Hydrocarbons chemical composition

Martmez-Checa, F., Toledo, F. L., El Mabrouki, K, Quesada, E. Calvo, C. (2007). Characteristics of bioemulsifer V2-7 synthesized in culture media added of hydrocarbons Chemical composition, emulsifying activity and rheological properties. Bioresour Technol, 98, 3130-3135. 

Wax usually refers to a substance that is a plastic solid at ambient temperature and that, on being subjected to moderately elevated temperatures, becomes a low viscosity hquid. Because it is plastic, wax usually deforms under pressure without the appHcation of heat. The chemical composition of waxes is complex all of the products have relatively wide molecular weight profiles, with the functionaUty ranging from products that contain mainly normal alkanes to those that are mixtures of hydrocarbons and reactive functional species. 

Most waxes are complex mixtures of molecules with different carbon lengths, stmctures, and functionaHty. Attempts to measure the exact chemical composition are extremely difficult, even for the vegetable waxes, which are based on a relatively few number of basic molecules. Products such as oxidised microcrystaHine wax not only have a mixture of hydrocarbon lengths and types as starting materials, but also add complexity through the introduction of various types of carboxyHc functionaHty onto those hydrocarbons during the oxidation process. 

Chemical Composition. Wool wax is a complex mixture of esters of water-soluble alcohols (168) and higher fatty acids (169) with a small proportion (ca 0.5%) of hydrocarbons (170). A substantial effort has been made to identify the various components, but results are compHcated by the fact that different workers use wool waxes from different sources and employ different analytical techniques. Nevertheless, significant progress has been made, and it is possible to give approximate percentages of the various components. The wool-wax acids (Table 9) are predominantiy alkanoic, a-hydroxy, and CO-hydroxy acids. Each group contains normal, iso, and anteiso series of various chain length, and nearly all the acids are saturated. 

Would you expect to find the same chemical composition of the hydrocarbons from the exhaust of a gasoline-powered automobile as that of gasoline in the vehicle s tank Why What would be the effect on emissions from a gasoline-powered vehicle if it was designed to be operated on leaded fuel and an unleaded fuel was used ... 

The performance of a novel microwave-induced pyrolysis process was evaluated by studying the degradation of HDPE and aluminiutn/polymer laminates in a semibatch bench-scale apparatus. The relationship between temperature, residence time of the pyrolytic products in the reactor, and the chemical composition of the hydrocarbon fraction produced was investigated. 28 refs. 

Optimizing the formulation of micellar surfactant solutions used for enhanced oil recovery consists of obtaining interfacial tensions as low as possible in multiphase systems, which can be achieved by mixing the injected solution with formation fluids. The solubilization of hydrocarbons by the micellar phases of such systems is linked directly to the interfacial efficiency of surfactants. Numerous research projects have shown that the amount of hydrocarbons solubilized by the surfactant is generally as great as the interfacial tension between the micellar phase and the hydrocarbons. The solubilization of crude oils depends strongly on their chemical composition [155]. 

Bonaga, G. and Giumanini, A. G. (1986). Chemical composition of chestnut honey Analysis of the hydrocarbon fraction. J. Apicult. Res. 25,113-120. 

A hard resinous thermoplastic substance of the same chemical composition as rubber hydrocarbon but having the ftvms-structure. See Cis-trans Isomerism. Formerly extensively used for the insulation of submarine cables (now superseded by polyethylene) and in the early manufacture of golf balls (now superseded by... 

The chemical composition of birch bark tar is dependent on the temperature at which tar is produced. In producing simulated tars in the laboratory for comparison with an adhesive used to repair a Roman jar from Stan wick, Charters et al. (1993) found that tars prepared at 350 °C displayed an increase in triterpenoid hydrocarbons as well as unresolved components presumably resulting from pyrolysis, although the precise nature of these molecules has not been elucidated. Binder et al. (1990) and Charters et al. (1993) also report the presence of allobetul-2-ene [Structure 7.24] in aged birch bark tars. Since this molecule has not been reported in extracts from fresh birch bark, it could be formed during heating to produce the tar (Regert et al., 2003). 

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 ... 

In micro PS a considerable number of silicon atoms are located at the inner surface, as shown in Table 6.1. Therefore, oxidation or absorption of hydrocarbons in the order of a monolayer will significantly change the chemical composition of the material. It is therefore essential for the comparison of chemical data if they have been obtained in situ, directly after preparation, or after longer storage peri-... 

In contrast to the other large cats, the urine of the cheetah, A. jubatus, is practically odorless to the human nose. An analysis of the organic material from cheetah urine showed that diglycerides, triglycerides, and free sterols are possibly present in the urine and that it contains some of the C2-C8 fatty acids [95], while aldehydes and ketones that are prominent in tiger and leopard urine [96] are absent from cheetah urine. A recent study [97] of the chemical composition of the urine of cheetah in their natural habitat and in captivity has shown that volatile hydrocarbons, aldehydes, saturated and unsaturated cyclic and acyclic ketones, carboxylic acids and short-chain ethers are compound classes represented in minute quantities by more than one member in the urine of this animal. Traces of 2-acetylfuran, acetaldehyde diethyl acetal, ethyl acetate, dimethyl sulfone, formanilide, and larger quantities of urea and elemental sulfur were also present in the urine of this animal. Sulfur was found in all the urine samples collected from male cheetah in captivity in South Africa and from wild cheetah in Namibia. Only one organosulfur compound, dimethyl disulfide, is present in the urine at such a low concentration that it is not detectable by humans [97]. 

Table 1. Typical hydrocarbon identifications structures are shown in Fig. 1) and chemical compositions (representative ...

The chemical composition of petroleum also varies over a wide range. A broad functional definition of petroleum hydrocarbons is that hydrocarbons are composed primarily of many organic compounds of natural origin and low water solubility. 

Petroleum is typically described in terms of its physical properties (such as density and pour point) and chemical composition (such as percent composition of various petroleum hydrocarbons, asphaltenes, and sulfur). Although very complex in makeup, crude can be broken down into four basic classes of petroleum hydrocarbons. Each class is distinguished on the basis of molecular composition. In addition, properties important for characterizing the behavior of petroleum and petroleum products when spilled into waterways or onto land and/or released into the air include flash point, density (read specific gravity and/or API gravity), viscosity, emulsion formation in waterways, and adhesion to soil. 

There are several hundred individnal hydrocarbon chemicals defined as petroleum based. Furthermore, each petroleum product has its own mix of constituents because (Chapter 2) petroleum varies in composition from one reservoir to another, and this variation may be reflected in the finished produces). 

Most investigations involving petrolenm hydrocarbons are regulated by various agencies that may require methodologies, action levels, and cleanup criteria that are different. Indeed, the complex chemical composition of petroleum and petroleum products can make it extremely difficult to select the most appropriate analytical test methods for evaluating environmental samples and to interpret and use the data accurately. 

As already noted, the chemical composition of petroleum and petroleum products is complex and may change over time following release into the environment. These factors make it essential that the most appropriate analytical methods are selected from a comprehensive hst of methods and techniques that are used for the analysis of environmental samples (Dean, 1998 Miller, 2000 Budde, 2001 Sunahara et al., 2002 Nelson, 2003 Smith and Cresset, 2003). But once a method is selected, it may not be the ultimate answer to solving the problem of identification and, hence, behavior (Patnaik, 2004). There are a significant number of petroleum hydrocarbon-affected sites, and evaluation and remediation of these sites may be difficult because of the complexity of the issues (analytical, scientific, and regulatory not to mention economic) regarding water and soil affected. 

Several hundred individual hydrocarbon chemicals defined as petroleum-based have been identified. Furthermore, each individual crude oil and each individual petroleum product has a specific mixture of the various constituents because of the variation in petroleum composition (Chapter 2), and this variation is reflected in the composition of the finished petroleum product. At this point it is worthy of note that the term petroleum hydrocarbons (PHC) is widely used to refer to the hydrogen- and carbon-containing compounds originating from crude oil, but petroleum hydrocarbons should be distinguished from total petroleum hydrocarbons because the term total petroleum hydrocarbons is specifically associated with environmental sampling and analytical results (Weisman, 1998 CFR, 2004). 

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