نتایج جستجو برای: catalyst selectivity
تعداد نتایج: 86617 فیلتر نتایج به سال:
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 proc...
Lewis base catalyzed bromo- and iodolactonization reactions have been developed and the effects of catalyst structure on rate and cyclization selectivity have been systematically explored. The effects of substrate structure on halolactonization reactions and the interaction of those effects with the effects of catalyst structure have been investigated, leading to synthetically useful improvemen...
A novel, heterogeneous Pd-MCM-48 catalyst has been developed by encapsulating palladium nanoparticles into the cubic phase of mesoporous MCM-48 matrix at room temperature. The catalyst demonstrated excellent chemo- and regioselectivity for the hydrogenation of olefins at room temperature within 30-80 min. The turnover frequency for the hydrogenation is very high (4400 h(-1)). Interestingly, sel...
A rare example of the application of a catalytic, enantioselective Diels-Alder cycloaddition to affect a kinetic resolution has been developed. Chiral pyrazolidinones are resolved with high selectivity through a process that utilizes a relay of stereochemical information from a permanent chiral center to a fluxional chiral center to enhance the inherent selectivity of the chiral Lewis acid cata...
In the present study, the synthesis of diethylene triamine supported on cellulose biopolymer as a biodegradable solid basic heterogeneous catalyst was suggested. Then, the applicability of the synthesized catalyst cellulose bonded N-propyl diethylene triamine (CBPDETA) was tested for the synthesis of oxindole derivatives, an important class of potentially bioactive compounds. A various series o...
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 proc...
A novel heterogeneous Pd/polymer catalyst containing co-catalytic functional groups catalyses the direct alkenylation of anisole with ethyl trans-cinnamate under oxygen. The properties of the polymeric catalyst were compared to other immobilised catalysts. The activity of the polymeric catalyst typically increased with temperature and oxygen pressure exhibiting the optimal activity up to 100 TO...
The influence of NaNO2, HNO3 and H2SO4 on the structure and morphology of gamma-alumina was investigated by XRD, BET, SEM and FT-IR spectroscopy. Selected amounts of NaNO2, HNO3 and H2SO4 were added to a solution of aluminum isopropoxide (as a precursor for the boehmite synthesis). The boehmite samples were calcined at 350 and 600 ℃ to form the semi-crystalline high surface area gamma-Al2O3. Th...
امروزه مشتقات t- بوتیل فنل از اهمیت بسیار زیادی در صنعت برخوردار هستند. بطور مثال از این ترکیبات به عنوان حدواسطی برای ساخت آفت کش ها، خوشبو کننده ها، چاشنی ها، حدواسط های دارویی, کرومانها, فنانتهای مورد استفاده در فرایند تولید برخی از روان کننده ها, دسته وسیعی از رزین ها، استرهای فسفات، قارچ کش ها، جوهر چاپ، مینای سیم ها، آنتی اکسیدانت ها, عامل تثبیت کننده پلی وینیل کلرید (pvc) , جاذب پرتو uv,...
Biomimetic aerobic oxidation of primary benzylic amines has been achieved by using a quinone catalyst. Excellent selectivity is observed for primary, unbranched benzylic amines relative to secondary/tertiary amines, branched benzylic amines, and aliphatic amines. The exquisite selectivity for benzylic amines enables oxidative self-sorting within dynamic mixtures of amines and imines to afford h...
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