CH3CH+* formation from some C3H6O+* isomers according to theory

Dissociations to alkane ions in gas phase ion chemistry are rare and poorly characterized. Therefore, the pathways to CH3CH3+* + CO from *CH2CH2O+=CH2 and some of its isomers are investigated by theory. The pathway found for this reaction is *CH2CH2O+=CH2 --> CH3CH2O+=CH* --> [CH3CH2- -H- -CO]+* --> CH3CH+* + CO. The crucial intermediate in this pathway is the stable hydrogen-bonded ion-neutral complex [CH3CH2- -H- -CO]+*, a species held together by a strong hydrogen bond. CH3CH3+* + CO rather than CH3CH3 + CO+* is formed from *CH2CH2O+=CH2 and other C3H6O+* ions because the former pair is much more stable than the latter. The photoionization appearance energies of CH3CH3+* from CH3CH2CHO+* and from CH3CH2CO2H+* demonstrate that the onsets of these reactions are at to just above their thermochemical thresholds, consistent with the intermediacy of ion-neutral complexes. We also found transition states for interconversion of CH3CH2CHO+* and CH3CH2O+=CH* and transformation of CH3CH2C:=OH+* to CH3CH2CHO+*; the latter reaction occurs by a 1,2-H-shift from O to C.     

An esr study of the photoreaction of nitroalkanes with tetraphenylbiphosphine and tetraethylpyrophosphite

Some paramagnetic species formed in the photoreactions of nitroalkanes with P-compounds have been characterized by ESR. The observed radicals are mostly nitroxides whose structures are consistent with the trapping of P-centred radicals by intermediate nitroso compounds.     

Lanthanide and Transition Metal Complexes of Dialkyl α-Hydroxyiminophosphonates

Abstract

α-Hydroxyiminophosphonic acid derivatives are widely known not only as intermediates in the synthesis of the important aminophosphonic acids,^1,2 but also as phosphorylating agents,³ potential metalloenzyme inhibitors,⁴ and as compounds having fungicidal activity.⁵ In this work the scope of these compounds has been extended considerably by the synthesis of a number of novel dialkyl derivatives. Novel lanthanide (La^III, Pr^III, Nd^III, Gd^III and Dy^III) and transition metal (Co^II and Ni^III) complexes of dialkyl α-hydroxyiminophosphonates (RO)₂P(O)C(R')N(OH) where R = Et. Prⁱ and R′ = Me, Et have been prepared and the NMR shift properties of the Pr^III complex (R = Et; R′ = Et) indicate the potential of these compounds as NMR shift reagents for the analysis of geometric isomers.^6,7 X-ray crystal structure analysis of [Ni(L¹)₂C1₂] (L¹: R = Et; R′ = Et) shows a distorted cis octahedral coordination at the nickel atom giving two symmetry related diethyl-(E)-α-hydroxyiminopropanephosphonate ligands and two chlorine donors, and those of [Pr(L²)₃Cl₃] and [Nd(L²)₂(NO₃)₃(H₂O)] (L²: R = Prⁱ; R′ = Et) show nine-coordination geometries with asymmetric bidentate and monodentate L² bonding respectively. Thus the metal complexes show unusual coordination ambivalence, changing from symmetrically bidentate to asymmetrically bidentate and then to monodentate bonding modes, to accommodate the different steric requirements of the coordinating anions in facilitating neutral complex formation.     

Boehmite@tryptophan‐Pd nanoparticles: A new catalyst for C–C bond formation

A boehmite@tryptophan‐Pd nanoparticulate catalyst was prepared by a simple, fast and convenient route. The nanomaterial was characterized using various techniques and employed as a thermally stable catalyst for Heck, Stille and Suzuki cross‐coupling reactions. Optimized conditions for these reactions are described. The catalyst could be isolated, post‐reaction, by simple filtration and recycled for several consecutive cycles without a notable change in its activity.     

A method for organic/inorganic differentiation using an x‐ray forward/backscatter personnel scanner

A method is proposed for performing organic/inorganic materials discrimination using an x‐ray forward/backscatter scanner. The method is demonstrated using a commercially available personnel security‐screening system and requires only image post processing. The method relies upon x‐ray interaction physics, and the exact registration of forward‐ and backscattered images, permitting reliable discrimination between low and high atomic number materials over a range of thicknesses. The materials information is used to colorize images, and examples of the results are given. Copyright © 2013 John Wiley & Sons, Ltd.     

Schwefelbestimmung in Eisen, Stahl u. dergl.

Ohne Zusammenfassung     

An International Laboratory Comparison Study of Volumetric and Gravimetric Hydrogen Adsorption Measurements

In order to determine a material's hydrogen storage potential, capacity measurements must be robust, reproducible, and accurate. Commonly, research reports focus on the gravimetric capacity, and often times the volumetric capacity is not reported. Determining volumetric capacities is not as straight-forward, especially for amorphous materials. This is the first study to compare measurement reproducibility across laboratories for excess and total volumetric hydrogen sorption capacities based on the packing volume. The use of consistent measurement protocols, common analysis, and figure of merits for reporting data in this study, enable the comparison of the results for two different materials. Importantly, the results show good agreement for excess gravimetric capacities amongst the laboratories. Irreproducibility for excess and total volumetric capacities is attributed to real differences in the measured packing volume of the material.