Absolute rate constants for the reactions between amino and alkyl radicals at 298 K

Abstract

The absolute rate constants for the reactions of NH2 radicals with ethyl, isopropyl, and t-butyl radicals have been measured at 298 K, using a flash photolysis-laser resonance absorption method. Radicals were generated by flashing ammonia in the presence of an olefin.A new measurement of the NH2 extinction coefficient and oscillator strength at 597.73 nm was performed. The decay curves were simulated by adjusting the rate constants of both the reaction of NH2 with the alkyl radical and the mutual interactions of alkyl radicals. The results are k(NH2 + alkyl) = 2.5 (f0.5), 2.0 (f0.41, and 2.5 (f0.5) X 1Olo A4-l.s-l for ethyl, isopropyl, and t-butyl radicals, respectively. The best simulations were obtained when taking k(alky1 + alkyl) = 1.2,0.6, and 0.65 X 10IOM-'-s-l for ethyl, isopropyl, and t -butyl radicals, respectively, in good agreement with literature values.

A kinetic study about the reactions of NH(X3Σ−) with hydrocarbons part 1: Saturated hydrocarbons and acetaldehyde

“…No data could be found about the reaction of NH2 with CH,, C3H7 and C H 3 C 0 in the literature. For the reaction of NH2 with C2H5 a value of 2.5-IOl3 cm3/mol s at room temperature is reported by Demissy and Lesclaux [24]. The value for k -2 obtained in this work is about eight orders of magnitude lower than that reported in [24].…”

“…For the reaction of NH2 with C2H5 a value of 2.5-IOl3 cm3/mol s at room temperature is reported by Demissy and Lesclaux [24]. The value for k -2 obtained in this work is about eight orders of magnitude lower than that reported in [24]. Hence direct H abstraction from NH2 by C2H5 in the reaction of C2H, with NH2 plays only a minor role at room temperature.…”

On the abundance of non-cometary HCN on Jupiter

“…1e) is produced in our model through the reaction NH 2 + C 2 H 5 + M → C 2 H 5 NH 2 + M, with loss due to photolysis and abstraction by H atoms to form C 2 H 5Ṅ H. These pathways are consistent with previous suggestions. 38 Although the rate coefficient for the reaction of C 2 H 5 with NH 2 has been measured, 87 the relative roles of addition and disproportionation are not clear, and the assumed relative rates of the different product pathways for this reaction can affect our results. To prevent large quantities of ethylamine from building up in our cell, we have assumed that NH 2 +…”

“…These pathways are consistent with previous suggestions. 38 Although the rate coefficient for the reaction of C 2 H 5 with NH 2 has been measured, 87 the relative roles of addition and disproportionation are not clear, and the assumed relative rates of the different product pathways for this reaction can affect our results. To prevent large quantities of ethylamine from building up in our cell, we have assumed that NH 2 + C 2 H 5 / NH 3 + C 2 H 4 is about three times faster than NH 2 + C 2 H 5 / C 2 H 5 NH 2 .…”

Reactivity and kinetic properties of the NH2 radical in the gas phase

“…This value is probably too high since they used an overestimated value of k15 in the calculations. Demissy and Lesclaux [53] determined the rate constants of Reactions (12), (14) and (16) by the flash photolysis of an~nonia in the presence of small amounts of olefins and by computer simulation of the above mechanism. The experimental conditions were very favourable since Reaction (II) was negligible and Reaction (8a) was slow at the low total pressure used (~ 3 Torr).…”