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

Abstract

AbstractThe 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 (10−5‐10−4M), but with a high total pressure of CF4 (∼0.9 atm) and small extents of reaction (2‐6%), the first‐order homogeneous rates of CH2O formation are a direct measure of reaction (1), since k3bk2(NO): equation image Addition of large amounts of NO(∼0.9 atm) completely suppressed CH2O formation in agreement with the observed value for k3b.The rate of reaction (1) is given by k1 = 1016.0‐41.8/θ−1. Since (E1 + RT) and ΔH±1 are identical, both may be equated with D(EtO‐NO) = 42.4 ± 0.9 kcal/mol and E2 = O± 1 kcal/mol. The thermochemistry leads to the result ΔHDelta;f(EN) = ‐24.5 ± 1 kcal/mol. From ΔS1 and A1, k2 is calculated to be 1010.3M−1θ−1. From an independent observation that k6/k2 = 0.3 ± 0.05 independent of temperature it is concluded that k6 = 109.8M−1Δ−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 kobs = 1013.7‐37.5/θ−1. By using isobutane (t‐BuH) as a radical trap for EtO (4), a value for k3b was determined to be 1015.0‐21.6/θ s−1.From an independent observation that k2:k2:k6:k6 was 1: 0.4: 0.3: 0.18 equation image we find k2θ = 109.9M−1→ s−1, k1θ = 1016.0‐40.0/θ s−1, and k6± = 109.6M−1 · s−1.