Fused Ring Compounds Research Articles

Studies on 5-8 Fused Ring Compounds. I. Halogenation of 4,4-Dimethylbicyclo[6.3.0]undecane-2,6-dione

Abstract Bromination and chlorination of 4,4-dimethylbicyclo[6.3.0]undecane-2,6-dione (2) with pyridinium bromide perbromide and sulfuryl chloride gave several α-halo-diones. The substituted positions and the stereochemistry of the halogen atoms have been assigned on the basis of their dehydrohalogenation and spectral data. The chlorination of 2 also gave a tricyclic dione (8) containing a cyclopropane ring. The structure of 8 was determined by means of 13C-NMR, as well as other types of spectroscopy. Dehydrochlorination of 7 gave a 5H-benzocyclo-heptene derivative (18).

The pseudorotation of cycloheptane—I

The pseudorotation of cycloheptane is described by means of the Fourier expansion of the endocyclic torsion angle ω i = A sin φ j + B sin 3φ j + C sin 5φ j + D sin 7φ j; φ j = Δ/2 + 2πj/7; j = 0, 1,...,6; i = 2j + 4, mod 7 and Δ being a phase angle. The topography of the pseudorotational itineries for the chair/twist-chair and the boat/twist-boat families is discussed. X-ray diffraction data concerning the geometry of 7-membered rings occurring in fused ring compounds are analysed by means of the proposed relationship. The least squares procedure for evaluation of the parameters A, B, C and D is given in an appendix. The calcium salt of cycloheptane car☐ylic acid, (C 7H 13·COO) 2Ca·5H 2O in solid state, displays disorder closely related to pseudorotation. Preliminary X-ray diffraction data of this structure (to be published elsewhere) are given.

A structural investigation of the constituents of Athabasca bitumen by proton magnetic resonance spectroscopy

A structural investigation has been made of the constituents of the Athabasca bitumen by proton magnetic resonance spectroscopy. The chemical structures within the bitumen are expressed in terms of carbon-type distribution which is derived from proton distribution, elemental analyses, and molecular weight data. An estimate has been made of the structure of the aromatics within the fractions by determining the peripheral and internal aromatic carbon atoms and relating ratios of peripheral aromatic carbons to total aromatic carbons to those of known fused ring compounds.

Electron-Impact Studies of Aromatic Hydrocarbons. II. Naphthacene, Naphthaphene, Chrysene, Triphenylene, and Pyrene

The systematic survey of ionization-dissociation processes of fused-ring aromatic compounds initiated previously is continued. Mass spectra and appearance potentials of the singly and doubly charged molecule ions are reported. The observed ionization energies of naphthacene (6.95 eV), naphthaphene (7.53 eV), chrysene (8.01 eV), triphenylene (8.19 eV), and pyrene (7.72 eV) are compared with available spectroscopic data, with values obtained from molecular orbital calculations, with the available empirical and semiempirical methods, and with other electron-impact data.

Effect of Pressure on the Resistance of Fused-Ring Aromatic Compounds

The effect of pressure to several hundred kilobars has been measured on the resistance of seven-fused ring aromatic compounds, including two polyacenes and five quinones. In general, there is a rapid drop in resistance at lower pressures, followed by a marked leveling at above 200–250 kbars. The leveling is apparently associated with the rapid decrease in compressibility at high pressure observed by Bridgman. The resistance at high pressure varied by several orders of magnitude among the compounds. It seems to be closely associated with the amount of overlap between adjacent molecules in the unit cell. The temperature coefficient of resistance at high pressure was obtained for three compounds. They all remained semiconductors at the highest pressure studied, but the activation energy was about one-sixth of the atmospheric pressure value.

Synthetic Investigations on Fused-ring Compounds. Part I. Synthesis of cis-β-Decalone and α-Methyl-cis-β-decalone

Synthetic Investigations on Fused-ring Compounds. Part I. Synthesis of cis-β-Decalone and α-Methyl-cis-β-decalone

Electron Impact Studies of Aromatic Hydrocarbons. I. Benzene, Naphthalene, Anthracene, and Phenanthrene

A systematic survey of ionization-dissociation processes of fused-ring aromatic compounds is initiated. Mass spectra and appearance potentials of the singly and doubly charged molecule ions are reported. The observed ionization potentials of benzene (9.38 ev), naphthalene (8.26 ev), anthracene (7.55 ev), and phenanthrene (8.03 ev) are compared with available spectroscopic data, with values obtained from molecular orbital calculations, and with other electron impact data. The empirical method of group equivalents is extended to the calculation of the ionization potentials of the fused-ring aromatic compounds.

Study of the Compressions of Several High Molecular Weight Hydrocarbons

Isothermal compressions were measured for thirteen high-purity liquid hydrocarbons and two binary mixtures of liquid hydrocarbons. These hydrocarbons have a molecular weight range of 170 to 351 and included normal paraffins, cycloparaffins, aromatics, and fused ring compounds. The pressure range for these measurements was from atmospheric to as high as 10 000 bars, being limited to lower values for some compounds to avoid possible solidification of the liquid. The volume changes due to pressure were measured at six temperatures spaced about equally in the range 37.8°C to 135.0°C. The volume changes and pressures were measured by methods similar to those of P. W. Bridgman. Pressure-volume isotherms can be described adequately by the Tait equation, v0—v=C log(1+P/B), or for pressures above a certain minimum, whose value depends on the compound, by the Hudleston equation log[v2/3P/(v01/3−v1/3)]=A+B(v01/3−v1/3).For the Tait equation the parameter C can be predicted for hydrocarbon liquids from the relation C=0.2058 v0. Compressibility for a given hydrocarbon decreases with increasing pressure at constant temperature and increases with increasing temperature at constant pressure. The compression, and the compressibility, of liquid hydrocarbons are strongly dependent on molecular structure. Cyclization introduces a rigidity of molecular shape which decreases the compressibility markedly. Furthermore, fused ring cyclization as exemplified by naphthyl and decalyl structures has a considerably greater effect in decreasing compressibility than cyclization to nonfused rings such as cyclopentyl, cyclohexyl, or phenyl, even at equivalent carbon atom in ring percentages. Isobars and isochores were drawn and studied over the full range of temperature and pressure. The coefficient of thermal expansion, (1/v0) (δv/δT) P, for a given hydrocarbon, decreases with increasing pressure at constant temperature. (δ2v/δT2) P undergoes a sign change at a certain pressure, whose value depends on the compound; (δv/δT) P increases with increasing temperature below this pressure and decreases with increasing temperature above this pressure. The pressure coefficient, (δP/δT) v, is not a function of volume alone but is also dependent on the temperature and pressure. (δE/δv) T and (δE/δP) T go to zero and then reverse sign for compounds that can be studied to sufficiently high pressures.

Hydrolysis of methylethoxydisilylmethanes

AbstractHydrolysis of monomers of the type (I) should give polymers with the skeleton SiCSiO, which might possess better properties than siloxanes. The monomers were prepared by the action of methylmagnesium bromide on hexaethoxydisilylmethane. From mono‐ up to pentamethylethoxydisilylmethanes were obtained, the symmetrically substituted and even‐numbered methyl compounds being obtained in preferential yields.Hydrolysis of these five monomers gave interesting results. The strong tendency of ring formation reduced their functionality and thus gave less chance to form crosslinks. While pentamethylmonoethoxydisilylmethane gave the normal product (II), tetramethyldiethoxydisilylmethane gave a ring dimer (III), which, although closely analogous to cyclosiloxane D4, resisted all attempts at ring opening to give a linear polymer. The trifunctional trimethyl compound gave an oil of the type (IV), consisting of rings connected into a chain by oxygen atoms. Dimethyltetraethoxydisilylmethane, although tetrafunctional, gave, on hydrolysis, a highly crystalline compound with a cage structure (V). Only the pentafunctional monomer, monomethylpentaethoxydisilylmethane, gave an insoluble infusible powder of high stability.Co‐hydrolysis of the monomers gave fused ring compounds; dimethyltetraethoxydisilylmethane and tetramethyldiethoxydisilylmethane, when hydrolyzed together, gave a compound of formula (VI). magnified image