A new sphingolipid from the gorgonian Junceella juncea of the Indian Ocean

A new sphingolipid, (2S,3R,4E)-1,3-dihydroxy-2-[(nonadecanoyl) amino]-octadec-4-ene (1) along with ubiquitous batyl alcohol is isolated from the gorgonian, Junceella juncea Pallas (Gorgonaceae) of the Indian Ocean. The structure of 1 is determined on the basis of 1H- and 13C-NMR, COSY, FABMS, and GC-EIMS experiments.     

Structure of 4-[4-(Dimethylamino)-Phenylazo] Benzeneboronic Acid and Its Cyclic Esters with D-Glucose: A Computational Study

We present results from a computational study of 4-[4-(dimethylamino)-phenylazo] benzene boronic acid (DABBA) (the 4'-boronic acid isomer of the aminoazobenzene dye N,N-dimethylaminoazobenzene) and its associated anion, as well as, several cyclic esters formed from these azoborates and various conformers of D-glucose. Azo dyes that also contain one or more boronic acid functional groups are of practical importance in the development of chemical sensors for saccharide recognition because of their ability to induce a visible color change upon binding. The lowest-energy DABBA:D-glucose esters found in this investigation consistently involved at least one of the exocyclic hydroxymethyl groups on the D-glucose moiety rather than vicinal cis or trans diol arrangements of hydroxyl groups on the ring.     

Stereochemical applications of mass spectrometry: 1—The utility of electron impact and chemical ionization mass spectrometry in the differentiation of stereoisomeric benzoin oximes and phenylhydrazones

A study of the electron impact and chemical ionization (H₂, CH₄, and iso-C₄H₁₀) mass spectra of stereoisomeric benzoin oximes and phenylhydrazones indicates that while the former can be distinguished only by their chemical ionization mass spectra the latter are readily distinguishable by both their electron impact and chemical ionization mass spectra. The electron impact mass spectra of the isomeric oximes are practically identical; however, the chemical ionization spectra show that the E isomer forms more stable [MH]⁺ and [MH? H₂O]⁺ ions than the Z isomer for which both the [MH]⁺ and [MH? H₂O]⁺ ions are relatively unstable. In electron impact the Z-phenylhydrazone shows a lower [M]⁺˙ ion abundance and more facile loss of H₂O than does the E isomer. This more facile H₂O loss also is observed for the [MH]⁺ ion of the Z isomer under chemical ionization conditions.     

Gas chromatographic determination of residual hydrazine and morpholine in boiler feed water and steam condensates

Summary Hydrazine, an oxygen scavenger in boiler water, was derivatised to the corresponding acetone azine and determined at the ng ml^–1 level by gas chromatography. Morpholine, a corrosion inhibitor used in steam boilers, was estimated either directly (if >2.0 g ml^–1) or by quantitative preconcentration (0.1 ng – 2.0 g ml^–1). To obtain symmetrical peaks for these amines, the column packing was coated with KOH. Use of a nitrogen-specific detector improved accuracy of estimation of hydrazine and morpholine, giving a RSD of 1.9–3.6%. Chromatographic analysis of these amines in boiler feed water and steam condensate samples collected from boilers servicing a petroleum refinery is described. Environmental safety regulations calls for monitoring of hydrazine and the methods developed can easily be adapted for this purpose.     

Spectrophotometric determination of aromatic primary amines and nitrite by flow injection analysis

Aromatic primary amines are determined by injection into dilute hydrochloric acid carrier which merges sequentially with 4-N-methylaminophenol and dichromate. The purple-red color formed by oxidative coupling of amines with 4-N-methylaminophenol is measured at 530 nm. In contrast to the manual procedure, the flow-injection procedure avoided errors arising from the instability of the coupling intermediate, oxidation of the amine, and too great an excess of the oxidant. The method improves the selectivity for certain amines in the presence of those which are sterically hindered or have an electron-deficient aromatic nucleus. Nitrite is determined by diazotization of sulfanilamide and quantifying the residual sulfanilamide by oxidative coupling. The sample thourghout for the assay of amines (0.05–20 μg ml^?1 NH₂-N) and nitrite (1–10 μg ml^?1 NO₂^--N) was 120 h^?1. A system for the consecutive determination of aromatic primary amines and nitrite is decribed.     

Analysis of certain mixtures ofα-Amino acids

Summary -Amino acids are determined by reaction with perinaphthindan-2,3,4-trione hydrate to form dihydroxyperinaphthindenone which is titrated with chloramine-T in the presence of acidified bromide and methyl red. The thiol group of cysteine is blocked by cyano-ethylation before determination. Some amino acids can be directly titrated with chloramine-T in the presence of bromide and methyl red, e. g., cysteine (after cyanoethylation), methionine and lanthionine, or in the presence of iodide and starch, e. g., cysteine (after tetrathionate reaction) when concomitant amino acids do not interfere. These methods are used to analyze model mixtures of cysteine with serine, methionine with glycine and cysteine with methionine.

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Analyse bestimmter Gemische von -Aminosäuren

Zusammenfassung -Aminosäuren werden mit Peri-Naphthindan-2,3,4-trion-hydrat umgesetzt, wobei sich Dihydroxyperinaphthindenon bildet, das mit Chloramin T in der Gegenwart von angesäuertem Bromid und Methylrot titriert wird. Die Thiolgruppe des Cysteins wird vor der Bestimmung durch Cyanoäthylierung blockiert. Manche Aminosäuren können unmittelbar mit Chloramin T in der Gegenwart von Bromid und Methylrot titriert werden, z. B. Cystein (nach Cyanoäthylierung), Methionin und Lanthionin, oder in Gegenwart von Jodid und Stärke Cystein (nach Umsetzung mit Tetrathionat), wenn die begleitende Aminosäure nicht stört. Diese Verfahren wurden benutzt, um Modellgemische von Cystein mit Serin, Methionin mit Glycin und Cystein mit Methionin zu analysieren.

     

Crystal structure of phenyl bis(O-isopropylxanthato s,s′)arsenic(III)

The crystal structure of the title compound PhAs(S₂COPrⁱ)₂ has been determined by single crystal X-ray diffraction and refined by full matrix least squares analysis with anisotropic temperature factors. The crystal is monoclinic, space groupP2₁/c,a=8.889(6),b=16.174(19),c=13.506(14) Å,=102.02(7)°,V=1899.2 ų,Z=4,D _c=1.478 g cm^–3, monochromated Mo-K radiation, =0.71069 Å,=22.07 cm^–1.The geometry around the arsenic atom is square pyramidal. Each ligand is bonded to an arsenic atom through two unequal As-S bonds measuring 2.298 and 3.041 Å. The apical position is occupied by a phenyl group and a lone pair of electrons is presenttrans to the phenyl group.     

Studies on chromium(III) complexes of some new dithiocarbamato ligands

Summary Tris-chelates of chromium(III) have been synthesised with five new dithiocarbamates, [RR'NCS₂]^–, where R=PhCH₂ and R/t'=H, PhCH₂, Me, Et and i-Pr. Magnetic moments together with electronic, i.r. and e.s.r spectra of the complexes have been described. Various ligand-field parameters have been evaluated and discussed.     

A novel conversion of erythro phospholane epoxides to one-carbon atom homologated allylic alcohols

A novel synthetic approach is described to incorporate one more carbon atom at C-2 position of phospholane oxides as homologated allylic alcohol by treatment of erythro-2,3-epoxy-3-methylphospholane 1-oxides with excess of dimethylsulfonium methylide.     

Electroweak tests with τ leptons at LEP

We report on two sensitive tests of lepton universality carried out by the 4 LEP experiments at the Z⁰ pole. From measurements of the τ polarization in e⁺ e^?→τ ⁺ τ ^?, the ratios of the vector and axial vector coupling constants of the electron and the tau lepton to the weak neutral current are obtained to beg _{v e} /g _{a e} =0.066±0.015 andg _{V τ} /g _{A τ} =0.070±0.009 respectively. From measurement of the τ lifetime and the τ leptonic branching ratios, the ratio of the coupling constants describing weak leptonic decays of the τ and the μ is measured to beG _τ /G _μ =0.996±0.008.