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

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 EX (10-5-10-4M), but with a high total pressure of CF, (-0.9 atm) and small extents of reaction (2-60/,), the first-order homogeneous rates of CHZO formation are a direct measure of reaction (l), since k3b >> k z ( X O ) :Addition of large amounts of NO(m0.9 atm) completely suppressed CH20 formation in agreement with the observed value for k3a.Since (El + R?') and AH"1 are identical, both may be equated with D(Et0 -NO) = 42.4 =k 0.9 kcal/mol and E2 = 0 f 1 kcal/mol. The thermochemistry leads to the result AH",(EN) = -24.5 f 1 kcal/mol.From AS"1 and AX, k2 is calculated to be 10i0.3M-1 . s-'. From an independent observation that ks/kz = 0.3 f 0.05 independent of temperature it is concluded that ks = 10g-*M-' -s-l.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):The rate of reaction (1) is given by kl = 10i6.0-41.8/8 s-l.EtO + NO -% AcH + HNO The addition of NO has no effect on the AcH yields. E N A AcH + HNO and reaction (6). isobutane (t-BuH) as a radical trap for EtO (4),The rate of AcH formation is given by kobr = 1013.7-37.5/8 s-l. By using EtO + t-BuH A EA + (1-Bu) a value for k3a was determined to be 1016.0-*1,6/8 5-1.From an independent observation that kz:kp: kg:k6, was 1: 0.4: 0.3: 0.18 EtONOl+ EtO + NOz EtO + NOz -% AcH + HONO we find kz. = 109.9M-1 . 8-1, kl, = 1016.0-40.0/@ s-1, and ks, = 109.6M-1. 8-1.

The very‐low‐pressure pyrolysis (VLPP) of n‐propyl nitrate, tert‐butyl nitrite, and methyl nitrite. Rate constants for some alkoxy radical reactions

“…The rate for t-BuO + N O is in good agreement with the results by Batt and coworkers [3]. Phillips and Shaw [13] and Baker and Shaw [14] reported relative rates for recombination of NO and NO2 with RO (R = Me, Et, t-Bu) between 1.7 and 2.7.…”

“…We suggest that tert-butyl nitrite decomposition is autocatalytic in the low-temperature range, in that acid produced in the @-scission is absorbed onto the walls, where it both decomposes and catalyzes elimination of more HONO. Surface effects for R O N 0 have been described by Batt and coworkers [3] and the decomposition of tert-butanol in our system to give isobutene must be a catalyzed process, because the homogeneous rate is prohibitively slow. The origin of tert-butanol and tert-butyl nitrite is not clear.…”

“…The data could be equally well fitted by the parameters of [3] (Fig. 2), and since the value of A H L s is uncertain by at least f 1 kcal/mole, no distinction is possible.…”

“…The value of kuni was 20 sec-'. From Batt and coworkers, data, [3] we predict kL500K = 93 sec-' for the fission into RO and KO, and RRK calculations indicate k,,,/k, is about lop5, so we cannot be observing a homogeneous process.…”

Dinámica de reacciones unimoleculares en fase gas: Desviaciones del comportamiento estadístico

“…Para este sistema [60][61][62][63][64] se encontró que la dinámica es estadística a las energías más bajas para la reacción de disociación (MeONO ® MeO + NO) mientras que la reacción de eliminación (MeONO ® CH 2 O + HNO) tiene un comportamiento no estadístico a todas las energías estudiadas. En particular, las constantes de velocidad calculadas mediante TC para la disociación se muestran en la Figura 1 (círculos).…”