2-Azidoacetone (N3CH2COCH3) has been synthesized and characterized by a variety of spectroscopic techniques, and the thermal decomposition of this molecule at temperatures in the region 300−1150 K has been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. The results show the effectively simultaneous production of six prominent decomposition products:  CH2NH, CH2CO, HCN, CO, N2, and CH3CHO, and several reaction pathways are proposed to account for their formation. Results of ab initio molecular orbital calculations indicate that the primary reaction intermediate is the imine HNCHCOCH3, with the nitrene NCH2COCH3 being a transition state. No experimental evidence was found for the presence of the imine HNCHCOCH3, but mechanistic considerations, and the existence of several weak unassigned IR bands point to the presence of a further decomposition product, which may be CH2NCH3.

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This paper addresses the investigation of the fractionation of saccharide mixtures and saccharide mixtures with calcium using ultrafiltration (UF) and nanofiltration (NF). A set of cellulose acetate membranes covered a wide range of molecular weight cut-off (MWCO) ranging from 250 to 46,000 Da and the total feed concentration of saccharides mixtures varied from 1550 to 4700 ppm with the ratio of the two saccharides-solutes (glucose to raffinose) being kept constant at the value of 1.8. The evolution pattern of the saccharide concentration ratio in the UF/NF permeate streams displayed a dependence on the membrane MWCO, on the total sugar concentration and on the presence of calcium ions. For the highest total sugar content, the membranes with MWCO from 2000 to 7000 Da showed saccharide fractionation capability that was enhanced in the presence of calcium. The Steric Pore Flow Model was used to predict individual solute permeation behaviours and to assess the deviations to steric hindered transport of the solutes in multi-component saccharide solutions. (C)

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The energetics and phase behavior of the MIL-53­(Al) metal–organic framework upon low-temperature (15–260 K), subatmospheric H2 adsorption are studied experimentally using a volumetric technique and theoretically by grand canonical Monte Carlo simulation. The adsorption equilibrium data are recorded for a fixed amount of H2 in the system at stable increasing temperature steps starting from 15 K while recording the equilibrium pressure attained at each step. The adsorption isotherms are generated by repeating the experiments for different fixed amounts of adsorbate in the system and connecting the equilibrium points obtained at the same temperature. The solid–fluid interactions are modeled using the TraPPE-UA force field and the fluid–fluid interactions using a parametrization consistent with the same force field; quantum effects on H2 adsorption are taken into account via a quartic approximation of the Feynman–Hibbs variational approach. The use of a consistent force field with proven transferability of its parameters provides an accurate description of the experimental adsorption equilibria and isosteric heats of adsorption. Because of the weak solid–fluid interaction, the Henry constant for H2 adsorption in the large-pore (LP) form of MIL-53­(Al) surpasses that for H2 adsorption in the narrow-pore (NP) form at a temperature lower than that at which the dehydrated structure of the material collapses. However, the saturation capacity of the LP form is always higher than that of the NP phase. The phase behavior of MIL-53­(Al) upon temperature-induced H2 desorption is interpreted in terms of the osmotic thermodynamic theory. For the conditions spanned in the experiments MIL-53­(Al) exhibits at most a single structural transition and its phase behavior depends not only on pressure and temperature but also on the thermal history of the bare material.

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