Stereoselective synthesis of novel beta,gamma-epoxyhydroxylamines and 4-hydroxyalkyl-1,2-oxazetidines

A simple and efficient stereoselective synthesis of polysubstituted beta,gamma-epoxyhydroxylamines and 4-hydroxyalkyl-1,2-oxazetidines, based on the addition of alpha-lithiated aryloxiranes to nitrones and subsequent cyclization of the corresponding intermediates in a 4-exo-tet mode, is described.     

Integral geometry for \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}${\mathcal {D}}$\end{document}‐modules on dual flag manifolds and generalized Verma modules

Given a pair of dual generalized flag manifolds of a semisimple algebraic group, we show that the integral transform between them given by the open orbit in their product is an equivalence. We also describe the links of this problem with the structure of generalized Verma modules, and how the above construction can be applied to the representation theory of real forms of the group.     

Linear sets and MRD-codes arising from a class of scattered linearized polynomials

Journal of Algebraic Combinatorics - A class of scattered linearized polynomials covering infinitely many field extensions is exhibited. More precisely, the q-polynomial over $${{\mathbb...     

Metal complexes of chiral pyridine ligands. X-ray structure of nitratobis {2-(2S)-2-pyrrolidinyl]pyridine} copper (II) nitrate

Cobalt(II), nickel(II), and copper(II) complexes of 2-[(2S)-2-pyrrolidinyllpyridine (L) have been synthesized and characterized. The crystal structure of the complex [Cu(L)₂(NO₃)]NO₃ has been determined by X-ray diffraction. Crystals are monoclinic, space groupP2+, witha=10.766(3).b=7.525(2),c=13.447(4) Å. =104.64(2)°. and Z=2. The structure consists of [Cu(L)₂(NO₃)]⁺ cations and NO ₃ ^t- anions. The copper atom has a distorted trigonal bipyramidal coordination geometry with the two pyrrolidine nitrogens and one nitrate oxygen occupying the equatorial positions and the two pyridine nitrogens at the apices. The crystalline cohesion is ensured by a network of hydrogen bonds involving the pyrrolidine groups as donors and both coordinate and uncoordinate nitrates as acceptors.     

Reactions of aromatic nitro compounds with acetophenone in the presence of alkali. Crystal structure of (E)-1,2-dibenzoyl-o-tolylaminoethylene

Methyl and methoxy substituted nitroarenes were reacted with acethophenone in the presence of sodium ethoxide in ethanol giving arylamino-conjugated diketo derivatives. A case ofipso-substitution of a methoxy group is discussed. The title compound C₂₃H₁₉NO₂ (M _r =341.4) crystallizes in the monoclinic system, space groupP2₁/n witha=21.579(4),b=8.526(2),c=9.983(2) Å;=92.3(1)°;V=1835.2(7) ų,Z=4,D _c =1.24 g cm^–3,(Cu-K )=5.9 cm^–1, =1.5418 Å,F(000)=720. The molecule adopts theE configuration with the C=O carbonyl groupstrans with respect to the ethylenic double bond.     

Crystal structure of 1,1-diphenyl-2,4-dimethyl-5-(N-benzamide)-1,3-pentadiene

Crystals of the title compound are monoclinic (C₂₆H₂₅NO): space groupP2₁/c,a=16.565(3),b=10.328(2),c=12.621(3) Å,=104.02(3)°. The structure was solved by direct methods and refined by block-matrix least-squares to giveR=0.056 andR _w =0.061 for 1613 reflections above 2(I). The amide moiety is tilted by 19.3(2)° with respect to the mean aromatic ring plane. The two othergem phenyl rings subtend a dihedral angle of 112.2(4)° to each other. The molecules are joined in the solid by N-HO hydrogen bonds.     

Determination of sulfonic acids and alkylsulfates by ion chromatography in water

A fast ion chromatographic method with suppressed conductivity detection has been developed for the simultaneous determination of methane-, ethane-, 1-propane-, 1-butane-, 1-pentane-, 1-hexane-, 1-heptane-, 1-octane-, 1-nonane-, 1-decane-, 1-dodecane-, dodecylbenzene-, p-toluene-, benzenesulfonic acids, octylsulfate and dodecylsulfate in water samples. Due to the high number of analytes and their heterogeneity, the effect of the mobile phase parameters (NaOH, CH(3)OH and CH(3)CN concentration) on the retention factors has been studied in detail, so achieving, for the first time, the separation among 15 of these analytes by a gradient elution. Detection limits included within 0.06-0.16 microM have been obtained. Interferences from Cl(-), NO(3)(-) and SO(4)(2-), possible anions present in water samples, have been considered and a SPE procedure has been developed for analytes enrichment and matrix removal in a seawater sample. This is the first application of an ion-exchange chromatographic method to a seawater sample for this kind of analytes.     

High performance ion chromatography of haloacetic acids on macrocyclic cryptand anion exchanger

A new high performance ion chromatographic method has been developed for the separation of the nine chlorinated-brominated haloacetic acids (HAAs) that are the disinfection by-products of chlorination of drinking water, using a macrocycle-based adjustable-capacity anion-exchange separator column (IonPac Cryptand A1). A gradient method based on theoretical and experimental considerations has been optimized in which 10 mM NaOH-LiOH step gradient was performed at the third minute of the analysis. The optimized method allowed us to separate the nine HAAs and seven possibly interfering inorganic anions in less than 25 min with acceptable resolution. The minimum concentrations detectable for HAAs were between 8.0 (MBA) and 210 (TBA) microg L(-1), with linearity included between 0.9947 (TBA) and 0.9998 (MBA). To increase sensitivity, a 25-fold preconcentration step on a reversed phase substrate (LiChrolut EN) has been coupled. Application of this method to the analysis of haloacetic acids in real tap water samples is illustrated.