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The gas‐phase pyrolysis of alkyl nitrites. IV. Ethyl nitrite

1977; Wiley; Volume: 9; Issue: 4 Linguagem: Inglês

10.1002/kin.550090405

1097-4601

L. Batt, R. T. Milne,

Catalysis and Oxidation Reactions

Abstract The rate of decomposition of ethyl nitrite (EN) has been studied in a static system over the temperature range of 162‐218°C. The main products are formaldehyde, acetaldehyde, ethanol, and nitrous oxide. For low concentrations of EN (10 −5 ‐10 −4 M ), but with a high total pressure of CF 4 (∼0.9 atm) and small extents of reaction (2‐6%), the first‐order homogeneous rates of CH 2 O formation are a direct measure of reaction (1), since k 3b k 2 (NO): equation image Addition of large amounts of NO(∼0.9 atm) completely suppressed CH 2 O formation in agreement with the observed value for k 3b . The rate of reaction (1) is given by k 1 = 10 16.0‐41.8 /θ −1 . Since ( E 1 + RT ) and Δ H ± 1 are identical, both may be equated with D ( E tO‐NO) = 42.4 ± 0.9 kcal/mol and E 2 = O± 1 kcal/mol. The thermochemistry leads to the result Δ H Delta; f (EN) = ‐24.5 ± 1 kcal/mol. From Δ S 1 and A 1 , k 2 is calculated to be 10 10.3 M −1 θ −1 . From an independent observation that k 6 / k 2 = 0.3 ± 0.05 independent of temperature it is concluded that k 6 = 10 9.8 M −1 Δ −1 . The addition of NO has no effect on the AcH yields. Although the yields of AcH are affected by the surface‐to‐volume ratio of different reaction vessels, it is concluded that in a spherical reaction vessel, the AcH arises as the result of an essentially homogeneous elimination of HNO from EN(5): and reaction (6). The rate of AcH formation is given by k obs = 10 13.7‐37.5 /θ −1 . By using isobutane ( t ‐BuH) as a radical trap for EtO (4), a value for k 3b was determined to be 10 15.0‐21.6 /θ s −1 . From an independent observation that k 2 : k 2 : k 6 : k 6 was 1: 0.4: 0.3: 0.18 equation image we find k 2θ = 10 9.9 M −1 → s −1 , k 1θ = 10 16.0‐40.0 /θ s −1 , and k 6± = 10 9.6 M −1 · s −1 .