Phosphorus-containing photoinitiators

Phosphorus containing photoinitiators are useful in pigmented as well as in water based systems. Compounds like trimethylbenzoyl diphenyl phosphine oxide and its derivatives generally undergo a-cleavage. 

Other examples of modification in the Michaelis-Arbuzov reaction in the formation of phosphorus-carbon bonds in compounds other than esters are reactions between dichlorophosphites " or difluorophosphites and organic halogen-containing compounds in the presence of iron(III) chloride (reactions 2 and 3). A similar reaction takes place with diethyl fluorophosphite A further variation is that of the photoinitiated reaction, a... 

Later work has, however, shown that the oxidation of P4 by Sg can occur at temperatures below 100°C to give complex mixtures containing as many as 12 different phosphorus sulphides. Such reactions may involve radicals moreover, photoinitiation is sometimes believed to be possible at temperatures as low as 0°C [5,6]. 

---