Hydroxylamine hydrochloride
[CAS# 5470-11-1]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Hydrazine and hydroxylamine and their inorganic salts
• Name: Hydroxylamine hydrochloride
• Synonyms: Hydroxylammonium chloride; Oxammonium hydrochloride
• Molecular Formula: H₃NO.HCl
• Molecular Weight: 69.49
• CAS Registry Number: 5470-11-1
• EC Number: 226-798-2
• SMILES: NO.Cl

Properties

• Density: 1.67
• Melting point: 155-158 °C
• Water solubility: 560 g/L (20 °C)

Safety Data

• Hazard Symbols: GHS05;GHS08;GHS07;GHS09 Warning
• Risk Statements: H290-H302+H312-H302-H312-H315-H317-H319-H351-H373-H400-H412
• Safety Statements: P203-P234-P260-P261-P264-P264+P265-P270-P272-P273-P280-P301+P317-P302+P352-P305+P351+P338-P317-P318-P319-P321-P330-P332+P317-P333+P317-P337+P317-P362+P364-P390-P391-P405-P406-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin sensitization	Skin Sens.	1	H317
Skin irritation	Skin Irrit.	2	H315
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Acute toxicity	Acute Tox.	4	H312
Carcinogenicity	Carc.	2	H351
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H302
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Germ cell mutagenicity	Muta.	2	H341
Acute toxicity	Acute Tox.	3	H301
Serious eye damage	Eye Dam.	1	H318
Specific target organ toxicity - single exposure	STOT SE	2	H371
Eye irritation	Eye Irrit.	2A	H319

• Transport Information: UN 2923

Discovery and Applications

Hydroxylamine hydrochloride is a white crystalline solid with the chemical formula NH2OH·HCl. It is a salt formed from hydroxylamine and hydrochloric acid, characterized by its strong reducing properties. Hydroxylamine was first synthesized in the 19th century, with its discovery attributed to German chemist Emil Fischer and his colleagues. They described its formation through the reduction of nitrous oxide or the hydrolysis of nitramine compounds. The hydrochloride salt was subsequently produced to enhance its stability and solubility in aqueous solutions, making it a useful reagent in various chemical applications.

Hydroxylamine hydrochloride is primarily employed as a reducing agent in organic synthesis. Its ability to donate electrons makes it invaluable in a range of reactions, particularly in the conversion of carbonyl compounds to their corresponding oximes. The reaction involves the nucleophilic attack of hydroxylamine on the carbonyl carbon, leading to the formation of oximes, which are essential intermediates in the synthesis of various pharmaceuticals, agrochemicals, and fine chemicals. The versatility of hydroxylamine hydrochloride extends to its role in the preparation of hydroxamic acids, which are significant for their bioactivity and applications in drug discovery.

In addition to its applications in organic synthesis, hydroxylamine hydrochloride serves as a crucial reagent in analytical chemistry. It is widely used in the determination of aldehydes and ketones, as the resulting oxime derivatives can be easily characterized and quantified. Furthermore, hydroxylamine hydrochloride is utilized in the analysis of nitrites and nitrates, where it reacts to form azo dyes, providing a colorimetric method for detection. This property is particularly useful in environmental monitoring, allowing for the assessment of nitrite levels in water samples.

The compound also finds applications in the field of polymer chemistry. Hydroxylamine hydrochloride acts as a chain transfer agent in the polymerization of various monomers, enabling the production of polymers with specific molecular weights and functionalities. Additionally, it is employed in the modification of polysaccharides and other biopolymers, enhancing their properties for specific applications in food, pharmaceuticals, and materials science.

Moreover, hydroxylamine hydrochloride is significant in the pharmaceutical industry. It has been investigated for its potential therapeutic effects, particularly in the treatment of certain diseases. Research has shown that hydroxylamine derivatives possess anti-inflammatory and antimicrobial properties, making them candidates for drug development. Hydroxylamine hydrochloride has also been explored for its role in the synthesis of prodrugs, which can enhance the bioavailability and therapeutic efficacy of active pharmaceutical ingredients.

Despite its utility, the handling of hydroxylamine hydrochloride requires caution due to its potential hazards. It is classified as a hazardous substance, with the potential for skin and eye irritation. Additionally, it is important to note that hydroxylamine can decompose under certain conditions, leading to the release of nitrogen oxides, which are toxic. Therefore, proper safety measures and regulatory compliance are essential when working with this compound in industrial and laboratory settings.

In summary, hydroxylamine hydrochloride is a valuable chemical reagent with diverse applications in organic synthesis, analytical chemistry, and the pharmaceutical industry. Its reducing properties and ability to form stable derivatives make it a key player in various chemical reactions and processes. Ongoing research continues to explore its potential in drug development and environmental applications, highlighting its significance in modern chemistry.

References

2025. Oxidative stress-induced degradation of Brinzolamide: Isolation and in-depth characterization of unique hydroxylamine and oxime degradation products. Journal of Pharmaceutical and Biomedical Analysis, 251.
DOI: 10.1016/j.jpba.2024.116491

2025. Revisit the role of hydroxylamine in sulfur-driven autotrophic denitrification. Water Research, 270.
DOI: 10.1016/j.watres.2024.122596

2024. Hydroxylamine hydrochloride-driven activation of NiFe2O4 for the degradation of phenol via peroxymonosulfate. Environmental Research, 263.
DOI: 10.1016/j.envres.2024.120057