Rm Pr Research Articles

The gas‐phase pyrolysis of alkyl nitrites. III. Isopropyl nitrite

AbstractThe rate of decomposition of isopropyl nitrite (IPN) has been studied in a static system over the temperature range of 130–160°C. For low concentrations of IPN (1–5 × 10−5M), 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 (1), since k3 » k2(NO): \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$ {\rm IPN}\begin{array}{rcl} 1 \\ {\rightleftarrows} \\ 2 \\ \end{array}i - \Pr \mathop {\rm O}\limits^. + {\rm NO},i - \Pr \mathop {\rm O}\limits^. \stackrel{3}{\longrightarrow} {\rm AcH} + {\rm Me}. $\end{document} Addition of large amounts of NO (∼0.9 atm) in place of CF4 almost completely suppressed AcH formation. Addition of large amounts of isobutane – t‐BuH – (∼0.9 atm) in place of CF4 at 160°C resulted in decreasing the AcH by 25%. Thus 25% of \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^{\rm .} $\end{document} were trapped by the t‐BuH (4): \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^. + t - {\rm BuH} \stackrel{4}{\longrightarrow} i - \Pr {\rm OH} + (t - {\rm Bu}). $\end{document} The result of adding either NO or t‐BuH shows that reaction (1) is the only route for the production of AcH. The rate constant for reaction (1) is given by k1 = 1016.2±0.4–41.0±0.8/θ sec−1.Since (E1 + RT) and ΔH°1 are identical, within experimental error, both may be equated with D(i‐PrO‐NO) = 41.6 ± 0.8 kcal/mol and E2 = 0 ± 0.8 kcal/mol. The thermochemistry leads to the result that \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta H_f^\circ (i - {\rm Pr}\mathop {\rm O}\limits^{\rm .} ) = - 11.9 \pm 0.8{\rm kcal}/{\rm mol}. $\end{document} From ΔS°1 and A1, k2 is calculated to be 1010.5±0.4M−1·sec−1. From an independent observation that k6/k2 = 0.19 ± 0.03 independent of temperature we find E6 = 0 ± 1 kcal/mol and k6 = 109.8+0.4M−;1·sec−1: \documentclass{article}\pagestyle{empty}\begin{document}$ i - \Pr \mathop {\rm O}\limits^. + {\rm NO} \stackrel{6}{\longrightarrow} {\rm M}_2 {\rm K} + {\rm HNO}. $\end{document}In addition to AcH, acetone (M2K) and isopropyl alcohol (IPA) are produced in approximately equal amounts. The rate of M2K formation is markedly affected by the ratio S/V of different reaction vessels. It is concluded that the M2K arises as the result of a heterogeneous elimination of HNO from IPN. In a spherical reaction vessel the first‐order rate of M2K formation is given by k5 = 109.4–27.0/θ sec−1: \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm IPN} \stackrel{5}{\longrightarrow} {\rm M}_2 {\rm K} + {\rm HNO}. $\end{document} IPA is thought to arise via the hydrolysis of IPN, the water being formed from HNO. This elimination process explains previous erroneous results for IPN.

Synergistic Killing of Bacteria by X-Rays, Ultraviolet Light and P-32 Decay

Interaction of x-ray, ultraviolet (uv) light, and P-32 decay in killing cells was studied for the strain E. coli 15 ${\rm T}^{-}{\rm A}^{-}{\rm U}^{-}{\rm M}^{-}{\rm Pr}^{-}{\rm Tr}^{-}{\rm Sm}^{{\rm r}}$ . It was found that previous P-32 decay was capable of sensitizing the cells to later x- or uv-irradiation. It also resulted in the removal of the shoulders from the corresponding survival curves. Also, previous uv-irradiation sensitized the cells to subsequent killing by P-32 decay. This increase in sensitivity of the cells grown at 1.5 mCi/mg of P was maximum at the pre-uv dose of $1600 {\rm ergs}/{\rm mm}^{2}$ . However, on x-ray exposures the sensitivity of the cells to P-32 decay was not affected up to 24 krads. But when the cells were previously x-irradiated to 36 krads, an observable increase in the sensitivity of the cells to killing by incorporated P-32 decay was noticed.