Dimethylformamide

Abstract: The singlet oxygen luminescence method and the photochemical methods using 1,3-diphenylisobenzofuran (DPBF) or bilirubin ditaurate (BDT) as chemical quenchers were employed to determine the single oxygen quantum yields (ΦΔ) of different phthalocyanines and tris(2,2″-bipyridyl)ruthenium(II) dichloride in dimethylformamide (DMF) or aqueous micellar solution of 0.1 M CTAC (cetyltrimethylammonium chloride). Additionally, a perylenetetracarboxylic acid diimide derivative was examined in DMF. In a series of tetrasulfonated phthalocyanines (PTS) the following order was found: ZnPTS > GaPTS > AlPTS ≈ H2PTS > CoPTS. In general, the singlet oxygen quantum yields are higher in DMF than in 0.1 M CTAC/H2O. The results obtained with the photochemical systems are comparable with those obtained by the photophysical method. The photochemical DPBF method results in absolute values of ΦΔ. However, in micellar solution, chain reactions occur when DPBF is used as chemical quencher in the photo-oxidative process. This problem ...

Abstract: Rapid, selective, and high-yield hydrogenation of CO2 can be achieved if the CO2 is in the supercritical state (scCO2). Dissolving H2, a tertiary amine, a catalyst precursor such as RuH2[P(CH3)3]4 or RuCl2[P(CH3)3]4, and a promoting additive such as water, CH3OH, or DMSO in scCO2 at 50 °C leads to the generation of formic acid with turnover frequencies up to or exceeding 4000 h-1. In general, experiments in which a second phase was formed by one or more reagents or additives had lower rates of reaction. The high rate of reaction is attributed to rapid diffusion, weak catalyst solvation, and the high miscibility of H2 in scCO2. The formic acid synthesis can be coupled with subsequent reactions of formic acid, for example, with alcohols or primary or secondary amines, to give highly efficient routes to formate esters or formamides. With NH(CH3)2, for example 420 000 mol of dimethylformamide/mol of Ru catalyst was obtained at 100 °C. The demonstrated solubility and catalytic activity of complexes of tertiary...

Abstract: Wholly aromatic polybenzimidazoles were synthesized from aromatic tetraamines and difunctional aromatic acids and characterized as new thermally stable polymers. The melt polycondensation of aromatic tetraamines and the diphenyl esters of aromatic dicarboxylic acids was developed as a general procedure of wide applicability. Polybenzimidazoles containing mixed aromatic units in the chain backbone were prepared from 3,3′-diaminobenzidine, 1,2,4,5-tetraaminobenzene and a variety of aromatic diphenyl dicarboxylates. Phenyl 3,4-diaminobenzoate could also be polymerized by melt condensation to give poly-2,5(6)-benzimidazole. The polymers were characterized by a high degree of stability, showing great resistance to treatment with hydrolytic media and an ability to withstand continued exposure to elevated temperatures. Most of the polymers were infusible, but some had melting points above about 400°C. Many of the polymers exhibited no change in properties on being heated to 550°C. and showed a weight loss of less than 5% when heated under nitrogen for several hours to 600°C. The polymers were soluble in concentrated sulfuric acid and formic acid, producing stable solutions. Many of the polymers were soluble in dimethyl sulfoxide and some also in dimethylformamide. The inherent viscosities of a number of polymers in 0.5% dimethyl sulfoxide solution ranged from approximately 0.4 to 1.1. The higher polymers could be cast into stiff and tough films from formic acid and dimethyl sulfoxide solutions.

Abstract: Carbon dioxide reacts with hydrogen, alcohols, acetals, epoxides, amines, carbon–carbon unsaturated compounds, etc. in supercritical carbon dioxide or in other solvents in the presence of metal compounds as catalysts. The products of these reactions are formic acid, formic acid esters, formamides, methanol, dimethyl carbonate, alkylene carbonates, carbamic acid esters, lactones, carboxylic acids, polycarbonate (bisphenol-based engineering polymer), aliphatic polycarbonates, etc. Especially, the productions of formic acid, formic acid methyl ester and dimethylformamide with a ruthenium catalyst; dimethyl carbonate and urethanes with a dialkyltin catalyst; 2-pyrone with a nickel-phosphine catalyst; diphenyl carbonate with a lead phenoxide catalyst; the alternating copolymerization of carbon dioxide and epoxides with a zinc catalyst has attracted attentions as the industrial utilizations of carbon dioxide. The further development of these production processes is expected.