جستجوی مقالات مرتبط با کلیدواژه « Phase transfer catalyst » در نشریات گروه « شیمی »
تکرار جستجوی کلیدواژه « Phase transfer catalyst » در نشریات گروه « علوم پایه »-
In this research, we develop and prepare some of the polymers based on polythioesters using cetrimide as an ionic liquid and phase transfer catalyst. All of the polymers were prepared through the reaction of 5,5'-methylenebis (1,3,4-oxadiazole-2-thiol) with five types of diacyl chloride derivatives in the presence of cetrimide as phase transfer catalyst in the mixture of water and chloroform at room temperature. The chemical structure of synthesized polymers was determined using 1H NMR and 13C NMR spectroscopy. The mechanical and thermal stability of the synthesized polymers were investigated. In addition, using DFT calculation, the chemical optimization of synthesized polymers was presented. Moreover, the catalytic activity of cetrimide was compared with four types of ionic liquid with phase transfer catalyst roles. Additionally, the application of synthesized polymers in bone cement was investigated.Keywords: polymer, Ionic liquid, Phase transfer catalyst, polythioesters, Bone cement, cetrimide}
-
An environmentally benign procedure for the synthesis of vicinal nitrohydrins via the regioselective ring opening reaction of epoxides with nitrite anion using silica-bound 3-{2-[poly(ethylene glycol)]ethyl}-substituted 1-methyl-1H-imidazol-3-ium bromide as an effective heterogeneous phase transfer catalyst was described. Short reaction time, high yield of products, simple work-up procedure, and recyclability of the catalyst were some of the striking features of the present protocol. The recovered catalyst could be reused five times without any loss in its catalytic activity and selectivity.Keywords: 2-Nitroalcohols, Phase transfer catalyst, Ring opening of epoxides, Regioselective, Green chemistry}
-
یک روش ملایم و موثر جدید برای باز کردن حلقه اپوکسیدها با آنیون استات در حضور مقادیر کاتالیزوری سیلیکاژل متصل به پلی اتیلن گلیکول استخلاف شده با 1- متیل ایمیدازولیوم برمید (SiO2-PEG-ImBr) به عنوان یک کاتالیزگر انتقال فاز ناهمگن موثر در محیط آبی گزارش شده است. β- استوکسی الکل های مختلف با راندمان بالا و ناحیه گزینی فوق العاده، در مدت زمان کوتاهی به دست آمده است. مهم-ترین مزایای این روش عبارتند از: بهبود راندمان، ناحیه گزینی بالا، استفاده از مقادیر کمتری از کاتالیزگر، جداسازی راحت، سادگی بازیافت کاتالیزگر و سازگاری با محیط زیست. کاتالیزگر بازیافت شده حداقل چهار مرتبه دیگر بدون کاهش چشمگیری در توانایی کاتالیزوری آن قابل استفاده است.
یک روش ملایم و موثر جدید برای باز کردن حلقه اپوکسیدها با آنیون استات در حضور مقادیر کاتالیزوری سیلیکاژل متصل به پلی اتیلن گلیکول استخلاف شده با 1- متیل ایمیدازولیوم برمید (SiO2-PEG-ImBr) به عنوان یک کاتالیزگر انتقال فاز ناهمگن موثر در محیط آبی گزارش شده است. β- استوکسی الکل های مختلف با راندمان بالا و ناحیه گزینی فوق العاده، در مدت زمان کوتاهی به دست آمده است. مهم-ترین مزایای این روش عبارتند از: بهبود راندمان، ناحیه گزینی بالا، استفاده از مقادیر کمتری از کاتالیزگر، جداسازی راحت، سادگی بازیافت کاتالیزگر و سازگاری با محیط زیست. کاتالیزگر بازیافت شده حداقل چهار مرتبه دیگر بدون کاهش چشمگیری در توانایی کاتالیزوری آن قابل استفاده است.کلید واژگان: شیمی سبز, کاتالیزگر انتقال فاز ناهمگن, بازکردن حلقه اپوکسیدها, β- استوکسی الکل ها, قابلیت بازیافت}A new mild and efficient procedure for the ring opening of epoxides by acetate anion in the presence of catalytic amounts of silica-bound polyethylene glycol substituted 1-methylimidazolium bromide, SiO2-PEG-ImBr, as an effective heterogeneous phase transfer catalyst in aqueous media is developed. A variety of β-acetoxy alcohols are obtained in high yields with excellent regioselectivity in short reaction times. The remarkable features of this procedure are improved yields, high regioselectivity, small quantity of catalyst, easy work-up, ease of recyclability of catalyst and environmentally friendliness. The recycled catalyst could be reused over four times with almost no loss of catalytic activity.
A new mild and efficient procedure for the ring opening of epoxides by acetate anion in the presence of catalytic amounts of silica-bound polyethylene glycol substituted 1-methylimidazolium bromide, SiO2-PEG-ImBr, as an effective heterogeneous phase transfer catalyst in aqueous media is developed. A variety of β-acetoxy alcohols are obtained in high yields with excellent regioselectivity in short reaction times. The remarkable features of this procedure are improved yields, high regioselectivity, small quantity of catalyst, easy work-up, ease of recyclability of catalyst and environmentally friendliness. The recycled catalyst could be reused over four times with almost no loss of catalytic activity.Keywords: Green chemistry, Phase transfer catalyst, Ring opening of epoxides, ?-Acetoxy alcohols, Recyclability} -
In the present study, application of porous acidic catalyst functionalized with an imidazoleionic liquid ([SBA-Im]HSO4) as a phase transfer catalyst for the facile preparation of benzylthiocyanates and azides in water has been described. The catalyst has been characterized byFourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmissionelectron microscopy (TEM), thermogravimetric analysis (TGA) and derivative thermogravimetricanalysis (DTG). The polymeric phase transfer catalyst, easily recovered by simplefiltration, shows no appreciable loss of activity when recycled several times.
Keywords: Phase transfer catalyst, Nucleophilic substitution, Porous catalyst, Benzyl halides} -
The use of a recyclable phase transfer catalyst, SiO2-PEG-ImBr, is demonstrated in a simple and highly efficient synthesis of phenacyl derivatives by nucleophilic substitution reaction of phenacyl halides with different anions in water. Advantages of this system are easy work-up, moderate to good yields, and recyclable catalyst. The catalyst can be recycled and reused several times with no loss of its efficiency.
Keywords: Phenacyl derivatives, Phenacyl halides, Phase transfer catalyst, Nucleophilic substitution, Silica supported} -
Trifluoromethylated organic compounds, especially chiral quaternary alcohols bearing trifluoromethyl group are of important intermediates in drugs, agrochemicals and etc. An efficient epoxidation of β-CF3-β,β-disubstituted unsaturated ketones (6) has been developed with environmental benign hydrogen peroxide as the oxidant and F5-substituted chiral quaternary ammonium salt (1g or 5) derived from cinchona-alkaloid as the catalyst. Using 3 mol% of the catalyst, both enantiomers of (R,R) and (S,S) β-trifluoromethyl-α,β-epoxy ketones (7, 8) were obtained in excellent diastereoselectivities (up to 100:1 d.r.) and enantioselectivities (up to 99.7% ee). The effects of catalyst structure, catalyst loading, substrate structure, the nature of oxidant, and reaction conditions on the catalyst capacities have been discussed in full length. The reaction mechanism was proposed to explain the origin of chiral induction. By subsequent reduction with zinc the epoxides are exhibited to be converted into trifluoromethylated quaternary alcohols without any loss in enantioselectivities. All new compounds are fully characterized by IR, NMR, elemental analysis and or high resolution mass spectrum.Keywords: Asymmetric catalysis, Epoxidation, Hydrogen peroxide, Phase transfer catalyst, Trifluoromethyl}
-
1,4-bis(triphenylphosphonium)-2-butene dichloride was developed as a new phase transfer catalyst. This quaternized phosphonium salt catalyzed the regioselective ring opening of epoxides by thiocyanate ion to give β-hydroxy thiocyanates in high yields under mild conditions.Keywords: 4-bis(triphenylphosphonium)-2-butene dichloride, Phase transfer catalyst, β-hydroxy thiocyanates, epoxides}
نکته
- نتایج بر اساس تاریخ انتشار مرتب شدهاند.
- کلیدواژه مورد نظر شما تنها در فیلد کلیدواژگان مقالات جستجو شدهاست. به منظور حذف نتایج غیر مرتبط، جستجو تنها در مقالات مجلاتی انجام شده که با مجله ماخذ هم موضوع هستند.
- در صورتی که میخواهید جستجو را در همه موضوعات و با شرایط دیگر تکرار کنید به صفحه جستجوی پیشرفته مجلات مراجعه کنید.
©2000-2024 magiran.com All Rights Reserved.