纯硅MCM-41中孔分子筛合成因素的研究Ⅰ.Na~+、K~+阳离子对合成的影响

本文采用表面活性剂十六烷基三甲基溴化铵（Ｃ１６ＴＡＢｒ，以下为１６３１），在（Ｎａ，Ｋ）ＯＨＳｉＯ２Ｃ１６ＴＡＢｒＨ２Ｏ体系中分别利用室温、水热及干粉法进行了纯硅ＭＣＭ４１中孔分子筛的合成，考察了阳离子Ｎａ＋、Ｋ＋对ＭＣＭ４１合成及稳定性的影响。通过ＸＲＤ对结晶度的测定，发现ＮａＭＣＭ４１的晶化速率明显高于ＫＭＣＭ４１，而热稳定性和水热稳定性较差，且ａ０值小于后者。同时发现，就合成方法而言，室温法得到的产物具有很高的结晶度，利用水热法合成的样品的热稳定性明显较高，而干法得到的分子筛产品具有优良的水热稳定性。     

Mechanistic aspects of the Wolff-Kishner reaction. V. The cation effect on the reaction of benzophenone hydrazone in butyl carbitol and decyl alcohol

The rate of the Wolff-Kishner reaction of benzophenone hydrazone in butyl carbitol increases as the cation of the alkoxide base is varied in the order K>Na>Li>Mg. The replacement of butyl carbitol by 1-decanol also accelerates the reaction, and an additional increase is caused by the presence of crown ether. On the basis of changes in the activation parameters, it is concluded that the reactivity of the hydrazone anion increases as the contact ion pair becomes more fully solvated and dissociated.     

Alginate Properties and Heavy Metal Biosorption by Marine Algae

The physical properties of the alginate component in four different brown seaweeds (Sargassumfluitans, Ascophyllum nodosum, Fucus vesiculo-sus, andLaminaria japonica) were characterized using potentiometric titration,¹³C-nuclear magnetic resonance (NMR), chemical analysis, and viscosity measurements. The heavy metal binding capacities of the corresponding seaweeds were directly proportional to their respective total carboxyl group content, and related to the electronegativity of the elements investigated (Ca, Zn, Cd, Cu, and Pb). The uronic acid composition or sequence of the alginate component did not affect the metal uptake properties of the biosorbents studied here. However, the alginate leaching owing to its solubilization by Na ions was observed to decrease with increasing intrinsic viscosity of the extracted alginate, related to its molecular weight, and with increasing apparent acidic dissociation constant, related to the alginate density inside the biomass.     

Synthesis and Antiradical Activity of 5-Acetyl-2-alkylthio-4-aryl-6-methyl-1,4-dihydropyridine-3-carboxylic Acid Nitriles

The alkylation of 3-cyano-1,4-dihydropyridine-2(3H)-thiones or the condensation of an aromatic aldehyde, cyanothioacetamide, acetylacetone, and methyl iodide in the presence of piperidine has given a series of novel 5-acetyl-2-alkylthio-4-aryl-6-methyl-1,4-dihydropyridine-3-carboxylic acid nitriles. A compound was obtained from 3,5-di(tert-butyl)-4-hydroxybenzaldehyde in the molecule of which were combined the active part of the antioxidant ionol and a 1,4-dihydropyridine ring. It was found that, among the compounds synthesized, the highest antiradical activity occurred in a compound having two hydroxyl groups in the 4-phenyl substituent.     

DFT and CIS(D) theoretical study on the ground and excited states of pentanitrogen cation

Different isomers of N₅⁺ were modeled at DFT(PBE0)/aug-cc-pV(Q + d)Z, and their ground(transition) state characteristics were assessed through frequency calculations. Single-point energies were accomplished at PBE0/aug-cc-pV(5 + d)Z. Nonlinear optical susceptibilities (NLO) of isomers were accomplished using Firefly, while the linear optical invariant was examined using the finite-field method, Firefly, and modified dipole field tensor in the presence of two different screening factors. The excited states, singlets and triplets, of were modeled at the CIS and CIS(D) and then their optical parameters were estimated at TDFT(PBE0)/aug-cc-pV(Q + d)Z using Firefly. The singlet is found the most stable isomer, with the inversional rate constant larger than that of the Cs isomer and high energy barrier with the triplet counterpart. Isomers 2 , 3 , and 4 are found local minima, while 5 and 6 are saddle points: transition states between equivalent invertomers. Energy calculations of the singlet and triplet isomers were in excellent agreement with the literature. An excellent correlation is found between the average polarizability and the impulse factor. Substantial variations were found between the singlet and triplet excited states in terms of energy, geometry, and optical properties from one side and with from the other side. Reactivity indices showed that N1 and N5 are the optimum nucleophilic and electrophilic reactivity sites.     

First radical cation salts of 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP) with copper(II) metal complex anions: β-(BDA-TTP)4Cu2Cl6 and (BDA-TTP)2CuCl4

New radical cation salts based on 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP) with copper(II) metal complex anions, β-(BDA-TTP)₄Cu₂Cl₆ and (BDA-TTP)₂CuCl₄, were synthesized and structurally characterized. Single crystals were prepared by electrochemical oxidation of BDA-TTP under galvanostatic conditions. X-ray diffraction study demonstrated that the salts have a layered structure, in which the conducting BDA-TTP layers alternate with the [Cu₂Cl₆]²⁻ or [CuCl₄]²⁻ anions. Both salts show the semiconductor-type temperature dependence of the conductivity. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 48–54, January, 2007.     

Reactivity of Radical Cations of Trimesitylphosphine

Anodic oxidation of trimesitylphosphine in the presence of typical nucleophilic reactants is studied by cyclic voltammetry. The results and the literature data suggest that the manifestation of radical properties is more typical for radical cations of trimesitylphosphine, because, when realizing an electrophilic path of reacting, additional energy is needed for altering the configuration of radical cations of trimesitylphosphine.     

葡萄糖B-Z体系中酸度变化诱导的复杂振荡反应

本文首次报导了葡萄糖-KBrO₃-丙酮-MnSO₄-H₂SO₄体系的化学振荡反应,在这一体系中改变酸度可产生一系列复杂的振荡现象,当[H₂SO₄]₀>0.36mol·l^-1或[H₂SO₄]₀<0.074mol·l^-1时,体系分别出现二种不同类型的振荡波形OA和OB,OA振荡存在一诱导期,OB振荡无锈导期;OA的振幅较小,但振荡频率比OB快得多;OB的振荡周期逐渐缩短,但OA.却相反变化.当0.074mol·l^-1<[H₂SO₄]₀<0.36mol·l^-1时,体系同时出现上述二种类型的振荡波形,中间存在一过渡区域,即产生连续振荡波形.文章讨论了诱导期及过渡时间与[H₂SO₄]₀的关系,对酸度的影响机理作了说明.     

Use of the Second Derivative of TG Curves for Investigation of the Exchanged Interlayer Cation in Montmorillonite

Various cation-exchanged montmorillonites (Li+, Na+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Cu2+, Ag+, Cd2+, Hg2+, Al3+, Pb2+ and NH4+) were prepared from calcium montmorillonite and their properties were studied by means of X-ray diffraction and thermal analysis. The two methods give information on the cation exchange in the interlayer space only. X-ray diffraction studies at room temperature are mainly suitable for estimation of the exchange of cations of different valencies. At 500°C, when the structure is completely collapsed, the d value of montmorillonite depends on the non-hydrated ionic radius of the interlayer cation, but the measurement interval is limited for fine interpretation. The thermoanalytical method is suitable for a better distinction of different exchangeable cations of higher hydration energy on the basis of the DTG or DDTG curve. This revised version was published online in July 2006 with corrections to the Cover Date.