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 sulphur and

n is 0 or 1,

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

wherein the free-radical-forming substances (IV) is one or more compounds of formula (V)

wherein

R 6 independently at each occurrence represents hydrogen, (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 a metered stream (D1) is metered into the reactor, which comprises one or more compounds of formula (II) and one or more free-radical-forming substances (IV), and

wherein metered stream (D1) comprises 25-100 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the reaction.

2. The process according to claim 1 , wherein two separate metered streams (D1) and (D2) are metered into the reactor and these metered streams (D1) and (D2) have the following composition:

metered stream (D1) comprises one or more compounds of formula (II) and one or more free-radical-forming substances (IV), wherein metered stream (D1) comprises 25-100 ml % of the amount of the free-radical-forming substances (IV) altogether employed in the reaction

and

metered stream (D2) comprises one or more compounds of formula (III) and also optionally one or more compounds of formula (II) and optionally one or more free-radical-forming substances (IV).

3. The process according to claim 1 , wherein metered stream (D1) comprises 30-100 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the reaction.

4. The process according to claim 2 , wherein metered stream (D1) comprises 90-100 wt % of the entirety of the amount of compounds of formula (II) altogether employed in the metered streams (D1) and (D2).

5. The process according to claim 2 , wherein

metered stream (D2) comprises 80-100 wt % of the entirety of the amount of compounds of formula (III) altogether employed in the metered streams (D1) and (D2).

6. The process according to claim 2 , wherein

metered stream (D1) comprises 40-100 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the metered streams (D1) and (D2)

and/or

metered stream (D2) comprises 0-60 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the metered streams (D1) and (D2).

7. The process according to claim 1 , wherein the entirety of the compounds (II) and (IV) in the metered stream (D1) is 75 to 100 wt % in each case based on the total weight of the metered stream (D1).

8. The process according to claim 2 , wherein the metered streams (D1) and (D2) are metered into the reactor predominantly simultaneously.

9. The process according to claim 2 , wherein the metering of the metered streams (D1) and (D2) into the reactor is carried out substantially continuously.

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

11. 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.

12. The process according to claim 1 , wherein

one of the compounds or the compound of formula (II) is 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 of formula (IIIa)

13. A process for producing glufosinate

or one or more glufosinate salts, wherein in said process, a compound of formula (Ib) is employed

wherein

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 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, or methyl

and

wherein production of the compound of formula (Ib) is carried out by a process of claim 1 .

14. A process for producing one or more of glufosinate/glufosinate salts, comprising:

(a) producing of a compound of formula (I)/(Ib) produced by a process of claim 1 ,

(b) using the compound of formula (I)/(Ib) obtained in (a) for producing one or more of glufosinate/glufosinate salts.

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

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

17. The process according to claim 1 , wherein metered stream (D1) comprises 95-100 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the reaction.

18. The process according to claim 2 , wherein metered stream (D1) comprises 100 wt % of the entirety of the amount of compounds of formula (II) altogether employed in the metered streams (D1) and (D2).

19. The process according to claim 2 , wherein metered stream (D2) comprises 100 wt % of the entirety of the amount of compounds of formula (III) altogether employed in the metered streams (D1) and (D2).

20. The process according to claim 2 , wherein

metered stream (D1) comprises 90-100 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the metered streams (D1) and (D2)

and/or

metered stream (D2) comprises 0-10 mol % of the entirety of the amount of the free-radical-forming substances (IV) altogether employed in the metered streams (D1) and (D2).