Reaction of Recoil ³⁸Cl Atoms with Liquid Chlorobenzenes

Abstract

The reactions of recoil " C1 atoms (produced in a high flux nuclear reactor) with liquid chlorobenzenes were investigated. The yields of " CI-for-H and Q-replacement reactions, of inorganic Compounds and of polymers were measured in the presence of scavengers, by GLCtechniques and by gelfiltration over Sephadex. In unscavenged chlorobenzene, C^ Hj" C1 (52%) is formed via a direct hot replacement reaction (5%), via a thermal exchange reaction (28%) and via a radiation induced exchange reaction (19%). It is believed that hot H-abstraction leads to the inorganic yield, because this yield is not influenced by the addition of organic unsaturated Compounds. The total organic yield is not in-fluenced by the addition of organic scavengers, but the natura of the products depends considerably on the kind of scavenger used.Ophthalmie Research Institute (lOI)

Reactions of Recoil CI Atoms with Chloroanilines

“…The total yield of the dimeric and trimeric (φ 2 + φ 2 ) compounds as measured by gelfiltration experiments (3.0-4.3%), is somewhat lower than the "missing fraction" (6.3-7.9%) as measured by GLC. We have no reasonable explanation for the differences in these yields, but it is obvious that the yield of the high boiling products is much lower than that observed for other chloroarenes, such as C 6 H s C1, C 6 H 4 C1 2 [17] and C 6 H 4 C1CH 3 [9] irradiated under similar conditions. In general, the yields of high boiling 38 CI labeled compounds formed from substituted benzenes are in the order of 20-30%, but they are lowered in the presence of I 2 or Br 2 [24].…”

“…In the case of various substituted chlorobenzenes, only some percent of 100 Brought to you by | University of California Authenticated Download Date | 6/13/15 6:07 PM dimers were formed, and almost no higher polymers, as was found by gelfiltration experiments [9,17]. However, these results do not necessarily mean that addition of 38 C1 atoms -forming a 38 Cl-cyclohexadienylradicaldoes not take place, because it was found that for several substituted arenes (C 6 H S X, X = CI, N0 2 , CHO) the yield of monomeric species eluting from a gelfiltration column was much higher than the summed yield of the 38 Cl-for-H and X-substitution products, as determined by GLC experiments [17,20]. In the case of the 38 C1/C 6 H S C1/I 2 system, the difference in yield of monomeric compounds as determined by both methods was about 20%.…”

“…3) Polymer yields either as the "missing fraction" in the GLC experiments or by gelfiltration experiments. In the latter case aim column filled with Sephadex LH20 and CHC1 3 as the eluens were used [17]. The radioassay of 3 8 CI in GLC experiments was performed with an on-line flow-through window proportional counter operated at 373 K. 34m Cl containing peaks were trapped and off-line counted with a well type Nal(Tl) crystal by the 2078 keV gamma-ray in order to avoid interference of annihilation radiation of 11 C, produced by the 12 C(%n) n C reaction.…”

“…It can therefore be concluded that the 38 Cl-for-Cl substitution in the pure chloroanilines proceeds via a hot reaction. At higher doses (7.5 kGy), radiation induced effects result in enhanced 38 Cl-for-Cl substitution in C 6 H 5 C1 or in enhanced polymer formation in C 6 H 6 and C 6 F 6 [17,20]. No such effects are noticed in the chloroanilines.…”

“…In the case of the 38 C1/C 6 H S C1/I 2 system, the difference in yield of monomeric compounds as determined by both methods was about 20%. It was proposed that this fraction may consist of C-C 6 H 5 C1 38 C1I-formed by reaction of the 38 Cl-cyclohexadienylradical with I 2 , before dimerization takes place -but no information about the existence and thermal stability of trihalocyclohexadienes is available [17]. It was therefore concluded that I 2 does not prevent the addition of recoil 38 CI atoms to the aromatic ring, but that it prevents the -rather slow passing -dimerization reaction, which is then an indication that the addition proceeds by hot 38 C1 atoms.…”