Neutral phosphorus agents

Fontaine, G., Bourbigot, S., and Duquesne, S. 2008. Neutralized flame retardant phosphorus agent Facile synthesis, reaction to fire in PP and synergy with zinc borate. Polym. Deg. Stab. 93 68-76. 

The traditional method for transforming carboxylic acids into reactive acylating agents capable of converting alcohols to esters or amines to amides is by formation of the acyl chloride. Molecules devoid of acid-sensitive functional groups can be converted to acyl chlorides with thionyl chloride or phosphorus pentachloride. When milder conditions are necessary, the reaction of the acid or its sodium salt with oxalyl chloride provides the acyl chloride. When a salt is used, the reaction solution remains essentially neutral. 

For the purpose of implementing the CWC, toxic chemicals and precursors, which have been identified for the application of verification measures, are listed in Schedules contained in the Annex on Chemicals (for the Schedules, see Chapter 2). Schedule 1 includes chemicals developed, produced, stockpiled, or used as a chemical weapon as defined above, and chemicals structurally close to them. Schedule 2 lists three toxic chemicals not included in Schedule 1 and the degradation products and precursors of these toxic chemicals as well as of those of Schedule 1. Schedule 3 lists four toxic chemicals and precursors not listed in the other Schedules. The Schedules contain mainly organic chemicals with different chemical and physical properties, being neutral chemicals, acids, bases, volatiles, and nonvolatiles, where phosphorus, fluorine, sulfur, chlorine, nitrogen, and oxygen occur frequently. Riot control agents are not included in the Schedules. 

Some very good but specialized and reactive drying agents are potassium hydroxide, anhydrous potassium carbonate, sodium metal, calcium hydride, lithium aluminum hydride, and phosphorus pentoxide. Substances that are essentially neutral and unreactive and are widely used as drying agents include anhydrous calcium sulfate (Drierite), magnesium sulfate, molecular sieves, calcium chloride, and sodium sulfate. 

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