Structure and stereochemistry of a 7-phosphabicyclo[2.2.1]hept-2-ene-7-oxide from X-ray, multinuclear NMR, and 2D-J resolved NMR studies

1990 ◽  
Vol 68 (7) ◽  
pp. 1020-1028 ◽  
Author(s):  
Martin B. Hocking ◽  
Gordon W. Bushnell
Keyword(s):  
Nmr Assignments ◽  
Spectrometric Analysis ◽  
Fragmentation Pattern ◽  
Nmr Studies ◽  
X Ray ◽  
Thermal Fragmentation ◽  
Structural Assignment ◽  
Synthetic Reaction ◽  
Formed Adduct

Preparations of a 7-phosphanorbornene, from the reaction of 1,2,5-triphenylphosphole-1-oxide with inhibited acrylonitrile in benzene, were repeated under various conditions to determine if one, or more than one, stereoisomer was formed. Adduct formation failed to occur when the reaction was attempted in ethanol, or when the precursor 1,2,5-triphenylphosphole was substituted for the phosphole oxide. Elemental analysis and spectroscopic measurements confirmed that a 1:1 adduct had been obtained, and an X-ray structure determination of the ethanol complex established that this was 5-cyano-1,4,7-triphenyl-7-phosphabicyclo[2.2.1]hept-2-ene-7-oxide, 3a. Details of the 1H, 13C, and 31P NMR assignments, of potential value in the structural assignment of other similar adducts, are related to previous results. The results of a brief mass spectrometric analysis of the changes in the thermal fragmentation pattern of the adduct with temperature are discussed in relation to the synthetic reaction. Keywords: phosphole adduct, phosphanorbornene, phosphabicycloheptene, acrylonitrile.

Determination of total glucosinolates in oilseed rape by X-ray spectrometric analysis for oxidised sulphur (S6+)

1993 ◽  
Vol 61 (1) ◽  
pp. 79-86 ◽  
Author(s):  
Andrew Pinkerton ◽  
Peter J Randall ◽  
Patricia A Wallace ◽  
Margaret M Vonarx ◽  
Rodney J Mailer
Keyword(s):  
Oilseed Rape ◽  
Spectrometric Analysis ◽  
X Ray

scholarly journals Determination of the Surface Chromium Contents in Chromized Steel by X-Ray Fluorescence Spectrometric Analysis

1966 ◽  
Vol 30 (5) ◽  
pp. 469-473 ◽  
Author(s):  
Kazuo Kawamura ◽  
Toshio Watanabe ◽  
Kôichi Nishizaka
Keyword(s):  
Spectrometric Analysis ◽  
X Ray

Modes of Xanthine Complexation to Dirhodium Tetrakis[(R)-α-methoxy-α- (trifluoromethyl)-phenylacetate] in Solution and in the Solid State

2001 ◽  
Vol 56 (3) ◽  
pp. 319-324 ◽  
Author(s):  
Sven Rockitt ◽  
Rudolf Wartchow ◽  
Helmut Duddeck ◽  
Anna Drabczynska ◽  
Katarzyna Kiec-Kononowicz
Keyword(s):  
Solid State ◽  
Diffraction Analysis ◽  
Carbonyl Group ◽  
Enantiomeric Excess ◽  
Carbonyl Groups ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
C Nmr

Abstract It is show n by IR and NMR studies that the xanthines 1-5 prefer a side-on com plexation to the chiral dirhodium tetrakis[(R)-α-methoxy-α-(trifluoromethyl)phenylacetatel (Rh*) in solution whereas carbonyl groups are involved in the solid state. For 6, at least the carbonyl group C-6 contributes to complexation in solution as well. A lternating strands of 6 and Rh* exist in the solid state as revealed by X-ray diffraction analysis described in detail. The determination of enantiomeric excess of the chiral xanthine 6 can easily be accomplished by the “dirhodium method ” (1H and 13C NMR in the presence of Rh*).

X-ray crystal structure determination of [.eta.5-C5(CH3)5]Ta[P(CH3)3]2H4 and high-field NMR studies of phosphine derivatives of (pentamethylcyclopentadienyl)tantalum(V) hydrides

1983 ◽  
Vol 22 (8) ◽  
pp. 1149-1155 ◽  
Author(s):  
James M. Mayer ◽  
Peter T. Wolczanski ◽  
Bernard D. Santarsiero ◽  
Wendy A. Olson ◽  
John E. Bercaw
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
High Field ◽  
Crystal Structure Determination ◽  
Nmr Studies ◽  
X Ray ◽  
Phosphine Derivatives ◽  
Derivatives Of

Formation of a trimeric chloroguaiacol quinone in the preparation of tetrachloroguaiacol and crystal structure of its tetramethoxy derivative

1986 ◽  
Vol 64 (5) ◽  
pp. 950-954
Author(s):  
Nick Burlinson ◽  
Steven J. Rettig ◽  
James Trotter ◽  
Bruce McKague
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Conformational Isomerism ◽  
Nmr Studies ◽  
Full Matrix ◽  
X Ray ◽  
Expected Values ◽  
Intermolecular Distances ◽  
C Nmr

A by-product formed in the preparation of tetrachloroguaiacol is shown to be a trimeric quinone. Derivatization of the quinone to a crystalline tetramethoxy derivative allowed X-ray determination of its crystal structure as 3,6-dichloro-4,5-dimethoxy-1,2-bis(2′-methoxy-3′,4′,5′,6′-tetrachlorophenoxy)benzene, 4. Rarely observed long range JCH coupling between ring carbons and methoxyl hydrogens as well as conformational isomerism were observed in 1H and 13C nmr studies of 4. Crystals of 4 are triclinic, a = 12.562 (1), b = 12.708(1), c = 9.223(1) Å, α = 96.93(1), β = 97.478(7), γ = 101.285(8)°, Z = 2, space group[Formula: see text]. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.056 and Rw = 0.056 for 2946 reflections with I ≥ 1.5σ(I). The molecule contains a central six-membered dichloro-tetraoxo substituted aromatic ring, linked via oxygen bridges to two identical tetrachloro-dioxo substituted rings; intramolecular steric overcrowding causes significant deviations from a symmetrical conformation. Bond lengths, angles, and intermolecular distances are generally close to expected values.

Determination of Wear Metals in Oil by X-Ray Spectrometry

1985 ◽  
Vol 29 ◽  
pp. 503-509
Author(s):  
Ya-Wen Liu ◽  
A.R. Harding ◽  
D.E. Leyden
Keyword(s):  
Trace Elements ◽  
Thermal Degradation ◽  
Lower Limit ◽  
Organic Material ◽  
Limit Of Detection ◽  
Spectrometric Analysis ◽  
Trace Impurities ◽  
X Ray

AbstractTrace elements in oil may be determined by adsorption of the oil sample onto maguesium oxide followed by thermal degradation of the organic material. The resulting powder is easily pressed into a pellet suitable for X-ray spectrometric analysis. The lower limit of detection depends upon the trace impurities in the MgO and is a few parts per million for most elements determined.

X-Ray Spectrometric Determination of Atmospheric Aerosols

1972 ◽  
Vol 16 ◽  
pp. 165-176
Author(s):  
Henry Chessin ◽  
E.H. McLaren
Keyword(s):  
Atmospheric Aerosols ◽  
Cold Front ◽  
Analytical Tool ◽  
Spectrometric Analysis ◽  
Calibration Technique ◽  
X Ray ◽  
Aqueous Salt Solutions ◽  
Contamination Levels ◽  
Lower Limits

AbstractX-ray spectrometric analysis is examined as an analytical tool for elemental determinations of atmospheric aerosols. Contamination levels of the several filters used for collection purposes are examined and the results reported. A calibration technique is described for analysis of several elements in the microgram range based on collection of saturated vapors of aqueous salt solutions. The calibration curves together with an analysis of sensitivity and lower limits of detection are shown. The technique is employed to monitor continuously aerosol content in the atmosphere during passage of a cold front.

Accurate determination of copper in mixtures and ores by radioisotope-excited x-ray fluorescence spectrometric analysis using peak ratios

1973 ◽  
Vol 45 (11) ◽  
pp. 1804-1808 ◽  
Author(s):  
Cesia. Shenberg ◽  
Aharan. Ben Haim ◽  
Saadia. Amiel
Keyword(s):  
Accurate Determination ◽  
Spectrometric Analysis ◽  
X Ray ◽  
Determination Of Copper
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