June, 1935
COMMUNICATIONS TO THE EDITOR
REACTION IN ETHYLENEHYDROGEN MIXTURES INDUCED BY OXYGEN
Sir:
stant (E) and the density given by the equations e
=
€1
+ CYNZ
1147 (p)
of the solutions are P = PI
+ PNz
(2)
It has been found that small amounts of oxygen in ethylene-hydrogen mixtures cause greatly increased initial reaction rates in the homogeneous reaction a t 538’. Reaction was carried out a t constant volume. Pressure drops during the first, second and third minutes (AP1, AF’z, A P a ) appear in the accompanying table.
and then proceeds to substitute these in the equation for the polarization of the solute. Then in the limit, Nz = 0, we have P2 = P,, e = el, p = pl, and Nl = 1. The values of CY and p are consequently (de/dN2)Lv,= and (dp/dNz)N, = b, which may be seen from equation (2). Now if the dielectric constant and density of the solution are linear functions of TABLEI CY and p are the slopes of these the concentration, I N ETHYLENE-HYDROGEN MIXTURESINDUCED REACTION straight lines. If CY and p are functions of the BY OXYGEN Initial press., mm. APi APa, APa concentration then they are the slopes of the mm./min. Run Hz CaHd Na 0% 1 676 192 . .. ... 4.5 4 4 . 5 tangents to the dielectric constant and density 2 572 191 . .. 5 . 8 63 10 4 . 5 curves a t zero concentration. 3 191 573 ... 5 . 8 29 6 4.5 As it is rather difficult to obtain a tangent to a 4 . . . 770 . . . 5 . 8 18 6 4 . 5 curve it was suggested by Hedestrand (Zoc. cd.) . . . 382 382 5 . 8 5 3 2.5 5 that (Y and @ obtained from equation (2) be plotted The initial acceleration is much greater in against the concentration and extrapolated to hydrogen-rich mixtures (cf. No. 2 with No. 3 and infinite dilution. This was carried out for the compounds of No. 4). The effect could be due to accelerated ethylene polymerization, known to be induced Svirbely, Ablard and Warner and the results are by oxygen [Lenher, THIS JOURNAL, 53, 3752 listed below. (1931)l. It seems more likely that the hydroSvirbely, Ablard, Warner Recalculated Compound P, p x 10’8 Pm ir x 101* genation reaction itself is affected. 2.67 184 2.60 &Pinene 192 Further experiments are in progress. &Limonene 96 1.56 96 1.57 FRICKCHEMICAL LABORATORY ROBERT N. PEASE Methyl benzoate 2.52 173 2.54 170 PRINCETON UNIVERSITY AHLBORN WHEELER Ethyl benzoate 166 2.43 159 2.34 N. J. PRINCETON, RECEIVED hlAY 8, 1935 These are good checks and should serve to inTHE CALCULATION OF MOLAR POLARIZATION OF SOLUTES AT INFINITE DILUTION WITH HEDESTRAND’S FORMULA
Sir: It has been suggested by Svirbely, Ablard and Warner [THISJOURNAL, 57, 652 (1935)] that Hedestrand’s method of extrapolation should not be considered of general application if the values of a and p of the equation
are not constant for varying concentration or in other words if the dielectric constant and density are not linear functions of the concentration. In the derivation of the above equation Hedestrand [Z. physik. Chem., B2, 428 (1929)J says that for small concentrations the dielectric con-
dicate that Hedestrand’s formula can be used for substances in which the dielectric constant and density are not linear functions of the concentration. It is interesting to note that compounds like the phenylacetylenes [Otto and Wenzke, THIS JOURNAL, 56, 1314 (1934)l and the phenylethylenes [Otto and Wenzke, ibid., 57, 294 (1935)l have constant Q and p while the dialkoxyalkanes [Otto, ibid.,57,693 (1935)] have slowly increasing value of CY. The values o€ CY for the compounds of Svirbely, Ablard and Warner increase very rapidly and i t might be as they suggest indication of varying degrees of dipole orientation such as has been shown to exist in solutions of alcohols. OF CHEMISTRY DEPARTMENT UNIVERSITY OF NOTREDAME NOTRE DAME,IND. RECEIVED MAY11, 1935
M. M. OTTO
