Hydroxylamine Hydrochloride

Introduction

Hydroxylamine hydrochloride is a hygroscopic white crystalline powder (mp 151-152 °C). Explosion of the reagent may occur if it is heated above 115 °C. Hydroxyl­amine hydrochloride is harmful if inhaled or swallowed and it is irritating to eyes, skin, and respiratory tract. [1] The reagent decomposes slowly on contact with moisture and should not be stored above 65 °C. Hydroxylamine as a free base is available in the form of large white flakes or needles; however, due to its instability, commercially available hydroxylamine hydrochloride is used as a stable source of hydroxylamine. [2] This versatile reagent can be prepared by treatment of sulfur dioxide with a cold ­solution of potassium nitrate and potassium acetate under controlled reaction conditions below 0 °C.

For over a century, hydroxylamine hydrochloride has found wide application in organic synthesis including electrophilic substitution reactions, [1] oximation, [3] the ­synthesis of pyrazoles, [4] nitriles, [5] isoxazoles, [6] pyridines, [7] nitrones, [8] etc. It is also used as reducing agent [9] and its importance in areas like bioorganic and medicinal chemistry is also vivid. For example, this reagent greatly facilitates the synthesis of a new class of glycosylated β-amino ­acids, which exhibit good activity against human anti-­malarial parasite Plasmodium falciparum.¹⁰

References

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