Dehydration reactions in water. Brønsted Acid-surfactant-combined catalyst for ester,ether, thioether,and dithioacetal formation in water

Dehydration reactions in water have been realized by a surfactant-type catalyst, dodecylbenzenesulfonic acid (DBSA). These reactions include dehydrative esterification, etherification, thioetherification, and dithioacetalization. In these reactions, DBSA and substrates form emulsion droplets whose interior is hydrophobic enough to exclude water molecules generated during the reactions. Detailed studies on the esterification revealed that the yields of esters were affected by temperature, amounts of DBSA used, and the substrates. Esters were obtained in high yields for highly hydrophobic substrates. On the basis of the difference in hydrophobicity of the substrates, unique selective esterification and etherification in water were attained. Furthermore, chemospecific, three-component reactions under DBSA-catalyzed conditions were also found to proceed smoothly. This work not only may lead to environmentally benign systems but also will provide a new aspect of organic chemistry in water.     

Structures, stabilities, and electronic and optical properties of c(58) fullerene isomers, ions, and metallofullerenes.

The 1205 classical isomers of fullerene C58, as well as one quasi-fullerene C58 isomer with a heptagonal ring (labeled as Cs:hept) have been investigated by the quantum chemical methods PM3, HCTH/3-21G, and B3LYP/6-31G(d). Isomer C3v:0001, which has the lowest number of adjacent pentagons, is predicted to be the most stable isomer, but the quasi-fullerene isomer Cs:hept is only 2.50 kcal mol-1 higher in energy. Systematic investigations of the electronic properties of C3v:0001 and Cs:hept find that the C3v:0001 isomer has high vertical electron affinity (3.19 eV). The nucleus-independent chemical shifts (NICS) value at the center of Cs:hept (-5.1 ppm) is more negative than that of C60 (-2.8 ppm). The NICS value at the center of the heptagonal ring in Cs:hept (-2.5 ppm) indicates weakly aromatic character. In contrast, the C58(6-) and C58(8-) ions of the C3v:0001 and Cs:hept geometries possess large aromatic character, with NICS values between -14.0 and -26.2 ppm. To clarify the thermodynamic stabilities of C58 isomers at different temperatures, the entropy contributions are taken into account on the basis of the Gibbs energy at the B3LYP/6-31G(d) level. The C3v:0001 isomer prevails in a wide range of temperatures, and the Cs:hept isomer is also an important component around 2800 K. The IR spectra of C58 isomers are simulated to facilitate experimental identification of different isomers. In addition, the electronic spectra and the second-order hyperpolarizabilities are predicted by ZINDO and the sum-over-states model. The static second-order hyperpolarizability of the C3v:0001 isomer is 96.5 % larger than that of C60, and its second-order hyperpolarizabilities at external field frequencies are at least nine times larger than those of C60.     

合成2—芳氧基—5—氟—3H—4—嘧啶酮的新方法

由２－氰－５－氟－３Ｈ－４－嘧啶酮和取代苯酚钠在常压下反应，合成了７个未见文献报道的２－芳氧基－５－氟－３Ｈ－４－嘧啶酮化合物，产率７０￣８７％，结构经ＩＲ、＾１Ｈ ＮＭＲ和ＭＳ证实。     

Vibrational energy relaxation dynamics of Si---H stretching modes on stepped H/Si(111) 1×1 surfaces

The vibrational energy relaxation rates of excited Si---H stretching modes on the monohydride steps of miscut H/Si(111) 1×1 surfaces are calculated using Bloch-Redfield theory combined with classical molecular dynamics (MD) simulation. The structure and vibrational frequencies of the surface are first investigated using the Car-Parrinello ab initio MD method. The calculated Si---Si---H bending frequencies and relaxed structures are then used to refine the empirical potential for the classical MD simulations. The lifetime of the excited Si---H stretching mode at the step is found to be shorter than the modes on the terrace. Both the magnitude and the trend of the calculated results agree well with the experimental measurement on the 9° monohydride stepped surface. The vibrational relaxation rate of the Si---H stretching modes on the 15° monohydride stepped surface are also calculated and predicted to have a slightly shorter lifetime than for the 9° surface.     

健儿三宝冲剂治疗儿童钙,铁,锌缺乏症164例临床观察

用健儿三宝冲剂治疗的儿童钙，铁，锌缺乏症，经临床观察，取得了较好的疗效。     

凝胶型聚合物电解质的电导率与温度的关系

凝胶型聚合物电解质的电导率与温度的关系孙晓光，林云青，齐力，景遐斌，王佛松（中国科学院长春应用化学研究所长春１３００２２）关键词凝胶电解质，离子电导率，活化能无定形聚合物电解质电导与温度的依赖关系一般可用Ｖｏｇｅｌ－Ｔａｍｍａｎ－Ｆｕｌｃｈｅｒｃ（Ｖ...     

The structure of adducts of benzaldoxime and m-chlorobenzaldoxime dehydrodimers with styrene

The reaction of m-chlorobenzaldoxime dehydrodimer with styrene gives two 1:1 adducts.The main product 7 is a bisnitrone. The minor product 8 has been shown by X-ray diffraction anal-ysis to possess the structure: ArCH(N=O)CH_2CH (Ph)O--N=CHAr. The two C=N bonds areall in Z configuration. The structure of the adducts from benzaldoxime dehydrodimer and styrene isalso assigned.     

聚酯纤维与丙烯酸的辐照-过氧化法接枝聚合

聚对苯二甲酸乙二醇酯纤维在空气氛中经γ-射线辐照生成大分子过氧化物,通过联氨-铜离子催化分解生成大分子自由基,在丙烯酸水溶液中进行接枝反应,丙烯酸的接枝率不受介质中氧的影响。根据接枝条件,有一个对接枝最有利的联氨浓度范围。在铜离子浓度0—2.5×10~(-3)克分子/升的实验范围内,接枝率随铜离子浓度而增加。     

氯化二氯代四苯基卟啉磷合二氯甲烷的晶体结构

氯化二氯代四苯基叶啉磷（Dichloro（5，10，15，20－tetraphenylporphinato）－phosphorus（V）chloride，［PCl2TPP］Cl）是典型的非金属卟琳配合物．据文献报导［1］该配合物能够与噻吩类化合物反应，所得单体经电解氧化，可生成具有导电性的聚合物．因此，测定［PCl2TPP］Cl的分子结构有着十分重要的意义．1标题化合物的制备及单晶生长标题化合物技文献［2］合成．用于X－射线衍射的单晶样品是将标题化合物的二氯甲烷／正庚烷混合溶液静置数周后得到的．单晶为紫色，用于X－射线衍射测定的晶粒尺寸为0．38mm×0．38mm×0．28mm．…     

Spectrophotometric flow injection determination of trace iodide in table salt and laver through the reaction of iodate with 3,5-Br2-PADAP and thiocyanate

A new simple, rapid and sensitive spectrophotometric flow injection method for the determination of trace iodide is described based on an ion associate of iodate (IO₃ ^–) with 2- (3,5-dibromo-2-pyridylazo)-5-diethylamino-phenol (3,5-Br₂-PADAP) and thiocyanate (SCN^–). In a strongly acidic medium, this unstable violet product was formed with an absorption maximum at 605 nm. Flow injection is an ideal method to reproducibly monitor the transient signal. Various parameters were optimized using the Super Modified Controlled Weighted Centroid Simplex Method (SMCWC). Under the optimum experimental conditions, iodide could be determined in the range of 1.00 × 10^–6 and 2.4 × 10^–5 mol l^–1. The correlation coefficient of the calibration curve is 0.9991. With a sampling frequency of 80 h^–1, the detection limit for iodide is 5.0 × 10^–7 mol l^–1. The proposed method has been applied to the determination of trace iodide after oxidizing I^– in table salt or laver to IO₃ ^–. In addition, the mechanisms of the ion association reaction was studied. Received: 15 August 1996 / Revised: 10 October 1996 / Accepted: 16 October 1996