Halogen-free cyclic phosphate ester(s) useful as flame retardants

摘要

New halogen-free cyclic phosphate esters are of formula (I), where R = 2-, 3- or 4-methylphenyl or 2,3-, 2,4-, 2,5- or 3,4-dimethylphenyl. (I) are prepared by: (1) allowing 2,2-dimethyl-1,3-propane-diol (II) to react with phosphorus oxychloride (POCl3) to form cyclic phosphate ester chloride; and then (2) reacting this with a phenol R-OH for 2-12 hours at 20-150 deg C in the presence of a catalyst. Preferably the reactions are carried out in an inert solvent and/or stoichiometric amounts of suitable tertiary amines as hydrogen chloride (HCl) acceptor. A catalyst may also be used in stage (1).