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 in a reactor 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 of formula (V) ##STR00018## wherein R.sup.6 independently at each occurrence represents hydrogen or (C.sub.1-C.sub.10)-alkyl, R.sup.7 represents hydrogen or (C.sub.1-C.sub.10)-alkyl, and R.sup.8 represents methyl, ethyl, 2,2-dimethylpropyl or phenyl, wherein two separate metered streams (D1) and (D2) are metered into the reactor as mixtures 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 of formula (V) and metered stream (D2) comprises one or more compounds of formula (III), one or more compounds of formula (II), and optionally one or more free-radical-forming substances of formula (V), wherein the reaction is carried out in continuous fashion, and wherein the metered streams (D1) and (D2) are metered into the reactor predominantly simultaneously.

2. Process according to claim 1, wherein metered stream (D1) comprises one or more compounds of formula (II) and one or more free-radical-forming substances of formula (V), wherein metered stream (D1) comprises 10-100 mol % of the entirety of the amount of the free-radical-forming substances of formula (V) altogether employed.

3. Process according to claim 1, wherein metered stream (D1) comprises 20-100 mol % of the entirety of the amount of the free-radical-forming substances of formula (V) altogether employed in the reaction, optionally 25-100 mol %, optionally 30-100 mol %.

4. Process according to claim 1, wherein metered stream (D1) comprises 80-100 wt % of the entirety of the amount of compounds of formula (II) altogether employed in the metered streams (D1) and (D2).

5. Process according to claim 1, 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. Process according to claim 1, wherein metered stream (D1) comprises 40-100 mol % of the entirety of the amount of the free-radical-forming substances of formula (V) 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 of formula (V) altogether employed in the metered streams (D1) and (D2).

7. Process according to claim 1, wherein the entirety of the compound (II) and the free-radical-forming substances of formula (V) in the metered stream (D1) is 75 to 100 wt % based on the total weight of the metered stream (D1).

8. Process according to claim 1, wherein reaction is effected at a temperature in the range from 40 C. to 120 C.

9. 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. 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 R.sup.2 represents, and one of the compounds or the compound of formula (III) corresponds to formula (IIIa) ##STR00020##

11. Process for producing glufosinate ##STR00021## or glufosinate salt, comprising reacting in a reactor a compound of formula (II) ##STR00022## with a compound of formula (III) ##STR00023## to obtain a compound of formula (Ib) ##STR00024## 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, or represents methyl, X represents oxygen or sulphur and n is 0 or 1, in the presence of one or more free-radical-forming substances of formula (V) ##STR00025## wherein R.sup.6 independently at each occurrence represents hydrogen or (C.sub.1-C.sub.10)-alkyl, R.sup.7 represents hydrogen or (C.sub.1-C.sub.10)-alkyl, and R.sup.8 represents methyl, ethyl, 2,2-dimethylpropyl or phenyl, wherein two separate metered streams (D1) and (D2) are metered into the reactor as mixtures and these metered streams (D1) and (D2) have the following composition: metered stream (D1) comprises a mixture of one or more compounds of formula (II) and one or more free-radical-forming substances of formula (V), and metered stream (D2) comprises one or more compounds of formula (III), one or more compounds of formula (II), and optionally one or more free-radical-forming substances of formula (V), wherein the reaction is carried out in continuous fashion, and wherein the metered streams (D1) and (D2) are metered into the reactor predominantly simultaneously.

12. Process for producing glufosinate and/or one or more glufosinate salts, optionally glufosinate, glufosinate sodium or glufosinate ammonium, comprising: (a) reacting in a reactor a compound of formula (II) ##STR00026## with a compound of formula (III) ##STR00027## to obtain a compound of either a ##STR00028## or a compound of formula (Ib) ##STR00029## 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 of formula (V) ##STR00030## wherein R.sup.6 independently at each occurrence represents hydrogen or (C.sub.1-C.sub.10)-alkyl, R.sup.7 represents hydrogen or (C.sub.1-C.sub.10)-alkyl, and R.sup.8 represents methyl, ethyl, 2,2-dimethylpropyl or phenyl, wherein two separate metered streams (D1) and (D2) are metered into the reactor as mixtures 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 of formula (V), and metered stream (D2) comprises one or more compounds of formula (III), one or more compounds of formula (II), and optionally one or more free-radical-forming substances of formula (V), wherein the reaction is carried out in continuous fashion, and wherein the metered streams (D1) and (D2) are metered into the reactor Predominantly simultaneously; and (b) using the compound of either formula (I) or formula (Ib) obtained in (a) for producing one or more glufosinate/glufosinate salts, optionally glufosinate, glufosinate sodium or glufosinate ammonium.

13. The process according to claim 1, wherein metered stream (D1) comprises 40-100 mol % of the entirety of the amount of the free-radical-forming substances of formula (V) 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 of formula (V) altogether employed in the metered streams (D1) and (D2).

14. The process according to claim 1, wherein the entirety of the compound (II) and the free-radical-forming substances of formula (V) in the metered stream (D1) is 85 to 100 wt % in each case based on the total weight of the metered stream (D1).

15. 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.

16. The process according to claim 1, wherein the one or more free-radical-forming substances of formula (V) employed in the reaction are selected from the group consisting of tert-butyl peroxypivalate, tert-amyl peroxypivalate, tert-butyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-butyl peroxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert-amyl peroxyneodecanoate, cumyl peroxyneodecanoate, cumyl peroxyneoheptanoate and cumyl peroxypivalate.

Description

EXAMPLES

(1) All data are based on weight unless otherwise stated.

(2) Abbreviations used:

(3) MPE: methanephosphonous acid mono-n-butyl ester

(4) ACA: acrolein cyanohydrin acetate

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

Example 1

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

(6) Discontinuous Mode of Operation

(7) 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.

(8) 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.13 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.

(9) 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.

(10) 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:

(11) 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).

(12) The concentration of the free-radical initiator was accordingly 1.0 wt % based on the overall mixture.

(13) 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)

(14) Continuous Mode of Operation

(15) 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.

(16) 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.

(17) 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.

(18) 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.

Comparative Example 1

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

(19) 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.

(20) 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 any subsequent experiments (for example the ACM production in the continuous mode of operation).

Comparative Example 1a

Discontinuous Mode of Operation

(21) 248.9 g of MPE (98% purity) were initially charged and heated to 85 C. and 0.9 mL (about 0.8 g) of the free-radical-initiator tert-butyl perneodecanoate (98% purity) were added. 5 minutes after addition of the free-radical-initiator tert-butyl perneodecanoate to the MPE was complete a mixture of 57.9 g of ACA (99% purity) and 3.0 g of the free-radical initiator tert-butyl perneodecanoate (98% purity) were metered into the reactor over a period of 4.0 hours. The concentration of the free-radical initiator was accordingly 1.0 wt % based on the overall mixture present in the reactor.

(22) The employed ACA had reacted completely.

Comparative Example 1b

Continuous Mode of Operation

(23) The reactor was initially charged with a mixture produced by the discontinuous mode of operation according to hereinabove-reported comparative example 1a. At a reaction temperature of 85 C., the metered streams (D1) and (D2) were then simultaneously and separately metered into the reactor.

(24) At 85 C., metered stream (D1), MPE, was added to the reactor at 63 mL/h and metered stream (D2), a mixture of ACA and free-radical initiator tert-butyl perneodecanoate, was added to the reactor at 15 mL/h,

(25) the content of the free-radical initiator in the ACA (5.0 wt %) being chosen such that a content of 1.0 wt % of free-radical initiator in the overall mixture in the reactor was achieved.

(26) 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.

(27) Once a steady-state had been achieved, samples of the reactor contents were withdrawn and a yield of 93-94% for the reaction of ACA to afford ACM was determined.