, the addition of a small amount of THF as a cosolvent remarkably increased the reaction rate; the reaction in the scCO2-THF system proceeded 1.5-fold faster than those in pure benzene and THF solvents.     

Effect of bending and torsional mode excitation on the reaction Cl+CH4-->HCl+CH3

A beam containing CH(4), Cl(2), and He is expanded into a vacuum chamber where CH(4) is prepared via infrared excitation in a combination band consisting of one quantum of excitation each in the bending and torsional modes (nu(2)+nu(4)). The reaction is initiated by fast Cl atoms generated by photolysis of Cl(2) at 355 nm, and the resulting CH(3) and HCl products are detected in a state-specific manner using resonance-enhanced multiphoton ionization (REMPI). By comparing the relative amplitudes of the action spectra of Cl+CH(4)(nu(2)+nu(4)) and Cl+CH(4)(nu(3)) reactions, we determine that the nu(2)+nu(4) mode-driven reaction is at least 15% as reactive as the nu(3) (antisymmetric stretch) mode-driven reaction. The REMPI spectrum of the CH(3) products shows no propensity toward the formation of umbrella bend mode excited methyl radical, CH(3)(nu(2)=1), which is in sharp distinction to the theoretical expectation based on adiabatic correlations between CH(4) and CH(3). The rotational distribution of HCl(v=1) products from the Cl+CH(4)(nu(2)+nu(4)) reaction is hotter than the corresponding distribution from the Cl+CH(4)(nu(3)) reaction, even though the total energies of the two reactions are the same within 4%. An explanation for this enhanced rotational excitation of the HCl product from the Cl+CH(4)(nu(2)+nu(4)) reaction is offered in terms of the projection of the bending motion of the CH(4) reagent onto the rotational motion of the HCl product. The angular distributions of the HCl(nu=0) products from the Cl+CH(4)(nu(2)+nu(4)) reaction are backward scattered, which is in qualitative agreement with theoretical calculation. Overall, nonadiabatic product vibrational correlation and mode specificity of the reaction indicate that either the bending mode or the torsional mode or both modes are strongly coupled to the reaction coordinate.     

合成文拉法星的2-氮杂-1,3-丁二烯杂Diels-Alder反应与其 单分子环合竞争反应的研究

研究了不同的Lewis酸催化剂、温度、微波等条件下, 4-(4-甲氧苯基)-1-苯基-3-三甲基硅氧基-2-氮杂-1,3-丁二烯(2-ABDE)和亲二烯体环己酮发生杂Diels-Alder反应生成[4＋2]的六元环合产物噁嗪酮衍生物, 伴随的2-ABDE的 [2＋2]单分子环合, 生成单环β-内酰胺衍生物. 结果表明: 在低温条件下如(－78 ℃)[4＋2]反应占主导; 而在高温条件下(如135 ℃)仅进行[2＋2]反应. 微波加热方式可显著提高[2＋2]反应的速率和产率. 不同的Lewis酸催化剂对[2＋2]反应和[4＋2]反应的催化效率不同. Lewis酸的酸性强弱、软硬对2-ABDE的[2＋2]反应的催化能力起决定性作用.     

Reactions of methylpyrylium,thiapyrylium, and flavylium salts with tetracyanoethylene

The reaction of 2- or 4-methyl-2,6-diphenylpyrylium perchlorate with tetracyanoethylene (TCNE) in pyridine gives 2- or 4-(2,3,3-tricyanopropylidene)-2,6-diphenylpyran in good yield. Similar results are obtained from 2- or 4-methyl-2,6-diphenylthiapyrylium and 4-methylflavylium perchlorates. In one case a stable charge-transfer salt is isolated from the reaction of a methylene base and TCNE. The reaction mechanism of dye formation is discussed.     

光引发BrC2F4Br+C2F4调聚反应的光强影响

实验发现，在光引发BrC2F4Br＋C2F4调聚反应中，光强（或光功率密度）能影响产品分布。提出了反应机理：此反应由加成反应与复合反应组成，而链转移反应可忽略．由此进行了动力学计算，为与实验结果吻合，拟合得的加成反应BrC2F4＋C2F4的速率常数为（2±1）×107cm3•mol-1•s-1，Br（C2F4）n≧2＋C2F4的速率常数为（1．2±0．4）×107Cm3•mol-1•s-1     

Reactions of 2-chloro-2-(4-pyridyl)propane with nucleophiles. Substitution on tertiary carbon

The reaction of 2-chloro-2-(4-pyridyl)propane ( 2 ) with lithium 2-propanenitronate affords the C-alkylation product 2-nitro-3-(4-pyridyl)-2,3-dimethylbutane ( 3 ), the Michael-adduct 2-nitro-2-methyl-4-(4-pyridyl)pentane ( 4 ), 4-isopropenylpyridine ( 5 ) and 2-(4-pyridyl)-2-propanol ( 6 ). Of these four products, only the formation of 3 is suppressed when the reaction is performed in the presence of radical inhibitors. The reaction of compound 2 with sodium azide gives the tertiary substitution product 2-azido-2-(4-pyridyl)propane ( 8 ). The reaction is not influenced by radical inhibitors. This is also the case in the reaction of 2 with sodium benzenethiolate, which affords 2-mercaptophenyl-2-(4-pyridyl)propane ( 9 ) and 1-mercaptophenyl-2-(4-pyridyl)propane ( 10 ). Compound 5 , the product of an E₂-type elimination is also formed in the azide and thiolate reactions. A Michael type addition of sodium benzenethiolate to 5 explains the formation of 10 . Similarly, generation of 5 in reactions of 2 with sodium methanethiolate and sodium cyanide accounts for the formation of 1-mercaptomethyl-2-(4-pyridyl)propane ( 11 ) and 3-(4-pridyl)butanenitrile ( 12 ), respectively.     

Reaction of 2-(5-aminopyrazol-1-yl)quinoxaline 4-oxides with dimethyl acetylenedicarboxylate

The reaction of 6-chloro-2-hydrazinoquinoxaline 4-oxide 6 with ethyl 2-(ethoxymethylene)-2-cyanoacetate or (1-ethoxyethylidene)malononitrile gave 2-(5-amino-4-ethoxycarbonylpyrazol-1-yl)-6-chloroquinoxaline 4-oxide 7a or 2-(5-amino-4-cyano-3-methylpyrazol-1-yl)-6-chloroquinoxaline 4-oxide 7b , respectively. The reaction of compound 7a or 7b with dimethyl acetylenedicarboxylate resulted in the 1,3-dipolar cycloaddition reaction and then ring transformation to afford 4-(5-amino-4-ethoxycarbonylpyrazol-1-yl)-8-chloro-1,2,3-trismethoxycarbonylpyrrolo[1,2-α]quinoxaline 8a or 4-(5-amino-4-cyano-3-methylpyrazol-1-yl)-8-chloro-1,2,3-trismethoxycarbonylpyrrolo[1,2-α]quinoxaline 8b , respectively.     

Keggin结构纳米硅钨酸铵的室温固相合成与物性

首次以H4SiW12O40 * 22H2O和(NH4)2C2O4 * H2O为原料,室温固相反应合成出(NH4)4SiW12O40纳米微粒;用元素分析、 FTIR确定产物的组成和结构; XRD、 TEM和BET对产物的形貌、晶粒尺寸和比表面积进行了表征; TG-DTA确定了产物的稳定温区.结果表明,产物为纳米粒子,平均粒径为60 nm,比表面积为108.7 m2/g,在430℃以下具有良好的热稳定性.在固相反应中,研磨和放热反应热效应能加快反应物扩散速率和生成物成核速率,使产物粒径减小;反应物含有结晶水和生成物H2C2O4 * 2H2O,对形成小粒径的(NH4)4SiW12O40纳米粒子起关键作用.     

双室聚丙烯低温反应瓶的设计制造及在硅芴合成中的应用

设计制造了瓶底有一大一小2个室的聚丙烯（PP）塑料反应瓶,将其用于活泼的金属有机反应中硅芴的合成。 首先将制备的2,2′-二锂基联苯（2）转移到小室中,然后将SiCl4溶液注入大室内,再将反应瓶倾斜,使得化合物2的溶液分次进入大室进行反应,保证反应在SiCl4充分过量条件下进行,可大大降低螺硅芴（4）副反应产物的生成,使9,9-苯基硅芴的产率由20%提高至35%~40%,SiCl4的用量降至4倍摩尔量,从而也降低了产物后处理中柱分离的处理量。     

Reduction of colloidal manganese dioxide by manganese(II)

The reduction of colloidal MnO(2) by Mn(2+) in aqueous HClO(4) has been studied by a spectrophotometric method. The reaction product is Mn(III). The reaction is of first order in both colloidal MnO(2) and H(+), whereas it presents a fractional order (0.58+/-0.02) in Mn(2+). The reaction is retarded by addition of NaClO(4), but is not affected by addition of tert-butanol. The corresponding activation energy is 29.5+/-1.3 kJ mol(-1). The reaction is catalyzed by Na(4)P(2)O(7), and the pyrophosphate-catalyzed reaction is of first order in both colloidal MnO(2) and pyrophosphate and of fractional order (0.64+/-0.01) in Mn(2+), whereas its rate presents a complex dependence on the concentration of H(+). The pyrophosphate-catalyzed reaction is accelerated by addition of both NaClO(4) and tert-butanol. The corresponding activation energy is 49.7+/-3.0 kJ mol(-1). Mechanisms in agreement with the experimental data are proposed for both the parent and the pyrophosphate-catalyzed reactions.     

Practical synthesis of 2'-deoxy-4'-thioribonucleosides: substrates for the synthesis of 4'-thioDNA

We report herein a practical synthesis of 4'-thiothymidine (15) and appropriately protected 2'-deoxy-4'-thiocytidine (16), -thioadenosine (27), and -thioguanosine (29) derivatives, substrates for the synthesis of 4'-thioDNA, from the corresponding 4'-thioribonucleosides. 2'-deoxy-4'-thiopyrimidine nucleosides were synthesized using a radical reaction of the corresponding 2'-alpha-bromo derivatives, which were prepared via 2,2'-O-anhydro derivatives. 2'-deoxy-4'-thiopurine nucleosides were synthesized using the same radical reaction of the corresponding 2'-beta-bromo derivatives.     

Catalytic transformation of methane over in-loaded ZSM-5 zeolite in the presence of ethene

Methane is shown to react with ethene over In-loaded ZSM-5 to higher hydrocarbons such as propene and toluene at around 673 K. Such methane conversion is not catalyzed by proton-exchanged ZSM-5 (H-ZSM-5) under the same conditions, only C2H4 being converted to higher hydrocarbons. By using 13C-labeled methane (13CH4) as a reactant, the reaction paths for the formation of propene, benzene and toluene were examined. 13C-labeled propene (13CC2H6) is formed by the reaction of 13CH4 with C2H4. The lack of 13C-labeled benzene revealed that propene is not transformed to benzene, which instead originates entirely from C2H4. The 13C atom is inserted both into the methyl group and benzene ring in the toluene formed. This indicates that toluene is formed by two reaction paths; the reaction of 13CC2H6 with butenes formed by the dimerization of C2H4 and the reaction of benzene with 13CH4. The existence of the latter path was proved by the direct reaction of 13CH4 with benzene. The reaction of methane with benzene was also carried out in a continuous flow system over In-loaded ZSM-5. The reaction afforded 7.6% and 0.9% yields of toluene and xylenes, respectively, at 623 K.     

The unexpected desulfurization of 4-aminothiophenols

Thermolysis of 4-aminophenyl benzyl sulfide at 523 K in the hydrogen donor solvent (HDS), 9,10-dihydroanthracene (AnH2), gave 4-aminothiophenol and toluene as the predominant products of the homolytic S-C bond cleavage. Under these conditions, a portion of the 4-aminothiophenol was desulfurized to aniline with first-order kinetics and with a rate constant estimated by kinetic modeling to be 7.0x10(-6) s-1. Starting with 4-NH2C6H4SH at 523 K, it was found that sulfur loss was more efficient in the non-HDSs, anthracene and hexadecane, than in AnH2. Under similar (competitive) reaction conditions, YC6H4SHs with Y=H, 4-CN, and 3-CF3 were completely inert; with Y=4-CH3O, there was some very minor desulfurization, whereas with Y=4-N(CH3)2 and 4-N(CH3)(H), the sulfur extrusions were as fast as that for Y=4-NH2. We tentatively suggest that this apparently novel reaction is a chain process initiated by the bimolecular formation of diatomic sulfur, S2, followed by a reversible addition of ground state, triplet 3S2 to the thiol sulfur atom, 4-NH2C6H4S upward arrow(SS upward arrow)H, and insertion into the S-H bond, 4-NH2C6H4SSSH. In a cascade of reactions, aniline and S8 are formed with the chains being terminated by reaction of 4-NH2C6H4S upward arrow(SS upward arrow)H with 4-NH2C6H4SH. Such a reaction mechanism is consistent with the first-order kinetics. That this reaction is primarily observed with 4-YC6H4SH having Y=N(CH3)2, N(CH3)(H), and NH2 is attributed to the fact that these compounds can exist as zwitterions.