نتایج جستجو برای: preparation of ethers
تعداد نتایج: 21171003 فیلتر نتایج به سال:
We examined the effect of p-substituents in p-substituted cinnamyl methyl ethers and 1-(p-substituted phenyl)allyl methyl ethers with CSI, and confirmed that the CSI reaction of allyl ethers (p-substituted ethers) is a competitive reaction of S(N)i and S(N)1 mechanism according to the stability of the carbocation. And, the only terminal allylic amine was obtained through the migration reaction ...
The Cosmetic Ingredient Review (CIR) Expert Panel assessed the safety of 131 alkyl polyethylene glycol (PEG)/polypropylene glycol ethers as used in cosmetics, concluding that these ingredients are safe in the present practices of use and concentration described in this safety assessment when formulated to be nonirritating. Most of the alkyl PEG/PPG ethers included in this review are reported to...
Preparation of .BETA.-lactams from Optically Active Isocyanate and Vinyl Ethers under High Pressure.
1,1’-(Ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) was used as a chemoselective and effective organocatalyst for the silylation of hydroxyl groups as well as desilylation of trimethylsilyl ethers under mild conditions at room temperature with good to excellent yields.
An efficient and chemoselective cleavage of silyl ethers (primary, secondary and aromatic) by using catalytic quantities of trimethylsilyl bromide (TMSBr) in methanol is reported. A wide range of alkyl silyl ethers such as TBS, TIPS, and TBDPS can be chemoselectively cleaved in high yield in the presence of aryl silyl ethers. The deprotection of silyl esters was also achieved employing catalyti...
دسته ای از ترکیبات شیمیائی که مخصوصا با گسترش زندگانی جدید (ماشینی)اهمیت فرآینده ای پیدامی کنند، افزودنیهای مختلف غذائی میباشند که در صنایع مربوطه بکار گرفته می شوند بکارگیری بخشی از این موا تحت عنوان طعم دهنده ها بمنظور تامین طعم و مزه طبیعی درفرآورده های صنعتی تقریبا اجتناب ناپذیر گشته و همگام با توسعه تولیدات روبه توسعه می رود. یک شناخت سیستماتیک و جامع از خواص و آثار اینگونه مواد طبیعتا مست...
Magnetic nanoparticle (MNP)-supported crown ethers were successfully prepared and evaluated as catalysts for solid-liquid phase-transfer reactions; the catalytic activities of the MNP-supported crown ethers were not inferior to those of non-supported crown ethers; after the reactions, the catalysts could be readily separated using an external magnet and reused without significant loss of cataly...
here, we report analysis of in vitro and in vivo drug release from an in situ formulation consisting of triamcinolone acetonide (tr) and poly(d,l-lactide-co-glycolide) (plga) and the additives glycofurol and hydroxyapatite nanoparticles (ha). we found that these additives enhanced drug release rate. we used the taguchi method to predict optimum formulation variables to minimise the initial burs...
Template-directed protocols provide a routine approach to the synthesis of mechanically interlocked molecules (MIMs), in which the mechanical bonds are stabilized by a wide variety of weak interactions. In this Article, we describe a strategy for the preparation of neutral [2]catenanes with sliding interlocked electron-rich rings, starting from two degenerate donor-acceptor [2]catenanes, consis...
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