Kinetic investigation of the radiation-induced isotopic exchange between iodobenzene and iodine in benzene

Riess, R.W.; Elias, Horst

doi:10.1021/j100700a009

Cited by 1 publication

(2 citation statements)

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“…Such a process, first reported by Noyes,6 was later studied by Anbar and Rein7 who suggested the step Arl + !•*-> Arl* + I • as the major exchange path. This conclusion appears to be inconsistent with observations (see ref 5 and later in this work) indicating that iodine atoms are unreactive with iodoaromatics.…”

Section: Introductioncontrasting

confidence: 89%

“…The isotopic exchange process AI + PI -* AI* + I2 where A is aliphatic, olefinic, or aromatic, can be induced by thermal, radiation-, or photochemical activation. [1][2][3][4][5][6][7][8] The mechanisms of the thermal3 and radia-tion4,5 induced exchange in aromatic iodides have been recently investigated and discussed. However, only partial and controversial information appears to be available concerning the corresponding photochemical exchange process.…”

Section: Introductionmentioning

confidence: 99%

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Photochemically induced isotopic exchange between iodobenzene and molecular iodine

Levy¹,

Meyerstein²,

Ottolenghi³

1971

J. Phys. Chem.

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The photochemical isotopic exchange between iodobenzene and radioactive molecular iodine (ImI) was studied in methylcyclohexane solutions. The limiting exchange yields, <#>EX°, measured at several excitation wavelengths in the uv range were found to be identical with the corresponding deiodination limiting yields, <£de°• This observation and a study of the effects of dissolved oxygen and iodine concentrations suggest that the exchange is initiated by photocleavage of iodobenzene to phenyl (Ph•) and iodine radicals, with 02 and I2 competing in the scavenging of Ph-(fci!+ph./fco,+ph.= 2.1 ± 0.5). The photocleavage of iodobenzene was found to be wavelength dependent in the near-uv range {e.g., 334 and 365 nm), where part of the absorption leads directly to the iodobenzene triplet. It is suggested that dissociation takes place from the lowest excited singlet, but practically not from the triplet state. It is shown that iodine atoms, produced by selective excitation in the visible range, do not exchange with iodobenzene. Neither does excitation of the charge-transfer (CT) complex between iodobenzene and iodine lead to exchange or deiodination.

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Section: Introductioncontrasting

confidence: 89%