PClösningar

PClösningar refers to solutions of phosphorus trichloride (PCl3) dissolved in dry organic solvents. PCl3 is a moisture‑sensitive, reactive phosphorus(III) chloride that is commonly handled under inert atmosphere in solvents such as dry diethyl ether, tetrahydrofuran (THF), benzene, toluene, or chlorinated solvents like carbon tetrachloride. In dry conditions, these solutions are used as reagents in organic synthesis.

Handling and preparation require strict exclusion of water. PCl3 rapidly hydrolyzes upon contact with moisture, producing phosphorous acid (H3PO3) and hydrogen chloride (HCl). Therefore, solutions are prepared and stored under dry nitrogen or argon and in tightly closed containers. The solutions are typically used directly for chlorination or phosphorylation reactions and are kept in a fume hood due to corrosive fumes.

Chemical behavior in solution is dominated by the tendency of PCl3 to react with nucleophiles. In the presence of alcohols, PCl3 can phosphorylate to form phosphate esters (for example, converting alcohols into alkyl phosphates) with the release of HCl. In the absence of moisture, PCl3 solutions can also participate in chlorination and activation steps in organic synthesis, serving as a chlorinating or phosphorylation reagent depending on the substrate and conditions. Hydrolysis or exposure to air will rapidly convert PCl3 solutions to phosphorous acids and hydrochloric acid, often changing the solution’s properties and effectiveness.

Applications include the preparation of phosphate esters and various phosphorus‑containing intermediates in medicinal chemistry and materials science. Because of their high reactivity, PCl3 solutions are used with care, under strictly dry conditions, and disposed of as hazardous chemical waste.

See also: phosphorus trichloride, phosphate esters, chlorination reagents.