Paraffinic hydrocarbons physical properties

Because of the chemical inertness of the paraffin hydrocarbons and of the closely related cycZoparaffins, no satisfactory crystalline derivatives can be prepared. Reliance is therefore placed upon the physical properties (boding point, density, and refractive index) of the redistilled samples. These are collected together in Table III,6. 

Physical Properties. Furfuryl alcohol (2-furanmethanol) [98-00-0] is aHquid, colorless, primary alcohol with a mild odor. On exposure to air, it gradually darkens in color. Furfuryl alcohol is completely miscible with water, alcohol, ether, acetone, and ethyl acetate, and most other organic solvents with the exception of paraffinic hydrocarbons. It is an exceUent, highly polar solvent, and dissolves many resins. 

At room temperature phenol is a white, crystalline mass. Phenol gradually turns pink if it contains impurities or is exposed to heat or light. It has a distinctive sweet, tarry odor, and burning taste. Phenol has limited solubiUty in water between 0 and 65°C. Above 65.3°C phenol and water are miscible in all proportions. It is very soluble in alcohol, ben2ene, chloroform, ether, and partially disassociated organics in general. It is less soluble in paraffinic hydrocarbons. The important physical properties of phenol are Hsted in Table 1. 

Hydrocarbons are segmented into a variety of categories. Each category possesses a distinct molecular profile and, in turn, set of chemical and physical properties. Each class of hydrocarbons therefore has historically served different markets. Crude petroleum is composed of four major hydrocarbon groups paraffins, olefins, naphthenes, and aromatics. 

It has been shown (9) that asphaltenes contain a broad distribution of polarities and molecular weights. According to these studies, the concept of asphaltenes is based on the solubility behavior of high-boiling hydrocarbonaceous materials in benzene and low-molecular weight n-paraffin hydrocarbons. This solubility behavior is a result of physical effects that are caused by a spectrum of chemical properties. Long also... 

Relation of Physical Properties and Chemical Constitution was the title of a book published in 1920 by Kauffmann 20). It lists the freezing and boiling points of the normal paraffins and records the increments of rise with the addition of each methylene group. The same year Thomas Midgley 26) observed wide differences in the combustion of fuels in internal combustion engines. The differences were found not only in different classes of hydrocarbons but also between isomeric hydrocarbons of the same class. 

The agreement between the physical properties of the pure hydrocarbons and the binary physical mixture is much poorer for these hydrocarbons which contain the aromatic phenyl group than it is for the naphthenic-paraffinic mixtures. The derivatives for the aromatic mixtures are from four to nine times those of the physical mixtures of the pure hydrocarbons where no aromatic rings are present. 

Kurtz and Ward 22) have described a composite function of the refractive index and density which they call the refractivity intercept. The equation is R. Int = n — d/2. The value of the refractivity intercept lies in the fact that for hydrocarbon isomers it is more constant than most other functions. Its chief uses are the rapid checking of physical property data found in the literature and distinguishing between naphthenes, paraffins, and aromatics. 

The implications of these deductions seem to lead to the conclusion that such structural factors as chain length, methyl groups, and double bonds influence not only the physical properties but the chemical properties of the hydrocarbon as well. Hydrocarbons are limited in their chemical reactivity. The paraffins are compounds having small affinity. The hydrocarbon molecules are armor-plated with hydrogen. Since structure plays so vital a role in the rate of combustion, there must be a fundamental difference in the relative reactivity of the hydrogen atoms. Experimental evidence that such is the case is accumulating. There are reasons to believe that methods are at hand by which the... 

The viscosity of a liquid is related directly to the type and size of the molecules which make up the liquid. The variation of liquid viscosity with molecular structure is not known with exactness however, the viscosities of liquids which are members of a homologous series are known to vary in a regular manner, as do most other physical properties. For example, pure paraffin hydrocarbons exhibit a regular increase in viscosity as the size and complexity of the hydrocarbon molecules increase. 

The four first members of the methane series are gases those containing a greater number of atoms of carbon up to eleven are liquids, and the higher members are solids. The paraffin oil which is burned in lamps consists of a mixture of the liquid members, and paraffin candles largely consist of the solid members. They are all practically insoluble in water. The olefines have similar physical properties, and benzene is a volatile liquid. Iodine, sulphur, and phosphorus dissolve in the liquid hydrocarbons. 

As their name implies, chlorinated paraffins are chlorinated derivatives of paraffinic hydrocarbons. They are referred to in this review as polychlorinated alkanes (PCAs) because they are produced by chlorination of n-alkane feedstocks. Commercial PCA mixtures fall into different categories C10-C13 (short), C 4-C17 (medium) and C2o-C30 (long). These mixtures are further subcategorized into their weight content of chlorine 40-50%, 50-60%, and 60-70% [1,2]. Knowledge of the environmental chemistry of PCAs is needed because the physical properties of short and medium chain mixtures are similar to those of the... 

Values for the index between 0 and 15 indicate a predominance of paraffinic hydrocarbons in the fraction. A value from 15 to 50 indicates predominance of either naphthenes or mixtures of paraffins, naphthenes, and aromatics. An index value above 50 indicates a predominance of aromatic species. However, it cannot be forgotten that the data used to determine the correlation index are average for the fraction of feedstock under study and may not truly represent all constituents of the feedstock, especially those at both ends of a range of physical and chemical properties. 

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