5340
Vol. 7 2
KOTES
Anal. Calcd. for C l & ~ 0 ~ N ~ 1 . 5 H n 0C, : 48.6; H, 4.7: N.20.9. Found: C,48.4; H,5.0; N,20.9. The crystal form, ultraviolet absorption spectrum and paper partition chromatography (Rf,0 (n-butanol) ; 0.11 (collidine-lutidine, 1:1) ; 0.22 (acetic aeid-n-butanol-water, 1:4: 1); 0.40 (phenol-waterammonia solution, 80:18:2))l* showed the identity of this product with an authentic sample of pteroylglutamic acid.
Packing the reaction vessel with approximately 5 g. of soft glass wool strikingly demonstrated this effect, approximately three times as much hydrogen peroxide being adsorbed than was present In the vapor phase. Attempts to minimize surface effects by coating Pyrex glass surfaces with microcrystalline wax (Cerese wax AA) and with silicone (Dri-Film (12) Kuwada, Mizuno and Masuda read a paper on the paper partitlon chromatography of folic acid and related compounds a t the 9987) were unsuccessful. A comparison of the meeting of the Pharmaceutical Society of Japan in September, 1949. rate of decomposition a t 45.0’ showed that the THEDEPARTMENT OF PHARMACY wax only slightly decreased the rate as compared FACULTY OF MEDICINE with the chromic acid cleaned surface whereas OF KYOTO UNIVERSITY the silicone surface catalyzed the reaction. RECEIVED MARCH 29, 1950 KYOTO,JAPAN For photochemical experiments, the reaction vessel was a cylindrical Pyrex glass cell to which Adsorption Effects in the Decomposition of a Vycor window was sealed with Apiezon W. Hydrogen Peroxide Vapor The cell, which was 4 cm. inside diameter and of 250-cc. capacity, was jacketed with a copper BY MILTONTAMRES AND ARTHUR A. FROST coil through which water at 26.2’ was circulated. Adsorption phenomena in studying the kinetics The ultraviolet source was a Hanovia quartz of hydrogen peroxide vapor decomposition were mercury discharge lamp, emitting predominantly reported by MacKenzie and Ritchie’ and by 2537 A. radiation. The rate of the photochemical Gigu&re2who investigated extensively the sensi- reaction was much faster than that of the thermal tivity of the reaction to surface conditions. The reaction, and was not influenced by the introducreaction was studied a t this Laboratory by a tion of 0.05 to 8.0 mm. pressure of nitrogen static method employing an oil (Nujol heavy (except as described below), oxygen or water mineral oil) manometer to follow the reaction vapor, nor by 0.05 to 1.0 mm. pressure of hyrate. Results a t 45’ and room temperature drogen or air. This is in agreement with results showed a pressure increase during a run in excess reported by Volman.3 of the 50yoexpected for a homogeneous reaction. The complete photolysis of the vapor from a This can only be explained by adsorption effects supply of approximately 95% liquid hydrogen of hydrogen peroxide and water. peroxide resulted in a pressure change which was For experiments a t 21’) a small quantity of from 49 to 61% of the initial pressure, again liquid hydrogen peroxide of approximately 90% indicating adsorption of peroxide. The fact concentration was distilled a t room temperature that Volman reported an over-all change in under reduced pressure until a trace of the liquid pressure which was less than 50% of the initial remained. Decomposition of the resulting vapor pressure, does not eliminate the possibility of a t initial pressures of 0.5 to 0.7 mm. and pre- adsorption in his experiments since his liquid sumably of very high peroxide concentration. hydrogen peroxide supply was of lower concenwas studied in two spherical 500-cc. Pyrex vessels, tration. The observed over-all change in pressure was An interesting observation in the photochemical approximately 62% of the initial pressure for one studies should be mentioned. In the initial vessel and 50y0 for the other although their sur- experiments, when nitrogen was being used as the faces were treated identically. That this differ- inert gas, decomposition was very rapid for ence in adsorption was not due to possible slight nitrogen pressures less than 0.1 mm., while a t d8erences in experimental conditions was shown higher nitrogen pressures the rate was decreased by employing a n experimental technique whereby noticeably if the nitrogen were admitted first to hydrogen peroxide vapor could be introduced the cell, but was unaffected by the presence of simultaneously into both reaction vessels, equaliz- nitrogen if peroxide were iirst introduced. A ing the pressure of vapor between them and change to oxygen as the foreign gas showed no such following the “differential” rate of reaction with pressure dependence and a return to nitrogen the oil manometer each end of which was con- no longer produced this effect. nected to one of the vessels. The “differential” These observations confirm the heterogeneous rate of reaction showed that initial decomposition character of the thermal reaction and indicate proceeded more rapidly in the vessel where that the photochemical reaction also has some adsorption was greater, the difference in extent heterogeneous characteristics. of adsorption being noted by the difference in work was supported final pressures in the reaction vessels. Each run byAcknowledgment.-This a fellowship from the U. S. Rubber Company. required several days and consequently few were made. The results, however, seemed reproducible. DEPARTMENT OF CHEMISTRY NORTHWESTERN UNIVERSITY
(1) R C. MacKrnztc and XI. R i t c h c . PYOCRoy Soc (London), 6186, 207 (1946) 12) P A Gigii&re,Can J . Research, 86B,135 11947)
EVANSTON, ILLINOIS
RECEIVEDJUNE23, 1950
(3) D.H.Volman, J. Chcm. Phys , 17,947 (1949).
