Process for preparing diaryl methylphosphonate and derivatives thereof

DETAILED DESCRIPTION What is claimed is: 1.
A process for preparing diaryl methylphosphonate which comprises reacting the corresponding triayl phosphite with methanol in the presence of a methyl iodide catalyst, said catalyst being employed in an amount of from about 0.
5% to about 5% by weight based on the triaryl phosphite, at a temperature of from about 170.
degree.
C.
to about 250.
degree.
C.
2.
The process of claim 1 wherein the methyl iodide is employed in an amount of from about 1% to about 3% by weight methyl iodide.
3.
The process of claim 1 wherein the diaryl methylphosphonate is diphenyl methylphosphonate.
4.
The process of claim 1 wherein the triaryl phosphite employed is tris-p-tolyl phosphite.
5.
The process of claim 1 wherein the triaryl phosphite employed is tris-m-tolyl phosphite.
6.
The process of claim 1 wherein the triaryl phosphite employed is tris(p-chlorophenyl)phosphite.
7.
The process of claim 1 wherein the triaryl phosphite employed is tris(p-tert-butylphenyl)phosphite.
8.
The process of claim 1 wherein the triaryl phosphite employed is tris(p-methoxyphenyl)phosphite.
9.
The process of claim 1 wherein the triaryl phosphite employed is triphenyl phosphite.




Description:
BACKGROUND OF THE INVENTION Diaryl methylphosphonates and methods for their preparation have long been known in the art.
Inter alia, Michaelis et al.
, Ber.
31, 1048 (1898); Morgan et al.
, J.
Am.
Chem.
Soc.
, 74, 4526 (1952); Landauer et al.
, J.
Am.
Chem.
Soc.
, 1953, 2224; and Behrman et al.
, J.
Org.
Chem.
, 35, 3063 (1970) all disclose the preparation of diphenyl methylphosphonate.
The prior art method involves the reaction of methyl iodide with triphenyl phosphite to form a phosphonium iodide intermediate which is subsequently decomposed by alcohols or aqueous cuastic to form diphenyl methylphosphonate.
This earlier reaction is characterized by the use of a relatively large ratio (at least one molar equivalent) of costly methyl iodide and relatively low yields, generally less than 70%.
It is believed that these factors have reduced the commercial potential of diphenyl methylphosphonate and other diaryl methylphosphonates in spite of the fact that these compounds have long been known as useful intermediates in the preparation of various other compounds