RESUMEN
The separation of 1,3-butadiene from C4 hydrocarbon mixtures is imperative for the production of synthetic rubbers, and there is a need for a more economical separation method, such as a pressure swing adsorption process. With regard to adsorbents that enable C4 gas separation, [Zn(NO2 ip)(dpe)]n (SD-65; NO2 ip=5-nitroisophthalate, dpe=1,2-di(4-pyridyl)ethylene) is a promising porous material because of its structural flexibility and restricted voids, which provide unique guest-responsive accommodation. The 1,3-butadiene-selective sorption profile of SD-65 was elucidated by adsorption isotherms, inâ situ PXRD, and SSNMR studies and was further investigated by multigas separation and adsorption-desorption-cycle experiments for its application to separation technology.
RESUMEN
A series of palladium/alkylphosphine-sulfonate catalysts were synthesized and examined in the homopolymerization of ethylene and the copolymerization of ethylene and polar monomers. Catalysts with alkylphosphine-sulfonate ligands containing sterically demanding alkyl substituents afforded (co)polymers whose molecular weight was increased by up to 2 orders of magnitude relative to polymers obtained from previously reported catalyst systems. The polymer molecular weight was found to be closely correlated to the Sterimol B5 parameter of the alkyl substituents in the alkylphosphine-sulfonate ligands. Thus, the use of bulky alkylphosphine-sulfonate ligands represents an effective and versatile method to prepare high-molecular-weight copolymers of ethylene and various polar monomers, which are difficult to obtain by previously reported methods.
RESUMEN
Coordination-insertion copolymerization of allyl monomers with ethylene was developed by using a palladium/phosphine-sulfonate catalyst. A variety of allyl monomers, including allyl acetate, allyl alcohol, protected allylamines, and allyl halides, were copolymerized with ethylene to form highly linear copolymers that possess in-chain -CH(2)CH(CH(2)FG)- units.
RESUMEN
A series of palladium complexes bearing a bisphosphine monoxide with a methylene linker, that is, [κ2-P,O-(R12P)CH2P(O)R22]PdMe(2,6-lutidine)][BArF4] (Pd/BPMO), were synthesized and evaluated as catalysts for the homopolymerization of ethylene and the copolymerization of ethylene and polar monomers. X-ray crystallographic analyses revealed that these Pd/BPMO complexes exhibit significantly narrower bite angles and longer Pd-O bonds than Pd/BPMO complexes bearing a phenylene linker, while maintaining almost constant Pd-P bond lengths. Among the complexes synthesized, menthyl-substituted complex 3f (R1 = (1R,2S,5R)-2-isopropyl-5-methylcyclohexan-1-yl; R2 = Me) showed the best catalytic performance in the homo- and copolymerization in terms of molecular weight and polymerization activity. Meanwhile, complex 3e (R1 = t-Bu; R2 = Me) exhibited a markedly higher incorporation of comonomers in the copolymerization of ethylene and allyl acetate (≤12.0 mol %) or methyl methacrylate (≤0.6 mol %). The catalytic system represents one of the first examples of late-transition-metal complexes bearing an alkylene-bridged bidentate ligand that afford high-molecular-weight copolymers from the copolymerization of ethylene and polar monomers.
RESUMEN
We have developed a direct esterification of aqueous acetic acid with ethanol (molar ratio=1:1) catalyzed by polystyrene-supported or homogeneous sulfonic acids toward the recovery of acetic acid from wastewater in chemical plants. The equilibrium yield was significantly increased by the addition of toluene, which had a high ability to extract ethyl acetate from the aqueous phase. It was shown that low-loading and alkylated polystyrene-supported sulfonic acid efficiently accelerated the reaction. These results suggest that the construction of hydrophobic reaction environments in water was critical in improving the chemical yield. Addition of inorganic salts was also effective for the reaction under not only biphasic conditions (toluene-water) but also toluene-free conditions, because the mutual solubility of ethyl acetate and water was suppressed by the salting-out effect. Among the tested salts, CaCl(2) was found to be the most suitable for this reaction system.