Fe1/2Al1/2PO4催化1,2-二氯丙烷脱氯氧化制备环氧丙烷

Fe1/2Al1/2PO4催化1;2-二氯丙烷脱氯氧化制备环氧丙烷     

Determination of constant‐volume combustion energy for the complexes of zinc nitrate with three amino acids

Five solid complexes of zinc with L‐α‐methionine, L‐α‐phenylalanine and L‐α‐histidine were prepared. The constant‐volume combustion energies of the complexes, ΔE_c (coordination), were determined by a precise rotating bomb calorimeter at 298.15 K. They were ‐ 2969.03 ± 0.34, ‐2929.46 ± 1.59, ‐9597.13 ± 6.12, ‐4378.98 ± 3.27 and ‐14047 ± 6.75 kJ/mol, respectively. Their standard enthalpies of combustion, ΔH^θ_m,c(coordination, s, 298.15 K), and standard enthalpies of formation, ΔH^θ_m,f (coordination, s, 298.15 K), were calculated. They were ‐2959.73 ± 0.34, ‐2923.88 ± 1.59, ‐9649.18 ± 6.12, ‐4373.40 ± 3.27, ‐14048.53 ± 6.75 kj/mol and ‐1180.94 ± 0.92, ‐1401.26 ± 1.77, ‐2501.69 ± 6.50, ‐1381.47 ± 3.49, ‐1950.19 ± 7.65 kJ/mol, respectively.     

Structure and stability of X4Y4H4 (XY=CC,BN)

Ab initio calculations have been carried out to study the structures and relative stabilities of the planar eight‐membered ring B₄N₄H₄ and its isoelectronic species C₈H₄ at the HF/6‐31G*, MP2/6‐31G*, MP2/6‐311G**, and MP4SDQ/6‐31G* levels. The analyses of Milliken population, vibration frequencies, π‐molecular orbital components, and orbital energy levels were used to evaluate the relative stabilities of these two similar systems. The homodesmotic reactions were also taken to be a useful index of relative stability for X₄Y₄H₄ (XY=CC, BN) and gave the resonance energies with MP4SDQ/6‐31G* of C₈H₄ (?37.2 kcal/mol) < B₄N₄H₄ (?29.2 kcal/mol). Furthermore, we calculated the thermodynamic functions of these reactions to discuss the influence of temperature. It is concluded that B₄N₄H₄ may exist in theory and could be a little more stable than C₈H₄. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 293–298, 2001     

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones from anthranilamide and ketones over Hβ zeolite in aqueous media*

The synthesis of 2,3-dihydroquinazolin-4(1H)-ones by cyclocondensation of anthranilamide with ketones in aqueous media using Hβ zeolite is reported. The scope of the reaction was explored by various ketones such as aromatic, aliphatic and cyclic ketones. Based on the preliminary mechanistic results, a tentative mechanism for the formation of 2,3-dihydroquinazolin-4(1H)-ones using zeolite catalyst (Hβ) is predicted. The reusability study, large-scale experiment and water as solvent showed significant benefits of this catalytic protocol in comparing to earlier methods.     

Solvent effects on hydrogen bond formation

Enthalpies of solution have been used to calculate transfer enthalpies for phenol, pyridine, and DMSO between the solvent cyclohexane and the solvents CCl₄, benzene, and CHCl₃. By use of model compounds, enthalpies due to interactions with phenol, pyridine, and DMSO have been determined. These enthalpies are used to calculate the effect of solvation relative to cyclohexane on hydrogen bonded complexes in CCl₄ and benzene solvents. Correlations with enthalpies due to interactions and frequency shifts for the hydroxyl stretch in these solvents have also been made.     

The ionization of perchloric and hydrofluoric acids in aqueous solution

Cyclical bifurcated hydrogen bonded structures are proposed for aqueous solutions of hydrofluoric acid and for the bifluoride ion which are consistent with the spectral data. The structure proposed for HF is also applicable to solutions in organic solvents. Raman spectra of tetramethylguanidinium perchlorate suggest that the corresponding Raman spectra of perchloric acid solutions may not be interpreted in terms of a completely dissociated acid. Other evidence including activity coefficient, heat capacity and partial molal volume data suggest that there is some association in relatively dilute perchloric acid solutions between the perchlorate ion and the hydrated proton. This association decreases in concentrated aqueous solutions.     

Raman spectral study of the constitution and equilibria of nitric acid and d-nitric acid

From relative integrated intensity measurements of the symmetric stretching vibration of nitrate ion in nitric acid solutions (both HNO ₃ /H ₂ O and DNO ₃ /D ₂ O), the mass law concentration quotients, Q were obtained as functions of concentration. By extrapolation the limiting dissociation constants were estimated to be 24.4 and 15 respectively at 25°C. It is shown that this constant refers to a process in which the ion pair H ₃ O⁺ NO ₃ ^– is in equilibrium with the dispersed, solvated H ₃ O⁺ and NO ₃ ^– ions.     

Isocamphananaloge mandelsäure

The synthesis of some new potentially, nitrogenefree spasmolytics is described. Formally the benzene nucleus in some mandelic acid esters, known by their mild spasmolytic activity, is substituted for the isocamphane bicyclus by a) SeO₂ oxidation of 1-(3,3-Dimethyl-2-exo-norbornyl)-ethanone (5) to the corresponding ketoaldehyde6, b) oxidation of6 to the isocamphane analogous mandelic acid4 and c) esterification of derivatives of4 with isoamylalcohol and benzylalcohol. Attemps to dehydrate the methylester7 to camphenylideneacetic acid methylester (12) by various methods failed, probably because of the ring strain.

Teil der Diplomarbeit vonB. Blach, Universität Wien 1981.     

Synthesis of macrocyclic 1,1′-biarenol derivatives by the tandem Claisen rearrangement and their binding properties

Crown ether-type macrocycles consisting of an enantiopure biarenol derivative and an oligoethylene glycol were synthesized by the Lewis acid-mediated tandem Claisen rearrangement. This is the first example of the successful application of the tandem Claisen rearrangement to the synthesis of enantiopure macrocyclic biarenol derivatives. The enantiopure macrocyclic biarenols were found to form 1:1 complexes with amino acid salts and to discriminate their chirality.