Sodium hypochlorite
[CAS# 7681-52-9]

Identification

• Classification: API >> Synthetic anti-infective drugs >> Disinfectant antiseptic
• Name: Sodium hypochlorite
• Synonyms: sodium hypochlorite
• Molecular Formula: NaClO
• Molecular Weight: 74.44
• CAS Registry Number: 7681-52-9
• EC Number: 231-668-3
• SMILES: [O-]Cl.[Na+]

Properties

• Density: 1.2 g/mL (Expl.)
• Melting point: 18 ºC (Expl.)
• Boiling point: 40 ºC (decomp.) (Expl.)
• Water solubility: 29.3 g/100 g (0 ºC) (Expl.)

Safety Data

• Hazard Symbols: GHS05;GHS07;GHS09 Danger
• Hazard Statements: H314-H318-H400-H410
• Precautionary Statements: P234-P260-P261-P264-P264+P265-P271-P273-P280-P301+P330+P331-P302+P361+P354-P304+P340-P305+P354+P338-P316-P317-P319-P321-P363-P390-P391-P403+P233-P405-P406-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Skin corrosion	Skin Corr.	1B	H314
Serious eye damage	Eye Dam.	1	H318
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Specific target organ toxicity - single exposure	STOT SE	3	H335
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Acute toxicity	Acute Tox.	4	H302
Skin corrosion	Skin Corr.	1A	H314
Oxidising solids	Ox. Sol.	2	H272

• Transport Information: UN 1791

Discovory and Applicatios

Sodium hypochlorite, with the chemical formula NaOCl, is a widely used disinfectant and bleaching agent known for its powerful oxidizing properties. The history of sodium hypochlorite traces back to the 18th century when French chemist Claude Louis Berthollet discovered its bleaching abilities while working with a solution of chlorine in water. Berthollet’s work led to the establishment of the Javel Company in Paris, which produced sodium hypochlorite and sold it as “Eau de Javel,” marking one of the first large-scale productions of bleach. Its popularity grew rapidly, and by the 19th century, sodium hypochlorite had become recognized for its versatility in disinfection, sanitation, and industrial applications.

The primary use of sodium hypochlorite is in disinfection and sanitation. Due to its antimicrobial properties, it is a key component in household bleach and disinfectant solutions used to clean surfaces, purify water, and disinfect equipment in medical and food industries. Sodium hypochlorite solutions typically contain around 5–6% NaOCl for household use and 10–12% for industrial applications. In healthcare, it serves as an effective agent for eliminating pathogens in hospitals, reducing the risk of disease transmission. In water treatment, sodium hypochlorite is employed to disinfect drinking water and wastewater, effectively removing harmful bacteria, viruses, and other microorganisms.

In the food industry, sodium hypochlorite is used as a sanitizer for equipment and surfaces that come into contact with food, helping prevent contamination and ensuring food safety. The use of NaOCl in food processing adheres to strict safety guidelines, as its residues must be carefully controlled to avoid affecting food quality. Sodium hypochlorite’s role in sanitation extends to agriculture, where it is used to disinfect tools, surfaces, and irrigation systems, minimizing the spread of plant pathogens and ensuring crop health.

Another significant application of sodium hypochlorite is in the textile and paper industries, where it acts as a bleaching agent. In the textile industry, NaOCl is used to bleach fabrics, removing unwanted colors and achieving a brighter white finish. Similarly, in paper manufacturing, it serves as a bleaching agent for paper pulp, contributing to the production of high-quality white paper. The use of sodium hypochlorite in these industries highlights its value in producing materials with specific aesthetic and functional properties.

In addition to its widespread industrial applications, sodium hypochlorite is an important reagent in laboratories, where it is utilized for oxidative reactions. Due to its strong oxidizing nature, it can facilitate the synthesis of certain organic compounds, making it useful in chemical research and development. It is also used in waste treatment processes to neutralize toxic chemicals, including cyanides, through oxidation, thereby reducing environmental pollution.

Although sodium hypochlorite is effective, it requires careful handling due to its reactive nature. It can release toxic chlorine gas if mixed with acids or ammonia, posing health hazards. Additionally, prolonged exposure can damage surfaces and materials, so its use is regulated in industrial and household settings. Proper storage and handling practices help mitigate these risks, ensuring that sodium hypochlorite can be used safely and effectively.

Overall, sodium hypochlorite remains an essential chemical with diverse applications in disinfection, sanitation, industry, and research. Its discovery and development have had a substantial impact on public health, environmental safety, and industrial efficiency. With ongoing improvements in production and handling, sodium hypochlorite continues to play a vital role in modern sanitation and industry.

References

1987. The synergistic relationship between ultrasound and sodium hypochlorite: A scanning electron microscope evaluation. Journal of Endodontics, 13(11).
DOI: 10.1016/s0099-2399(87)80034-1

1987. The use of 4 per cent sodium hypochlorite, with or without ultrasound, in cleansing of uninstrumented immature root canals; SEM study. Australian Dental Journal, 32(3).
DOI: 10.1111/j.1834-7819.1987.tb01856.x

1987. Dentin surface treatments for the removal of the smear layer: an SEM study. Journal of the American Dental Association, 115(1).
DOI: 10.14219/jada.archive.1987.0202