General and physical chemistry

1890 Journal of the Chemical Society Abstracts  
Dispersion of Carbon Compounds. By P. B m s m and L. Roux (Comp,t. !rend., 111, 180-183; conipare Abstr., 1589, 865, this TO]., 11. 1036) .--Measurements of the refractive and dispersive powers of simple and mixed ethers of !he methane series show that the dispersive power and the specific dispersive power increase with the molecular weight., but are practically the same for all isomerides containing the same quantity of carbon. The introduction of CH2 into the molecule raises the specific
more » ... s the specific rnolecdar dispersive power by about 8.2, I n the equation ( : -h)X = a, the value of a is -6.443, and of b +0-5790 ; in the equation (B -/ 3 ) ( : ) = R, # I = 0.6626 and K = --1*E4. In methyl allyl, ethyl allyl, and propyl ailyl ethers, the dispersive power and specific dispersive power remain practically constant, and do not increase with the molecuiar weight. Comparing these ethers with others containing the same number of carbon atoms, it is seen that the dispersive power increases as the proportion of hydrogen diminishes. In the case of methyi benzyl, ekhyl benzyl, propyl bencyl, isoibuhyl benzyl, and nmyi benzyl ethers, the dispersive power diminiahes as the molecular weight increases, but the addition of CH, produces a variation in the specific molecular dispersion equal, as in the methane series, to about 5.2. For the series. in the first equation, a = +40*87, and 6 = +0,5834; in the second equation, / 3 = 0, and K about 4.4. I n all cases the specific molecular dispersive power of the ethers is equal to the sum of the dispersive powers of the two alcohols from which they have been formed, minus the dispersive power of the water eliminated, c. H. €3. By ,I?. BARBINK, and L. Roux (Cornpi. rend., 111,(235)(236).--The dispersive power of acids of the acetic series increases with their mo1ec:ular weight. Formic acid is an exception, if the dispersive power B i; alone considered, but the exception disappears in the case of the specific dispersive power. The dispersive powers of isomerides are pi-actically the same, but the values are highest in the case of the normal acids. The differences between the successive values of the specific molecular dispersive power% atre pradically coltstant, and equal to 7.8, so that the miriation of the specific power niny be represented as a function of the molecular weight, thus, ( , :b)M = u; in which a = -11,515, b = 0.5625. The relation between the dispersive power and the molecular rolume is the same as in the case of the corresponding alcotiols (this lo!., p. 1034), the values of the constants being /3 = +0*6353, K = -1.08.
doi:10.1039/ca8905801353 fatcat:zpohx4efxzcq7ggjq7kdbhglx4