Nature of (η, γ) and (I.T.)-Activated Bromine Reactions in Liquid Isomers of Hexane

Abstract

The 82 Br organic yields from 82m Br (I. T.) 82 Br activations were found to be generally 1.7 to 1.8 times the yields of 80 "Br, 82 m Br, and 82 Br from (n, y)-induced reactions in all of the liquid isomers of hexane at Br, concentrations above 0.05 m.f. Scavenger curves and product distributions were found and evaluated with regard to several existing hypotheses of the mechanisms of liquid state bromine reactions resulting from nuclear activation. A possible correlation was found between organic yields at given Br a concentrations and G-values for total organic radicals produced by X-rays in the hexanes. This and other considerations support the Auger electron reaction hypothesis for the reactions and systems studied. Zusammenfassung Die Ausbeuten an organisch gebundenem 82 Br waren bei der Reaktion 8anl Br (I.T.) 82 Br im allgemeinen 1,7 bis 1,8 mal so groß wie die Ausbeuten an Verbindungen von """Br, 82m Br und 82 Br nach (η, γ) Reaktionen in allen flüssigen Hexanisomeren und bei Bromkonzentrationen > 0,05 m.f. Es wurden Fängerk «rwenerhalten und die Verteilung der Reaktionsprodukte ausgewertet entsprechend den verschiedenen Hypothesen, die über Mechanismen der Reaktionen nach der Aktivierung von Brom bekannt geworden sind. Es wird eine Beziehung vermutet zwischen den Ausbeuten an organischen Verbindungen bei den gegebenen Bromkonzentrationen und den G-Werten für die Summe der organischen Radikale, die durch Röntgenstrahlen in den verschiedenen Hexanen erzeugt wurden. Diese Beziehung und andere Überlegungen stützen die Hypothese über die Bedeutung der Amperelektronen bei den hier betrachteten Reaktionen und Systemen. R6sum£ On a trouv6 que le rendement en 82 Br organique de Ia r6action e2m Br (I.T.) 82 Br etait en g6n6ral 1,7 a 1,8 fois plus grand que les rendements en 80m Br, 82m Br et 82 Br des factions (η, γ) induites dans les divers isomeres liquides d'hexane pour des concentrations en Br 2 supirieures k 0,05 m.f. On a obtenu certaines courbes de balayage et mesure la distribution des produits que l'on a par ailleurs calcul6e conform6ment λ differentes hypothfeses connues sur le n^canisme de reaction du brome a l'etat liquide apr£s activation nucleaire. On trouve une certaine correlation entre les rendements organiques ä des concentrations donnies en Br a et les valeurs de Ο pour la somme des radicaux organiques produits par les rayons X dans les hexanes. Cette corr61ation et d'autres considerations sont en faveur de l'hypothese d'une action des electrons AUGER pour les factions et dans les systtmes considers.

The Gas to Liquid to Solid Transitions in Halogen Hot Atom Chemistry

“…In previous studies of halogen hot atom chemistry in the condensed state [4][5][6][7], various molecular and caging mechanisms have been assumed, based upon systematic trends and additive studies on product yields. At the present time there is still no good understanding of the (n, y) and (IT) activation processes in the condensed states.If what RICHARDSON and WOLFGANG [2] report for 18 F reactions in CH 3 F is generally true for gas to condensed phase transitions in hot atom chemistry, we should observe a similar effect for bromine reactions activated by radiative neutron capture in CH 3 F, rather than the linear increase found by RICE and WILLARD [3],In this Note we report the effect of density change upon the 80 Br organic product yields from the (η, γ)activated reactions in CH 3 F.A description of our sample making techniques, irradiation procedures, and extraction techniques can be found elsewhere [8][9][10][11], with the following modifications: (1) Small (^ 1 ml), thick, quartz ampoules were filled with sufficient CH 3 F and Br 2 (at 0.0167 mole fraction Br 2 ) so that, when the ampoule was sealed and thawed, the homogeneous mixture was in the liquid state. The ampoules were filled to maximum capacity, minimizing gas phase contributions.…”

“…A description of our sample making techniques, irradiation procedures, and extraction techniques can be found elsewhere [8][9][10][11], with the following modifications: (1) Small (^ 1 ml), thick, quartz ampoules were filled with sufficient CH 3 F and Br 2 (at 0.0167 mole fraction Br 2 ) so that, when the ampoule was sealed and thawed, the homogeneous mixture was in the liquid state. The ampoules were filled to maximum capacity, minimizing gas phase contributions.…”

Recoil and chargin contributions to organic incorporation of radiobromine atoms following neutron activation

“…The quantity F°org(81 /82m/82g) becomes equivalent to F0org(82m/82g). Making the appropriate substitutions in eq 5, the F°org(82g) is given by F°org(82g) = 0.100 [/r(81/82g)P°o,gl, + /"(81/82g)P°org,c] + 0.900(0.495) = 0.438 ± 0.005 (7) Within the limits of experimental error, we have the surprising result that the internal conversion contribution from the 82mBr(IT)82gBr transformation alone accounts for essentially all of the measured 82gBr organic yield (i.e., 0.438 ± 0.005 = (0.900 ± 0.003) X (0.495 ± 0.005) = 0.445 ± 0.005). Thus the first term of eq 7, corresponding to the 81Br(n,y)82gBr transformation is zero, within the range of experimental uncertainty.…”

HALOGEN ATOM REACTIONS ACTIVATED BY RADIATIVE NEUTRON CAPTURE AND /sup 82m/ Br AND /sup 130m/I ISOMERIC TRANSITION. Progress Report No. 2, February 1967--February 1968.

“…Since similar products were produced by the radiative neutron capture (n,y) and isomeric transition (IT) activated reactions of bromine atoms, in ((14' n-hexane5 and the isomers of hexane, support was given to the autoradiation hypothesis. 13 However, for CCl and all the kydrocarbons studied5' 13 the isomeric transition induced organic yields were greater than those of (n, yields with the duration of time ·13 I (IT) I processes were allowed to occur in the liquid phase. Similar effects were reported for8289 -kydrocarbon systems,13 where 828rm (IT) 82Br induced yialds were greater than those of (n,y) activated 828rm.…”