Process for the manufacture of dialkylphosphites
View Patent ↗A process for the manufacture of dialkyl phosphites is disclosed. In detail, dialkyl phosphites are prepared starting from P 4 O 6 , or partially hydrated species thereof cumulatively P—O, by reacting specific molar ratios of alcohol and P—O, containing from 1 to 6 P—O—P bonds in the molecule, in the presence of trialkylphospite (TAP) to thus yield high purity and high yield of dialkyl phosphites. The P—O reactant is preferably represented by liquid P 4 O 6 .
1. A process for the manufacture of dialkyl phosphites starting from a P—O component having from 1 to 6 P—O—P bonds in the molecule comprising the step of:
a) reacting a mixture of R′OH and the P—O component expressed in molar ratios of R′OH:P—O of at least 1:1 to 6:1,
wherein R′ is selected from alkyl groups having from 1 to 20 carbon atoms in branched or linear configuration; and
P(OA) 3 (trialkyl phosphite, TAP),
wherein A stands for linear or branched alkyl groups having from 1 to 20 carbon atoms;
whereby the minimum number of mole(s) of TAP, per P atom in the P—O molecule, required for the process, is represented by “z”, and z is determined by the formula z=2n−m,
wherein;
n is the number of P atoms in P—O and
m is the number of P—O—P bonds in P—O;
by adding the P—O, simultaneously with or separately from the TAP, to a reaction medium comprising the R′OH; and bringing the reaction mixture to a temperature in the range of from 40° C. to 180° C. for a period from 10 minutes to 10 hours.
2. The process in accordance with claim 1 wherein the P—O has from 2 to 6 P—O—P bonds.
3. The process in accordance with claim 1 , wherein the P—O is represented by liquid P 4 O 6 .
4. The process in accordance with claim 1 , wherein the P—O is added to the reaction medium comprising the R′OH and the TAP.
5. The process in accordance with claim 1 , wherein the P—O has less than 1000 ppm of elemental phosphorus, P 4 , expressed in relation to P—O being 100%.
6. The process in accordance with claim 1 , wherein the alkyl groups in the alcohol, R′OH, and TAP are identical.
7. The process in accordance with claim 1 , wherein the molar ratio of R′OH:P—O is in the range of from 1:1 to 8:1.
8. The process in accordance with claim 1 , wherein the trialkyl phosphite is selected from the group of: tri-methyl phosphite; tri-ethyl phosphite; tri-n-propyl phosphite; tri-isopropyl phosphite; tri-n-butyl phosphite; tri-isobutyl phosphite; tri-n-pentyl phosphite; tri-t-butyl phosphite; tri-2-ethylhexyl phosphite; tri-n-decyl phosphite; tri-n-octyl phosphite; tri-n-dodecyl phosphite; tri-n-hexyl phosphite; tri-(propyl-2,2-dimethyl) phosphite; and tri-(8-methyl nonyl) phosphite.
9. The process in accordance with claim 1 , wherein the P—O is added to the reaction medium comprising water in a molar level of 4 or less H 2 O per P—O.
10. The process in accordance with claim 1 , wherein the alkyl groups in the alcohol and the TAP have from 1 to 12 carbon atoms.
11. The process in accordance with claim 1 , wherein the alkyl group in the alcohol has from 1 to 8 carbon atoms.
12. The process in accordance with claim 1 , wherein the reaction is conducted for a period of 15 minutes to 6 hours at a temperature from 70° C. to 150° C.
13. The process in accordance with claim 1 , wherein the P—O compound prepared starting from PCl 3 having less than 400 ppm of chlorine, expressed in relation to the P—O compound (100%).
14. The process in accordance with claim 1 , wherein the alcohol is methanol and the TAP is P(OCH 3 ) 3 , further comprising the steps of
b) reacting the dimethyl phosphate obtained in step a) with methylmaleate; followed by
c) reacting the system resulting from step b) with methyl acrylate in the presence of sodium methoxide; followed by
d) hydrolysing the ester groups formed in step c) with water in the presence of hydrochloric acid,
to obtain 2-phosphonobutyl-1,2,4-tricarboxylic acid.