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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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Journal ArticleDOI
TL;DR: In this paper, the authors measured the mixing and densities of very dilute aqueous solutions (mol) fraction concentration < 2 × 10−3 of cyclic ether derivatives at several temperatures.
Abstract: Heats of mixing and densities of very dilute aqueous solutions (mol) fraction concentration < 2 × 10–3 of cyclic ether derivatives have been measured at several temperatures. The solutions studied included tetrahydrofuran, tetrahydropyran, 1,4-dioxan, tetrahydrofurfuryl alcohol, and tetrahydropyran-2-carbinol. Limiting partial heats, heat capacities, volumes and expansibilities are discussed in terms of current ideas on polar and apolar hydration.

167 citations

Journal Article
TL;DR: Several cobalt porphyrins (CoP) have been reduced by radiation chemical, photochemical, and electrochemical methods, in aqueous and organic solvents as discussed by the authors.
Abstract: Several cobalt porphyrins (CoP) have been reduced by radiation chemical, photochemical, and electrochemical methods, in aqueous and organic solvents. In aqueous solutions, the CoIP state is stable at high pH but is shorter lived in neutral and acidic solutions. Stable CoIP is also observed in organic solvents and is unreactive toward CO2. One-electron reduction of CoIP leads to formation of a species that is observed as a transient intermediate by pulse radiolysis in aqueous solutions and as a stable product following reduction by Na in tetrahydrofuran solutions. The spectrum of this species is not the characteristic spectrum of a metalloporphyrin π-radical anion and is ascribed to Co0P. This species binds and reduces CO2. Catalytic formation of CO and HCO2- is confirmed by photochemical experiments in acetonitrile solutions containing triethylamine as a reductive quencher. Catalytic reduction of CO2 is also confirmed by cyclic voltammetry in acetonitrile and butyronitrile solutions and is shown to occur ...

167 citations

Journal ArticleDOI
TL;DR: A review article summarizes the results obtained with the isolated aNHCs, which successfully accomplished the metal-free catalytic formylation of amides using CO2 and the catalytic reduction of carbon dioxide, including atmospheric CO2, into methanol, under ambient conditions.
Abstract: Although N-heterocyclic carbenes (NHCs) have been known as ligands for organometallic complexes since the 1960s, these carbenes did not attract considerable attention until Arduengo et al. reported the isolation of a metal-free imidazol-2-ylidene in 1991. In 2001 Crabtree et al. reported a few complexes featuring an NHC isomer, namely an imidazol-5-ylidene, also termed abnormal NHC (aNHCs). In 2009, it was shown that providing to protect the C-2 position of an imidazolium salt, the deprotonation occurred at the C-5 position, affording imidazol-5-ylidenes that could be isolated. Over the last ten years, stable aNHCs have been used for designing a range of catalysts employing Pd(II), Cu(I), Ni(II), Fe(0), Zn(II), Ag(I), and Au(I/III) metal based precursors. These catalysts were utilized for different organic transformations such as the Suzuki–Miyaura cross-coupling reaction, C–H bond activation, dehydrogenative coupling, Huisgen 1,3-dipolar cycloaddition (click reaction), hydroheteroarylation, hydrosilylation reaction and migratory insertion of carbenes. Main-group metal complexes were also synthesized, including K(I), Al(III), Zn(II), Sn(II), Ge(II), and Si(II/IV). Among them, K(I), Al(III), and Zn(II) complexes were used for the polymerization of caprolactone and rac-lactide at room temperature. In addition, based on the superior nucleophilicity of aNHCs, relative to that of their nNHCs isomers, they were used for small molecules activation, such as carbon dioxide (CO2), nitrous oxide (N2O), tetrahydrofuran (THF), tetrahydrothiophene and 9-borabicyclo[3.3.1]nonane (9BBN). aNHCs have also been shown to be efficient metal-free catalysts for ring opening polymerization of different cyclic esters at room temperature; they are among the most active metal-free catalysts for e-caprolactone polymerization. Recently, aNHCs successfully accomplished the metal-free catalytic formylation of amides using CO2 and the catalytic reduction of carbon dioxide, including atmospheric CO2, into methanol, under ambient conditions. Although other transition metal complexes featuring aNHCs as ligand have been prepared and used in catalysis, this review article summarize the results obtained with the isolated aNHCs.

166 citations

Journal ArticleDOI
G Curthoys1, V. Ya. Davydov1, A.V Kiselev1, S.A Kiselev1, B.V Kuznetsov1 
01 Jul 1974
TL;DR: In this article, a spectral and calorimetric investigation was carried out into hydrogen bonding between the surface hydroxyl groups of silica and molecules of n -hexane, cyclohexane and carbon tetrachloride, benzene, nitromethane, acetonitrile, acetone, diethyl ether, dioxane, tetrahydrofuran, pyridine, and triethylamine.
Abstract: A spectral and calorimetric investigation was carried out into hydrogen bonding between the surface hydroxyl groups of silica and molecules of n -hexane, cyclohexane, carbon tetrachloride, benzene, nitromethane, acetonitrile, acetone, diethyl ether, dioxane, tetrahydrofuran, pyridine, and triethylamine. The integral intensity of the absorption band due to the stretching vibration of free hydroxyl groups on the surface of aerosil and the integral intensities of the absorption bands of these hydroxyl groups perturbed by adsorbed molecules were determined. From the difference in the heats of adsorption on hydroxylated and strongly dehydroxylated surfaces of a pure macroporous silica the heats of formation of the hydrogen bond between adsorbed molecules and free surface hydroxyl groups were evaluated. They were compared with the change in the integral intensity of the stretching vibration band of the hydroxyl groups resulting from adsorption and with their frequency shifts. The relation between the spectral and energetic characteristics of the hydrogen bond resulting from adsorption is approximately the same as that which occurs when the hydrogen bond is formed in solution.

166 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023194
2022382
2021124
2020154
2019193
2018218