PC13 Phosphorus chloride

NaCl — Sodium chloride PC13 — Phosphorus trichloride... 

Benzoic acid reacts less readily with PC13, but energetically with PC15. Since the separation of the excess of the chloride (or oxychloride) of phosphorus is much less simple than removal of excess of thionyl chloride, the latter, which is now cheap and easily obtained, is to be preferred (H. Meyer). 

Chlorine reacts with most elements, both metals and non-metals except carbon, oxygen and nitrogen, forming chlorides. Sometimes the reaction is catalysed by a trace of water (such as in the case of copper and zinc). If the element attacked exhibits several oxidation states, chlorine, like fluorine, forms compounds of high oxidation state, for example iron forms iron(III) chloride and tin forms tin(IV) chloride. Phosphorus, however, forms first the trichloride, PC13, and (if excess chlorine is present) the pentachloride PC15. 

Other halides that are useful in converting alcohols to alkyl halides are PC15, PC13, PBr3, and Pl3, which are acid halides of phosphorus oxyacids. As with thionyl chloride, a weak base often is used to facilitate the reaction. The base acts to neutralize the acid formed, and also to generate bromide ion for SN reactions ... 

J. L. Gay Lussac and L. J, Thenard 2 about 1808, and H. Davy about 1810, prepared liquid phosphorus trichloride, or phosphorous chloride, PC13, by the action of chlorine on phosphorus. If the phosphorus be in excess, the liquid trichloride is formed, and if the chlorine be in excess, the pentachloride is produced as indicated in connection with the la reaction tr s vive between these two elements. H. Davy said ... 

Acid chlorides can be prepared from carboxylic acids using thionyl chloride (SOCl2), phosphorus trichloride (PC13), or oxalyl chloride (C1COCOC1) ... 

Because they are readily available from a number of synthetic reactions, carboxylic acids are the most common starting materials for the preparation of the other members of this family. Conversion of a carboxylic acid to an acyl chloride provides access to any of the other derivatives because the acyl chloride is at the top of the reactivity scale. Bui how can the acyl chloride be prepared from the acid when the acid is lower on the reactivity scale This can be accomplished by using an even more reactive compound to drive the equilibrium in the desired direction. The reagent that is employed in the vast majority of cases is thionyl chloride, SOCl2. Phosphorus trichloride, PC13, and phosphorus pentachloride, PC15, are also used occasionally. Examples are provided in the following equations ... 

The formation of H3PO2 by hydrolysis of elemental phosphorus has been noted, as has been the preparation of H3P03 by hydration of P406 phosphorous acid is somewhat more conveniently prepared by hydrolysis of phosphorus(III) chloride, PC13. 

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