Preparation of trans-Difluorodiazine

Abstract

Abstract : Pure trans-difluorodiazine can readily be prepared in about 45% yield from commercially available tetrafluorohydrazine and aluminum chloride: 3N2F4 + 2AlCl3 yields 3N2F2 + 3Cl2 + 2AlF3. Consistent yields of 45-48% trans-N2F2 were obtained from both batch and flow reactions involving excess AlCl3 and N2F4 at 15-20 mm. and -80 with contact times ranging from 0.5 to 5 min. Because of the necessarily low pressures, flow systems are strongly recommended. A convenient reactor can be prepared by subliming anhydrous AlCl3 (15-20 g. for 30-50 mmoles of N2F4) onto the side-arm walls of a conventional Pyrex U-tube (16 mm. o.d.) by heating the material in the bottom of the vessel with a bunsen burner. It is necessary to activate the AlCl3 before use by keeping it in contact with a small quantity of N2F4 at room temperature for 30 min. The product is purified by washing with aqueous caustic soda followed by trap-to-trap vacuum distillation. (Extracted)