Diisopropyl fluorophosphate

Another homologue of this series of esters, Diisopropyl fluorophosphate, was developed by British scientist Bernard Charles Saunders.

On his search for compounds to be used as chemical warfare agents, Saunders was inspired by the report by Lange and Krueger and decided to prepare the new homologue which he labeled PF-3.

It was often mixed with mustard gas, forming a more effective mixture with significantly lower melting point, resulting in an agent suitable for use in cold weather.

In military research, due to its physical and chemical similarities and comparatively low toxicity, it is used as a simulant of G-agents (GA, GB, GD, and GF).

DFP and other analogous organophosphate neurotoxins are inactivated by the enzyme paraoxonase, which is present in widely varying levels in humans.

It is marketed under many brand names including Difluorophate, Diflupyl, Diflurphate, Dyflos, Dyphlos, Fluropryl, Fluostigmine, Neoglaucit.

Reaction of the DIFP with a serine protease
Protease-Inhibitor Complex.
Crystal structure of Herpes Simplex Virus Protease/Inhibitor (DFP) complex. The active site serine (yellow) has undergone phosphonylation resulting in irreversible inhibition. Rendered from PDB 1AT3 .