A gas electron diffraction and ab initio quantum-mechanical investigation into the molecular structure of tricyclo-(3.1.002,4)-hexane

The structure of tricyclo-(3.1.00^2,4)exane has been determined by gas phase electron diffraction. The molecule has an inversion centre. The mean carbon—carbon bond length, averaged over both three- and four-membered rings is 1.508 A. A model with equal C-C bond lengths fits to the measured diffraction intensities. The four-membered ring is planar with valency angles of 90°, while the carbon atoms of the three-membered rings form isosceles triangles. Ab initio quantum mechanical calculations at the STO-3G level support this geometry. The valency angle CCC (between three- and four-membered rings) for the equilateral four-membered ring model has been found experimentally to be 109.9°. The average C-H bond distance (1.080 Å) is small as a result of increased s-character in these bonds in agreement with reported INDO—LMO calculations.     

Semiclassical statistical mechanics of two-dimensional hard-body fluids

The problem of calculating the thermodynamic properties of two-dimensional semiclassical hard-body fluids is studied. Explicit expressions are given for the first-order quantum corrections to the free energy, equation of state, and virial coefficients. The numerical results are calculated for the planar hard dumbbell fluid. Significant features are the increase in quantum corrections with increasing eta and increasing L*=L/sigma(0).     

Flavonoids ofGnaphalium uliginosum

The herb low cudweed has yielded for the first time a new acylated flavone glycoside, for which the structure of 3,4,5,7-tetrahydroxy-6-methoxyflavone 7-O-(6-O-caffeyl--D-glucopyranoside) has been established. In addition, 6-methoxyluteolin, 6-hydroxyluteolin 7-O--D-glucopyranoside, and scutellarein 7-O--D-glucopyranoside have been isolated. Identification was made on the basis of UV, IR, PMR, and mass spectra, the products of alkaline and acid hydrolyses, and the results of elementary analyses, melting points, and specific rotations.Vitebsk State Medical Institute, All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 483–487, July–August, 1979.     

A supersonic beam ion cyclotron resonance instrument for the study of van der Waals cluster ions

For the study of ionized van der Waals cluster ions an instrument is presented, which consists of a supersonic beam cluster source coupled to an ICR spectrometer with external ion source. The neutral van der Waals clusters are generated by supersonic expansion and ionized by electron impact in the external source. The cluster ions are extracted at right angle to the neutral cluster beam and fly collision-free parallel to the magnetic field direction into the differentially pumped ICR cell. For the ion transfer, an improved lens system is presented. The cluster ion transfer lens system is capable of focusing ions with energies of a few eV perpendicular to the magnetic field direction through the differential pumping orifice. The ions are injected into the ICR cell with a trap barrier pulse, ion accumulation is possible. With this system the first ICR spectra of small cluster ions of carbon dioxide are obtained.     

Influence of wilt infection on the gossypol pigments of seeds and roots of a cotton plant of the variety Tashkent-1

A study has been made of the gossypol pigments of the seeds and roots of a cotton plant of the variety Tashkent-1 infected with wilt in comparison with a healthy plant. The amount of gossypol in the infected plant was lower than in the healthy plant. In the diseased plant, gossypurpurin was concentrated in the roots, and in the healthy plant it was concentrated in the seeds. Gossypol possessing optical activity was detected in the seeds and roots of both the healthy and the diseased plants.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 63–66, January–February, 1989.     

Reaction of 2-substituted 4,4-dimethyl-5-methylene-1,3-dioxolanes with dichlorocarbene and certain transformations of adducts obtained

A series of derivatives of 4,4-dimethyl-5-methylene-1,3-dioxolane has been synthesized, and their reaction with dichlorocarbene, obtained under interphase catalysis conditions, has been studied. The adducts obtained undergo thermal isomerization into dichloroethylidene derivatives.     

Thermal decomposition of dicyclopentadienylarylvanadium compounds

The thermolysis of compounds of the type Cp₂VR (R = aryl) in the solid state has been studied. A distinct increase in thermal stability is observed upon substitution of the ortho-position of the aryl group. Thermal decomposition occurs with formation of RH, Cp₂ V, a vanadocene homologue with the group R substituted in one of the Cp rings and, probably, a vanadocene homologue with two substituted Cp rings. It is shown that the abstraction of the hydrogen atom from the cyclopentadienyl ring, necessary for the formation of RH, is an intermolecular process, whereas the substitution of the aryl group in the Cp ring is intramolecular. A decomposition mechanism is proposed in which the group R is transferred from the vanadium atom to the C₅H₅ ring of the same molecule by interaction with an aryl group of another molecule. The thermal decomposition of Cp₂VR is compared with that of the analogous titanium compounds.     

Synthetic and modified isoflavonoids XVII. Interaction of synthetic analogs of isoflavones with guanidine

Under the influence of guanidine, 1,3-benzodioxolane, 1,4-benzodioxane, and 1,5-benzodioxepane analogs of isoflavone are converted into 2-aminopyrimidine derivativesTranslated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 636–640, September–October, 1994.     

Nitration of 5-formyl-substituted 2-cyclopropylfurans and 2-methylfurans and the corresponding thiophenes

In the nitration of 5-formyl-substituted 2-cyclopropylfurans and the corresponding thiophenes, in addition to the formation of the corresponding 3-nitro derivative the replacement of the formyl group by a nitro group takes place. For a thiophene derivative the latter direction of the reaction is observed to a substantially smaller degree. Under nitration conditions, 5-formylsylvane is converted only into 5-nitrosylvane, while the corresponding formylmethylthiophene is nitrated exclusively in position 3. The difference observed in the behavior on nitration of the furans and thiophenes studied is explained by the different degrees of participation of the heteroatom in the delocalization of the charges in the heterocyclic ipso-ions formed as intermediates.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 455–460, April, 1980.