Search results for "mass spectrum"
showing 10 items of 302 documents
Spektroskopische analyse mehrfacher methacrylsäureester von oligo[(2-hydroxy-1,3-phenylen)methylen]en mittels UV-, IR-, 1H NMR- und massenspektren
1977
The structures of two homologous series of oligo[(2-hydroxy-1,3-phenylene)methylene]s completely esterified with methacrylic acid, were spectroscopically analysed. The molar decadal absorption coefficients of ultraviolet absorption maxima of the two homologous series confirm Hunter's relation. The vinylidene, ester, and substitution bands of the infrared spectra as well as the mass spectra agree with the accepted structures. The 1H NMR spectra permit to differentiate between exterior and interior groups of the molecules.
Hydrogen-bonded dimers of a thiacalixarene substituted by carbamoylmethylphosphineoxide groups at the wide rim.
2006
A thiacalix[4]arene derivative bearing four carbamoylmethylphosphineoxide groups at the wide rim forms hydrogen-bonded, dimeric capsules with S8 symmetry in the crystalline state and in apolar solvents, where the inclusion of cationic guests could be proved by 1H NMR and ESI mass spectra.
Studies in organic mass spectrometry. Part 20: a hidden ortho effect in the electron ionisation mass spectra of some 2′-alkyl substituted 2-and 3-thi…
1996
The electron-ionisation-induced amide-bond cleavage of some 2′-methyl- and 2′-ethyl-substituted 2- and 3-thiophenecarboxanilides, which yields formally anilylium ions having relative intensities apparently in contrast with the Stevenson‐Audier rule, has been investigated by mass-analysed ion kinetic energy (MIKE) spectrometry and compared to that of the 3 ′- and 4′-isomers. It has been shown that, in the case of the 2 ′-methyl and 2′-ethyl derivatives, the amide-bond cleavage is anchimerically assisted through the hidden migration of a benzyl hydrogen to the nitrogen. Analysis of the MIKE and collision-induced decomposition (CID) MIKE spectra of model compounds indicates that this cryptic o…
Antidiabetische wirkstoffe, IV [1] trifluormethylsubstituierte 2-(4-toluidino)pyrimidine
1985
Zusammenfassung Durch Umsetzung von 4-Tolylguanidin mit den entsprechenden fluorierten β-Diketonen in Gegenwart von Natriumcarbonat im Schmelzfluβ sind die folgenden 4-Trifluormethyl-2-(4-toluidino) pyrimidine zuganglich gemacht worden: die 6-Methyl-, 6-Ethyl-, 6-Isopropyl-, 6-tert. Butyl- und 6-Isopentyl-Abkommlinge. Zur Charakterisierung der dargestellten Verbindungen sind IR-, 1H-NMR- und MS-Daten herangezogen worden. In dem neuen Strukturtyp sind besonders antidiabetische, antimykotische, trichomonazide und herbizide Wirksamkeit ausgepragt.
Preparation and structural characterization of (Me(3)SiNSN)(2)Se, a new synthon for sulfur-selenium nitrides.
2002
The reaction of (Me(3)SiN)(2)S with SeCl(2) (2:1 ratio) in CH(2)Cl(2) at -70 degrees C provides a route to the novel mixed selenium-sulfur-nitrogen compound (Me(3)SiNSN)(2)Se (1). Crystals of 1 are monoclinic and belong the space group P2(1)/c, with a = 7.236(1) A, b = 19.260(4) A, c = 11.436(2) A, beta = 92.05(3) degrees, V = 1592.7(5) A(3), Z = 4, and T = -155(2) degrees C. The NSNSeNSN chain in 1 consists of Se-N single bonds (1.844(3) A) and S=N double bonds (1.521(3)-1.548(3) A) with syn and anti geometry at the N=S=N units. The N-Se-N bond angle is 91.8(1) degrees. The EI mass spectrum shows a molecular ion with good agreement between the observed and calculated isotopic distributions…
Über polygermane
1986
Summary Reaction of LiGePh2GePh3 with Cl2GePh2 at −65°C in ether yields n-Ge5Ph12 as the main product, in addition to shorter-chained polygermanes. The analysis of the resulting products and the isolation of the pentagermane was done by HPLC. The crystal structure was determined (R = 0.095). The conformation of the Ge5 chain is antiperiplanar-anticlinal (−179.3 and +114.4°) with mean Ge-Ge distances of 247.6 (central) and 244.3 pm (terminal).
Bismuth trihalide complexes with nitrogen and phosphorus chelating ligands
1985
Abstract Bismuth(III) halides react with 1,10-phenanthroline, 2-pyridinecarboxaldehyde-2-pyridylhydrazone and diphenylphosphynoethane in methanol. A stoichiometry differing from 1:1 is found only for BiCl 3 (Phen) 1.33 and BiCl 3 (Dpe) 1.5 . Characterization of these compounds, which are not very soluble in common solvents, follows from analytical, mass and IR spectral data. In the low frequency region, the IR spectra proved to be useful to ascertain the presence of bridging halogens.
Synthesis and characterization of some arsenic, antimony and bismuth complexes of 2-mercaptoaniline
1983
Abstract The complexes of arsenic, antimony and bismuth as well as phenylantimony and phenylbismuth with monoanionic 2-mercaptoaniline are reported. IR spectra are consistent with chelating behaviour of the ligand but only a weak nitrogen to metal bonding interaction is advanced. The mass spectra fragmentation pattern is also presented. It can be interpreted with the loss of successive ligand units and, as a general feature, the abundance of a given ion decreases as the mass of the metal increases. Species with one or two protons less give more intense peaks possibly corresponding to ions containing the dianionic form of the ligand.
A new potential toxaphene congener: synthesis, GC/EI-MS study, crystal structure, NMR analysis, and ab initio calculations of 3-endo,5-endo-dichloro-…
2001
Abstract A new potential toxaphene congener 3- endo ,5- endo -dichloro-7,7-bis-chloromethyl-4-dichloromethyl-tricyclo[2.2.1.0 2,6 ]heptane 2 has been isolated from reaction mixture obtained by the chlorination of 2- exo ,10,10-trichlorobornane 1 . The X-ray structural analysis of 2 revealed an unusual tricyclic structure, where the two chlorine atoms occupying endo -positions are in close spatial proximity with each other and near to the neighbouring CHCl 2 group. Further, it revealed that the symmetry of the molecule is distorted. The 1 H and 13 C NMR spectra of 2 have been assigned by means of 1 H, 1 H d ouble- q uantum f iltered co rrelation s pectroscop y (DQF COSY), PFG 1 H, 13 C HMQC …
Synthesis and characterization of lithocholic acid derived dipyrromethanes: precursors for pyrrole-steroidal macrocycles
2004
Abstract Three steroidal dipyrromethanes, 3,3,24,24-tetrakis(pyrrol-2-yl)-5β-cholane 1 , 3,3-bis(pyrrol-2-yl)-5β-cholan-24-oic acid 2 , and methyl 3,3-bis(pyrrol-2-yl)-5β-cholan-24-oate 3 , have been prepared from 3α-hydroxy-5β-cholan-24-oic acid (lithocholic acid) 4 in good overall yields. The structures of 1 – 3 have been fully characterized by 1 H, 13 C, PFG DQF 1 H– 1 H COSY, 1 H– 1 H ROESY, 13 C DEPT-135, PFG 1 H– 13 C HMQC, PFG 1 H– 13 C HMBC, and PFG 1 H– 15 N HMBC NMR spectra. Their molecular weights and compositions have been determined by ESI-TOF and EI mass spectra, and elemental analyses. The energetically optimised geometry and isotropic 13 C NMR chemical shifts of 3,3,24,24-te…