Kinnear–Perren reaction
{{Short description|Chemical 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).{{cite encyclopedia |author=Svara, J. |author2=Weferling, N. |author3=Hofmann, T.|title=Phosphorus Compounds, Organic |entry=Phosphorus Compounds, Organic|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|publisher=Wiley-VCH|location=Weinheim|year=2008|doi=10.1002/14356007.a19_545.pub2|isbn=978-3-527-30673-2}}. The reactants are alkyl chloride, phosphorus trichloride, and aluminium trichloride as catalyst.{{cite journal|title=The Synthesis of Dialkyl α-Halogenated Methylphosphonates|author=Rachel Waschbüsch |author2=John Carran |author3=Angela Marinetti |author4=Philippe Savignac |journal=Synthesis|year=1997|volume=1997|issue=7|pages=727–743|doi=10.1055/s-1997-1417|url=https://hal.archives-ouvertes.fr/hal-03166421/file/Waschbusch_Synthesis_1997_727.pdf}} 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{{cite journal |last1=Clay|first1=John P. |title=A New Method for the Preparation Of Alkane Phosphonyl Dichlorides |journal=The Journal of Organic Chemistry |date=June 1951 |volume=16 |issue=6 |pages=892–894 |doi=10.1021/jo01146a010}} and expanded upon by Kinnear and Perren, who demonstrated that the four chlorinated methanes (CH4−xClx) give the corresponding CH3-, CH2Cl-, CHCl2-, and CCl3-substituted derivatives. They also demonstrated workup with hydrogen sulfide to give the alkylthiophosphoryl dichlorides.{{cite journal|title=Formation of Organo-Phosphorus Compounds by the Reaction of Alkyl Chlorides with Phosphorus Trichloride in the Presence of Aluminium Chloride|author=A. M. Kinnear |author2=E. A. Perren |journal=J. Chem. Soc.|year=1952|pages= 3437–3445|doi=10.1039/JR9520003437}}