Process for producing phosphorus-containing cyanohydrin esters

1. 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) in a reactor with mixing, wherein the mixing is effected under the following parameters:

the specific power input is at least 0.03 kW/m 3

and/or

the mixing time to achieve a coefficient of variation of 0.01 or lower (CoV≤10 −2 ) is less than 10 seconds.

2. Process according to claim 1 , wherein the mixing is effected under the following parameters:

the specific power input is at least 0.3 kW/m 3

and/or

the mixing time to achieve a coefficient of variation of 0.01 or lower (CoV≤10 −2 ) is less than 1 second.

3. Process according to claim 1 , wherein the mixing is effected under the following parameters:

the specific power input is at least 3 kW/m 3

and/or

the mixing time to achieve a coefficient of variation of 0.01 or lower (CoV≤10 −2 ) is less than 0.1 seconds.

4. 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)

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).

5. Process according to claim 4 , wherein 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 10-100 mol % of the entirety of the amount of free-radical-forming substances (IV) altogether employed.

6. Process according to claim 4 , wherein metered stream (D1) comprises 20-100 mol % of the entirety of the amount of free-radical-forming substances (IV) altogether employed, optionally 25-100 mol %, optionally 30-100 mol %.

7. Process according to claim 4 , wherein metered stream (D1) comprises 80-100 wt %, optionally 90-100 wt %, optionally 95-100 wt %, optionally 100 wt %, of the entirety of the amount of compounds of formula (II) altogether employed in the metered streams (D1) and (D2).

8. Process according to claim 4 , wherein the metered streams (D1) and (D2) are metered into the reactor predominantly simultaneously, optionally simultaneously.

9. Process according to claim 4 , wherein the metering of the metered streams (D1) and (D2) into the reactor is effected substantially continuously, optionally continuously.

10. Process according to claim 1 , wherein one, more than one or all of the free-radical-forming substances (IV) conform to formula (V)

wherein

R 6 independently at each occurrence represents hydrogen, (C 1 -C 10 )-alkyl, by preference (C 1 -C 6 )-alkyl, optionally (C 1 -C 4 )-alkyl,

R 7 represents hydrogen or (C 1 -C 10 )-alkyl, by preference hydrogen or (C 1 -C 6 )-alkyl, optionally hydrogen or (C 1 -C 4 )-alkyl,

and

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

11. Process according to claim 1 , wherein the reaction is effected at a temperature in the range from 40° C. to 120° C., optionally at a temperature in the range from 50° C. to 110° C., optionally at a temperature in the range from 55° C. to 100° C. and optionally at a temperature in the range from 60° C. to 95° C.

12. 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 a range from 8:1 to 1:1, optionally in the range from 5:1 to 2:1.

13. Process according to claim 1 , wherein

one of the compounds or the compound of formula (II) corresponds to 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) corresponds to formula (IIIa)

14. Process for producing glufosinate

or glufosinate salt, 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 represents methyl and

the production of the compound of formula (Ib) is effected by a process of claim 1 .

15. Process for producing one or more glufosinate/glufosinate salts, optionally glufosinate, glufosinate sodium or glufosinate ammonium, comprising:

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

(b) using a compound of formula (I)/(Ib) obtained in (a) for producing glufosinate/glufosinate salts, optionally glufosinate, glufosinate sodium or glufosinate ammonium.