PROCESS FOR PREPARING PHOSPHORUS CONTAINING CYANOHYDRINS

Abstract

The present invention relates primarily to a process for preparing certain phosphorus-containing cyanohydrins of the formula (I), and also to certain phosphorus-containing cyanohydrins per se and to their use for the preparation of glufosinate and/or glufosinate salts. The present invention further relates to certain mixtures particularly suitable for preparing the phosphorus-containing cyanohydrins of the formula (I).

Claims

1. Process for preparing a compound of formula (I) ##STR00017## comprising reacting a compound of formula (II) ##STR00018## with a cyanohydrin of formula (III) ##STR00019## at a temperature in a range from 50 to 105 C., where in each case: R.sup.1 is (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 is (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 are in each case independently of one another hydrogen, (C.sub.1-C.sub.4)-alkyl, phenyl or benzyl, X is oxygen or sulphur, and n is 0 or 1.

2. Process according to claim 1, wherein the reacting takes place at a temperature in a range from 60 to 95 C., optionally at a temperature in a range from 65 to 90 C.

3. Process according to claim 1, wherein a compound of formula (IIa) ##STR00020## is reacted with an acrolein cyanohydrin of formula (IIIa) ##STR00021## where: R.sup.1 is (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, R.sup.2 is (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.

4. Process according to claim 1, wherein the reacting is carried out with aid of a radical-forming radiation source or in the presence of one or more radical-forming substances.

5. Process according to claim 1, wherein the reacting takes place in the presence of one or more radical initiators of formula (IV) ##STR00022## where R.sup.5 is methyl, ethyl, 2,2-dimethylpropyl or phenyl, R.sup.6 independently at each occurrence is (C.sub.1-C.sub.10)-alkyl, optionally (C.sub.1-C.sub.6)-alkyl, optionally (C.sub.1-C.sub.4)-alkyl, and R.sup.7 is hydrogen or (C.sub.1-C.sub.10)-alkyl, optionally hydrogen or (C.sub.1-C.sub.6)-alkyl, optionally hydrogen or (C.sub.1-C.sub.4)-alkyl.

6. Process according to claim 5, wherein the reacting takes place in the presence of one or more radical initiators selected from the group consisting of tert-butyl peroxypivalate, tert-amyl peroxypivalate, tert-butyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-butylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert-amyl peroxyneodecanoate, cumyl peroxyneodecanoate, cumyl peroxyneoheptanoate, and cumyl peroxypivalate.

7. Process according to any claim 1, wherein the molar ratio of the total amount of the phosphorus-containing reactant (II) used to the total amount of the cyanohydrin of the formula (III) used is in a range from 2:1 to 8:1.

8. Process according to claim 1, wherein the radical initiator or initiators of the formula (IV) or a portion of the radical initiators of the formula (IV) is premixed with a portion or the entirety of compound (II), and this mixture is metered into the reaction vessel simultaneously with the compound of the formula (III).

9. Mixture selected from the group consisting of mixtures comprising one or more compounds of the formula (IV) and one or more compounds of the compound (III) formula, mixtures comprising one or more compounds of the formula (IV) and one or more compounds of the compound (II) formula, mixtures comprising one or more compounds of the formula (III) and one or more compounds of the compound (III) formula, where the compounds of the formula (II) and (III) are as follows: ##STR00023## R.sup.1 is (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 is (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 are in each case independently of one another hydrogen, (C.sub.1-C.sub.4)-alkyl, phenyl or benzyl, X is oxygen or sulphur, and n is 0 or 1 and the compounds of the formula (IV) have the structure as follows: ##STR00024## where R.sup.5 is methyl, ethyl, 2,2-dimethylpropyl or phenyl, R.sup.6 independently at each occurrence is (C.sub.1-C.sub.10)-alkyl, optionally (C.sub.1-C.sub.6)-alkyl, optionally (C.sub.1-C.sub.4)-alkyl, and R.sup.7 is hydrogen or (C.sub.1-C.sub.10)-alkyl, optionally hydrogen or (C.sub.1-C.sub.6)-alkyl, optionally hydrogen or (C.sub.1-C.sub.4)-alkyl.

10. Mixture according to claim 9, where the compounds of the formula (II) and (III) have the structure as follows: ##STR00025## where: R.sup.1 is (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, R.sup.2 is (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 the compounds of the formula (IV) are selected from the group consisting of tert-butyl peroxypivalate, tert-amyl peroxypivalate, tert-butyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, tert-butylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, tert-amyl peroxyneodecanoate, cumyl peroxyneodecanoate, cumyl peroxyneoheptanoate, and cumyl peroxypivalate.

11. Process for preparing one or more glufosinate and/or glufosinate salts ##STR00026## comprising: reaction of a compound of the formula (Ib) to give a corresponding compound of formula (V), ##STR00027## where R.sup.2 is in each case either n-butyl or n-pentyl, optionally n-butyl.

12. Process according to claim 11, wherein the preparation of compound (V) takes place by reaction of compound (Ib) with NH.sub.3.

13. Process according to claim 11, wherein the preparation of compound (Ib) takes place according to a process for preparing a compound of formula (I) ##STR00028## comprising reacting a compound of formula (II) ##STR00029## with a cyanohydrin of formula (III) ##STR00030## at a temperature in a range from 50 to 105 C., where in each case: R.sup.1 is (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 is (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 are in each case independently of one another hydrogen, (C.sub.1-C.sub.4)-alkyl, phenyl or benzyl, X is oxygen or sulphur, and n is 0 or 1.

14. Compound of formula (AMN) ##STR00031## where Q is either OH or NH.sub.2, and R.sup.2 is either n-butyl or n-pentyl, optionally n-butyl.

15. A compound according to claim 14 capable of being used for preparing glufosinate and/or glufosinate salts, optionally glufosinate, glufosinate-sodium or glufosinate-ammonium.

Description

EXAMPLES

[0124] Unless otherwise indicated, all figures are given by weight.

Example 1

Acrolein Cyanohydrin (Not Subject Matter of the Present Invention)

[0125] 100 g (0.791 mol) of acrolein cyanohydrin acetate (99% purity) (obtainable for example as described in U.S. Pat. No. 4,336,206) were mixed with 300 ml of dry methanol, with inertizing using nitrogen, and the mixture was stirred at 20 C. for 6 days with 60 g of dried, previously activated* ion exchanger (Amberlyst 15, Rohm & Haas). After the end of hydrolysis (GC check), the ion exchanger was removed by filtration and washed with dry methanol

[0126] The combined filtrates were admixed with 5 drops of concentrated phosphoric acid (H.sub.3PO.sub.4) and then the solvent was removed on a rotary evaporator at max. 30 C. and 0.5 mbar at the end. The residue obtained was 65.6 g of acrolein cyanohydrin (98% purity by GC and NMR), corresponding to a yield of 97.8% of theory. The resulting acrolein cyanohydrin was used without further purification.

[0127] NMR (CDCl.sub.3):

[0128] .sup.1H: 3.97 ppm (s); 5.01 ppm (d); 5.47 ppm (d); 5.63 ppm (d); 5.95 ppm (m);

[0129] .sup.13C: 62.03 ppm; 116.41 ppm; 117.38 ppm; 131.53 ppm.

[0130] *The ion exchanger was activated by washing with half-concentrated hydrochloric acid, then with water, and lastly with ethanol. After that the ion exchanger was dried under reduced pressure at 60 C. (the ion exchanger can be used more than once, i.e. used again, for the same reaction).

Example 2

n-Butyl (3-cyano-3-hydroxypropyl)methylphosphinate (ACM-H)

[0131] In a stirring apparatus with impeller stirrer, 20 g (0.1445 mol) of mono-n-butyl methanephosphonate (98.5% purity, MPE, corresponding to formula (IIb) with R.sup.2=n-butyl) were introduced under nitrogen and heated to 85 C. Added to this initial charge with vigorous stirring was 0.1 g of tert-butyl peroxyneodecanoate (radical initiator of the formula (IV)). Subsequently, the following mixtures were metered in simultaneously from two different syringe pumps: in one syringe pump, a mixture of 5.0 g (0.036 mol) of MPE and 5.1 g of acrolein cyanohydrin (0.058 mol, purity: 94%), and in the other syringe pump a mixture of 15 g (0.1084 mol) of MPE and 0.6 g of tert-butyl peroxyneodecanoate. The total amount of tert-butyl peroxyneodecanoate was therefore 0.003 mol. The simultaneous metered introduction of the two mixtures into the stirring apparatus took place at constant temperature with vigorous stirring over a period of 2.5 hours. The resulting pale yellow reaction mixture, after the end of simultaneous metered introduction of the two mixtures, was stirred at 85 C. for 30 minutes more and then cooled.

[0132] According to .sup.31P NMR, the reaction mixture contained 21.3 mol % of the desired product (ACM-H) and 78.7 mol % of the MPE reactant.

[0133] According to .sup.1H NMR, the reaction mixture no longer contained any acrolein cyanohydrin reactant.

[0134] 30.0 g of the excess MPE were separated off (for the purpose of re-use as well) via a short-path evaporator distillation (outer jacket temperature of 105 C. and down to a pressure of 0.2 mbar). Remaining in the bottom were 12.5 g of the desired n-butyl (3-cyano-3-hydroxypropyl)methylphosphinate product (ACM-H) with a purity of 95% (according to GC and NMR analysis). The yield of ACM-H therefore corresponds to 93.6% of theory, based on acrolein cyanohydrin.

[0135] NMR (CDCl.sub.3):

[0136] .sup.1H: 0.95ppm (t); 1.41ppm (m); 1.52 ppm (d,d); 1.65 ppm (m); 2.0 ppm (m); 2.1 ppm (m); 4.0 ppm (m); 4.58 ppm (m); 6.15 ppm (s).

[0137] .sup.31P NMR: 55.5 ppm.

Example 3

n-Butyl (3-cyano-3-hydroxypropyl)methylphosphinate (ACM-H)

[0138] The batch size corresponded to that from Example 2, and the reaction procedure was in analogy to Example 2, but using tert-butyl peroxy-2-ethylhexanoate as radical initiator instead of tert-butyl peroxyneodecanoate, and the amount of tert-butyl peroxy-2-ethylhexanoate was 0.04 mol per mole of acrolein cyanohydrin. The reaction temperature was 88 C., the metering time 1.5 hours.

[0139] The reaction mixture also contained 3% of the acrolein cyanohydrin reactant. Acrolein cyanohydrin and excess MPE were removed as described above via a short-path evaporator distillation.

[0140] The yield of ACM-H found was 90% of theory, based on acrolein cyanohydrin.

Example 4

n-Butyl (3-cyano-3-hydroxypropyl)methylphosphinate (ACM-H)

[0141] The batch size corresponded to that from Example 2, and the reaction procedure was in analogy to Example 2, but using a mixture of tert-butyl peroxy-2-ethylhexanoate and tert-butyl peroxyneodecanoate (in each case 0.04 mol per mole of acrolein cyanohydrin) as radical initiator. The reaction temperature was 88 C., the metering time 2 hours. Further work-up was as described above.

[0142] The reaction mixture also contained traces of the acrolein cyanohydrin reactant.

[0143] The yield of ACM-H found was 93% of theory, based on acrolein cyanohydrin.

Example 5

n-Butyl (3-cyano-3-hydroxypropyl)methylphosphinate (ACM-H)

[0144] Apparatus: First stirring vessel with heating jacket, two metering pumps, and bottom drain valve, connected to a second stirring vessel; the stirring vessels were each equipped with an impeller stirrer.

[0145] Procedure: quasi-continuous mode

[0146] Process section 1:

[0147] In analogy to the experimental description in Example 2, the first stirring vessel was charged with 21 g of MPE under a nitrogen atmosphere, 0.1 g of tert-butyl peroxy-2-ethylhexanoate was added, and the mixture was heated to 88 C. Thereafter, with vigorous stirring, two different syringe pumps supplied metered feeds to this first stirring vessel, the first feed being a mixture of 8.06 g of acrolein cyanohydrin and 11.94 g of MPE, and the other feed being a mixture of 19 g of MPE, 0.93 g of tert-butyl peroxyneodecanoate and 0.7 g of tert-butyl peroxy-2-ethylhexanoate, the feeds taking place at constant temperature over a period of 2 hours.

[0148] Process section 2:

[0149] The reaction temperature was held further at 88 C. Subsequently, over a further 2 hours, once again the same amounts of the same two mixtures of acrolein cyanohydrin and MPE and of MPE, tert-butyl peroxyneodecanoate and tert-butyl peroxy-2-ethylhexanoate as described above were metered separately into the first stirring vessel via the same syringe pumps. In addition, a further 21 g of MPE were added dropwise and simultaneously from the first stirring vessel, by slow run-off through the bottom valve, a constant run-off into the second stirring vessel, heated at 80 C., was ensured, and hence a constant fill level in the first reactor was obtained as well.

[0150] Process section 3:

[0151] After the end of the metered addition of the two mixtures and of the MPE, process section 2 was repeated once again.

[0152] In the reaction mixture subsequently obtained, there was no longer any acrolein cyanohydrin.

[0153] For working up, the mixture was purified via a short-path evaporator at a jacket temperature of 115 C., 0.2-0.5 mbar. The excess MPE obtained as distillate (115 g) was used again in later batches.

[0154] In the distillation bottom product there remained 58.6 g of n-butyl (3-cyano-3-hydroxypropyl)-methylphosphinate (94.8% crude yield), which could be used directly, i.e. without further purification, in the subsequent reactions, for the preparation, for example, of glufosinate-ammonium.

Example 6

n-Butyl (3-cyano-3-hydroxypropyl)methylphosphinate (ACM-H)

[0155] In a jacketed stirring vessel inertized using nitrogen and possessing thermometer, impeller stirrer and a bottom drain valve whose drain led into a heatable flask fitted with stirrer, the initiating reaction was first of all carried out.

[0156] Initiating reaction:

[0157] First of all 27 g of MPE were introduced and heated to 76 C. Thereafter 0.1 g of initiator (1,1,3,3-tetramethylbutyl peroxyneodecanoate, acquired commercially as Trigonox 423) was added. Subsequently, by means of two different syringe pumps, the following mixtures were metered in simultaneously: in one syringe pump, a mixture of 9.7 g (97% purity) of acrolein cyanohydrin and 10.0 g of MPE, and simultaneously, in the other syringe pump, a mixture of 18.0 g of MPE and 2.4 g of Trigonox 423. The two mixtures were metered in at a uniform rate over 2 hours, the temperature in the jacketed stirring vessel being held at 76 C.

[0158] Continuous reaction regime:

[0159] As described above, two mixtures were metered subsequently into the reaction vessel simultaneously and at a uniform rate over 6 hours, at the same temperature:

[0160] Via a first pump, a mixture of 29.1 g of acrolein cyanohydrin and 30 g of MPE, and, via a second pump, a mixture of 54 g of MPE and 7.2 g of Trigonox 423 were metered into the reaction vessel. Simultaneously over the same period of time, from a third metering vessel, a total of 81 g of MPE were added dropwise at a uniform rate. In order to keep a constant fill level in the reaction vessel, a total of 195 g of the resultant reaction mixture were drained off through the bottom valve into the flask which was maintained at 76 C. and provided with a stirrer, throughout the duration of metering.

[0161] The reaction mixture was pale yellow and clear. After an after-reaction time of around 15 minutes, the reaction mixtures were combined. For working up, the low-boiling components (including the excess MPE) were distilled off via a short-path evaporator (0.2 mbar/115 C.). The crude product remaining in the bottom can be used directly in this form for further reactions. 101.8 g of product (the GC purity of ACM-H was 9.15%) were obtained, corresponding to a yield of 94% of theory, based on acrolein cyanohydrin.

Example 7

Ammonium D,L-homoalanin-4-yl(methyl)phosphinate (Glufosinate-Ammonium)

[0162] From 218 g (0.885 mol) of n-butyl (3-cyano-3-hydroxypropyl)methylphosphinate (purity: 89%), further reaction was carried out with ammonia and with hydrochloric acid, similarly to the processes described in U.S. Pat. No. 6,359,162B1 or CN 102399240A. Lastly, ammonia was added, giving an aqueous solution of the ammonium salt.

[0163] Obtained in this way were 742.2 g of an aqueous solution containing 22.5% of glufosinate-ammonium, corresponding to a yield of 95.2% of theory.