Phosphorus-based alkylating agents

Halogen-free phosphorus based ionic liquids can be produced by direct reaction of (1) phosphines with sulphates (2) tertiary phosphines or imidazoles with alkylating agents such as trialkylphosphates, dialkylphosphonates andmonoalkylphosphinates or (3) phosphines with acid (Scheme 7). 

Organophosphorus compounds (OPs) are utilized on a large scale as flame retarding agents and plasticizers in a variety of products, such as plastic materials, rubbers, varnishes, lubricants, hydraulic fluids, and other industrial applications. This family of chemicals consists of alkylated and arylated phosphate or phosphonate esters and related compounds such as phosphites, phosphines, and related dimeric forms as well as ionic forms (Figure 31.2). " The low volatility of phosphoric acid and derivatives makes it the preferred choice of the phosphorus based FRs. These FRs are most effective in polymers that char readily. Also halogenated phosphate esters, such as tris(l-chloroisopropyl) phosphate (TCPP), and tris(2-chloroethyl) phosphate (TCEP), are widely used. These combine the properties of both the halogen and the phosphorus compounds. 

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