Chlorendic anhydride

Chlorendic anhydride (CAS 115-27-5, EC 204-077-3), also known commercially as HET anhydride, is a chlorinated cyclic anhydride derived from hexachlorocyclopentadiene. It carries no assigned E-code and is classified under HS code 29172090. Its high chlorine content makes it a reactive flame-retardant intermediate rather than an additive.

In epoxy resin formulations, chlorendic anhydride acts as a curing agent, chemically bonding into the polymer network to deliver inherent flame retardancy without relying on a separate additive. This approach is used in printed circuit boards, flame-retardant laminates, and structural composites for aerospace and automotive applications where burn resistance must survive processing conditions.

Chlorendic anhydride is supplied as a white crystalline powder or chunks and is subject to REACH registration requirements within the European Economic Area. Procurement teams should confirm substance compliance status and any applicable restrictions before sourcing. Standard industrial packaging applies; consult your supplier for available lot sizes and documentation.