Bronopol
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217535912
2008-06-06T14:01:34Z
Edgar181
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removing bad rotating image
{{Chembox new
| Name = Bronopol
| ImageFile = Bronopol.png
| ImageSize = 200px
| ImageName = Bronopol
| IUPACName = 2-bromo-2-nitropropane-1,3-diol
| Section1 = {{Chembox Identifiers
| CASNo = 52-51-7
| SMILES = OCC([N+]([O-])=O)(Br)CO
}}
| Section2 = {{Chembox Properties
| Formula = C<sub>3</sub>H<sub>6</sub>BrNO<sub>4</sub>
| MolarMass = 199.989 g/mol
| Appearance = Crystals / crystalline powder, varying from<br\> white to pale yellow depending on the grade
| Density =
| MeltingPt = 130 °C
| BoilingPt = 140 °C (decomposes)
}}
}}
'''Bronopol''' (INN) is a highly active [[antimicrobial]] chemical compound whose [[chemical formula]] is 2-bromo-2-nitropropane-1,3-diol.
Bronopol was invented by [[Boots Group|The Boots Company PLC]], [[Nottingham, England]] in the early [[1960]]s and first applications were as a [[preservative]] for [[pharmaceutical]]s. Bronopol's low [[mammal]]ian [[toxicity]] (at in-use levels) and exceptional activity against [[bacteria]] (especially the troublesome [[Gram-negative]] species) ensured that it became popular as a preservative in many consumer products such as [[shampoo]]s and [[cosmetics]].
Bronopol was subsequently taken up as an effective antimicrobial in many industrial environments such as [[paper mill]]s, [[oil exploration]] and production facilities, as well as cooling water disinfection plants.
World production soared from the tens of [[ton]]nes in the late [[1970]]s to current estimates in excess of 5,000 tonnes. This is quite something considering the effective use-concentration which can be as low as 0.0025% (25 parts per million). Manufacturing today is the business of low cost producers, mainly in [[China]].
Pharmaceutical products containing Bronopol are registered in a number of countries and Bronopol is the subject of a specific [[monograph]] in the [[British Pharmacopoeia]] 1998.
==Applications==
Today, Bronopol is used in consumer products as an effective preservative agent, as well as a wide variety of industrial applications (almost any industrial water system is a potential environment for bacterial growth, leading to [[slime]] and [[corrosion]] problems - in many of these systems Bronopol can be a highly effective treatment).
It is also used as a substitute for [[Formaldehyde]] in [[chemical toilet]]s.
The use of Bronopol in [[personal care products]] ([[cosmetics]], [[toiletries]]) has declined since the late [[1980]]s due to the recognized potential for [[nitrosamine]] formation.
===The Nitrosamine Problem===
Although fairly ubiquitous in our diet and the environment, and even produced within the [[stomach]] from various foodstuffs, many nitrosamines are known or suspect [[carcinogen]]s and therefore should be avoided in manufactured goods.
Nitrosamines are relatively easily produced from secondary [[amines]] and [[amides]] in the presence of [[nitrite]] [[ion]]s (this is why they are formed in-vivo from foodstuffs).
While Bronopol is not in itself a nitrosating agent, under conditions where it decomposes ''([[alkaline]] solution and/or elevated temperatures)'' it can liberate nitrite and low levels of formaldehyde and these decomposition products can react with any contaminant secondary amines or amides in a personal care formulation to produce significant levels of nitrosamines (due to the toxicity of thes substances, the term 'significant' means levels as low as 10s of parts per billion).
Manufacturers of personal care products are therefore instructed by regulatory authorities to 'avoid the formation of nitrosamines' which might mean removing amines or amides from the formulation, removing Bronopol from a formulation, or using nitrosamine inhibitors.
==Physical and chemical properties==
===Appearance ===
Bronopol is supplied as [[crystal]]s or crystalline powder, which may vary from white to pale yellow in colour depending on the grade of material being offered.
===Melting point===
As a pure material, Bronopol has a [[melting point]] of about 130°C. However due to its [[Polymorphism (materials science)|polymorphic]] characteristics, Bronopol undergoes a [[lattice]] rearrangement at 100 to 105°C and this can often be wrongly interpreted as the melting point.
At temperatures above 140°C Bronopol will decompose [[exothermic]]ally releasing [[Hydrogen bromide]] and oxides of [[Nitrogen]].
===Solubility ===
Bronopol is readily soluble in water although the dissolution process is [[endothermic]]. Solutions containing up to 28% w/v are possible at [[ambient temperature]].
Bronopol is poorly soluble in non-polar [[solvent]]s but shows a high affinity for polar organic solvents.
{| border="1" cellpadding="5"
|+ Solubilities at 22–25°C
|-
!Solvent!!%w/v
|-
|align="center"|[[Water]]||align="center"|28
|-
|align="center"|[[Methanol]]||align="center"|89
|-
|align="center"|[[Ethanol]]||align="center"|56
|-
|align="center"|[[Isopropanol]]||align="center"|41
|-
|align="center"|Liquid [[Paraffin]]||align="center"|<0.5
|}
===Partition coefficient===
Study of the solubility data clearly shows that Bronopol has a high affinity for polar rather than non-polar environments. In two phase systems, Bronopol partitions preferentially into the polar (usually aqueous) phase.
{| border="1" cellpadding="2"
|+ Partition coefficients at 22–24°C
|-
!Solvent Combination!!Partition Co-efficient
|-
|align="center"|[[1-Hexanol|Hexanol]]/Water||align="center"|0.74
|-
|align="center"|Liquid Paraffin/Water||align="center"|0.043
|-
|align="center"|[[Chloroform]]/Water||align="center"|0.068
|}
===Stability in aqueous solution===
In aqueous solutions, Bronopol is most stable when the [[pH]] of the system is on the [[acid]] side of neutral. Temperature also has a significant effect on stability in alkaline systems.
===Degradation===
When conditions are such that Bronopol decomposes in aqueous solution, very low levels of formaldehyde are produced. ''Liberated formaldehyde is not responsible for the biological activity associated with Bronopol''.
Amongst other decomposition products detected after Bronopol breakdown are, bromide ion, nitrite ion, Bromonitroethanol and 2-Hydroxymethyl-2-nitropropane-1,3-diol.
==See also==
* [[Bronidox]]
==References==
* [http://www.ascc.com.au/position/position/nitrosamines_in_cosmetics.htm Nitrosamines in Cosmetics, Toiletries and Personal Care Products] The Australian Society of Cosmetic Chemists
* [http://www.verichem.com/uploads/MSDS%20Vericide%20Bronopol.pdf Material Safety Data Sheet for Bronopol]
==External links==
* http://www.furrental.com/pages/fj/bronopol.pdf
[[Category:Bromides]]
[[Category:Nitro compounds]]
[[Category:Alcohols]]
[[nl:Bronopol]]
[[pl:Bronopol]]