Behavior Of Amides Research Articles

Dielectric Relaxation Behavior of Amide and Phenol Mixtures in C6H6 Under Microwave Field

Dielectric Relaxation Behavior of Amide and Phenol Mixtures in C6H6 Under Microwave Field

Interaction between Li2Mg(NH)2 and CO: Effect on the hydrogen storage behavior of the Li4(NH2)3BH4 doped Mg(NH2)2-2LiH composite

Metal hydrides have been studied as a promising solution for the hydrogen recovery from gas mixtures of industrial processes. However, scarce information is available about the behavior of amides as hydrogen purification material. In this work, the tolerance against CO, hydrogen sorption kinetics and the thermodynamics of the Li4(NH2)3BH4 doped Mg(NH2)2-2LiH composite after repetitive dehydrogenation and rehydrogenation cycles with 0.1 mol% of CO-H2 mixture were investigated. A progressive degradation of the hydrogen storage capacity of the material and an improvement in the dehydrogenation rate (50%) was observed for the composite after 20 cycles of the CO containing gas mixture. The formation of Li2CN2 and MgO, which are the main responsible for the deterioration of the hydrogen storage properties, was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRPD). For the first time, the reaction between pure CO and the dehydrogenated product Li2Mg(NH)2 was demonstrated. This reaction is fast and produces mainly Li2CN2 and MgO as solid products. When a high CO pressure was diluted with H2 (mol ratio 1:8), the reactivity of Li2Mg(NH)2 with CO was notably reduced and mainly MgO formation was detected. No clear reaction of CO with Mg(NH2)2 was detected by FTIR, XRPD and volumetric measurements. Evaluation of the reactivity of CO with LiNH2-LiH, Mg(NH2)2-2LiH and LiBH4 systems provides the following decreasing ranking of reactivity: [NH]2− > [NH2]− > [BH4]−.

Physicochemical Properties of Solutions of Amides in H2O and in D2O

Excess volume, partial molar volumes, viscosity, and ultrasound velocity in H2O and D2O solutions of formamide (FM), acetamide (AM), dimethylformamide (DMF), and dimethylacetamide (DMA) were studied at 20°C. The change in the excess volume of the various amide solutions on substitution of D2O for H2O varies both in magnitude and direction. On the other hand, the isotope effect on the ultrasound velocity behaves similarly in all cases. Its magnitude is greatest for pure water and then decreases monotonically with increasing amide concentration. Although the behavior of the concentration dependence of viscosity is similar to that for ultrasound velocity, the isotope effect on the viscosity behaves in a different way. For methyl-substitued amides, a maximum isotope effect is observed at amide mole fraction 0.2, but the isotope effect for FM and AM increases monotonically with increasing amide concentration. The differences in the behavior of amides in aqueous solution are discussed in terms of their interactions with water.

Amides of the Alkali and the Alkaline Earth Metals

AbstractFollowing preparative work, the behavior of amides towards excess ammonia (ammoniate formation) and on removal of ammonia (degradation to imides)was studied particularly with regard to the solid state (crystal structure) and the transition to the liquid phase (melting point). Energy relationships are discussed on the basis of enthalpies of formation. Studies on ternary amides and imides are still in the initial stage. – Emphasis is laid here on the establishment of parallels between amides and hydroxides as well as between the aquo and ammono systems, and also on the differences between the amides with their dipolar NH2‐ anion, and the halides. The results, although still incomplete, permit a survey to be given of experimental data with the aid of information obtained from the pertinent literature.