β Scribed by J. Kroh; E. Hankiewicz
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Benzene and toluene. saturated with tritiated water, have been subjected to 6OCo y-radiation and UVlight. The yields of H-H substitution are higher for benzene than for toluene. Naphthalene decreases the substitution yield for benzene. The excited molecule mechanism of substitution is discussed.
he study of radiation and photochemically ind substitution reactions of tritium atoms in latic hydrocarbons would appear to be a val-3 method for investigating the behaviour of :a&, ions, and excited molecules in primary esses taking place in the irradiated hydroons. Kroh and PTonka [l] have recently stated tritium substitution yields are higher for benthan for toluene even though toluene displays :her radical yield. Similar results have been ned for deuterium substitutions in the gas e [Z], and indicate that free radicals cannot ' deciding importance in the substitution reacwhich have been investigated so far. In phoically induced reactions, on the other hand, cannot take part since the energy of the W ition applied (A -2300 A) is lower than the .ation energy of the compounds being studied. Icreasing amount of work has been published, [3], quoting high radiation yields of excited s in benzene. It is generally considered that ed states play a very important part in eneransfer phenomena, particularly in solutions e one of the components is benzene, e.g. [4]. recently it has been stated [5, S] that the of proton addition to aromatic molecules is I higher for their excited states (singlet or et) than for the ground ones. resent evidence indicates that excited aroc molecules take part in the investigated subtion reactions. The arguments are derived from direct measurements and by discounthe iikelihood that competing reactions (ionic tdical) occur; they follow from experiments lotochemidally initiated .substitutions and on nfluence of oxygen and naphthalene on radiasubstitution yields.
π SIMILAR VOLUMES
Using an improved set of lactose-auxotrophic Escherichia coli tester strains, the proportion of the six possible transitions and transversions after mutagen exposure was assessed. Mutagenic specificity was determined in plate-incorporation assays using lactose-containing minimal medium for the selec
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