Paraffin hydrocarbons, chain

The majority of secondary plasticizers ia use are chlotinated paraffins, which are hydrocarbons chlotinated to a level of 30—70%. Eor a given hydrocarbon chain, viscosity iacreases with chlorine content, as does the fire retardancy imparted to the formulation. These materials aid fire retardancy due to thein chlorine content. Chlotinated paraffins of the same chlorine content may, however, have different volatiHties and viscosities if they are based on different hydrocarbon chaias (see Cm OROCARBONS and cm OROHYDROCARBONS, cm.ORiNATDD paraffins). 

Catalytic Oxidation for Straight-Chain Paraffinic Hydrocarbons. Synthetic fatty acids (SFA) are produced by Eastern European countries, Russia, and China using a manganese-catalyzed oxidation of selected paraffinic streams. The technology is based on German developments that were in use during World War II. The production volume in 1984 was estimated to be about 5.5 x ICf t/yr. The oxidation is highly exothermic and is carried out at about 105—125°C, mostly in continuous equipment. 

Paraffins are relatively inactive compared to olefins, diolefins, and aromatics. Few chemicals could be obtained from the direct reaction of paraffins with other reagents. However, these compounds are the precursors for olefins through cracking processes. The C -Cg paraffins and cycloparaffms are especially important for the production of aromatics through reforming. This section reviews some of the physical and chemical properties of C1-C4 paraffins. Long-chain paraffins normally present as mixtures with other hydrocarbon types in different petroleum fractions are discussed later in this chapter. 

More often than what has been mentioned above regarding the cyclization of paraffins over the platinum catalyst, the formed olefin species reacts with the acid catalyst forming a carbocation. Carbocation formation may occur by abstraction of a hydride ion from any position along the hydrocarbon chain. However, if the carbocation intermediate has the right configuration, cyclization occurs. For example, cyclization of 1-heptene over the alumina catalyst can occur by the following successive steps ... 

The paraffin hydrocarbon containing four carbon atoms is called butane, but two 4-carbon (C4) paraffins are possible. The butane with its carbons in a line is known as normal butane or n-butane. The branched chain butane is isobutane or i-butane. Although each compound has the formula C4H10, they have different properties for example, n-butane boils at -0.5°C while isobutane boils at -11.7°C. n-Butane and i-butane are isomers of each other. The straight-chain paraffin is always called the normal form. 

It has been generally accepted that the thermal decomposition of paraffinic hydrocarbons proceeds via a free radical chain mechanism [2], In order to explain the different product distributions obtained in terms of experimental conditions (temperature, pressure), two mechanisms were proposed. The first one was by Kossiakoff and Rice [3], This R-K model comes from the studies of low molecular weight alkanes at high temperature (> 600 °C) and atmospheric pressure. In these conditions, the unimolecular reactions are favoured. The alkyl radicals undergo successive decomposition by [3-scission, the main primary products are methane, ethane and 1-alkenes [4], The second one was proposed by Fabuss, Smith and Satterfield [5]. It is adapted to low temperature (< 450 °C) but high pressure (> 100 bar). In this case, the bimolecular reactions are favoured (radical addition, hydrogen abstraction). Thus, an equimolar distribution ofn-alkanes and 1-alkenes is obtained. 

Fischer-Tropsch synthesis can be regarded as a surface polymerization reaction since monomer units are produced from the reagents hydrogen and carbon monoxide in situ on the surface of the catalyst. Hence, a variety of hydrocarbons (mainly n-paraffines) are formed from hydrogen and carbon monoxide by successive addition of C, units to hydrocarbon chains on the catalyst surface (Equation 12.1). Additionally, carbon dioxide (Equation 12.3) and steam (Equations 12.1 and 12.2) are produced C02 affects the reaction just a little, whereas H20 shows a strong inhibiting effect on the reaction rate when iron catalysts are used. 

Franks, F. (1966) Solute-water interactions and the solubility behaviour of long-chain paraffin hydrocarbons. Nature 210, 87-88. 

For maximum yield of liquid hydrocarbons and minimum yield of gases, FT synthesis is optimised to produce predominantly heavy products (heavy paraffins),7 i.e., producing hydrocarbon chains as long as possible at maximum hydrocarbon chain growth probability. 

Cycloparaffins naphthenes), saturated hydrocarbons containing one or more rings, each of which may have one or more paraffinic side chains (more correctly known as alley die hydrocarbons). 

Aromatics, hydrocarbons containing one or more aromatic nuclei, such as benzene, naphthalene, or phenanthrene ring systems, that may be linked up with (substituted) naphthalene rings and/or paraffinic side chains. 

Catalytic dewaxing, in which straight-chain paraffin hydrocarbons are selectively cracked on zeolite-type catalysts, and the lower-boiling reaction products are separated from the dewaxed lubricating oil by fractionation. 

Isomerization the conversion of a normal (straight-chain) paraffin hydrocarbon into an iso (branched-chain) paraffin hydrocarbon having the same atomic composition. 

Furthermore from the computed area of the cross-section of the interface occupied by one soap molecule it is clear that the molecules of the soap are relatively close together and orientated in a plane at right angles to the interface. As has already been noted in the case of the air-water interface the fatty acids are orientated with their polar carboxyl groups in the water phase we would consequently anticipate that in the oil-water interface the same orientation would occur, the hydrocarbon chain being immersed in the paraffin phase and the polar —OOONa or —COOK group in the aqueous phase. Such orientation is an important factor in the... 

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