Refractometric investigations on unbranched alkenes with a terminal double bond. The refraction equivalent of the >C  C< bond

Abstract

AbstractThe preparation of the alkenes with a terminal double bond from C5to C10, C12, C16and C18inclusive in a high degree of purity is described. The refractive indices have been measured at 20° C and 25° C for 9 wavelengths and the densities measured at the same temperatures. After discussing the calculation of the refraction equivalent for the CH2group and the increment for the double bond according toEisenlohr, our experimental material has been used to calculate by the method of least squares, the refraction equivalents of the CH2group and the double bond for 9 wavelengths and the dispersion equivalents at 20° C and 25° C according to theLorentz‐LorenzandGladstone‐Daleformulae. The value for the terminal double bond [H2]1according to the method used byEykmanhas also been determined. In this way it has been possible to obtain accurate values for the refraction increment of the double bond, for the refraction equivalent of the CH2group and for the dispersion in the series of 1‐alkenes. The values we have obtained for the refraction equivalent of the double bond differ considerably from those ofEisenlohr, which are at present in general use.