It was established by chemical degradation that RhCl3·3H2O catalyzed tritiation with HTO occurred with virtually 100% regioselectivity at the ortho-positions of benzamide as well as various anilides and benzoic acid. While tritiation has not been found in the alkyl C–H bond in anilide molecules, in the present experiments tritium was incorporated into the active methylene group of -phenylacetamide. This finding suggests that the present tritiation occurs more readily at polar C-–H+ bonds than at nonpolar ones in accordance with previous results.
Benzoic acid, lithium benzoate, and sodium benzoate were tritiated with virtually 100% regioselectivity in the ortho-positions by the T-for-H exchange reaction with HTO in the presence of RhCl3.3H2O. The labeling of both alkali metal salts was favored by a factor of about 3 over that of benzoic acid. Methyl benzoate was essentially inactive in the present reaction.
Toluene was tritiated singly or as an equimolar mixture with benzene using HTO in the presence of FeCl3 as a catalyst. An o, poriented tritium distribution in the ring of toluene at the initial stage of reaction changed into uniform one with elapse of reaction time at 40 °C, whereas such a rapid change was not observed at 5 °C. By tritiation of the equimolar mixture at 6 °C, the partial rate factors were determined as of=264, mf=7, and pf=189 at the initial stage of the reaction. A possible reaction mechanism is discussed.
Acetanilide and para-substituted acetanilides were tritiated by heating with HTO in the presence of RhCl3.3H2O as a catalyst in an N,N-dimethylformamide solution at 105–107°C for 18 h. Under such conditions, tritium introduced into
the anilide molecules was found at the adjacent ortho positions to the acetamido group with virtually 100% regioselectivity.
The substituent effect on the rate of tritiation was observed.
Authors:K. Oohashi, N. Nogawa, Y. Tanno, and N. Morikawa
The reactivity of recoil tritium in the T-for-H substitution was studied in mixtures of benzene, hexane, cyclohexane or cyclohexane-d12 with lithium carbonate which were irradiated in a reactor. The relative rates per C–H bond of hexane and cyclohexane to benzene were somewhat less than one third. The H/D isotope effect in cyclohexane was given as 1.14.
Authors:N. Nogawa, S. Momose, K. Miyazawa, Y. Makide, K. Oohashi, K. Hashimoto, and N. Morikawa
Optimum conditions were determined for high-yield synthesis of186Re- and188Re-meso-2, 3-dimercaptosuccinic acid complexes applicable to animal injection. The yield was more than 95% under the conditions
used. The bone accumulation of the complexes was remarkable in the biodistributions in mice.
Authors:N. Nogawa, K. Oohashi, H. Matuoka, T. Moki, T. Moriya, and N. Morikawa
Reactions of recoil tritium with benzoic acid, acetanilide and -phenethyl alcohol were studied using the3He/n,p/3H reaction. The tritium distribution in the aromatic ring is approximately uniform in all the irradiated compounds and the tritium activity per C–H bond in the methyl and ethylene groups is 7 to 8 relative to that of the corresponding ring as standard /=100/. These findings are substantially the same as those obtained previously by the6Li/n,/3H reactions, suggesting the same mechanism of tritiation for both recoil reactions. The tritiated parent compounds were obtained in high radiochemical yields; 45% for benzoic acid, 30% for acetanilide, 12% for -phenethyl alcohol.