Low boiling aromatics

Industrial polymerisation processes with the use of titanium-, cobalt- and nickel-based aluminium alkyl-activated Ziegler-Natta catalysts, which are employed for the manufacture of cis- 1,4-poly butadiene, involve a solution polymerisation in low-boiling aromatic hydrocarbons such as toluene or in a mixture of aromatic and aliphatic hydrocarbons such as n-heptane or cyclohexane. The polymerisation is carried out in an anhydrous hydrocarbon solvent system. The proper ratio of butadiene monomer and solvent is blended and then completely dried in the tower, followed by molecular sieves. The alkyla-luminium activator is added, the mixture is agitated and then the transition metal precatalyst is introduced. This blend then passes through a series of reactors in a cascade system in which highly exothermic polymerisation occurs. Therefore, the reaction vessels are cooled to slightly below room temperature. 

A direct pyrolysis-gas chromatography of the kerogens was also performed and is presented in Figure 7 (9). The chromatograms taken at pyrolysis temperature of 475°C show the total distribution of hydrocarbons, with the relative importance of long-chain molecules up to C30 in types I and III. It also shows the importance of low-boiling aromatics (B benzene T toluene ... 

Although a major advantage of epoxy adhesives is their ability to be formulated without solvents, under certain circumstances solvents may be included. On porous substrates solvents may be added to reduce viscosity and assist penetration. On certain nonporous substrates, particularly some plastics, addition of a small percentage (1 to 3%) of a suitable solvent will improve adhesion. Common solvents are low-boiling aromatic solvents, ketones, or esters. 

Some light, low boiling aromatic hydrocarbon solvents are used with epoxy resins to obtain fluidity. These aromatics are of assistance during the application of thin films. The solvent volatilizes during cure and has no effect on the ultimate finished properties of the compound. 

Charts of the vapor pressures of parafiin, olefin, and naphthene hydrocarbons exhibit a consistent pattern, but the lines for low-boiling aromatic hydrocarbons are quite erratic even showing curvature. Nevertheless the effect of the kind of hydrocarbon series or Characterization Factor is very small, and need not be considered except when the range of vapor pressure is very great (tenfold or more). Maximum corrections for Characterization Factor are only about plus or minus 10 F when correcting conventional materials from 0.1 mm up to atmospheric pressure. Figs. 5-25 and 5-26 are based on a Characterization Factor of 12.0, and corrections may be computed from ... 

BTX A mixture of low boiling point aromatics, i.e. benzene, toluene and xylenes. 

A convenient method for the synthesis of these low boiling materials consists of the reaction of /V,/V-dimethy1iirea [96-31-1] with toluene diisocyanate to yield an aUphatic—aromatic urea (84). Alternatively, an appropriate aUphatic—aromatic urea can be prepared by the reaction of diphenylcarbamoyl chloride [83-01-2] with methylamine. Thermolysis of either of the mixed ureas produces methyl isocyanate ia high yield (3,85). 

Benzene is the simplest and most important member of the aromatic hydrocarbons and should not be confused with benzine, a low boiling petroleum fraction composed chiefly of aUphatic hydrocarbons. The term benzole, which denotes commercial products that are largely benzene, is not common in the United States, but is stiU used in Europe. 

A continuous distillation process has been studied for the production of high boiling esters from intermediate boiling polyhydric alcohols and low boiling monocarboxyhc aUphatic or aromatic acids (56). The water of reaction and some of the organic acid were continuously removed from the base of the column. 

THE ANALYSIS OF BENZENE, TOLUENE AND HIGHER AROMATICS IN LOW-BOILING FRACTIONS... 

The reduction of an aromatic system under controlled conditions is an important source of cycloalkanes. The procedure given here employs a solution of lithium in a mixture of low-boiling amines to accomplish that end and affords a mixture of octalins as product. The mixture may be separated by selective hydroboration (Chapter 4, Section III). 

Petroleum crude oil, gas condensate, and natural gas are generally complex mixtures of various hydrocarbons and nonhydrocarbons with diverse molecular weights. In order to analyze the contents of a petroleum fluid it is a general practice to separate it first into five basic fractions namely, volatiles, saturates, aromatics, resins, and asphaltenes [74, 77]. Volatiles consist of the low-boiling... 

The pressurised dissolution/cooling procedure of Macko el al. [490], which uses a UV-transparent low-boiling point solvent, is fast and simple as no additional evaporation of the solvent, preconcentration or redissolution of the additive is necessary. Macko el al. [491] have given an extensive listing of HPLC analyses of aromatic antioxidants and UVAs which can be separated with n-heptane and n-hexane as the main component of the mobile phase. The method was also used for HPLC quantification of thioether antioxidants (Santonox R, Chimox 14 and Irganox PS 802) in MDPE [612],... 

Asphaltene (asphaltenes) the brown to black powdery material produced by treatment of petroleum, petroleum residua, or bituminous materials with a low-boiling liquid hydrocarbon (e.g., pentane or heptane) soluble in benzene (and other aromatic solvents), carbon disulfide, and chloroform (or other chlorinated hydrocarbon solvents). 

Propylene oxide is a low boiling point, flammable liquid, readily soluble in both water and the more common organic solvents, such as alcohol, ether, and aliphatic and aromatic hydrocarbons. Commercial sales involve only technical grade (about 98%), and bulk movements require a hazardous material shipping label. Standard transport equipment (trucks, tank cars, and barges) can be used. 

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