Ionic liquids (ILs) containing the tris(pentafluoroethyl)trifluorophosphate anion [FAP]- have attracted increased attention due to their unique properties including ultrahigh hydrophobicity, hydrolytic stability, and wide electrochemical window. In this study, the solvation parameter model is used via gas chromatography to characterize the solvation interactions of seven ILs containing amino, ester, and hydroxyl functional groups appended to the cation and paired with [FAP]-, as well as three ILs containing the bis[(trifluoromethyl)sulfonyl]imide anion [NTf2]-. The role of the functional groups, nature of the counter anion, and cation type on the system constants were evaluated. ILs containing [FAP]- possessed lower hydrogen bond basicity than NTf2-based ILs having the same cationic component; in the case of hydroxyl-functionalized cations, the presence of [FAP]- led to an enhancement of the hydrogen bond acidity, relative to the NTf2-analogs. The system constants support the argument that [FAP]- weakly coordinates the cation and any appended functional groups, promoting properties of the cation which might be masked by stronger interactions with other anion systems. The chromatographic performance of the IL stationary phases was evaluated by examining the retention behavior and separation selectivity for chosen analytes. The results from this work can be used as a guide for choosing FAP-based ILs capable of exhibiting desired solvation properties while retaining important physical properties including high thermal stability and high hydrophobicity.
The synthesis, characterization, and thermal behavior of the dicopper(I) oxalate complexes L 2 Cu 2 O 4 C 2 (L ) Me 3 SiCtCSiMe 3 (1), Me 3 SiCtC n Bu (2), EtCtCEt (3), H 2 CdC(H)SiMe 2 t Bu (4), H 2 CdC(H)SiEt 2 Me (5), norbornene ( 6)) is reported. All complexes can be prepared in a straightforward manner by the reaction of stoichiometric amounts of Cu 2 O and oxalic acid with 2 equiv of the respective alkyne or alkene. The complexes are stable at room temperature, and in solid form they can be handled in air for some time. Their thermal behavior was studied by thermal gravimetric analysis (TGA). The order of thermal stability was found to be 1 > 6 > 4 > 2 ≈ 3 > 5. Decomposition starts between 50 and 100 °C and is completed between 300 and 350 °C. All compounds fully decompose via an efficient internal redox process to give elemental copper, CO 2 , and the free alkyne or alkene ligands, which makes these new complexes promising precursors for copper deposition (in the case of 4, it is likely that H 2 CdC(H)SiMe 2 H and isobutene is formed via β-hydrogen elimination from H 2 CdC(H)SiMe 2 t Bu). Distinct two-or three-step decomposition sequences for the individual complexes are revealed by the TGA analyses and are discussed. The single-crystal X-ray structures of 1 and 3 are reported, which are the first for copper(I)/oxalato compounds. Both complexes exhibit the anticipated planar dinuclear structure with the oxalate in a µ-1,2,3,4 bridging mode and the alkynes or alkenes as capping ligands.
SynopsisVinyl aromatic polymers such as polystyrene can be made nonflammable by the addition of halogen compounds. The amount of halogen required to make such polymers nonflammable can now be greatly reduced by the addition of small amounts of certain free radical initiators. Normally about 5 phr of acetylene tetrabromide (parts of additive per hundred parts of polymer) must be added to polystyrene to obtain a self-extinguishing polymer. Only 0.5 phr of acetylene tetrabromide is required if 0.5 phr dicurnyl peroxide is added. This synergistic effect has been observed with a series of peroxides, hydroperoxides, azo compounds, quinone imines, benzothiazole sulfenamides, disulfides, and a bibenzyl compound. The synergistic mechanism seems to be based on a series of reactions involving attack of the polymer by the initiator and subsequent reaction between polymer fragments and the halogen compound. The result is a delay in the loss of halogen from the polymer mass and thus a more efficient use of the halogen additive for flame quenching. Known inhibitors of free radical reactions have a detrimental effect on the synergistic mechanism.
The hydroalumination of the allyl ethers CH 2 dCHCH 2 OR with i Bu 2 AlH yields the (3alkoxypropyl)diisobutylaluminum complexes i Bu 2 Al(CH 2 ) 3 OR (R ) Me (1), Et (2), Bu (3)). Et 2 AlCl and i Bu 2 AlCl react with (2-(methoxymethyl)phenyl)lithium and (2-methoxybenzyl)magnesium chloride, yielding (2-(methoxymethyl)phenyl)diethylaluminum ( 4), (2-(methoxymethyl)phenyl)diisobutylaluminum (5), and (2-methoxybenzyl)diisobutylaluminum ( 7), respectively. The reaction of i Bu 2 AlCl with (2-methoxyphenyl)lithium affords the dimeric bis((2-methoxyphenyl)diisobutylaluminum) (6). Et 2 AlCl and (8-ethoxynaphthyl)lithium form (8-ethoxynaphthyl)diethylaluminum ( 10) along with a few crystals of bis(8-ethoxynaphthyl)aluminum chloride (13). AlCl 3 reacts with 2 equiv of (2-methoxybenzyl)magnesium chloride, yielding bis(2-methoxybenzyl)aluminum chloride (9). Ligand redistribution followed by metathesis was observed for the reactions of Me 2 AlCl and Et 2 AlCl with (2-methoxybenzyl)magnesium and (8-methoxynaphthyl)lithium, yielding bis(2-methoxybenzyl)methylaluminum (8), bis(8-methoxynaphthyl)methylaluminum (11), and bis(8-methoxynaphthyl)ethylaluminum (12), respectively. The new compounds have been characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. The solid-state structures of 6, 8, 9, and 11-13 were determined by single-crystal X-ray diffraction. The new aluminum alkyls are very active cocatalysts in the TiCl 4 -catalyzed ethylene polymerization. 7 and 10 cause a higher productivity compared to the common cocatalyst Al 2 Et 6 . The activity depends strongly on the structure of the oxygen-stabilized aluminum alkyls and is also influenced by the Al/Ti ratio.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.