Chlorinated paraffins

Structure of 2,3,4,5,6,8-hexachlorodecane, an example of a short-chained chlorinated paraffin (61% Cl by weight)
Structure of 2,5,6,7,8,11,15-heptachloroheptadecane, an example of a medium-chain chlorinated paraffin (52% Cl by weight)

Chlorinated paraffins (CPs) are complex mixtures of polychlorinated n-alkanes. The chlorination degree of CPs can vary between 30 and 70 wt%. CPs are subdivided according to their carbon chain length into short chain CPs (SCCPs, C10–13), medium chain CPs (MCCPs, C14–17) and long chain CPs (LCCPs, C>17). Depending on chain length and chlorine content, CPs are colorless or yellowish liquids or solids.

Industrial applications

Production of CPs for industrial use started in the 1930s.[1] Currently, over 200 CP formulations are in use for a wide range of industrial applications, such as flame retardants and plasticisers, as additives in metal working fluids, in sealants, paints, adhesives, textiles, leather fat and coatings.[2]

Safety

Short chain CPs are classified as persistent and their physical properties (octanol-water partition coefficient logKOW 4.4–8, depending on the chlorination degree) imply a high potential for bioaccumulation. Furthermore, SCCPs are classified as toxic to aquatic organisms, and carcinogenic to rats and mice. SCCPs (average chain-length of C12, chlorination degree 60 wt%) were categorised in group 2B as possibly carcinogenic to humans from the International Agency for Research on Cancer (IARC).[3] A global ban on SCCPs is being considered under the Stockholm Convention on Persistent Organic Pollutants.

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