Topic
Tetrahydrofuran
About: Tetrahydrofuran is a research topic. Over the lifetime, 11778 publications have been published within this topic receiving 158241 citations. The topic is also known as: diethylene oxide & 1,4-epoxybutane.
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TL;DR: In this paper, the authors report the kinetics and selectivity of 1,2-propanediol dehydration in pure water and in aqueous mixtures of the polar aprotic cosolvents γ-valerolactone, 1,4-dioxane, tetrahydrofuran, N-methyl-2-pyrrolidone, tetramethylene sulfoxide, and dimethyl sulfoxide at 433 K.
Abstract: The composition of the liquid phase can alter the rates of individual reaction steps and thus alter the selectivity of acid-catalyzed reactions, but these solvent effects are difficult to anticipate for design purposes. Herein, we report the kinetics and selectivity of Bronsted acid-catalyzed 1,2-propanediol dehydration in pure water and in aqueous mixtures of the polar aprotic cosolvents γ-valerolactone, 1,4-dioxane, tetrahydrofuran, N-methyl-2-pyrrolidone, tetramethylene sulfoxide, and dimethyl sulfoxide at 433 K. We find that the major product of 1,2-propanediol dehydration is propanal in most mixed-solvent environments with selectivities between 1 and 68 mol %. In contrast, 1,2-propanediol dehydration in aqueous mixtures of dimethyl sulfoxide affords acetone as the major product with up to 48% selectivity with minimal propanal formation. We use classical molecular dynamics simulations to probe these solvent effects by computing the difference between the solvation free energies of 1,2-propanediol and ...
41 citations
TL;DR: A new cardo diamine diamine monomer, 1,1-bis[4-(4-aminophenoxy)phenyl]-4-tert-butylcyclohexane containing tertbutyl cyclohexylhexylidene units was prepared in three steps from 4tert butylcycloehexanone as mentioned in this paper.
Abstract: A new cardo diamine monomer, 1,1-bis[4-(4-aminophenoxy)phenyl]-4-tert-butylcyclohexane containing tert-butylcyclohexylidene units was prepared in three steps from 4-tert-butylcyclohexanone. The monomer was reacted with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to produce polyamides and polyimides, respectively. All the polymers, characterized by X-ray diffraction, are amorphous. These cardo polymers exhibit good solubility in a variety of solvents. Almost all polymers are soluble in N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, and even in tetrahydrofuran (THF) and cyclohexanone. The polymers show glass transition temperatures between 244-310°C. and decomposition temperatures at 10% mass loss ranging from 486-526°C in nitrogen. The tough and flexible polymer films have tensile strength of 77-137 MPa, elongations at breaks of 5-14% and tensile moduli of 2.0-2.6 GPa.
41 citations
TL;DR: In this paper, a series of photosensitive hyperbranched polyimides (HB-PIs) were prepared through facile end-group modifications of the fully imidized polymer.
Abstract: A series of photosensitive hyperbranched polyimides (HB-PIs) were prepared through facile end-group modifications of the fully imidized polymer. A triamine, 1,3,5-tris(4-aminophenoxy)benzene, and a dianhydride, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, were condensed with a dropwise addition method in a molar ratio of 1/2 to afford an anhydride-terminated poly(amic acid) precursor, which was then end-capped by 4-aminophenol and chemically imidized to yield a phenol-terminated HB-PI. The modifications of the terminal phenol groups of the polyimide by acyl chloride compounds (acryloyl chloride, methylacryloyl chloride, and cinnamoyl chloride) gave the target polymers. The photosensitive HB-PIs showed good thermal properties and excellent solubility even in low-boiling-point solvents at room temperature, such as acetone, 1,1,2-trichloroethane, tetrahydrofuran, and chloroform. Photosensitive property studies revealed good photolithographic properties with a resolution greater than 3 μm and a sensitivity of 650–680 mJ/cm2. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1735–1744, 2004
41 citations
TL;DR: Perfluoroalkyl iodides reacted with alkenes in acetonitrile solution containing catalytic amounts of an organophosphine under mild conditions to give the corresponding adducts in moderate to high yields as mentioned in this paper.
41 citations
TL;DR: In this article, the reaction of titanium dichloride with sodium cyclopentadienide in tetrahydrofuran solution is described, and a green paramagnetic form which transforms spontaneously into a brown diamagnetic form is described.
41 citations