Carbon‐14‐labeled 2,3,7,8‐ and 1,2,7,8‐tetrachlorodibenzofuran

作者：Allan P. Gray, William J. McClellan, Vito M. Dipinto · 发表于：Journal of Labelled Compounds and Radiopharmaceuticals · 年份：1981 · DOI：10.1002/jlcr.2580180408 · 被引用次数：5 · 研究领域：Radioactive element chemistry and processing、Coordination Chemistry and Organometallics、Organometallic Complex Synthesis and Catalysis

Abstract Both 2,3,7,8‐ and 1,2,7,8‐ tetrachlorodibenzofuran ‐U14C, specific activity 57 mCi/mmol, have been obtained in low yield but at < 98% purity via Pschorr cyclization of o‐phenoxyaniline ‐U14C, chlorination of the resultant dibenzofuran and separation of the tetrachloro isomers by hplc. The lower yields obtained in the Pschorr cyclization of “hot” o‐phenoxyaniline in comparison with the “cold” material are postulated to result from enhanced homolytic relative to heterolytic cleavage of the “hot” diazonium ion leading to a “hot” free radical which polymerizes. The completely anomalous results observed in the attempted palladium acetate‐mediated cyclization of diphenyl ether‐ U14C are likewise interpreted in terms of the intervention of a “hot” free radical.