Kinnear–Perren reaction

In organophosphorus chemistry, the Kinnear–Perren reaction (sometimes the Clay-Kinnear-Perren reaction) is used to prepare alkylphosphonyl dichlorides (RP(O)Cl₂) and alkylphosphonate esters (RP(O)(OR')₂).^[1] The reactants are alkyl chloride, phosphorus trichloride, and aluminium trichloride as catalyst.^[2] The reaction proceeds via the alkyltrichlorophosphonium salt:

RCl + PCl₃ + AlCl₃ → [RPCl₃]⁺AlCl₄⁻

Reduction of this trichlorophosphonium intermediate with aluminium powder gives alkyldichlorophosphines (RPCl₂).

Partial hydrolysis of the same intermediate gives the alkylphosphonyl dichloride:

[RPCl₃]⁺AlCl₄⁻ + H₂O → RP(O)Cl₂ + AlCl₃ + 2 HCl

The reaction was first reported by Clay^[3] and expanded upon by Kinnear and Perren, who demonstrated that the four chlorinated methanes (CH_4−xCl_x) give the corresponding CH₃-, CH₂Cl-, CHCl₂-, and CCl₃-substituted derivatives. They also demonstrated workup with hydrogen sulfide to give the alkylthiophosphoryl dichlorides.^[4]

References

1. Svara, J.; Weferling, N.; Hofmann, T. (2008). "Phosphorus Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_545.pub2. ISBN 978-3-527-30673-2..
2. Rachel Waschbüsch; John Carran; Angela Marinetti; Philippe Savignac (1997). "The Synthesis of Dialkyl α-Halogenated Methylphosphonates" (PDF). Synthesis. 1997 (7): 727–743. doi:10.1055/s-1997-1417.
3. Clay, John P. (June 1951). "A New Method for the Preparation Of Alkane Phosphonyl Dichlorides". The Journal of Organic Chemistry. 16 (6): 892–894. doi:10.1021/jo01146a010.
4. A. M. Kinnear; E. A. Perren (1952). "Formation of Organo-Phosphorus Compounds by the Reaction of Alkyl Chlorides with Phosphorus Trichloride in the Presence of Aluminium Chloride". J. Chem. Soc.: 3437–3445. doi:10.1039/JR9520003437.