Synthesis, refractometric constants, and some other physical properties of a homologous series of branched alkenes

Abstract

The preparation of eleven terms of the homologous series of the 2-methyl-1 -alkenes (2-methyl-a-alkenes) is described. The purity of the preparations obtained was determined by measuring the melting curves. The densities and refractive indices of the synthesized compounds at 20" C and 25" C were determined; the measurements of the refractive indices were carried out at nine wave-lengths. From the values of the densities and the refractive indices the molecular refractions were determined according to the formula of Lorentz-Lorenz. By the method of the least squares we derived, with the aid of these data, the values of the refraction equivalent of the CH,-group and the increment of the double bond. The densities and refractive indices determined experimentally appeared to correspond excellently with values calculated from empirical formulae. Besides densities and refractive indices the final melting points, the boiling points and the infra-red spectra of the synthesized compounds were determined. 1.In the latter half of the 19th and the first part of the 20th century many investigators held the opinion that it should be possible to assign specific atomic and group refractions to atoms and atomic groups. The molecular refraction of an organic compound was assumed to be equal to the sum of the refractions of the atoms constituting that compound.In 191 1 Eisenlohr 1) published his table of atomic refractions, using experimental data which at present can no longer be considered sufficiently accurate.Moreover, as far back as 1893 Eykman 2 ) realized that the additivity Scope of the investigation.

Group Contribution Approach To Predict the Refractive Index of Pure Organic Components in Ambient Organic Aerosol

“…As discussed above, real RIs can be influenced by the complex interplay of various factors such as component density, MW, and functional group type and molecular structure. Any general trends previously observed may not be observable if all of these vary from compound to compound and if the coverage of compounds (size of the training set) is too small. − From Figure , the model shows good accuracy and reliability independent of degree of oxidation and aging.…”