Synthese du chloro‐7 nitro‐4 benzooxa‐2 diazole‐1,3 uniformement marque au carbone‐14: Chlorure DE NBD‐ 14 C (U) “chloro ‐ 4 nitro‐7 benzofurazane 14 C (U)”

The little compound, a useful reagent in biochemistry, has been synthasised in 14 steps from barium carbonate 14 C via benzene 14 C‐U, through aniline 14 C‐U, p‐aminobenzene oulfamide 14 C‐U and 2, 6 dichloroaniline 14 C(U). The axidation of the latter into 2,6 dichloronitrosobenzene 14 C(U) is best performed with m‐chloro peroxybenoic acid; other reagents reported in the literature give rise to substantial amounts of 2,6 dichloronitrobenzene 14 C‐U. Sodium axide and the 2,6 dichloronitrosobenzene 14 C(U) give p‐chlorobenzfurazane‐ 14 C(U). Nitration of the latter is conveniently obtained with the complex: trifluoromethan sulfonic acid + nitric acid which gives NBD, chloride 14 C(U) with a 96 % yield. The overall yield is 14% basen on Ba 14 CO 3 . Specific activity: 199 mci/mMoLe ‐ Schelf‐life at − 20°C, as liophilised power kept under vaccum, so for has been good.