Hydrocarbons structures

A petrochemical is a chemical compound or element recovered from petroleum or natural gas, or derived in whole or in part from petroleum or natural gas hydrocarbons, and intended for chemical markets. 

Hydrocarbons in general are simply compounds of hydrogen and carbon that can be characterized based on their respective chemical composition and structure. Each carbon atom can essentially bond with four hydrogen atoms. Methane is the simplest hydrocarbon, as illustrated below  

Each dash represents a chemical bond of which the carbon atom has four and each hydrogen atom one. 

More complex forms of methane can be developed by adhering to the simple rule that a single bond exists between adjacent carbon atoms and that the rest of the 

FIGURE 4.1 Ternary diagram showing representative crude oils and their respective composition in respect to paraffins, naphthenes, and aromatics. Note the clustering of the California crudes toward the naphthenes and the Oklahoma crudes toward the paraffins. 

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Microbumer Studies of Flame Radiation as Related to Hydrocarbon Structure, Report 3752-64R, Navy Buweps Contract NOw 63-0406d, Phillips Petroleum Co., Bartiesville, OHa., May 1964. 

If required by the model(s) to be used, back-up data for each entry in the matrix or table may be supplied to resolve the total mass flow into spatial cells (UTM coordinates, depth or height), temporal cells (hourly frequency distributions, diurnal cycles, seasonal subdivisions or secular trends on annual intervals) or speciation cells (by valency state of anions or by hydrocarbon structure, for example). The level of difficulty encountered by the user in supplying these data may influence the choice of model(s). 

The spectroscopic evidence indicates that the catalyst concentration had very little effect on the "gross" hydrocarbon structure present and this is substantiated by the H/C atomic ratios of the oils which showed no significant change with catalyst concentration. 

It would appear that increasing the amount of stannous chloride catalyst, under our experimental conditions, as well as increasing the amount of oil formed decreases the amount of polar compounds in the oil which decreases the hydrogen bonding and therefore helps to decrease the viscosity of the oil. Spectroscopic evidence indicates that there is little change in the hydrocarbon structures present. 

The heteroatom content and viscosity are reduced while the gross hydrocarbon structure is little changed. However, for economic reasons high catalyst concentrations are unlikely to be used. 

In discussing the way in which hydrogenolysis occurs, it needs to be recognized at the outset that more than one reaction pathway is possible, and their relative importance depends both on hydrocarbon structure and on the nature of the catalyst. 

Intramolecular Friedel-Crafts reactions can sometimes compete with organosil-icon hydride reductions of benzylic-type alcohols to cause formation of undesired products. An example is the attempted reduction of alcohol 26 to the corresponding hydrocarbon. When 26 is treated with triethylsilane in trifluoroacetic acid at room temperature for 15 hours, a mixture of the two fluorene isomers 27 and 28 is obtained in a combined yield of 45%. None of the hydrocarbon structurally related to the substrate alcohol 26 is obtained.171 Whether this problem could be circumvented by running the reduction at a lower temperature or with a different acid remains subject to experimentation. 

McCarthy, J.F., Jimenez, B.D., Barbee, T. (1985) Effect of dissolved humic material on accumulation of polycyclic aromatic hydrocarbons structure-activity relationships. Aqua. Toxicol. 7, 15-24. 

Most plastics react chemically with chlorine because of their hydrocarbon structural makeup. This reactivity is avoided with some plastics in which fluorine atoms nave been substituted into the hydrocarbon molecule. The Chlorine Institute recommends that hoses constructed with such an inner lining "have a structural layer braid of polyvinyli-dene fluoride (PVDF) monofilament material or a structural braid of Hastelloy C-276. An underlying lesson here is material compatibility. Material compatibility tables exist that engineers can consult, including in other sections within this volume. 

Crebelli, R., Andreoli, C., Carere, A., Conti, L., Crochi, B., Cotta-Ramusino, M., Benigni, R. Toxicology of halogenated aliphatic hydrocarbons Structural and molecular determinants for the disturbance of chromosome segregation and the induction of lipid peroxidation. Chem. Biol. Interact. 1995, 98, 113-129. 

The composition of crude oil may vary with the location and age of an oil field, and may even be depth dependent within an individual well or reservoir. Crudes are commonly classified according to their respective distillation residue, which reflects the relative contents of three basic hydrocarbon structural types paraffins, naphthenes, and aromatics. About 85% of all crude oils can be classified as either asphalt based, paraffin based, or mixed based. Asphalt-based crudes contain little paraffin wax and an asphaltic residue (predominantly condensed aromatics). Sulfur, oxygen, and nitrogen contents are often relatively higher in asphalt-based crude in comparison with paraffin-based crudes, which contain little to no asphaltic materials. Mixed-based crude contains considerable amounts of both wax and asphalt. Representative crude oils and their respective composition in respect to paraffins, naphthenes, and aromatics are shown in Figure 4.1. 

Sovadinova, I., Blaha, L., Janosek, J., Hilscherova, K., Giesy, J.P., Jones, P.D. and Holoubek, I. (2006) Cytotoxicity and aryl hydrocarbon receptor-mediated activity of N-heterocydic polycyclic aromatic hydrocarbons structure-activity relationships. Environmental Toxicology and Chemistry, 25, 1291-1297. 

In later studies by various groups, the enyneallene motif was incorporated into more complex hydrocarbon structures, allowing not only a better understanding of the Myers cyclization but also the generation of polycyclic hydrocarbons, some of them resembling the steroid core unit. Conceptually, these latter cyclizations are reminiscent of Johnson s biomimetic cyclization reactions with the main difference that here radical intermediates are involved rather than carbocations. Typical starting materials in these studies are the allenes 221 [87], 222 [88] and 223 [89], their cyclization behavior being discussed in Chapter 20. 

From your previous studies of solubility, you might hypothesize that lipid molecules must have large hydrocarbon parts, since they are soluble in hydrocarbon solvents. Your hypothesis would be correct. Lipids contain large hydrocarbon chains, or other large hydrocarbon structures. 

Sander, L.C. and Wise, S.A., Polycyclic Aromatic Hydrocarbon Structure Index, Natl. Inst. Stand. Technol. Spec. Publ. 922. U.S. Government Printing Office, Washington, 1997. 

If one or more of the hydrogen atoms of a non-metal hydride are replaced formally with another group, R—e.g., alkyl residues—then derived compounds of the type R-XHn-i, R-XHn-2-R, etc., are obtained. In this way, alcohols (R-OH) and ethers (R-O-R) are derived from water (H2O) primary amines (R-NH2), secondary amines (R-NH-R) and tertiary amines (R-N-R R") amines are obtained from ammonia (NH3) and thiols (R-SH) and thioethers (R-S-R ) arise from hydrogen sulfide (H2S). Polar groups such as -OH and -NH2 are found as substituents in many organic compounds. As such groups are much more reactive than the hydrocarbon structures to which they are attached, they are referred to as functional groups. 

Water is an excellent solvent for ions and for substances that contain polarized bonds (see p.20). Substances of this type are referred to as polar or hydrophilic ( water-loving ). In contrast, substances that consist mainly of hydrocarbon structures dissolve only poorly in water. Such substances are said to be apolar or hydrophobic. 

Polymeric materials that act as fuels and oxidizers are composed of nitrogen, oxygen, carbon, and hydrogen atoms. The hydrocarbon structures act as fuel components, and the oxidizer fragments, such as -C-NOj, -O-NOj, -O-NO, or -N-NO2, are attached to the hydrocarbon structures through covalent chemical bonds. 

NC is an energetic nitropolymer consisting of a hydrocarbon structure with -O-NO2 bonds as oxidizer fragments. In general, NC is produced from the cellulose, C6H702(0H)3 j of cotton or wood, which is nitrated using nitric acid (HNO3) to introduce -O-NO2 bonds into its structure. 

Inert polymers are classified according to their chemical bond structures. Figure 4.4 shows typical basic polymer units and bond structures.Pil These polymers are based on hydrocarbon structures that have relatively low viscosities during... 

Molecules in which fuel and oxidizer components are chemically bonded within the same structure are suitably predisposed for the formulation of energetic materials. Nitropolymers are composed of O-NO2 groups and a hydrocarbon structure. The bond breakage of O-NO2 produces gaseous NO2, which acts as an oxidizer fragment, and the remaining hydrocarbon structure acts as a fuel fragment. NC is a typical nitropolymer used as a major component of propellants. The propellants composed of NC are termed nitropolymer propellants . 

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