Calcium hypochlorite

History

Charles Tennant and Charles Macintosh developed an industrial process in the late 18th century for the manufacture of chloride of lime, patenting it in 1799.

Uses

Sanitation

Calcium hypochlorite is commonly used to sanitize public swimming pools and disinfect drinking water. Generally the commercial substances are sold with a purity of 65% to 73% with other chemicals present, such as calcium chloride and calcium carbonate, resulting from the manufacturing process. In solution, calcium hypochlorite could be used as a general purpose sanitizer, but due to calcium residue (making the water harder), sodium hypochlorite (bleach) is usually preferred.

Organic chemistry

Calcium hypochlorite is a general oxidizing agent and therefore finds some use in organic chemistry. For instance the compound is used to cleave glycols, α-hydroxy carboxylic acids and keto acids to yield fragmented aldehydes or carboxylic acids. Calcium hypochlorite can also be used in the haloform reaction to manufacture chloroform. Calcium hypochlorite can be used to oxidize thiol and sulfide byproducts in organic synthesis and thereby reduce their odour and make them safe to dispose of. The reagent used in organic chemistry is similar to the sanitizer at ~70% purity.

Production

Calcium hypochlorite is produced industrially by reaction of moist slaked calcium hydroxide with chlorine gas. The one-step reaction is shown below:

:

Industrial setups allow for the reaction to be conducted in stages to give various compositions, each producing different ratios of calcium hypochlorite, unconverted lime, and calcium chloride.

Reactions

Calcium hypochlorite reacts rapidly with acids producing calcium chloride, chlorine gas, and water: :

Safety

It is a strong oxidizing agent, as it contains a hypochlorite ion at the valence +1 (redox state: Cl+1).

Calcium hypochlorite should not be stored wet and hot, or near any acid, organic materials, or metals. The unhydrated form is safer to handle.

References

References

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6. (1982). "Oxidative cleavage of α-diols, α-diones, α-hydroxy-ketones and α-hydroxy- and α-keto acids with calcium hypochlorite [Ca(ClO)₂]". Tetrahedron Letters.
7. (1900). "Practical Organic Chemistry for Advanced Students". Macmillan & Co..
8. (1995). "Prudent Practices in the Laboratory: Handling and Disposal of Chemicals". The National Academies Press.
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10. {{cite encyclopedia. (2010). Wiley-VCH
11. Ca(OCl)2, dibasic calcium hypochlorite {{chem2. Ca3(OCl)2(OH)4 (also written as {{chem2. Ca(OCl)22Ca(OH)2), and dibasic calcium chloride {{chem2. Ca3Cl2(OH)4 (also written as {{chem2. CaCl22Ca(OH)2).W.L Smith, Inorganic Bleaches, Production of Hypochlorite in ''Handbook of Detergents,Part F'', (2009) Ed. U Zoller and Paul Sosis, CRC Press, {{ISBN. 978-0-8247-0349-3
12. Aleksandrova, M.M.; Dmitriev, G.A.; Avojan, R.L.. (1968). "The probable model of the crystal structure of the twobase calcium hypochlorite". Armyanskii Khimicheskii Zhurnal.