Photodecomposition of piperazine in water by ‘sunlight’ ultraviolet radiation

AbstractA solution of piperazine in water was photochemically oxidised by the dissolved oxygen when irradiated with ‘sunlight’ ultraviolet radiation obtained with a Hanau Q‐300 lamp, or with RUL‐300 nm lamps. Sensitisers (riboflavin, acetone and benzophenone) did not increase the rate of the oxidation induced by the RUL‐300 nm lamps; however, they (especially riboflavin) accelerated the oxidation induced by the Hanau Q‐300 lamp. A large number of products were observed in the sensitised oxidation but they were not analysed further. The irradiation mixture of the non‐sensitised photo‐oxidation, when 65% of the initial piperazine had been transformed, contained piperazine (35%), glycine (approximately 25%) and three unidentified compounds in equal amounts (approximately 13% each); the same products were obtained with both irradiation systems. The photo‐oxidation of piperazine, a metabolite of the fungicide triforine, 1,4‐bis(2,2,2‐trichloro‐l‐formamidoethyl)piperaerazine, could thus be a way for the latter's biodegradation at a surface, or in plant tissues, this biodegradation having already been observed.