The kinetics of reaction between cyclic monoimides (succinimide, phtalimide, and glutarimide) with ethylene and propylene oxides in presence of sodium hydroxide was studied. The effect of substrate and catalyst concen...The kinetics of reaction between cyclic monoimides (succinimide, phtalimide, and glutarimide) with ethylene and propylene oxides in presence of sodium hydroxide was studied. The effect of substrate and catalyst concentrations on the course of the reaction was investigated. Kinetics of reaction was studied by dilatometry, i.e. by measuring volume contraction of reaction mixture. The kinetic law describing the reaction of imides with oxiranes is: . where ccat, cAH and cB are concentrations of catalyst, imide, and oxirane, respectively. The relative reactivity of imides and oxiranes was: GI > PI ≥ SI and EO > PO. The reaction mechanism was proposed based upon experimentally determined rate law for the reaction of cyclic monoimides and oxiranes as well as analytical and instrumental analysis of products. The elementary reaction between oxirane and imide anion is rate determining step. The imide anion is formed by hydrogen cation transfer into catalytic hydroxide anion from dissociated NaOH. In the consecutive elemental reaction an imidate anion attack on the oxirane molecule occurs. It is the slowest stage of the reaction, limiting the entire process. All the studied reactions obey the same mechanism as can be concluded from isokinetic relationship of studied systems)展开更多
A ferrocenylsulfides 1-2 mediated sulfur ylide epoxidation reaction was found to stereoselectively afford trans-oxiranes in excellent yields with recoverable starting material.
Literature describes kinetics of reactions of alcohols, phenols, carboxylic acids, amines and amides with oxiranes such as ethylene oxide and propylene oxide. However, there is no information regarding kinetic of reac...Literature describes kinetics of reactions of alcohols, phenols, carboxylic acids, amines and amides with oxiranes such as ethylene oxide and propylene oxide. However, there is no information regarding kinetic of reaction of imides with oxiranes. In this article the kinetics of the reaction of cyclic monoimides: succinimide, phtalimide, and glutarimide, with ethylene and propylene oxides in presence of triethylamine in aprotic solvent was studied. The rate laws for those processes were established based upon on dilatometric measurements. I was said that cyclic monoimides react with oxiranes in presence of triethylamine to give N-(2-hydroxyalkyl)imides as major product. This product react further with oxiranes in consecutive reaction. The kinetics of the reaction of cyclic mono-imides with oxiranes obey the following rate law: V = k1/2 c1/2cat c3/2imide c1/2oxirane. Based upon kinetic data the following orders of reactivity of imides and oxiranes were obtained: phtalimide ≥ succinimide > glutarimide and ethylene oxide > propylene oxide. The solvent (DMF, DMSO and dioxane) effect was also studied. From temperature dependences the thermodynamic parameters: activation energy, enthalpy and entropy from linear Eyring plots were obtained.展开更多
The mechanism of reaction of cyclic monoimides with oxiranes was established based upon kinetic studies and product analysis. It has been established that the reaction proceeds through initial formation of an adduct o...The mechanism of reaction of cyclic monoimides with oxiranes was established based upon kinetic studies and product analysis. It has been established that the reaction proceeds through initial formation of an adduct of imide and triethylamine. The crucial bond in adduct has ionic character;in non-aqueous solvents it is present as ion pair, while in water the adduct dissociate and free ions are present. The adduct enables the proton transfer from imide to oxirane. The rate determining step is reaction of imide and this adduct. Different values of entropy of transition states obtained from thermodynamic calculations suggest slightly different structure of transition state of rate determining step.展开更多
Direct photolysis and quenching experiments with styrene oxide support the existence of an efficient triplet photochemical pathway to benzyl radical formation. Similar photolytic behavior for styrene glycol carbonate ...Direct photolysis and quenching experiments with styrene oxide support the existence of an efficient triplet photochemical pathway to benzyl radical formation. Similar photolytic behavior for styrene glycol carbonate strongly supports the 1,3-diradical, resulting from the scission of the benzylic C-O bond, as the geometric source of the triplet pathway. Primary photoproducts were determined by both NMR and HPLC analysis and we observed that toluene and bibenzyl were both primary photoproducts, not secondary photoproducts.展开更多
目的:Siloranes是一种含硅的新型牙科复合树脂环氧乙烷单体,较传统的含碳的环氧乙烷单体具有更好的生物相容性。本研究的目的为用哺乳动物细胞培养检测姐妹染色体交换的方法评估Siloranes的基因毒性,并与传统的环氧乙烷比较。方法:研究...目的:Siloranes是一种含硅的新型牙科复合树脂环氧乙烷单体,较传统的含碳的环氧乙烷单体具有更好的生物相容性。本研究的目的为用哺乳动物细胞培养检测姐妹染色体交换的方法评估Siloranes的基因毒性,并与传统的环氧乙烷比较。方法:研究所用的传统环氧乙烷为CyracureTM UVR6105。Silorane包括Ph-Sil,TET-Sil和二者50/50(w/w)的混合物(3M-ESPE)。用CHO细胞在有或无S9情况下检测姐妹染色体交换(SCE)。Bonferron post hoc统计分析检测有无显著性差异。结果:与溶剂对照相比,在有或无S9情况下,环氧乙烷UVR6105显著性地增加了培养CHO细胞的SCE数目。3种Silorane单体Ph-Sil,TET-Sil或Sil-Mix均未能增加SCE数目。结论:用哺乳动物细胞培养检测姐妹染色体交换的方法评估显示,3种新型Silorane单体Ph-Sil,TET-Sil或Sil-Mix均未检测出基因毒性效果,提示Silorane单体具有较低基因毒性,是适于研发牙科树脂的新型单体。展开更多
目的：建立反相高效液相色谱法（RP-HPLC）测定卡维地洛片有关物质。方法：采用YMC-Pack Pro C8色谱柱（150 mm×4.6 mm,5μm）,以乙腈-0.02 mol·L-1磷酸二氢钾溶液（用磷酸调p H 2.0）为流动相进行梯度洗脱,流速1.0 m L·...目的：建立反相高效液相色谱法（RP-HPLC）测定卡维地洛片有关物质。方法：采用YMC-Pack Pro C8色谱柱（150 mm×4.6 mm,5μm）,以乙腈-0.02 mol·L-1磷酸二氢钾溶液（用磷酸调p H 2.0）为流动相进行梯度洗脱,流速1.0 m L·min-1,柱温30℃,检测波长为220 nm（杂质E）和240 nm（其他杂质）。结果：卡维地洛与已知杂质及强制破坏实验产生的降解产物均能获得良好的分离,杂质D（4-环氧丙烷氧基咔唑）与杂质E[2-（2-甲氧基苯氧基）乙胺]质量浓度分别在0.063 98～12.80μg·m L-1（r=0.999 9）和0.089 33～8.933μg·m L-1（r=1.000）范围内与峰面积呈良好的线性关系。杂质D高、中、低浓度的回收率（n=3）分别为98.6%、96.5%、94.2%,RSD分别为1.1%、0.8%、1.4%;杂质E高、中、低浓度的回收率（n=3）分别为99.2%、86%、92.7%,RSD分别为0.15%、0.65%、9.5%。杂质D和杂质E精密度试验的RSD（n=6）分别为1.4%和0.31%,建立的方法与现行中国药典收载的方法相比能分离检测到更多的杂质。结论：本方法经方法学验证,可用于卡维地洛有关物质的检测和质量控制。展开更多
文摘The kinetics of reaction between cyclic monoimides (succinimide, phtalimide, and glutarimide) with ethylene and propylene oxides in presence of sodium hydroxide was studied. The effect of substrate and catalyst concentrations on the course of the reaction was investigated. Kinetics of reaction was studied by dilatometry, i.e. by measuring volume contraction of reaction mixture. The kinetic law describing the reaction of imides with oxiranes is: . where ccat, cAH and cB are concentrations of catalyst, imide, and oxirane, respectively. The relative reactivity of imides and oxiranes was: GI > PI ≥ SI and EO > PO. The reaction mechanism was proposed based upon experimentally determined rate law for the reaction of cyclic monoimides and oxiranes as well as analytical and instrumental analysis of products. The elementary reaction between oxirane and imide anion is rate determining step. The imide anion is formed by hydrogen cation transfer into catalytic hydroxide anion from dissociated NaOH. In the consecutive elemental reaction an imidate anion attack on the oxirane molecule occurs. It is the slowest stage of the reaction, limiting the entire process. All the studied reactions obey the same mechanism as can be concluded from isokinetic relationship of studied systems)
文摘A ferrocenylsulfides 1-2 mediated sulfur ylide epoxidation reaction was found to stereoselectively afford trans-oxiranes in excellent yields with recoverable starting material.
文摘Literature describes kinetics of reactions of alcohols, phenols, carboxylic acids, amines and amides with oxiranes such as ethylene oxide and propylene oxide. However, there is no information regarding kinetic of reaction of imides with oxiranes. In this article the kinetics of the reaction of cyclic monoimides: succinimide, phtalimide, and glutarimide, with ethylene and propylene oxides in presence of triethylamine in aprotic solvent was studied. The rate laws for those processes were established based upon on dilatometric measurements. I was said that cyclic monoimides react with oxiranes in presence of triethylamine to give N-(2-hydroxyalkyl)imides as major product. This product react further with oxiranes in consecutive reaction. The kinetics of the reaction of cyclic mono-imides with oxiranes obey the following rate law: V = k1/2 c1/2cat c3/2imide c1/2oxirane. Based upon kinetic data the following orders of reactivity of imides and oxiranes were obtained: phtalimide ≥ succinimide > glutarimide and ethylene oxide > propylene oxide. The solvent (DMF, DMSO and dioxane) effect was also studied. From temperature dependences the thermodynamic parameters: activation energy, enthalpy and entropy from linear Eyring plots were obtained.
文摘The mechanism of reaction of cyclic monoimides with oxiranes was established based upon kinetic studies and product analysis. It has been established that the reaction proceeds through initial formation of an adduct of imide and triethylamine. The crucial bond in adduct has ionic character;in non-aqueous solvents it is present as ion pair, while in water the adduct dissociate and free ions are present. The adduct enables the proton transfer from imide to oxirane. The rate determining step is reaction of imide and this adduct. Different values of entropy of transition states obtained from thermodynamic calculations suggest slightly different structure of transition state of rate determining step.
文摘Direct photolysis and quenching experiments with styrene oxide support the existence of an efficient triplet photochemical pathway to benzyl radical formation. Similar photolytic behavior for styrene glycol carbonate strongly supports the 1,3-diradical, resulting from the scission of the benzylic C-O bond, as the geometric source of the triplet pathway. Primary photoproducts were determined by both NMR and HPLC analysis and we observed that toluene and bibenzyl were both primary photoproducts, not secondary photoproducts.
文摘目的:Siloranes是一种含硅的新型牙科复合树脂环氧乙烷单体,较传统的含碳的环氧乙烷单体具有更好的生物相容性。本研究的目的为用哺乳动物细胞培养检测姐妹染色体交换的方法评估Siloranes的基因毒性,并与传统的环氧乙烷比较。方法:研究所用的传统环氧乙烷为CyracureTM UVR6105。Silorane包括Ph-Sil,TET-Sil和二者50/50(w/w)的混合物(3M-ESPE)。用CHO细胞在有或无S9情况下检测姐妹染色体交换(SCE)。Bonferron post hoc统计分析检测有无显著性差异。结果:与溶剂对照相比,在有或无S9情况下,环氧乙烷UVR6105显著性地增加了培养CHO细胞的SCE数目。3种Silorane单体Ph-Sil,TET-Sil或Sil-Mix均未能增加SCE数目。结论:用哺乳动物细胞培养检测姐妹染色体交换的方法评估显示,3种新型Silorane单体Ph-Sil,TET-Sil或Sil-Mix均未检测出基因毒性效果,提示Silorane单体具有较低基因毒性,是适于研发牙科树脂的新型单体。
