Hot Atom Chemistry of <sup>18</sup> F in Liquid Fluorobenzenes

Briνkman, G. A.; Veenboer, J.Th.; Visser, J. P.; Lindner, L.

doi:10.1524/ract.1977.24.4.161

Cited by 11 publications

(33 citation statements)

References 10 publications

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“…Ij seems the best choice as a scavenger. None of the additives decrease the yield of the unidentified products to a large extent, indicative of the fact that they are formed by the reactions of hot recoil atoms as was previously proposed [1][2][3].…”

Section: Anilinesupporting

confidence: 51%

“…Results and discussion "F-recoil atoms It has been Stated previously that hot atoms have a very high reactivity with aromatic Compounds and that they will probably not reach the thermal energy region [1,2] (unless moderated by an inert additive [4]). It is therefore not surprising that the addition of scavengers will often not greatly affect the yields of " F labeled Compounds.…”

Section: Methodsmentioning

confidence: 99%

“…We arrived at the conclusion that '' F-recoil atoms are very reactive in these systems and probably will not even become thermal [1,2], Hot '®F atoms seem to lead to the replacement and abstraction of aromatic bound atoms and groups, and to the formation of degradation and Polymerie Compounds. It is supposed [1][2][3][4][5][6] that the formation of excited n-or a-complexes are involved in the reactions leading to these products. Thermal '®F atoms also display a high reactivity towards gaseous aromatic Compounds, while forming long-lived ' ® F containing complexes [4].…”

Section: Introductionmentioning

confidence: 99%

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Reactions of Recoil F- and Cl-Atoms with Liquid Aromatic Compounds and Additives

1980

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Hot atom chemistry I Recoii labeling / "F / " "a j Aromatic substitution / Scavengers AbstractThe effect of additives such as elemental halogens, alkyliodides, satuiated and unsatuxated hydrocarbons, aniline, and diphenylpicrylhydrazil (DPPH) on the product yields for the reactions of "F, """CI, and "C1 recoii atoms with C.HSF and QH^CL was investigated. The behaviour of these additives as scavengers for thermal processes are compared with self-scavenging properties of aromatic Compounds towards halogen atoms.

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Section: Anilinesupporting

confidence: 51%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reactions of Recoil F- and Cl-Atoms with Liquid Aromatic Compounds and Additives

1980

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“…The experiments mentioned above indicated that the relative position of the substituents in the aromatic ring had no significant effect on the reactions of T [2,3,5], "F [4] or on the ^'Cl-for-CHs repiacement [6]. A measurable difference was, however, found in the case of hot ^'a-for-Cl repiacement in dichlorobenzenes [7], Higher yields from ortho and para compared with meta isomers are well in line with preliminary results [8].…”

mentioning

confidence: 97%

Substituent Effects in Hot Replacement by Recoil Halogens

1985

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Recoil ^'Cl/Hot atom chemistry IHot repiacement/Benzene derivatives SummaiyThe effect of the second substituent on the repiacement of Cl, F, NO, and OH in benzene derivatives by recoil "O was studied. The results show that the chemical nature as well as the relative Position of the second substituent in the benzene ring are of significance, except in the case of "Cl-for-F repiacement.A clear distinction between the different factors Controlling the energetic reactions of recoil halogens in Condensed systems cannot always be achieved. One of the drawbacks of comparing the absolute yields measured in individual systems is the consideration that different moderator properties of the given medium may result in different energy spectra of the reacting atoms [1]. This influence of the medium can be excluded by investigating intramolecular competition reactions, i. e. by comparing the yields of different reactions using one and the same molecule. Disubstituted benzene derivatives offer such a possibility to establish the main factors Controlling the hot repiacement of different atoms and groups in the aromatic ring. This idea was first used by WHITE and ROWLAND [2] to study the repiacement of various atoms and groups by recoil tritium in solid substituted benzoic acids. Though the results showed an increasing repiacement yield with decreasing bond energy of the replaced atom or group, the relative position of the substituents in the aromatic ring was not found to play any significant role. Later, SATO [3] showed that in liquid chlorotoluenes tritium replaces chlorine in a higher extent than the methyl group, conesponding to the lower bond energy of the former. have carried out extensive studies on T, "F and ^'Cl reacting with liquid difluorobenzenes, dichlorobenzenes and chlorotoluenes. They found a preference for Cl repiacement compared with that of CHa also in the case of recoU ^'Cl [6].The experiments mentioned above indicated that the relative position of the substituents in the aromatic ring had no significant effect on the reactions of T [2,3,5], "F [4] or on the ^'Cl-for-CHs repiacement [6]. A measurable difference was, however, found in the case of hot ^'a-for-Cl repiacement in dichlorobenzenes [7], Higher yields from ortho and para compared with meta isomers are well in line with preliminary results [8].In the present work we used liquid disubstituted benzene derivatives to study the repiacement of F and Cl atoms as well as NOz and OH groups by recoil ^'Cl. Our aim was to establish the role of the chemical nature of the second substituent and of its relative position in the aromatic molecule during the course of these reactions.The possibility of the secondary geminate recombinations between the thermalized recoil atom and the radical produced at its first encounter with the medium molecule is another factor greatly complicating the investigation of the liquid systems [9 -11 ]. It was, however, shown in our earlier studies [9,12,13] that the role of such recombinations in aromatic hydrocarbons can effectively...

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“…[27]) and also by others [28][29][30][31][32][33][34][35][36][37][38], the isomer distribution is not exactly statistical. The deviation shows a definite trend (see Fig.…”

Section: Hydrogen Replacementmentioning

confidence: 92%