The rate of decomposition of isopropyl nitrite (IPN) has been studied in a static system over the temperature range of 130-160Β°C. For low concentrations of IPN (1-5 X lO+M), but with a high total pressure of CF4 (-0.9 atm) and small extents of reaction ( ~1 % ) ~ the first-order rates of acetaldehyde (AcH) formation are a direct measure of reaction (l), since k 3 >> k2(NO): IPN i-PrO + NO, i-PrO -+ AcH + Me. Addition of large amounts of NO (-0.9 atm) in place of CF4 almost completely suppressed AcH formation. Addition of large amounts of isobutanet-BuH -( ~0 . 9 atm) in place of CFI at 160Β°C resulted in decreasing the AcH by 25%. Thus 25% of i-PrO were trapped by the t-BuH (4): i-PrO + t-BuH -% i-PrOH + (t-Bu). The result of adding either NO or t-BuH shows that reaction (1) is the only route for the production of AcH. The rate constant for reaction (1) is given by k l = 1016.2io. c-ri.o-+o.s/,g sec-~.
Since (El + R T ) and AH"* are identical, within experimental error, both may be equated with D(i-PrO-NO) = 41.6 =k 0.8 kcal/mol and Ez = 0 & 0.8 kcal/mol. The thermochemistry leads to the result that AH"f(i-Pr6) = -11.9 + 0.8 kcal/mol. From ASo, and AI, kz is calculated to be 1010.5*0.4M--1.sec-l. From an independent observation that ka/kZ = 0.19 =t 0.03 independent of temperature we find Ee = 0 f 1 kcal/mol and ks = 109~8*0.4M--l.sec-1:
In addition to AcH, acetone (MZK) and isopropyl alcohol (IPA) are produced in approxi-
The rate of M2K formation is markedly affected by the ratio S / V of It is concluded that the MZK arises as the result of a heterogeneous In a spherical reaction vessel the first-order rate of MZK IPA is thought to arise This elimination process 3 i-PrO + NO -% M ~K + HNO. mately equal amounts. different reaction vessels. elimination of HNO from IPX.
formation is given by k s = 109.4-27.0/8 sec-l: IPN -% M,K + HNO. via the hydrolysis of IPN, the water being formed from HNO. explains previous erroneous results for IPN.