Kinetics and mechanism of the cleavage of phthalic anhydride in glacial acetic acid solvent containing aniline

Apparent second-order rate constants (k(n)(app)) for the nucleophilic reaction of aniline (Ani) with phthalic anhydride (PAn) vary from 6.30 to 7.56 M(-1) s(-1) with the increase of temperature from 30 to 50 degrees C in pure glacial acetic acid (AcOH). However, the values of pseudo-first-order rate constants (k(s)) for the acetolysis of PAn in pure AcOH increase from 16.5 x 10(-4) to 10.7 x 10(-3) s(-1) with the increase of temperature from 30 to 50 degrees C. The values of k(n)(app) and k(s) vary from 5.84 to 7.56 M(-1) s(-1) and from 35.1 x 10(-4) to 12.4 x 10(-4) s(-1), respectively, with the increase of CH(3)CN content from 1% to 80% v/v in mixed AcOH solvents at 35 degrees C. The plot of k(s) versus CH(3)CN content shows a minimum (with 10(4) k(s) = 4.40 s(-1)) at 50% v/v CH(3)CN. Similarly, the variations of k(n)(app) and k(s) with the increasing content of tetrahydrofuran (THF) in mixed AcOH solvent reveal respective a maximum (with k(n)(app) = 17.5-15.6 M(-1) s(-1)) at 40-60% v/v THF and a minimum (with k(s) = approximately 0-1.2 x 10(-4) s (-1)) at 60-70% v/v THF. The respective values of DeltaH* and DeltaS* are 15.3 +/- 1.2 kcal mol(-1) and -20.1 +/- 3.8 cal K(-1) mol(-1) for k(s) and 1.1 +/- 0.5 kcal mol(-1) and -51.2 +/- 1.7 cal K(-1) mol(-1) for k(n)(app), while the values of k(n) (= k(n)(app)/f(b) with f(b) representing the fraction of free aniline base) are almost independent of temperature within the range 30-50 degrees C. A spectrophotometric approach has been described to determine f(b) in AcOH as well as mixed AcOH-CH(3)CN and AcOH-THF solvents. Thus, the observed data, obtained under different reaction conditions, have been explained quantitatively. An optimum reaction condition, within the domain of present reaction conditions, has been suggested for the maximum yield of the desired product, N-phenylphthalamic acid.     

不变变分问题

研究Lie意义下的允许连续群的变分 问题.基于形式变分学方法与Lie群理论方法的联系,得到以下两 个定理.定理1:如 果积分I= 相对某有限连续群D 是不变的,则Lagrange表 示ψ的ρ个线性独立组合将变为散度; 反之, 由后一条件得到积分I相对 某群Dρ的不变性.对无限多个参数的极限情形,定理也对.定理2:如果积分I 相对无限连续群D∞ρ是不变的,在此群中会出现直至 阶导 数的导数,那么Lagrange表示ψ及其至 阶导数之间有ρ个恒等关 系成立;这里反述也对.定理1在ψ=0时给出ρ个第一积分.定理2表 明,Lagrange方程总数中的ρ个方程是其余方程的结果.     

Idealtheorie in Ringbereichen

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Kinetics and mechanism of hydrolysis of N‐(2′‐hydroxyphenyl)phthalamic acid (1) and N‐(2′‐methoxyphenyl)phthalamic Acid (2) in a highly alkaline medium

A kinetic study on hydrolysis of N‐(2′‐hydroxyphenyl)phthalamic acid ( 1 ), N‐(2′‐methoxyphenyl)phthalamic acid ( 2 ), and N‐(2′‐methoxyphenyl)benzamide ( 3 ) under a highly alkaline medium gives second‐order rate constants, k_OH, for the reactions of HO^? with 1, 2 , and 3 as (4.73 ± 0.36) × 10^?8 at 35°C, (2.42 ± 0.28) × 10^?6 and (5.94 ± 0.23) × 10^?5 M^?1 s^?1 at 65°C, respectively. Similar values of k_OH for 3 , N‐methylbenzanilide, N‐methylbenzamide, and N,N‐dimethylbenzamide despite the difference between pK_a values of aniline and ammonia of ～10 pK units are qualitatively explained. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 1–11, 2009     

The role of neutral anions in ionic liquid as solvent media for the reactivity and stereoselectivity towards asymmetric Michael addition reaction of n-pentanal with β-nitrostyrene catalyzed by L-Proline

Michael addition reactions of n-pentanal with ß-nitrostyrene in achiral and chiral ionic liquids catalyzed by l-proline were studied. Results indicate anion plays an important role as weak coordination properties in the reactivity and stereoselectivity towards Michael product. 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf₂]) ionic liquid was found to be the best solvent media with a high yield (up to 90%) and a high diastereomeric ratio (syn/anti: 91/9), with moderate enantioselectivity (38% ee) among ten ionic liquids tested. The ionic liquid has been reusable over five numbers of cycles.     

Abstrakter Aufbau der Idealtheorie in algebraischen Zahl- und Funktionenkörpern

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Der Endlichkeitssatz der Invarianten endlicher Gruppen

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Über ganze rationale Darstellung der Invarianten eines Systems von beliebig vielen Grundformen

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Neuraminidase Inhibitor of Garcinia atroviridis L. Fruits and Leaves Using Partial Purification and Molecular Characterization

Neuraminidase (NA) is an enzyme that prevents virions from aggregating within the host cell and promotes cell-to-cell spread by cleaving glycosidic linkages to sialic acid. The best-known neuraminidase is the viral neuraminidase, which present in the influenza virus. Thus, the development of anti-influenza drugs that inhibit NA has emerged as an important and intriguing approach in the treatment of influenza. Garcinia atroviridis L. (GA) dried fruits (GAF) are used commercially as seasoning and in beverages. The main objective of this study was to identify a new potential neuraminidase inhibitor from GA. A bioassay-guided fractionation method was applied to obtain the bioactive compounds leading to the identification of garcinia acid and naringenin. In an enzyme inhibition study, garcinia acid demonstrated the highest activity when compared to naringenin. Garcinia acid had the highest activity, with an IC₅₀ of 17.34–17.53 µg/mL or 91.22–92.21 µM against Clostridium perfringens-NA, and 56.71–57.85 µg/mL or 298.32–304.31 µM against H1N1-NA. Based on molecular docking results, garcinia acid interacted with the triad arginine residues (Arg118, Arg292, and Arg371) of the viral neuraminidase, implying that this compound has the potential to act as a NA enzyme inhibitor.