Process for producing phosphorus-containing cyanohydrin esters

1. A process for producing a compound of formula (I)

wherein a compound of formula (II)

is reacted with a compound of formula (III)

wherein in each case:

R 1 represents (C 1 -C 12 )-alkyl, (C 1 -C 12 )-haloalkyl, (C 6 -C 10 )-aryl, (C 6 -C 10 )-haloaryl, (C 7 -C 10 )-aralkyl, (C 7 -C 10 )-haloaralkyl, (C 4 -C 10 )-cycloalkyl or (C 4 -C 10 )-halocycloalkyl,

R 2 represents (C 1 -C 12 )-alkyl, (C 1 -C 12 )-haloalkyl, (C 6 -C 10 )-aryl, (C 6 -C 10 )-haloaryl, (C 7 -C 10 )-aralkyl, (C 7 -C 10 )-haloaralkyl, (C 4 -C 10 )-cycloalkyl or (C 4 -C 10 )-halocycloalkyl,

R 3 and R 4 each independently of one another represent hydrogen, (C 1 -C 4 )-alkyl, phenyl or benzyl,

R 5 represents (C 1 -C 12 )-alkyl, (C 1 -C 12 )-haloalkyl, (C 6 -C 10 )-aryl, (C 6 -C 10 )-haloaryl, (C 7 -C 10 )-aralkyl, (C 7 -C 10 )-haloaralkyl, (C 4 -C 10 )-cycloalkyl or (C 4 -C 10 )-halocycloalkyl,

X represents oxygen or sulfur and

n is 0 or 1,

in the presence of one or more free-radical-forming substances (IV),

wherein at least one of the free-radical-forming substances (IV) is a compound of formula (V)

wherein

R 6 independently at each occurrence represents hydrogen or (C 1 -C 10 )-alkyl

R 7 represents hydrogen or (C 1 -C 10 )-alkyl, and

R 8 represents methyl, ethyl, 2,2-dimethylpropyl or phenyl,

wherein two separate mixtures (G1) and (G2) are metered into the reactor and these mixtures (G1) and (G2) have the following composition:

mixture (G1) comprises one or more compounds of formula (II) and one or more free-radical-forming substances (IV)

and

mixture (G2) comprises one or more compounds of formula (III), one or more compounds of formula (II) and optionally one or more free-radical-forming substances (IV), and

wherein mixture (G1) comprises 25-75 wt % of the entirety of the amount of compounds of formula (II) altogether employed in the mixtures (G1) and (G2).

2. The process according to claim 1 , wherein

mixture (G1) comprises one or more compounds of formula (II) and 20-100 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the mixtures (G1) and (G2),

and

mixture (G2) comprises one or more compounds of formula (III), one or more compounds of formula (II) and 0-80 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the mixtures (G1) and (G2).

3. The process according to claim 1 , wherein

mixture (G1) comprises 25-100 mol of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the mixtures (G1) and (G2),

and/or

mixture (G2) comprises 0-75 mol %, of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the mixtures (G1) and (G2).

4. The process according to claim 1 , wherein the entirety of the compounds (II) and (IV) in the mixture (G1) is 75 to 100 wt in each case based on the total weight of the mixture (G1).

5. The process according to claim 1 , wherein the mixtures (G1) and (G2) are metered into the reactor predominantly simultaneously or simultaneously.

6. The process according to claim 1 , wherein the metering of the mixtures (G1) and (G2) into the reactor is carried out substantially continuously or continuously.

7. The process according to claim 1 , wherein more than one or all of the free-radical-forming substances (IV) are compounds of formula (V)

wherein

R 6 independently at each occurrence represents hydrogen or (C 1 -C 6 )-alkyl,

R 7 represents hydrogen or (C 1 -C 6 )-alkyl,

and

R 8 represents methyl, ethyl, 2,2-dimethylpropyl or phenyl.

8. The process according to claim 1 , wherein the reaction is carried out at a temperature in the range from 40° C. to 120° C.

9. The process according to claim 1 , wherein the molar ratio of the entirety of the employed compound of formula (II) to the entirety of the employed compound of formula (III) is in the range from 8:1 to 1:1.

10. The process according to claim 1 , wherein

one of the compounds or the compound of formula (II) is a compound of formula (IIa)

wherein

R 1 represents (C 1 -C 6 )-alkyl, (C 1 -C 6 )-haloalkyl, (C 6 -C 8 )-aryl, (C 6 -C 8 )-haloaryl, (C 7 -C 10 )-aralkyl, (C 7 -C 10 )-haloaralkyl, (C 5 -C 8 )-cycloalkyl or (C 5 -C 8 )-halocycloalkyl and

R 2 represents (C 1 -C 6 )-alkyl, (C 1 -C 6 )-haloalkyl, (C 6 -C 8 )-aryl, (C 6 -C 8 )-haloaryl, (C 7 -C 10 )-aralkyl, (C 7 -C 10 )-haloaralkyl, (C 5 -C 8 )-cycloalkyl or (C 5 -C 8 )-halocycloalkyl,

and

one of the compounds or the compound of formula (III) is a compound of formula (IIIa)

11. The process according to claim 1 , wherein

mixture (G1) comprises 80-100 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the mixtures (G1) and (G2),

and

mixture (G2) comprises 0-20 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the mixtures (G1) and (G2).

12. The process according to claim 1 , wherein the entirety of the compounds (II) and (IV) in the mixture (G1) is 90 to 100 wt % in each case based on the total weight of the mixture (G1).

13. The process according to claim 1 , wherein R 6 independently at each occurrence represents hydrogen or (C 1 -C 4 )-alkyl.

14. The process according to claim 1 , wherein R 7 represents hydrogen or (C 1 -C 4 )-alkyl.

15. The process according to claim 1 , wherein

R 6 independently at each occurrence represents hydrogen or (C 1 -C 4 )-alkyl; and

R 7 represents hydrogen or (C 1 -C 4 )-alkyl.

16. The process according to claim 1 , wherein the molar ratio of the entirety of the employed compound of formula (II) to the entirety of the employed compound of formula (III) is in the range from 5:1 to 2:1.

17. The process according to claim 1 , wherein the reaction is carried out at a temperature in the range from 60° C. to 95° C.

18. A process for producing glufosinate

or one or more glufosinate salts, comprising

(a) obtaining a compound of formula (Ib)

by reacting a compound of formula (II)

with a compound of formula (III)

wherein in each case:

R 1 represents (C 1 -C 12 )-alkyl, (C 1 -C 12 )-haloalkyl, (C 6 -C 10 )-aryl, (C 6 -C 10 )-haloaryl, (C 7 -C 10 )-aralkyl, (C 7 -C 10 )-haloaralkyl, (C 4 -C 10 )-cycloalkyl or (C 4 -C 10 )-halocycloalkyl,

R 2 represents (C 1 -C 12 )-alkyl, (C 1 -C 12 )-haloalkyl, (C 6 -C 10 )-aryl, (C 6 -C 10 )-haloaryl, (C 7 -C 10 )-aralkyl, (C 7 -C 10 )-haloaralkyl, (C 4 -C 10 )-cycloalkyl or (C 4 -C 10 )-halocycloalkyl,

R 3 and R 4 each independently of one another represent hydrogen, (C 1 -C 4 )-alkyl, phenyl or benzyl,

R 5 represents (C 1 -C 12 )-alkyl, (C 1 -C 12 )-haloalkyl, (C 6 -C 10 )-aryl, (C 6 -C 10 )-haloaryl, (C 7 -C 10 )-aralkyl, (C 7 -C 10 )-haloaralkyl, (C 4 -C 10 )-cycloalkyl or (C 4 -C 10 )-halocycloalkyl,

X represents oxygen or sulfur and

n is 0 or 1,

in the presence of one or more free-radical-forming substances (IV),

wherein at least one of the free-radical-forming substances (IV) is a compound of formula (V)

wherein

R 6 independently at each occurrence represents hydrogen or (C 1 -C 10 )-alkyl, R 7 represents hydrogen or (C 1 -C 10 )-alkyl,

and

R 8 represents methyl, ethyl, 2,2-dimethylpropyl or phenyl,

wherein two separate mixtures (G1) and (G2) are metered into the reactor and these mixtures (G1) and (G2) have the following composition:

mixture (G1) comprises one or more compounds of formula (II) and one or more free-radical-forming substances (IV)

and

mixture (G2) comprises one or more compounds of formula (III), one or more compounds of formula (II) and optionally one or more free-radical-forming substances (IV), and

wherein mixture (G1) comprises 25-75 wt % of the entirety of the amount of compounds of formula (II) altogether employed in the mixtures (G1) and (G2); and

(b) reacting said compound of formula (Ib) with NH 3 .

19. The process according to claim 18 , wherein R 5 is methyl.