نتایج جستجو برای: ethers
تعداد نتایج: 7167 فیلتر نتایج به سال:
Catalytic amount of Ce(IV) as ceric triethylammonium nitrate (CTEAN) in dichloromethane or acetone can bring about an efficient tetrahydropyranylation of different types of alcohols to afford the corrsesponding tetrahydropyranyl ethers in high yields. Deportection of tetrahydropyranyl ethers can also be achieved efficiently in the presence of this catalyst in methanol.
Chemistry Department, College of Science, University of Texas, El Paso, T X 79968, USA Z. Naturforsch. 84b, 614-620 (1979); received September 11, 1978 Relative Basicity Parameter, Conductivity of Protonated Ethers, Calculation of PKA'S for R20H+ It is shown in this paper that a consistent set of values of pKBH+ for 24 ethers, in good agreement with the few which have been obtained b y other me...
A difference was observed in the reactivity of alcohols and ethers toward free electrons. Whereas the lowest core-excited state of the negative ion-a 2(n,3s2) Feshbach resonance-of the alcohols readily dissociates by losing a hydrogen atom, ethers show no observable signal from this resonance. This difference in reactivity has a parallel in the anomalous shapes and energies of the parent states...
In this chapter, a comprehensive review over the entire reserarch on liquid crystalline crown ethers since their discovery will be given. Monomeric and polymeric molecules containing crown ethers as well as aza crown ethers, thia crown ethers and crown ethers with several different heteroatoms will be presented. Liquid crystallinity is, in most cases, caused by the substituents attached to the ...
Crown-ethers have recently been used to assemble porous liquids (PLs), which are liquids with permanent porosity formed by mixing bulky solvent molecules (e.g., 15-crown-5 ether) with solvent-inaccessible organic cages. PLs and crown-ethers belong to a novel class of materials, which can potentially be used for gas separation and storage, but their performance for this purpose needs to be asses...
7-hydroxy coumarin undergoes neutral conditions with alkyl propiolates in the presence of triphenylphosphine, and bysubstituation the corresponding aryl vinyl ethers was obtained in good yields
In a heretofore-unreported reaction, 1,2-cyclohexandione reacts with a variety of alcohols under mild acid-catalyzed dehydration conditions to afford not only ethers of 1,2cyclohexanedione but the corresponding aryl ethers as well in moderate to good yield.
We describe the first synthesis of homoallyl ethers from acetals and allyltrimethylsilane using microwave heating and CuBr as a promoter. This method works best for aromatic acetals, giving the corresponding homoallyl ethers in good to quantitative yield.
Crown ethers are small, cyclic polyethers that have found wide-spread use in phase-transfer catalysis and, to a certain degree, in protein chemistry. Crown ethers readily bind metallic and organic cations, including positively charged amino acid side chains. We elucidated the crystal structures of several protein-crown ether co-crystals grown in the presence of 18-crown-6. We then employed biop...
Novel 4-acyl-5-pyrazolones having aza-15-crown-5 (HPMP-A15C5) and aza-18-crown-6 (HPMP-A18C6) moieties as an intramolecular synergist have been synthesized by simple coupling reactions between 1-phenyl-3-methyl-4-chloroacetyl-5-pyrazolone and the corresponding azacrown ethers. The solvent extraction of the divalent metal ions (Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Pb(2+)) were exam...
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