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

The pyrolysis of n-propyl nitrate and tert-butyl nitrite at very low pressures (VLPP technique) is reported. For the reaction the high-pressure rate expression at 300°K, log k1 (sec−1) = 16.5 − 40.0 kcal/mole/2.3 RT, is derived. The reaction was studied and the high-pressure parameters at 300°K are log k2(sec−1) = 15.8 − 39.3 kcal/mole/2.3 RT. From ΔS1,−10 and ΔS2,−20 and the assumption E−1 and E−2 ⋍ 0, we derive log k−1(M−1·sec−1) (300°K) = 9.5 and log k−2 (M−1·sec−1) (300°K) = 9.8. In contrast, the pyrolysis of methyl nitrite and methyl d3 nitrite afford NO and HNO and DNO, respectively, in what appears to be a heterogeneous process. The values of k−1 and k−2 in conjunction with independent measurements imply a value at 300°K for of 3.5 × 105M−1·sec−1, which is two orders of magnitude greater than currently accepted values. In the high-pressure static pyrolysis of dimethyl peroxide in the presence of NO2, the yield of methyl nitrate indicates that the combination of methoxy radicals with NO2 is in the high-pressure limit at atmospheric pressure.