Vanadyl phosphate dihydrate,a solid acid: the role of water in VOPO4·2H2O and its sodium derivatives Na x (VIV x VV 1−x O)PO4·(2−x)H2O

Sodium-containing intercalates having as general formula Na _x VOPOP₄·(2–x)H₂O (0.25x<0.50) have been obtained and characterized. Orthorhombic phases, which essentially maintain the structure of the layered oxide hydrate VOPO₄·2H₂O result. Intercalated sodium ions act as pillars. The presence of H₃O⁺ ions in the parent VOPO₄·2H₂O and also in some reduced phases, is detected. The understanding of the structural role of the water molecules is advanced and the topotactic dehydration/rehydration processes are studied. The formation of a new metastable VOPO₄·H₂O phase is established.     

Palladium-catalyzed arylation of alpha,alpha-disubstituted arylmethanols via cleavage of a C-C or a C-H bond to give biaryls

The palladium-catalyzed arylation of alpha,alpha-disubstituted arylmethanols with aryl halides proceeds not only via C-H bond cleavage at the ortho-position, but also via cleavage of the sp(2)-sp(3) C-C bond with the liberation of ketones (beta-carbon elimination) to give the corresponding biaryls. Both reactions appear to occur through common arylpalladium(II) alcoholate intermediates. The results of systematic studies with respect to which C-C or C-H bond is preferentially cleaved in the arylation are reported. Among the important findings is the selective elimination of ortho-substituted aryl groups even from aryl(diphenyl)methanols due to steric reasons. Thus, various biaryls having ortho-substituents can be produced efficiently by treatment of the corresponding aryl(diphenyl or dimethyl)methanols with aryl bromides and chlorides.     

Mass spectrometric characterisation of a condensation product between porphobilinogen and indolyl‐3‐acryloylglycine in urine of patients with acute intermittent porphyria

We document the presence of a previously unknown species in the urine of patients with acute intermittent porphyria (AIP). The compound was fully characterised by liquid chromatography tandem mass spectrometry. Interpretation of both full spectrum acquisition and product ion spectra acquired in positive and negative ionisation modes by quadrupole time of flight MS allowed for the identification of a condensation product arising from porphobilinogen (PBG, increased in the urine of AIP patients) and indolyl‐3‐acryloylglycine (IAG, derived from indolylacrylic acid and present in human urine). The structure was unequivocally confirmed through comparison between the selected reaction monitoring chromatograms obtained from the urinary species and the condensation product qualitatively synthesised in the laboratory. Owing to the large amounts of both PBG and IAG in urine of AIP patients, the possible ex vivo formation of PBG‐IAG in urine samples was evaluated. The product was spontaneously formed at room temperature, at 4 °C and even during storage at ?20 °C when spiking a control sample with PBG. A positive correlation was found between PBG and PBG‐IAG in samples collected from AIP patients. However, no correlation was found between PBG‐IAG and IAG. Purified PBG‐IAG did not form the characteristic chromogen after application of p‐dimethylaminobenzaldehyde in HCl, thus suggesting that the current techniques used to measure PBG in urine of AIP patients based on Ehlrich's reaction do not detect this newly characterised PBG‐IAG fraction. Copyright © 2015 John Wiley & Sons, Ltd.     

Practical synthesis of thiirene 1‐oxides that possess two bulky alkyl substituents

Acetylenes that possess two bulky alkyl substituents reacted with sulfur dichloride to furnish the corresponding 2,3‐dialkyl‐2,3‐dichlorothiiranes ( 5 ) nearly quantitatively. The alkaline hydrolysis of 5 afforded 2,3‐dialkylthiirene 1‐oxides ( 10 ) in high yields. These two reactions could be successively carried out in one flask, and 2,3‐di‐tert‐butyl‐, 2,3‐di‐(1‐adamantyl)‐, and 2‐(1‐adamantyl)‐3‐tert‐butylthiirene 1‐oxides ( 10a–c ) were obtained in 70, 80, and 90% yields, respectively, based on the starting acetylenes, thus providing the most convenient synthesis of thiirene 1‐oxides. Disulfur dichloride also reacted with acetylenes to give 5 in good yields with the elimination of one sulfur atom. Although the alkaline hydrolysis of 5 provided 10 exclusively, acid hydrolysis gave a mixture of α‐oxothioketone 9 and thiirene 1‐oxide 10 in modest yields. All thiirene 1‐oxides 10a–c isomerized to produce α‐oxothioketones 9 in high yields when heated in boiling toluene. Reactions of a bis‐acetylene ( 18 ) with disulfur dichloride and with sulfur dichloride gave a dihydropentathiepin ( 19 ) in high yields. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:424–430, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10070     

Lyapunov-Based Controller for the Inverted Pendulum Cart System

A nonlinear control force is presented to stabilize the under-actuated inverted pendulum mounted on a cart. The control strategy is based on partial feedback linearization, in a first stage, to linearize only the actuated coordinate of the inverted pendulum, and then, a suitable Lyapunov function is formed to obtain a stabilizing feedback controller. The obtained closed-loop system is locally asymptotically stable around its unstable equilibrium point. Additionally, it has a very large attraction domain.Contributed by Prof. F. Pfeiffer.     

Quantification of sterols, 5α- and 5β-stanols in sewage sludge, manure and soils amended with these both potential fertilizers

A method for the quantitative determination of sterols, 5α- and 5β-stanols is proposed to characterize the lipid fraction of two potential organic fertilizers, like sewage sludge and manure, as well as soils amended by them. It was possible to determine the kind of fertilizer added to the soil. Further studies were conducted to determine the accumulative effects of steroids in soils treated with manure and different doses of sewage sludge.     

Contact electromagnetic terms in inclusive photo- and electroproduction

It is shown that contact electromagnetic terms in the photo- and electroproduction exclusive channels can account for a substantial amount of the inclusive real and virtual γp total cross sections. In particular, one gets σ(γp)_exp?σVMD (?, ω, φ) + σ(contact) for Q²=0 and hence no infinite vector mesons (GVMD) seem to be required. The same result is valid for Q²<0. A parallelism with the parton approach is noted.     

A general and highly efficient asymmetric synthesis of optically active anthracyclinones

The title asymmetric synthesis has been developed by featuring bromolactonization of (−)-acetals, derived from 2-acetyl-3,4-dihydronaphthacene-6,11-diones and (2R,3R)-(+)-N,N,N′,N′-tetraalkyltartaric acid diamides, as a key diastereoselective reaction. The produced bromolactone mixtures could be readily converted to the highly optically active key synthetic intermediates of 4-demethoxy- and 11-deoxy-4-demethoxyanthracyclinones.     

Gravitational interaction of two spinning particles in general relativity. II

Within the framework of the previous paper, we complete the set of equations of motion by including the spin propagation equation at first order. We check this equation with the known result on the precession, which is obtained by means of slow motion approximation of our result. A new scheme of expanding equations of motion is also introduced. It will be useful to undertake higher-order calculations.     

Palladium-catalyzed dehydroarylation of triarylmethanols and their coupling with unsaturated compounds accompanied by C-C bond cleavage

Triarylmethanols are effectively dehydroarylated and reacted with some unsaturated compounds by using an appropriate palladium catalyst system such as Pd(OAc)2-P(1-Nap)3 (1-Nap = 1-naphthyl) to give the corresponding arenes and hydroarylation products, respectively, along with diaryl ketones.