4-Nitrophenyldiazonium tetrafluoroborate

A solution of 4-nitrophenyldiazonium tetrafluoroborate (60, 237 mg, 1 mmol) in acetone (300 ml) was added dropwise to the stirred solution of tetrakis(acetonitrile)copper(l) perchlorate (165 mg, 5 mmol, 5 eq.) and copper(ll) perchlorate tetrahydrate (135 mg, 4 mmol, 4 eq.) in acetone (200 ml) containing acetonitrile (3.75 ml, 0.75 vol%) and water (16 pi, 0.9 mmol) at 25 °C under nitrogen. The reaction mixture was stirred for 30 minutes, diluted with diethyl ether (20 ml) and 5% aqueous ammonia solution (20 ml). The resulting mixture was stirred for 10 min. The aqueous layer was separated and extracted with diethyl ether (5x20 ml). The combined organic phases were dried (Na2S04), and evaporated to dryness. The residue... 

This substance is best represented as the diazonium zwitterion 26 since its chemistry is analogous to diazonium ion chemistry rather than to diazoalkane chemistry. Because 26 is a diazonium compound without a counterion, it allows one to study pure diazonium ion chemistry. The diazonium nature of 26 is confirmed by its N- and C-NMR spectra compared to those of p-nitrophenyldiazonium tetrafluoroborate (27) and diazocyclopentadiene (28) (78JA4974). Chemical shifts of the carbon attached to the central nitrogen are in 26,5112.2 from Mc4Si in 27,6 121.8 and in 28,6 72.2. The central nitrogen shift is 6 146.0 from HNO3 for 26,152.2 for 27, and 106.2 for 28. The terminal nitrogen is d 59.4 for 26, 57.1 for Tl, and — 8.8 for 28. 

Treatment of L-ascorbic acid with p-nitrophenyldiazonium tetrafluoroborate gives the diazoderivative (46). 4 it has been shown that the 3,4-enediol form of 2,3-diketogulono-5-lactone is formed in about 10% 3deld from dehydroascorbic acid under nitrogen in neutral solution. ... 

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