NOTES
July 5 , 1955
3487
mixed with acetyl peroxide, the gaseous mixture pressure in a n atmosphere of nitrogen, and stored under decomposed, and the products analyzed. The re- d r ~ ~ ~ ~ ~ ~subjected ~ $ ! to ~ ; s and distilled sults are summarized in Table 111. It can be seen at reduced pressure. Methyl methacrylate (Rohm and Haas Company) was that the iodine does not react with acetyl peroxide (the rateconstant for the unimolecular decomposi- freed from inhibitor with sodium hydroxide solution, washed and dried, and distilled at 100 mm. pressure in a n atmostion is unaffected by the presence of iodine vapor), phere of nitrogen. It was transferred to a vacuum apparaHowever, iodine reacts efficiently with methyl radi- t u s and degassed four times and distilled twice in vacuo. I t cals, and consequently the ratio 2CzHe/C02 is re- was stored a t -80". Procedure.-Solutions of triazobenzene in the solvent, duced effectively to zero as the partial pressme of tetrahydronaphthalene or nitrobenzene, were made up over iodine vapor is raised to 0.23 mm. ~h~~~ a wide concentration range. Five ml. of solution was prove conclusively that reaction 4 does not take placed in the apparatus consisting of a reservoir of volume place and, therefore, we conclude finally that the 15 ml. attached to a capillary mercury manometer. T h e formation of ethane in the liquid phase decomposi- solution was thoroughly degassed and the apparatus sealed off. The reaction was followed by the pressure increase tion must be attributed to a cage reaction. due to evolution of nitrogen; about 0.95 mole nitrogen was TABLE I11 DECOMPOSITION OF D I ~ C E T YPEROXIDE L IN THE PRESENCE OF IODINE VAPOR Gaseous phase, T = 461'K.; flow system; partial pressure of peroxide about 0.1 mm.; partial pressure of the carrier gas (toluene) about 15 nun. P a r t i a l pressure of mm.
11,
2c1n8/~oz
0.00 ,064 .12 .23
k , sec. -1
1.00
1.95
0.034 ,020 ,0004
1.74 1.60 1.80
CHEMISTRY DEPARTMEST
STATE UNIVERSITY OF NEW YORK COLLEGEOF FORESTRY
SYRACUSE 10, N. Y .
The Thermal Decomposition of Triazobenzene in Solution BY K. E. RUSSELL RECEIVEDMARCH10, 1955
The thermal decomposition of azo compounds such as 2,2'-azo-bis-isobutyronitrilein solution involves the splitting out of nitrogen and the production of two monoradicals. It would be expected that triazobenzene would decompose to give a diradical and nitrogen. PhNa
+PhN
