Vol. 57
590
COMMUNICATIONS T O T H E EDITOR THE THERMAL. REACTION BETWEEN FORMALDEHYDE AND CHLORINE
tion vessel is cleaned. Whether increase of the surface-volume ratio produces any effect is doubtSir: ful. In the photochemical experiments an inSpence and Wild [J. Chem. SOC.,1588 (1934)] crease of surface appeared to increase the rate; report that the thermal reaction between chlorine but the increase may have been merely one of the and formaldehyde proceeds either by an explosion erratic variations which occur so frequently in or by a relatively slow process, depending on these experiments, or may have been due merely temperature, pressure and the condition of the to the relative freshness of the added surface. reaction vessel. They find further that any Spence and Wild report a slight decrease of rate excess of formaldehyde present in an explosive with increasing surface, but feel that the decrease mixture is decomposed into carbon monoxide and is not significant. hydrogen; that the slow reaction is preceded by Spence and Wild determined the amount of an induction period; that the rate of this latter carbon monoxide formed by analysis of their gas reaction is somewhat affected by the walls of the mixtures. In every case, the amount of carbon reaction vessel; and that the amount of carbon monoxide indicated by analysis was greater than monoxide produced in this reaction is apparently the amount calculated from the pressure change. somewhat greater than the amount predicted This result they explain by assuming that the from the observed pressure change. These ob- observed pressure increase is too small because of servations accord well with results obtained for a concurrent chlorine-sensitized polymerization of the photochemical reaction [Kkauskopf and formaldehyde. If formyl chloride is present, the Rollefson, THISJOURNAL, 56, 2542 (1934)] be- discrepancy can be alternatively explained by tween the two gases, and it seems probable that supposing that during the process of analyzing the the mechanism devised to account for the photo- reaction mixture some formyl chloride decomchemical change may be applied successfully to poses, thus increasing the amount of carbon monthe thermal process. oxide present. According to this mechanism, formyl chloride DEPARTMENT OF CHEMISTRY K. B. KRAUSKOPF OF CALIFORNIA G . K. ROLLEFSON is produced from formaldehyde and chlorine: UNIVERSITY BERKELEY,CALIFORNIA CHzO Clz -+ COHCl HC1, and decomRECEIVED JANUARY 16, 1935 poses subsequently into carbon monoxide and hydrogen chloride. The existence and comparaTHE CHEMICAL BASIS FOR SOME BIOLOGICAL tive stability of the intermediate have been EFFECTS OF HEAVY WATER demonstrated in ph~tochemicalreaction mixtures; its lifetime would be considerably shortened by Sir: Empirical physiological effects of heavy water the higher temperatures used by Spence and Wild, but its presence in their reaction mixtures require chemical explanations [cf. Barnes and seems entirely reasonable. The formation of Jahn, Quart. Rev. Biol., 9, 292 (1934)) We find formyl chloride according to the above reaction the contractile vacuole of protozoa an excellent involves no pressure change; the observed induc- object for heavy water experiments. Thus in a tion period, therefore, like the corresponding race of Paramecium caudatum the contractile period in the photochemical reaction, can be vacuole empties every 18.9 seconds in 30% DzO explained as the time during which the inter- compared to 11.3 seconds in controls (both at mediate is being produced faster than it decom- 18.8"). We have applied the Arrhenius equation : to data on the rate of conposes. This first reaction is a highly exothermic Velocity a chain process which under favorable conditions traction at various temperatures and in ordinary can become explosive. The second reaction is at water we find the following values of the constant least partially heterogeneous, since the pressure E or energy of activation of the controlling change in either the photochemical or the thermal catalyst: below 16' 24,000 calories; between 16 process is more rapid immediately after the reac- and 22" 17,000 calories and above 22" 14,000
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