The use of metastable ion characteristics for the determination of ion structures of some isomeric cannabinoids

The mechanism of formation of the prominent C₁₅H₁₉O₂ ion at m/e 231 in the mass spectra of Δ¹⁽⁶⁾-tetrahydrocannabinol and five isomeric cannabinoids has been investigated. Except via a well-documented two step process, involving an RDA mechanism, a sizeable percentage of these ions is formed by a novel one-step route from the molecular ion. This was deduced from the spectra of deuterium-labelled compounds and measurements of the kinetic energy release of metastable ions. The latter value for the one step process varies from 25–44 meV for the six compounds investigated, attributed to two interdependent effects, different transition state geometries and common transition states differing in the time elapsing before their formation.     

Thermal homolytic fission of the MoMo bond in (h5 -C5H5)2Mo2(CO)6

Kinetic studies of reactions of the MoMo bonded complex (h⁵-C₅H₅)₂Mo₂(CO)₆ in decalin show that it undergoes reversible homolytic fission and that the activation enthalpy required to break the MoMo bond is 135.9 ± 2.2 kJ mol^?1.     

Purification of human chorionic gonadotropin hormone by anion-exchange high-performance liquid chromatography

Chromatographia - A high-performance liquid chromatography (HPLC) method was developed for the purification of 50mg crude human chorionic gonadotropin (HCG) hormone sample in one chromatographic...     

Ein neuer Zugang zum tetracyclischen Grundgerüst des Cyclohepta (def)fluorens

A New Synthetic Way to the Tetracyclic Skeleton of Cyclohepta (def)fluorene The synthesis of 2-Methyl-4, 5, 6, 8, 9, 10-hexahydrocyclohepta (def)fluorene 2 is described starting with the reduction of the ketone 3 by a (1:1)-mixture of LiAlH₄/AlCl₃ to the hydrocarbon 4 . After metallation with butyllithium 4 was allowed to react with bromoacetic acid to yield 5 . The cyclization of this compound was performed with p-toluenesulfonic acid to give the tetracyclic ketone 6 which was converted to the tetracyclic hydrocarbon 2 by reduction with LiAlH₄/AlCl₃.     

Allylnadic-imides: A new class of heat-resistant thermosets

Allyl-bicyclo-(2,2,1)hept-5-en-dicarboxylic(2,3)imides (allylnadic-imides) are prepared by heating equivalent amounts of allylnadic anhydride and amines. Mixtures of isomers (1-allyl-endo, 6-allyl-endo and exo) were obtained, separated by flash chromatography and identified by ¹H- and ¹³C-NMR. A series of novel allylnadic-imide monomers is described. Upon heating to 250°C oligomers are obtained. Diels—Aider rearrangement and “ene” type addition reactions seem to play a major role in oligomer formation. Bis- and tris-allylnadic-imides are viscous liquids resins or low melting solids, which are soluble in common solvents. Upon heating to 250°C insoluble, high T_g solids are obtained with good thermooxidative and environmental stability and with reduced burning rate. Cured allylnadic-imide resins are excellent high temperature insulators and low permittivity dielectrics. Crosslinked copolymers with maleic-imides and epoxy resins are described. Neat resin and carbon fiber composite properties are reported.     

Structural aspects of polyimides. I. Polymerization and degradation of endo-N-phenylnadimide and endo-N-isobutylnadimide

The isomerization, polymerization, and degradation aspects of endo-N-phenylnadimide and endo-N-isobutylnadimide (NPNI-N and NIBNI-N) were investigated using infrared analysis (IR), differential thermal analysis (DTA), gel permeation chromatography (GPC), thermogravimetric analysis (TG), and capillary gas chromatography-mass spectroscopic (GC–MS) techniques. Although the endotherm related to the retro-Diels–Alder reaction is not registered in the DTA thermographs, on-line mass spectrometric studies revealed the occurrence of this process. The formation of the Diels–Alder adduct of cyclopentadiene with N-isobutylnadimide (NIBNI) during the polymerization of NIBNI-N is proved. GPC studies on NPNI-N and NIBNI-N cured at 300°C for 3.0 h showed the average degree of polymerization to be three to four. The polymers obtained by curing NPNI-N and NIBNI-N at 300°C for 3.0 h showed 109.8 kJ/mol as the activation energy for degradation. The dynamic and isothermal pyrolysis studies clearly indicated the presence of intact norbornyl units in the polymer, and the breakage of ? CH₂? bridges in the strained norbornyl structural elements was found to be the point of aromatization during degradation.     

QCD corrections to charm quark production in deep-inelastic neutrino scattering

We evaluate theO(_s) corrections to weak, charged current production of charm quarks. For perturbative subtractions and parton densities in the deep inelastic scheme the residual corrections to p and charm production structure functionsF ₂,F ₃ andF _L are presented. The consequences of these corrections with respect to they dependence of the cross section is discussed.Supported by Bundesministerium für Forschung und Technologie. 05 5HH91P (8), Bonn, FRG