Identifizierung der Radiolyseprodukte

Abstract

Single-phase Pr 2 CBr was prepared by heating a mixture of PrBr 3 , Pr and C (1 : 5:3) to 1140 • C for 18 d. The crystal structure was investigated by X-ray single crystal diffraction (space group P6 3 /mmc, a = 3.8071 (3), c = 14.7787(12)Å). In the structure the Pr atoms form C-centered octahedra condensed into Pr 2 C sheets via common edges; these sheets are separated by the Br atoms which are in a trigonal prismatic environment of Pr atoms. Pr 2 CBr is a black shiny compound with metallic conductivity. It is a ferromagnet with T c = 13.8(5) K.

Studies on the Chemical Basis of Cellular Radiosensitization by 5-bromouracil Substitution in DNA

“…Thus the t-butanol radical cannot be responsible for all the observed destruction of BU in N 2 -saturated solutions, and it can be concluded that eaq destroys BU irreversibly. This conclusion is supported by previously published data (Adams 1967, Reuschl 1966, Gilbert et al 1967.…”

“…Since the total G(OH' + H-) is -5-6, a fraction of the molecules attacked must be reconstituted to BU and T. Other studies on the radiolysis of aqueous T solutions have shown that OH-adds preferentially to the 5-6 carbon-carbon double bond and that the 5-6 glycol is a major radiolysis product (for example, see Ekert and Monier 1960). The corresponding glycol has been identified as a major product of OH-attack on BU in aqueous solution (Gilbert et al 1967). These data indicate that the reactions of OH-with BU and T are similar and support the hypothesis that OH-adds preferentially to the BU 5-6 carbon-carbon double bond.…”

“…The structure of the BU + eaq-reaction product and its subsequent reactions can be elucidated by combining our results with those of Adams (1967) and Gilbert et al (1967). These authors show that the irradiation of aqueous air-free BU solutions produces bromide ion in yields > G(eaq-).…”

“…It must be emphasized that all of the photolysed BU and IU solutions contained 02, and herein lies a major difference between the studies of the photolysis and radiolysis of BU. We have found (as did Reuschl 1966, Gilbert et al 1967) that no U is produced in y-irradiated BU solution (CBU > 10 -3 M) saturated with air. This result is expected if 02 reacts rapidly with the uracilyl radical produced from the dissociative electron attachment reaction.…”

“…Investigations of the reactions of 6 0 Co-radiation-produced hydroxyl radicals (OH.) with BU in acidic, oxygenated solutions were reported recently (Gilbert, Volkert and Schulte-Frohlinde 1967), and uracil was not identified among the major radiolysis products (these were diisobarbituric acid, isodialuric acid, alloxan, isobarbituric acid and urea).…”