Effects of Irradiation Temperature and Irradiation Time on ¹³N-Compounds Produced by Recoil Protons in Benzene and Cyclohexane

Abstract

The chemical state of nitrogen-13 produced by the 13 C(p, n) 13 Ν reaction by recoil protons in benzene and cyclohexane in the condensed phase was studied as a function of irradiation temperature in the range of -55° to +25°C, and of irradiation time from 5 to 20 min. The yields of HC' 3 N and C 6 H X C' 3 N showed remarkable phase dependence in both hydrocarbon media, i. e., the yield of HC 13 Ν increased and that of 13 N-nitrile decreased abruptly with an increase in irradiation temperature at the melting point. 13 N-ammonium and 13 N-amines like ethyl amine were produced in considerably greater amount in cyclohexane than in benzene, with a relatively small temperature dependence. These results suggest that hot 13 Ν forms C 13 Ν and 13 NH radicals as primary species, alongside with the hot insertion of 13 Ν into C-Η bonds. The degree of formation of C 13 N and 13 NH radicals seems to depend on the type of substrates, corresponding to the energies required to form these radicals by abstraction of a carbon or hydrogen atom. The data also suggest that C 13 N and 13 NH radicals undergo characteristic cage reactions depending on the phase.

Phase and (H/D)-lsotope Effects in the Radiochemical Yields of 13N-Compounds Formed in Pile- Irradiated Benzene and Cyclohexane

“…Pile irradiation technique and counting condition were the same as described in the previous papers [1,2,4].…”

“…An irradiation temperature effect in the yield of l3 Nspecies has been observed in pile-irradiated acetone and diethyl ether, in which the logarithm of the yield of 13 NH 3 has been found to run parallel with that of the reciprocal viscosity of the media [4].…”

“…It has been reported in the previous papers [1,2] that 13 Ν atoms produced by the 12 C(p, γ) 13 Ν or 13 C(p, n) 13 N reaction due to recoil protons in benzene and cyclohexane irradiated in a reactor are found in the various final compounds such as HCN, C 6 H S CN, NH 3 and C 6 H S NH 2 and that the yields showed a large phase effect. Drastic increase in the yields of light species such as HCN and NH 3 and decrease in the yields of heavy species such as C 6 H 5 CN and C 6 H S NH 2 have been found, by changing the phase of irradiated media from solid to liquid.…”

“…Drastic increase in the yields of light species such as HCN and NH 3 and decrease in the yields of heavy species such as C 6 H 5 CN and C 6 H S NH 2 have been found, by changing the phase of irradiated media from solid to liquid. This intriguing result has led us to propose a reaction mechanism forming the final products [2], which takes into account the differing diffusion rate of the radiolytic products from the substrate molecules [3], i.e., hydrogen atoms and residual radicals, produced in the vicinity of the thermalized CN or NH radical, formed as the primary product by the temperature independent abstraction reaction between a hot nitrogen atom and the collided molecules.…”

Chemical States of 13N Resulting from the Nuclear Reaction 14Ν (n, 2n)13N

“…The yields of individual fractions do not depend on the irradiation duration. SENSUI found for the nuclear reaction 13 C(p, n) 13 N a large negative temperature dependence of the yield of 13 NH 3 in acetone and diethyl ether [20]. We investigated the dependence of the 13 N distribution on irradiation temperature for nitrobenzene in the temperature range from -198°C to 100°C.…”