When heated to decomposition, Phosphorus pentachloride emits highly toxic fumes of chlorides and chlorine. Will react with water or steam to produce heat and toxic and corrosive fumes. Reacts violently with moisture, chlorine trioxide, fluorine hydroxylamine, magnesium oxides, diphosphorus trioxide, sodium and potassium. Decomposed by water to form hydrogen chloride, phosphoric acids, corrosive materials, and heat. This heat may be sufficient to ignite surrounding combustible materials. Incompatible with water, magnesium oxide, chemically active metals: sodium, potassium; alkalis; aluminum; chlorine dioxide; chlorine; diphosphorus trioxide; fluorine; hydroxylamine; magnesium oxide; 3'-methyl-2-nitrobenzanilide; nitrobenzene; sodium; urea; water.
Yellowish-white tetragonal crystals; pungent odor; fumes in air; deliquescent; density 2.1 g/cm3; decomposes on heating; melts at 166.8°C under the pressure of its own vapor(triple point); sublimes at 160°C; critical temperature 373°C; hydrolyzes in water; soluble in carbon disulfide and carbon tetrachloride.
Phosphorus pentachloride is used as a chlorinating agent in many organic syntheses, such as production of alkyl and acid chlorides. It also is a catalyst in manufacturing acetylcellulose.
Phosphorus pentachloride is prepared by reacting white phosphorus with excess dry chlorine. The white phosphorus is placed over sand in a retort from which air and moisture have been purged. The reaction is indicated by inflaming phosphorus:
P4 + 10Cl2 → 4PCl5
Also, the compound is obtained by reaction of dry chlorine with phosphorus trichloride:
PCl3 + Cl2 → PCl5
Phosphorus pentachloride can cause death due to pulmonary edemaor by circulatory shock.
As catalyst in manufacture of acetylcellulose; for replacing hydroxyl groups by Cl, particularly for converting acids into acid chlorides.
Phthalic anhydride is a white lustrous needle-like solid, phthalic anhydride is slightly
soluble in water.
Phthalic anhydride is an important chemical intermediate in the plastics industry. It has extensive industrial applications in the production of phthalic plasticisers, alkydic resins, polyesters resins, and synthetic resins. It is also used in dyes phenolphthalein, PVC stabilisers, drying agents for paints and aro. Phthalic anhydride itself is used as a monomer for synthetic resins such as glyptal, the alkyd resins, and the polyester resins. It is also used to make unsaturated polyesters that are used to manufacture fibreglassreinforced plastics, halogenated anhydrides used as fire retardants; polyester polyols for urethanes, phthalocyanine pigments; dyes, perfumes, pharmaceuticals, tanning and curing agents, as solvents, as insect repellents, and various chemical intermediates. Phthalic anhydride is released to the environment from chemical plants, mainly those that manufacture the chemical or use it in the production of plastics and resins. Phthalic anhydride is used in the synthesis of primary amines, the agricultural fungicide phaltan, and thalidomide.
[All operations should be carried out in an efficient fume cupboard.] Sublime it at 160-170o in an atmosphere of chlorine. Excess chlorine is then displaced by dry N2 gas. All subsequent manipulations should be performed in a dry-box [Downs & Johnson J Am Chem Soc 77 2098 1955]. It fumes in moist air and attacks the eyes and the mucous membranes of the nose. It should not be breathed in and has very HARMFUL VAPOURS (wash burning eyes with aqueous NaHCO3).
Phosphorus pentachloride absorbs moisture from air forming phosphoryl chloride:
PCl5 + H2O → POCl3 + 2HCl
The above reaction is difficult to control and progresses to complete hydrolysis. Thus, in the presence of excess water or when treated with water, the pentachloride is hydrolyzed to phosphoric acid:
PCl5 + 4H2O → H3PO4 + 5HCl
Reaction with sulfur dioxide yields thionyl chloride and phosphoryl chloride:
PCl5 + SO2 → SOCl2 + POCl3
Reaction with liquid hydrogen sulfide forms thiophosphoryl chloride, PSCl3:
PCl5 + H2S → PSCl3 + 2HCl
Phosphorus pentachoride converts arsenic to arsenic trichloride:
3PCl5 + 2As → 3AsCl3 + 3PCl3
Reaction with oxalic acid or boric acid yields phosphoryl chloride:
PCl5 + (COOH)2 → POCl3 + CO + CO2 + 2HCl
3PCl5 + 2B(OH)3 → 3POCl3 + B2O3 + 6HCl
Reaction with phosphorus pentoxide produces phosphoryl chloride:
3PCl5 + P2O5 → 5POCl3
The compound is strongly irritating to skin, eyes and mucous membranes.
Yellowish crystalline powder and scales
Phosphorus pentachloride is a lightly yellow, fuming crystalline material, highly caustic, corrosive and toxic. Flammable by chemical reaction. Violent exothermic reaction with water or steam. When heated to decomposition Phosphorus pentachloride emits highly toxic fumes of chlorides and oxides of phosphorus. Explosive reaction with alkaline metals (sodium, potassium), urea. Ignites on contact with fluorine. Violent reaction with aluminum, chlorine trioxide, hydroxylamine, magnesium oxide, nitrobenzene, phosphorus(III) oxide, potassium. Carbamates form explosive products [Bretherick, 5th ed., 1995, p. 1360]. Reaction with the mixture of chlorine and chlorine dioxide causes explosion [Mellor, 1941, vol. 2, p. 281; 1940, vol. 8, p. 1013].
Phosphorus pentachloride is a greenish-yellow crystalline solid with an irritating odor. Phosphorus pentachloride is decomposed by water to form hydrochloric and phosphoric acid and heat. This heat may be sufficient to ignite surrounding combustible material. Phosphorus pentachloride is corrosive to metals and tissue. Long term exposure to low concentrations or short term exposure to high concentrations can result in adverse health effects from inhalation.