PROCESS FOR PRODUCING PHOSPHORUS-CONTAINING CYANOHYDRIN ESTERS

Abstract

The present invention primarily relates to a process for producing certain phosphorus-containing cyanohydrin esters of formula (I) and the use thereof for producing glufosinate/glufosinate salts. The present invention further relates to a process for producing glufosinate/glufosinate salts.

Claims

1. Process for producing a compound of formula (I) ##STR00015## wherein a compound of formula (II) ##STR00016## is reacted with a compound of formula (III) ##STR00017## wherein in each case: R.sup.1 represents (C.sub.1-C.sub.12)-alkyl, (C.sub.1-C.sub.12)-haloalkyl, (C.sub.6-C.sub.10)-aryl, (C.sub.6-C.sub.10)-haloaryl, (C.sub.7-C.sub.10)-aralkyl, (C.sub.7-C.sub.10)-haloaralkyl, (C.sub.4-C.sub.10)-cycloalkyl or (C.sub.4-C.sub.10)-halocycloalkyl, R.sup.2 represents (C.sub.1-C.sub.12)-alkyl, (C.sub.1-C.sub.12)-haloalkyl, (C.sub.6-C.sub.10)-aryl, (C.sub.6-C.sub.10)-haloaryl, (C.sub.7-C.sub.10)-aralkyl, (C.sub.7-C.sub.10)-haloaralkyl, (C.sub.4-C.sub.10)-cycloalkyl or (C.sub.4-C.sub.10)-halocycloalkyl, R.sup.3 and R.sup.4 each independently of one another represent hydrogen, (C.sub.1-C.sub.4)-alkyl, phenyl or benzyl, R.sup.5 represents (C.sub.1-C.sub.12)-alkyl, (C.sub.1-C.sub.12)-haloalkyl, (C.sub.6-C.sub.10)-aryl, (C.sub.6-C.sub.10)-haloaryl, (C.sub.7-C.sub.10)-aralkyl, (C.sub.7-C.sub.10)-haloaralkyl, (C.sub.4-C.sub.10)-cycloalkyl or (C.sub.4-C.sub.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.sup.3 and/or the mixing time to achieve a coefficient of variation of 0.01 or lower (CoV10.sup.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.sup.3 and/or the mixing time to achieve a coefficient of variation of 0.01 or lower (CoV10.sup.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.sup.3 and/or the mixing time to achieve a coefficient of variation of 0.01 or lower (CoV10.sup.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) ##STR00018## wherein R.sup.6 independently at each occurrence represents hydrogen, (C.sub.1-C.sub.10-alkyl, by preference (C.sub.1-C.sub.6)-alkyl, optionally (C.sub.1-C.sub.4)-alkyl, R.sup.7 represents hydrogen or (C.sub.1-C.sub.10-alkyl, by preference hydrogen or (C.sub.1-C.sub.6)-alkyl, optionally hydrogen or (C.sub.1-C.sub.4)-alkyl, and R.sup.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) ##STR00019## wherein R.sup.1 represents (C.sub.1-C.sub.6)-alkyl, (C.sub.1-C.sub.6)-haloalkyl, (C.sub.6-C.sub.8)-aryl, (C.sub.6-C.sub.8)-haloaryl, (C.sub.7-C.sub.10)-aralkyl, (C.sub.7-C.sub.10)-haloaralkyl, (C.sub.5-C.sub.8)-cycloalkyl or (C.sub.5-C.sub.8)-halocycloalkyl and R.sup.2 represents (C.sub.1-C.sub.6)-alkyl, (C.sub.1-C.sub.6)-haloalkyl, (C.sub.6-C.sub.8)-aryl, (C.sub.6-C.sub.8)-haloaryl, (C.sub.7-C.sub.10)-aralkyl, (C.sub.7-C.sub.10)-haloaralkyl, (C.sub.5-C.sub.8)-cycloalkyl or (C.sub.5-C.sub.8)-halocycloalkyl, and one of the compounds or the compound of formula (III) corresponds to formula (IIIa) ##STR00020##

14. Process for producing glufosinate ##STR00021## or glufosinate salt, wherein in said process a compound of formula (Ib) is employed ##STR00022## wherein R.sup.2 represents (C.sub.1-C.sub.12)-alkyl, (C.sub.1-C.sub.12)-haloalkyl, (C.sub.6-C.sub.10)-aryl, (C.sub.6-C.sub.10)-haloaryl, (C.sub.7-C.sub.10)-aralkyl, (C.sub.7-C.sub.10)-haloaralkyl, (C.sub.4-C.sub.10)-cycloalkyl or (C.sub.4-C.sub.10)-halocycloalkyl, R.sup.5 represents (C.sub.1-C.sub.12)-alkyl, (C.sub.1-C.sub.12)-haloalkyl, (C.sub.6-C.sub.10)-aryl, (C.sub.6-C.sub.10)-haloaryl, (C.sub.7-C.sub.10) aralkyl, (C.sub.7-C.sub.10)-haloaralkyl, (C.sub.4-C.sub.10)-cycloalkyl or (C.sub.4-C.sub.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.

Description

EXAMPLES

[0217] All data are based on weight unless otherwise stated.

Abbreviations Used

[0218] MPE: methanephosphonous acid mono-n-butyl ester [0219] ACA: acrolein cyanohydrin acetate [0220] ACM: n-butyl (3-cyano-3-acetoxypropyl)methylphosphinate

Example 1: n-butyl (3-cyano-3-acetoxypropyl)methylphosphinate (ACM) (Noninventive)

Discontinuous Mode of Operation

[0221] A temperature-controllable, cylindrical glass reactor was filled with a portion of the required MPE to adequately cover the stirring means and the reactor contents were brought to reaction temperature (typically 85 C.). In the experiments with a pumped circulation system/circulation loop, the circulation loop including the associated pump was also filled with MPE. Commixing of the reactor contents was accomplished via a six-blade disc stirrer in combination with four baffles. The reactor contents were always blanketed with nitrogen and the reactor was operated without application of superatmospheric pressure.

[0222] To ensure reliable starting of the reaction (i.e. reliable initiation), 5 minutes before commencement of the metering of the reactants into the reactor a small amount of initiator (0.9-1.0 mL, corresponding to about 0.8-0.9 g) was injected into the initially charged MPE previously heated to reaction temperature (and possibly also circulating through the circulation loop). The time interval of 5 minutes corresponds approximately to the half-life of the free-radical initiator tert-butyl perneodecanoate at 85 C. Toward the end of the metering time of 4 hours (i.e. more than 40 half-lives of the employed free-radical initiator) the initially injected amount of tert-butyl perneodecanoate had fallen to <10.sup.12 parts of the starting amount and thus had no appreciable further relevance for the ACM production in the continuous mode of operation according to hereinbelow-reported example 2.

[0223] The reactants E1 and E2 were then separately metered into the reactor until the desired fill-level had been achieved, taking into account the respective stoichiometries.

[0224] 142.0 g of MPE (98% purity) were initially charged and heated to 85 C. 5 min before commencement of the metering of the reactants E1 and E2, 1.0 ml (about 0.9 g) of the free-radical initiator tert-butyl perneodecanoate (98% purity) was added. The following reactants E1 and E2 were then simultaneously metered into the reactor over a period of 4.0 h:

reactants E1 was a mixture of MPE (102.1 g, 98% purity) and tert-butyl perneodecanoate (3.0 g, 98% purity), reactant E2 was composed of 57.0 g of ACA (99% purity).

[0225] The concentration of the free-radical initiator was accordingly 1.0 wt % based on the overall mixture.

[0226] After expiry of the metering time the discontinuous batch had reached its endpoint; the employed ACA had reacted completely.

Example 2: n-butyl (3-cyano-3-acetoxypropyl)methylphosphinate (ACM) (Noninventive)

Continuous Mode of Operation

[0227] The reactor was initially charged with a mixture produced by the discontinuous mode of operation according to hereinabove-reported example 1. The reaction conditions and the apparatus parameters were the same as those from example 1. At a reaction temperature of 85 C., the metered streams (D1) and (D2) were then simultaneously and separately metered into the reactor.

[0228] At 85 C., metered stream (D1), a mixture of MPE and free-radical initiator tert-butyl perneodecanoate, was added to the reactor at 63 mL/h and metered stream (D2), ACA, was added to the reactor at 14 mL/h, the content of the free-radical initiator in the MPE (1.2 wt %) being chosen such that a content of 1.0 wt % of free-radical initiator in the overall mixture in the reactor was achieved.

[0229] Corresponding to the supplied volume flows, an adequately large volume flow of the reactor mixture was withdrawn from the reactor to keep the fill-volume in the reactor constant. The fill-volume in the reactor and the supplied/discharged volume flows resulted in an average hydrodynamic residence time of 4.0 hours in the reactor.

[0230] Once a steady-state had been achieved, samples of the reactor contents were withdrawn and a yield of 95-96% for the reaction of ACA to afford ACM was determined.

Example 3: n-butyl (3-cyano-3-acetoxypropyl)methylphosphinate (ACM)

Continuous Mode of Operation

[0231] The reactor was initially charged with a mixture produced by the discontinuous mode of operation according to hereinabove-reported example 1. The reaction conditions and the apparatus parameters were the same as those from example 1. At a reaction temperature of 85 C., the metered streams (D1) and (D2) were then simultaneously and separately metered into the reactor.

[0232] At 85 C., metered stream (D1), a mixture of MPE and free-radical initiator tert-butyl perneodecanoate, was added to the reactor at 63 mL/h and metered stream (D2), ACA, was added to the reactor at 14 mL/h, the content of the free-radical initiator in the MPE (1.2 wt %) being chosen such that a content of 1.0 wt % of free-radical initiator in the overall mixture in the reactor was achieved.

[0233] Corresponding to the supplied volume flows, an adequately large volume flow of the reactor mixture was withdrawn from the reactor to keep the fill-volume in the reactor constant. The fill-volume in the reactor and the supplied/discharged volume flows resulted in an average hydrodynamic residence time of 4.0 hours in the reactor.

[0234] The metered streams were supplied to the reaction mixture in the pumped circulation system/circulation loop of the stirred vessel via static mixers. Commixing of the reactor contents was furthermore accomplished via a six-blade disc stirrer in combination with four baffles.

[0235] Using various static mixers having structures on the millimetre and/or micrometre scale (for example Sulzer SMX, EMB cascade mixer) for a wide variety of volume flows in the pumped circulation system, mixing times (for a CoV of <0.01) of up to <1 s, in some cases even up to <0.1 s, were achieved in the static mixers. The specific power inputs (based on the total volume of the condensed phase in the reactor) for the static mixers varied from >0.001 W/L to <10 W/L (1 W/L=1 kW/m.sup.3).

[0236] Once a steady-state had been achieved, for mixing times of <1 s (in the static mixers) and specific power inputs of >0.1 W/L (based on the total volume of the condensed phase in the reactor), samples of the reactor contents were withdrawn and a yield of 98% for the reaction of ACA to afford ACM was determined.