Alkane carbon number , equation

Alkane carbon number, equivalent (EACN) definition, 392 equation, 282... 

Table 2 lists the characteristic parameter EPACNUS selected ionic surfactants. EPACNUS stands for extrapolated preferred alkane carbon number at unit salinity and no alcohol. It is the ACN value fround from equation (8) when In 5 = 0, f A) = 0 and AT= 0, and it is this characteristic of the surfactant. The EPACNUS parameter allows us to compare surfactant hydrophilicity against the ACN scale, which has exactly the same meaning in all correlations, whether for ionic or nonionic systems. The lower the value of EPACNUS, the higher the hydrophilicity of the surfactant. 

Similarly, the equations for the Rx factors as a function of the alkane carbon number Cfl, are... 

Here S is the NaCl concentration in wt%, ACN, or Alkane Carbon Number, is a characteristic parameter of the oil phase, A7 is the temperature deviation from a certain reference (25 C), f(A) is a function of the alcohol type and concentration, and K, o, and Ut are empirical parameters characterizing the surfactant. A similar empirical equation was proposed for nonionic surfactants - ... 

Possible inter relationships of natural substances are important. Similarities of the low molecular weight alkane isomers from crude oil and Fischer-Tropsch synthesis product have been reported. A similar composition for high temperature coal carbonization has been found. The C4 to C7 alkane isomers from these sources can be calculated quantitatively with equations developed for Fischer-Tropsch products. A reversal of the concentrations of the monomethyl isomers from CG (2 Me > 3 Me) to C7 (3 Me > 2 Me) occurs in all three products comparisons at higher carbon numbers indicate some dissimilarities. Naphthene isomers for crude oil and high temperature coal carbonization also have similar compositions. Aliphatic hydrocarbons from low temperature coal processes are considerably different. The C1 isotopic composition of pure compounds from the various sources are being compared in order to provide information on their origin. 

Costas et al. (1981) and Costas and Sanctuary (1981) reformulated the Sanchez-Lacombe equation of state so that the parameter r is not a regression parameter, but is actually the number of segments in the polymer molecule. In the original Sanchez-Lacombe treatment, r was regressed for several n-alkanes, and it was found that the r did not correspond to the carbon number of the alkanes. In addition, the Sanchez-Lacombe equation of state assumes an infinite coordination number. Costas et al. (1981) replaced the segment length r as an adjustable parameter with z. This modification involves the same number of adjustable parameters, but allows r to be physically significant. Thus, the model is more physically realistic, but there have been no definitive tests to determine whether this improves the correlative results from the model. 

Size Calibration. The -Styragel columns were calibrated to transform the elution data from the time domain to the size domain using both n-alkane and polystyrene (Pressure Chemicals) standards. The n-alkane sizes are related to the carbon number by Equation 1 (7). 

An excellent illustration of the LHHW theory is catalytic cracking of n-alkanes over ZSM-5 [8]. For this reaction, the observed activation energy decreases from 140 to -50 ( ) kj/mol when the carbon number increases from 3 to 20. The decrease appeared to linearly depend on the carbon number as shown in Fig. 3.11. This dependence can be interpreted from a kinetic analysis that showed that the hydrocarbons (A) are adsorbed weakly under the experimental conditions. The initial rate expression for a rate-determining surface reaction applies (3.30), which in the limiting case of weak adsorption of A reduces to Eqn. (3.52). The activation energy is then represented by equation (3.53). 

FIGURE 16.7 Average deviations in solid-liquid equilibrium calculations, as a function of the solute carbon number, for alkane systems using various FV models. E-FV is the Entropic-FV model. F-FVl.l is the Flory-FV model using c= 1.1. GCFLORY EoS is the GC-Flory equation of state. (From Coutinho, J.A.P. et al.. Fluid Phase Equilibria, 103, 23, 1995. With permission.)... 

Application of Equation (3) for RI determination requires measuring the retention times of the two n-alkanes which elute respectively before and after the analyte. However, in the usual a nonpolar-polar column configuration, polar compounds will require in the second column a pair of n-alkanes with higher carbon numbers than those of the two n-alkanes that bracket the compound when elutes in the nonpolar column. 

McGlashan and co-workers have shown that by use of the carbon number n of organic compounds forming an homologous series, BjVc may be expressed as a function of 71 by a single equation, valid for all members of the series. For n-alkanes the equation is... 

Dense fluid transport property data are successfully correlated by a scheme which is based on a consideration of smooth hard-sphere transport theory. For monatomic fluids, only one adjustable parameter, the close-packed volume, is required for a simultaneous fit of isothermal self-diffusion, viscosity and thermal conductivity data. This parameter decreases in value smoothly as the temperature is raised, as expected for real fluids. Diffusion and viscosity data for methane, a typical pseudo-spherical molecular fluid, are satisfactorily reproduced with one additional temperamre-independent parameter, the translational-rotational coupling factor, for each property. On the assumption that transport properties for dense nonspherical molecular fluids are also directly proportional to smooth hard-sphere values, self-diffusion, viscosity and thermal conductivity data for unbranched alkanes, aromatic hydrocarbons, alkan-l-ols, certain refrigerants and other simple fluids are very satisfactorily fitted. From the temperature and carbon number dependency of the characteristic volume and the carbon number dependency of the proportionality (roughness) factors, transport properties can be accurately predicted for other members of these homologous series, and for other conditions of temperature and density. Furthermore, by incorporating the modified Tait equation for density into... 

A 1.2.3 Over a limited range and with some loss in accuracy. Linear Retention Indices can be calculated by extrapolation rather than interpolation. In such cases, TV and TV + 1 would be defined as the carbon numbers of consecutive /t-alkanes, both eluting immediately after (or before) compound A. The equation otherwise remains unchanged. 

Index of hydrogen deficiency (Section 13 23) A measure of the total double bonds and nngs a molecule contains It is determined by comparing the molecular formula C Hj. of the compound to that of an alkane that has the same number of carbons according to the equation... 

The enthalpy of formation of methyl n-pentyl ether is unavailable from experiment, but a value of —316 kJmoP is obtained from the linear regression analysis of the known enthalpies of formation of methyl n-alkyl ethers vs. the number of carbon atoms in the ethers . The methylene increment of —25.3 kJmoP for this homologous ether series is nearly identical to the methylene increment for n-alkanes. Because the experimental protodelithiation enthalpies for the two primary lithio ethers are identical, the methylene increment in that homologous series as calculated here is necessarily identical to that of the homologous methoxy ethers. As calculated from the methylene increment or from equation 16, the enthalpy of formation of 5-lithiopentyl methyl ether is ca —309 kJmol. ... 

The constants ko (between 52 and 58) and kl (between 1.2 and 1.5) were found to be dependent on the number of carbon atoms, Cn, and since Tc is also found to be dependent on Cn, the expression for all the different alkanes that individually were fit to Equation A.5 culminated in a general equation where y was a function of Cn and T as follows (Birdi, 1997) ... 

In a GPC experiment a mixture of n-alkanes (up to n carbon atoms, where n represents a variable number) and butanol (CH3CH2CH2CH2OH) were injected onto a column maintained at a constant temperature and whose stationary phase was of silicone-type material. The equation of the Kovats straight line derived from the chromatogram is log Jr = 0.39n — 0.29 (where /r the adjusted retention time is in seconds). The adjusted retention time of... 

One aromatic ring causes a deficiency of 8 hydrogen atoms compared to an alkane with the same number of carbon atoms. This explains the term 8 Ra in equation (26). From equation (26) it follows for the molecular weight that... 

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