The Chemical State of F¹⁸ from the Fast Neutron Irradiation of Fluorobenzene

Abstract

Recent studies of the physical chemistry of the antihistamines2 have been valuable in the correlation of the pharmacological properties of such compounds with certain of their physical properties. It is thought that the ionic radius of an antihistamine may be important in its biological efficiency. This paper describes two techniques which were used to determine the ionic radius of the Histadyl and Pyrilamine cations. The radii obtained by the two methods for Histadyl are in close agreement; however no satisfactory radius could be obtained by the apparent molal volume method for Pyrilamine. Experimental Materials.-Histadyl (X,N-dimethyl-N',2-thenyl-N'-o:pyridylethylenediamine hydrochloride), which was furnished by Eli Lilly and Co., carried the manufacturers specifica-Department

Hot Atom Chemistry of 18 F in Liquid Fluorobenzenes

“…From our results we cannot decide conclusively which particular complex is responsible for the Η-replacement reactions. However, bond energy effects as suggested by BEREI and VASÁROS [6] cannot explain that F-replacement yields are higher than Η-replacement yields in the C6H3F3 isomers (Table 1). ad b) Thermal 18 F-for-H-replacement accounts for 7.1 % of the total yield in gaseous C6H5F [10], a value not quite twice our gasphase yield (4.3%).…”

“…Of particular interest are the mechanisms in aromatic systems for the substitution of hydrogen and halogen atoms and of more complex groups. Earlier work on the hot atom chemistry of 18 F with liquid fluorobenzenes has mainly been limited to the determination of the total organic yield [3][4][5][6]. Results given by BEREI and VASÁROS [7] and VAN DÜLMEN [8,9] for liquid C 6 H S F and C 6 F 6 are:…”

Reactions of radioactive recoil atoms with arenes

“…In case of nonfluorinated arenes, addition of perfluorobenzene or perfluorobiphenyl provides the necessary amount of fluorine atoms. The first 18F experiment was performed 25 years ago by Aten et al 38 and dealt, like some other investigations,39,40 with the determination of the inorganic yield. Anbar and Neta41 measured the yield of labeled substituted products in various fluorobenzenes using distillation as the separation technique.42 More detailed information was gained by van Dulmen and Aten43 in their investigations with perfluorobenzene and perfluorotoluene, by Berei and "Regarding the very high reactivity of thermal fluorine atoms towards gaseous arenes, it can be expected that recoil 18F atoms react with gaseous and liquid arenes as hot atoms and that they will not become thermalised".…”

Reactions of Nucleogenic Chlorine Atoms with Simple Aromatic Compounds

“…[asci]* + ArH -> Ar 38 « + Η· (4) cannot be the only source of Ar 38 Cl. A straight line going through the origin would have been expected in the case of reaction (4), since the radiochemical Ar 38 Cl-yield should be directly proportional to the ArH concentration, provided the absence of any moderator effects.…”

“…Even though a number of investigations have been carried out in which energetic halogen atoms were produced by nuclear processes in aromatic systems [1][2][3][4][5][6][7][8][9][10][11][12][13], the goal of these papers, the nuclear processes and the systems studied were too different to allow comparison and/or generalization. Additional difficulty has been shown to appear with respect to the reproducibility of the organic yield in the case of recoil bromine and iodine in aromatic compounds [3,5,6,7,12,13].…”