Asymmetrically Substituted s-Triazine Phosphonates by One-Step Synthesis

Asymmetrically substituted s-triazine phosphonates with up to three different phosphonate groups C3N3RR'R” with R, R’, R”=PO(OR”’) and R”’=for example, methyl, ethyl, isopropyl or n-butyl are interesting as polymer additives like flame retardants. Typically, these compounds are obtained by multiple synthesis steps. However, this leads to high production costs, which are a disadvantage for commercial use. Here we report the one-step synthesis of mixtures of asymmetrical s-triazine phosphonates which is an easy way to adjust the thermal behaviour and other properties such as viscosities of the compounds. The synthesis is based on a Michaelis-Arbuzov reaction. A complete conversion of the reactants to the target compounds is observed which was proofed by detailed 1H, 13C and 31P NMR investigations and elemental analysis. The thermal behaviour was compared with thermogravimetric analysis (TGA).