Phase transfer catalyst for synthesis of pentaerythritol diphosphites
The present invention pertains to a process for the preparation of pentaerythritol diphosphites via a one-pot, direct esterification of phosphorus trichloride with pentaerithritol, and either an alkylphenol or an arylalkylphenol which functions both as a reactant and as a solvent, with a phase transfer catalyst such as a quaternary ammonium salt.
1. A process for the in-situ formation of a bis(alkylphenyl)pentaerythritol diphosphite
wherein R is independently selected from the group consisting of C 1-22 alkyl, C 1-22 alkoxy, C 3-22 alkenyl, C 6-40 aryl, C 7-40 cycloalkyl, C 7-40 cycloalkylene, C 7-40 alkylaryl, C 7-40 arylalkyl, C 7-40 aryloxy, and n is an integral value ranging from 2 to 4 inclusive, comprising the steps of:
adding phosphorus trichloride (PCl 3 ) to a reaction vessel previously charged with pentaerythritol
adding a phenol selected from the group consisting of alkylphenol and arylalkylphenol
wherein R and n are as defined previously, the phenol acting as both a reactant and a solvent for the reaction; and
adding a phase transfer catalyst.
2. The process of claim 1 wherein
said phase transfer catalyst is selected from the group consisting of a quaternary ammonium salt and a quaternary phosphonium salt.
3. The process of claim 2 wherein
said quaternary salt is selected from the group consisting of
wherein R 1 -R 4 are independently selected from the group consisting of C 1-20 alkyl groups, C 2-24 alkoxy, C 3-24 alkenyls, C 6-45 phenyl including fused aromatic rings, C 7-45 alkylaryls and C 7-45 arylalkyls;
Z is selected from the atoms consisting of N and P, and further wherein
X is selected from the group consisting of halides (fluoride, chloride, bromide, iodide), sulfates, bisulfates, hydroxyl and further wherein
any of R 1 -R 4 may be covalently bonded to each other.
4. The process of claim 3 wherein
said quaternary ammonium salt is selected from the group consisting of benzyltriethylammonium halide, hexadecyltrimethylammonium halide, tetrabutylammonium halide, tetramethylammonium halide, tetraethylammonium halide and mixtures thereof.
5. The process of claim 3 wherein
said halide is selected from the group consisting of chloride and bromide.
6. The process of claim 1 wherein
said alkylphenol is 2,6-di-t-butyl-4-methylphenol,
and said arylalkylphenol is 2,4-dicumylphenol
7. The process of claim 1 wherein
said arylalkylphenol is 2,4-dicumylphenol
8. The process of claim 6 wherein
said bis(alkylphenyl)pentaerythritol diphosphite is selected from the group consisting of bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite
bis(2-t-butyl-4-nonylphenyl)pentaerythritol diphosphite,
and bis(2,4-dicumylphenyl)pentaerythritol diphosphite
9. The process of claim 6 wherein
said bis(alkylphenyl)pentaerythritol diphosphite is bis(2,4-dicumylphenyl)pentaerythritol diphosphite
10. The process of claim 1 wherein
a mole ratio of said PCl 3 to said pentaerythritol is from about 1.9:1 to 2.2:1 inclusive;
said catalyst is added in an amount from about 1.0 to 15 weight percent based on said amount of pentaerythritol;
said phenol ranges from about 1 to 10 times a stoichiometric amount of said phenol; and
an initial reaction temperature for said reaction ranges from about 40° C. to 100° C. inclusive;
a subsequent reaction for said reaction after PCl 3 addition ranges from about 120° C. to 180° C. inclusive.
11. The process of claim 10 which further comprises
a nitrogen sparge.