Analytical method for determination of disaccharides derived from keratan sulfates in human serum and plasma by high-performance liquid chromatography/turbo-ionspray ionization tandem mass spectrometry

We established a highly sensitive LC/MS/MS method for the analysis of the disaccharides produced from keratan sulfates (KS). It was revealed that the disaccharides produced by keratanase II enzymatic digestion of KS could be determined with high sensitivity by negative ion mode of multiple reaction monitoring. Furthermore, monosulfated and disulfated disaccharides can be separated using a Hypercarb (2.0 mm i.d. x 150 mm, 5 microm) with a gradient elution of acetonitrile-0.01 m ammonium bicarbonate (pH 10). This method was applied to the determination of KS in serum and plasma of control subjects. The intra-day precision expressed as %CV was within 6.8% for five replicate analyses with three different control serum. The inter-day (overall, n = 15) precision was within 7.3% for three days. This method is sensitive, reproducible and would be useful for clinical analysis.     

A comprehensive spectroscopic study of synthetic Fe2+, Fe3+, Mg2+ and Al3+ copiapite by Raman,XRD, LIBS,MIR and vis–NIR

The identification of iron sulfates on Mars by the Mars Exploration Rovers (MERs) and the Mars Reconnaissance Orbiter emphasized the importance of studying iron sulfates in laboratory simulation experiments. The copiapite group of minerals was suggested as one of the potential iron sulfates occurring on the surface and subsurface on Mars, so it is meaningful to study their spectroscopic features, especially the spectral changes caused by cation substitutions. Four copiapite samples with cation substitutions (Fe³⁺, Al³⁺, Fe²⁺, Mg²⁺) were synthesized in our laboratory. Their identities were confirmed by powder X‐ray diffraction (XRD). Spectroscopic characterizations by Raman, mid‐IR, vis‐NIR and laser‐induced‐breakdown spectroscopy (LIBS) were conducted on those synthetic copiapite samples, as these technologies are being (and will be) used in current (and future) missions to Mars. We have found a systematic ν₁peak shift in the Raman spectra of the copiapite samples with cation substitutions, a consistent atomic ratio detection by LIBS, a set of systematic XRD line shifts representing structural change caused by the cation substitutions and a weakening of selection rules in mid‐IR spectra caused by the low site symmetry of (SO₄)²⁻ in the copiapite structures. The near‐infrared (NIR) spectra of the trivalent copiapite species show two strong diagnostic water features near 1.4 and 1.9 µm, with two additional bands near 2.0 µm. In the vis‐NIR spectra, the position of an electronic band shifts from 0.85 µm for ferricopiapite to 0.866 µm for copiapite, and this shift suggests the appearance of a Fe²⁺ electronic transition band near 0.9 µm. Copyright © 2010 John Wiley & Sons, Ltd.     

PdCl2-catalyzed hydrogenolysis of a C-O bond in monoaryl sulfates by sodium phosphinate in an aqueous alkaline medium

The hydrogenolysis of the C-O bond in monoaryl sulfates by the action of an excess of NaH₂PO₂ in the presence of catalytic amounts of PdCl₂ and KOH is studied. The reaction proceeds chemoselectively with complete ester conversion to the corresponding arenes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 605–606, March, 1993.     

Metal Hydrogen Sulfates Catalyzed Methoxymethylation of Alcohols under Solvent‐Free Conditions

Methoxymethylation of a variety of alcohols was performed by using formaldehyde dimethoxy acetal in the presence of metal hydrogen sulfate M(HSO₄)_n at room temperature and solvent‐free conditions. The methoxymethyl ethers (MOM‐ethers) were obtained with high yields and purity.     

Polar steroidal compounds from the Far-Eastern starfish Lethasterias nanimensis chelifera

In addition to the salts described previously (with a sulfated steroid as the anion and the alkaloid salsolinol as the cation), nine other steroidal compounds including three new compounds were isolated from the Far-Eastern starfish Lethasterias nanimensis chelifera collected near the coast of the Onekotan island (Kuril isles). A nonsteroidal compound found in this starfish is (1S,3S)-1-methyl-1,2,3,4-tetrahydro--carboline-3-carboxylic acid. The structures of the isolated compounds were determined by NMR spectroscopy and mass spectrometry.     

Syntheses and Crystal Structures of Hydrated Ternary Cerium Sulfates: Mixed‐valence K5Ce2(SO4)6·H2O and K2Ce(SO4)3·H2O

A new chemical and structural interpretation of K₅Ce₂(SO₄)₆·H₂O ( I ) and a redetermination of the structure of K₂Ce(SO₄)₃·H₂O ( II ) is presented. The mixed‐valent compound I crystallizes in the space group C2/c with a = 17.7321(3), b = 7.0599(1), c = 19.4628(4) Å, β = 112.373(1)° and Z = 4. Compound I has been discussed earlier with space group Cc. In the structure of I , there are pairs of edge sharing cerium polyhedra connected by sulfate oxygen atoms in the μ₃ bonding mode. These cerium dimers are linked through edge and corner sharing sulfate bridges, forming layers. The layers are joined by potassium ions which together with the water molecules are placed between the layers. No irregularity in the distribution of the Ce^III and Ce^IV to cause the lost of a crystallographic center of symmetry was detected. We suggest that the charge exerted by the extra f¹ electron for every cerium dimer is delocalized over the Ce1–O₂–Ce2 moiety in a non‐bonding mode. As a result, the oxidations state of each cerium ion is a mean value between III and IV at each atomic position. Compound II crystallizes in the space group C2 with a = 20.6149(2), b = 7.0742(1), c = 17.8570(1) Å, β = 122.720(1)° and Z = 8. The hydrogen atoms have been located and the absolute structure has been established. Neither hydrogen atom positions nor anisotropic displacement parameters were given in the previous reports. In compound II , the cerium polyhedra are connected by edge and corner sharing sulfate groups forming a three‐dimensional network. This network contains Z‐shaped channels hosting the charge compensating potassium ions.     

Synthesis and transformations of metallacycles

A regioselective method for the synthesis of 1,1-dialkylcyclopropanes was developed. The method is based on the reaction of 2,3-dialkyl-1-ethylalumacyclopent-2-enes with an excess of dialkyl sulfates (Me₂SO₄ or Et₂SO₄). A plausible reaction mechanism was suggested. For Part 20, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1092–1095, June, 2000.     

An efficient synthesis of pentacyclo[4.2.0.02,5.03,8.04,7]octane-1,4-dicarboxylates

Dialkyl pentacyclo[4.2.0.0^2,5.0^3,8.0^4,7]octane-1,4-dicarboxylates (where alkyl is methyl,iso-propyl, 2-fluoro-2,2-dinitroethyl, or 2,2,2-trinitroethyl) were prepared in high yields by O-alkylation of 1,4-cubanedicarboxylic acid with the corresponding monoalkyl sulfates.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 801–802, April, 1993.     

“In situ”13C NMR study of ethyl alcohol interaction with sulfuric acid

“In situ” NMR study of ethyl alcohol interaction with sulfuric acid of various concentrations confirmed that in accordance with chemical experience the main reaction product in an excess of concentrated acid is the mono-ethyl sulfate. Only traces of diethyl sulfate are formed in a large excess of 95% acid. In addition, ethyloxonium ions and protonated esters, which rapidly exchange protons with solvating water molecules, are detected as the reaction intermediates. The¹³C chemical shifts of methylene fragments in protonated esters and ethyl oxonium ions are more than 10 ppm higher than in neutral molecules. The study of reaction products at different sulfuric acid concentrations indicated that similarly to dissociation of concentrated sulfuric acid, hydrolysis of mono-ethyl sulfate requires at least two water molecules. Dedicated to Professor Pál Tétényi on the occasion of his 70th birthday