Cycloparaffinic solvents

Highly pure / -hexane can be produced by adsorption on molecular sieves (qv) (see Adsorption, liquid separation) (43). The pores admit normal paraffins but exclude isoparaffins, cycloparaffins, and aromatics. The normal paraffins are recovered by changing the temperature and/or pressure of the system or by elution with a Hquid that can be easily separated from / -hexane by distillation. Other than ben2ene, commercial hexanes also may contain small concentrations of olefins (qv) and compounds of sulfur, oxygen, and chlorine. These compounds caimot be tolerated in some chemical and solvent appHcations. In such cases, the commercial hexanes must be purified by hydrogenation. 

Products from catalytic reformers (the reformate) is a mixture of aromatics, paraffins and cycloparaffins ranging from Ce-Cg. The mixture has a high octane rating due to presence of a high percentage of aromatics and branched paraffins. Extraction of the mixture with a suitable solvent produces an aromatic-rich extract, which is further fractionated to separate the BTX components. Extraction and extractive distillation of reformate have been reviewed by Gentray and Kumar. 

In 1951, Titov and Shchitov [103] when examining the action of nitric anhydride on normal paraffins and cycloparaffins, found that in the presence of an inert solvent the reaction already started at 0°C, with the evolution of heat. Nitric acid esters were formed in the reaction which, according to the authors, proceeded through the following stages ... 

In the solution process, the reaction is carried out in the presence of an inert hydrocarbon which dissolves the polymer as it is formed. The solvent may contain a portion of cycloparaffin. Both monomer and polymer remain in solution during the reaction while the catalyst is maintained in suspension by agitation. Reaction temperatures range from about 125°-175°C. and reaction pressures from 20-30 atm. The reactor product is withdrawn, and monomer is flashed off and recycled. Suspended catalyst is then removed by filtration, and solvent is flashed from the filtrate with steam. 

Paraffinic and naphthenic (cycloparaffinic) stocks may be used for the formulation of lubricating oils, each with favorable characteristics for particular uses. Paraffinic stocks are generally preferred for their superior lubricating power and oxidation resistance. Naphthenic stocks, on the other hand, have naturally lower pour points, i.e, they maintain flow characteristics at lower pour-points than paraffinics (Table 18.8) and are better solvents, features which are more important for applications such as heat transfer, metal working, and fire-resistant hydraulic fluids [33]. Any residual aromatics in the lubricating base stock will have been removed before formulation by solvent extraction, using N-methylpyrrolidone, furfural, or less frequently today, phenol (Eq. 18.39). 

Chem. Descrip. Dearomatized aliphatic hydrocarbon CAS 6474249-0 EINECS/ELINCS 203-777-6 Uses Solvent for architectural coatings, OEM and auto refinish coatings, industrial metal and wood coatings, maintenance and marine coatings Properties Sp.gr. 0.75 (15.6/15.6 C) dens. 6.22 Ib/gal (60 F) vapor pressure 13 mm Hg (20C) b.p. 116-144C flash pt. (TCC) IOC surf. tens. 22.1 dynes/cm KB value 36 59% paraffi, 41 % cycloparaffin, 0.01 % aromatics... 

When comparing the oil yield factor alone, 3-methylpentane was rated the best. When comparing the solvents based on the empirical Quality-Efficiency Rating formula, they concluded that methylpentanes (3- and 2-methylpentane) were superior extraction solvents for cottonseed oil. The normal paraffins, highly-branched isohexanes, cycloparaffins, and aromatics were progressively rated as less efficient than methylpentanes. Therefore, they recommended a tailor-made solvent for the extraction of cottonseed should exclude aromatic hydrocarbons, have low limits on cycloparaffin content, and consist largely of normal and isoparaffin hydrocarbons. 

The aromatic content of hydrocarbon mixture is estimated from the determination of aniline point.Aromatic hydrocarbons have the lowest and paraffins the highest aniline points. Cycloparaffins and olefins are between the two. Aniline point increases as the molecular weight increases. A mixture of specific aniline and solvent is heated at a controlled rate until it forms one phase. The mixture is then cooled and the temperature at which the miscible liquid separates into two phases is determined. Four methods are discussed in the standard suitable for transparent, non-transparent, easily vaporizing, and measured in small quantities. 

Cycloparaffins - par-o-fon (1900) n. Ring compounds of saturated hydrocarbon type based on groupings of methylene radicals (CH2). Typical cycloparaffins are cyclopropane, cyclobutane, cyclopheptane. etc. The cycloparaffins have very good solvent properties, and are constituents of crude petroleum s. 

Ziegler-Natta catalysts are very sensitive to moisture, oxygen, and peroxides. As solvents for polymerization reactions, any compounds may be used provided they do not react with the catalysts and they do not cause their decomposition. For practical application, paraffins, cycloparaffins, and aromatic hydrocarbons are utilized. The choice of solvent depends on reaction conditions and the catalyst, on its availability in sufficient quantities, and on its sufficient purity. Usually, pressure from 0.1 to 3 MPa is utilized. Often, the concentration of monomers is low in the case of reactive olefins however, their polymerization is sometimes carried out utilizing the excess of the olefin as a solvent (only small amounts of alkanes are present and are used to introduce the catalyst). The temperature of the process varies from 170 to 470 K depending on utilized catalysts, the olefin, and the desired product. 

The dearomatized aliphatic hydrocarbons sold by Exxon under the trademark Exxsol are listed in Table 15.3. These solvents boil in the range of 159-316°C, have moderately high flash points, low surface tensions, low evaporation rates, and high (300 ppm) occupational exposure limits (OEL). The presence of high cycloparaffin (naphthene) content in the Exxsols improves its solvency for certain resins. 

Cycloaliphatic hydrocarbons are also referred as cycloparaffins or naphthenes. Most of their properties such as solvency, odor, and specific gravity are intermediate between those of aliphatic and aromatic hydrocarbon solvents. The use of cycloaliphatic solvents is less common in paint and coatings than that of paraffin hydrocarbons. 

Aliphatic Solvent n Hydrocarbon solvents comprised primarily of paraffinic and cycloparaffinic (naphthenic) hydrocarbon compounds. Aromatic hydrocarbon content may range from less than 1% to about 35%. 

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