Cycloparaffins

Abstract: Summary A detailed account is given of a quantum-mechanical treatment of the lower cycloparaffins, cyclobutadiene and ethylene. It is found that strained bonds (in the original sense of Baeyer) are to be described as bent. Strain energies comparable with those derived from thermochemical data are calculated; the properties of strained systems are discussed; and, in particular, a detailed description of the bonds in cyclopropane is given. The stability of cyclobutadiene has been considered with respect to that of the related molecules benzene, cyclooctatetraene and diphenylene; and hybridization in ethylene has been re-examined. The pairing approximation is used throughout, but an Appendix is added, in which the molecular orbital method is applied qualitatively to cyclopropane.

Abstract: The photoelectron spectra of 67 organic compounds, including paraffins, cycloparaffins, olefines, dienes, aromatic hydrocarbons, alcohols, ethers, aldehydes, ketones, and diene iron tricarbonyl complexes, have been measured, using a simple retarding‐potential grid‐type spectrometer, and the results interpreted in terms of a recently developed semiempirical SCF MO treatment (MINDO approximation). The observed ionization potentials show a remarkably close relationship to the calculated Hartree–Fock MO energies over the whole range of ionization potentials (<20 eV) studied. An estimate is given for the first ionization potential of cyclobutadiene.

Abstract: Crude oil, shale oil, and sand oil are all sources of petroleum and contain hundreds of compounds whose components can be grouped into four main classes such as (1) saturates (alkanes and cycloparaffins), (2) aromatics (mono-, di-, and polynuclear aromatic hydrocarbons (PAHs) with alkyl side chains), (3) resins (aggregates with a multitude of building blocks such as sulfoxides, amides, thiophenes, pyridines, quinolines, and carbazoles), and (4) asphaltenes (aggregates of extended polyaromatics, naphthenic acids, sulfides, polyhydric phenols, fatty acids, and metalloporhyrins). The latter two classes contain many species that are nonvolatile and are therefore difficult to analyze. Currently, most analyses of petroleum compounds determine species with no more than six fused rings, a paucity of polar groups, and a molecular mass of less than 600. The volatility and stability of the compounds determine whether they are amenable to analysis using standard gas chromatography/mass spectrometry (GC/MS). Hence, to...

Abstract: The heats of combustion, melting points, heats of fusion, boiling points, refractive indices and in four cases the densities have been determined on selected samples of the cyclanes with 4 to 9 C-atoms; some hitherto unknown transition points were discovered and the heats of transition measured. The heats of vaporisation at 25° are estimated. Results of the measurements are discussed.