FI75831B - FOERFARANDE FOER FRAMSTAELLNING AV ESTRAR TILLHOERANDE N-FOSFONOMETYLGLYCINGRUPPEN. - Google Patents

Abstract

Phosphonic acid diesters having the formula: <IMAGE> in which R represents a hydrogenolysable group, preferably an aralkyl group, and R<1> represents a hydrolysable group, are obtained by a process wherein phosphonic acid esters of the formula (R<1>O)2P(O)H are reacted with formaldehyde and compounds of the formula R-NH-CH2-COOH, R and R<1> having the meanings given above. Compounds of the formula <IMAGE> may be obtained by hydrogenolysis of the above compounds.

Description

75831

Process for the preparation of esters belonging to the N-phosphonomethylglycine group

The present invention relates to a process for the preparation of N-substituted phosphonic acid esters belonging to the N-phosphonomethylglycine group, which esters can be used for the preparation of known herbicides.

Numerous herbicides belonging to the N-phosphonomethylglycine group are already known (U.S. Patents 3,455,675, 4,388,103 and 4,397,676, FR Patent 2,129,327, European Patents 53,871, 54,382, 73,574, PCT Patent No. 3,883,083, PCT Patent No. , GB patent 2,090,596, BE patents 894,244, 894,245, 894,590, 894,591, 894,592, 894,593, 894,594 and 894,595).

It is an object of the invention to provide a very simple and improved partial synthesis of the production of herbicides using simple reagents, in particular glycine and its simple derivatives.

Other objects and advantages of the invention will become apparent as the following specification proceeds.

Previously mentioned (FR patent 2,129,327) the formation of triesters of N-phosphonomethylglycine by the reaction of ethyl glycinate with formaldehyde and diethyl phosphite. This method is unsatisfactory because it is considered to be too oriented towards the formation of N, N-bis (phosphonomethyl) glycine. For this reason, it has been proposed (FR Patent 2,193,830) to prepare N-phosphonomethylglycine by reacting N-arylalkylglycine with formaldehyde and phosphoric acid and then removing the N-arylalkyl group with hydrobromic or hydroiodic acid. However, this method is no longer considered satisfactory due to the low yields obtained and the formation of the tear-causing benzyl bromide 75831 2 mide. Thus, it has been proposed to prepare N-phosphonomethylglycine by the reaction of N-substituted glycine with formaldehyde and phosphoric acid and then hydrogenolysis of the obtained (N, N-disubstituted) N-phosphonomethylglycine. The disadvantage of this method is that it is carried out in a very dilute medium and takes a long time. Subsequently (European Patent Publication 81,459) it is directed to reagents other than glycine and formaldehyde and the aminomethylphosphonic acid is reacted with glyoxal in the presence of SO.

2

It has now been discovered that herbicides belonging to the N-phosphonomethylglycine group can be prepared by means of new intermediates, which in turn can be prepared starting from N-substituted glycine derivatives and formaldehyde.

The above invention relates to a process for the preparation of phosphonic acid esters of formula 1

OR R

I l O = P - CH - N - CH - CO - OH (i)

112 2 OR

wherein R is a hydrogenolysable group, preferably an arylalkyl group, and R is a hydrolyzable group.

In particular, the radical R can be of the formula:

R

Ar - C - (II) 13

R

according to the radical with the formula

Ar is an aromatic group, preferably an aryl group and especially a phenyl group; the radical Ar may, if desired, contain

II

3,75831 one or more substituents which do not adversely affect the reactions involved in the process (alkyl, alkoxyl, nitro, etc., preferably having up to six carbon atoms). However, it does not appear particularly advantageous to use such substituents, and R and R represent hydrogen or a radical Ar or an alkyl group, preferably having up to 6 carbon atoms.

As the radicals R, mention may be made of the radicals benzyl, 1-phenylethyl, 1-phenylpropyl, naphthylmethyl, 1-naphthylethyl, 1-naphthylpropyl, diphenylmethyl, trityl (= triphenylmethyl). The benzyl radical is preferred.

R is a hydrolyzable radical; examples of hydrolysable radicals are hydrocarbyl radicals, optionally substituted, in particular alkyl or phenyl radicals optionally substituted by halogen atoms or phenyl, cyano, alkoxy or alkoxycarbonyl groups, R generally has up to 12 carbon atoms and is preferably an alkyl radical, having 1 to 6 carbon atoms or a phenyl radical.

The process according to the invention for the preparation of the compounds of formula (I) is characterized in that the phosphite (i.e. the phosphonic acid ester) of the formula 1

0 - R

O = P - H (III)

1 1 O - R

wherein R is as defined above, is reacted with an N-substituted derivative of formaldehyde and glycine, wherein the substituent attached to the nitrogen atom is a hydrolyzable substituent; this N-substituted derivative of glycine is in practice a compound of formula R - NH - CH - CO - OH.

2 75831 4 p

The reaction is generally carried out at a temperature in the range of 0 to 100 ° C, preferably in the range of 10 to 90 ° C, simply by stirring the reagents. Although a large excess (in 3/1 to 1/3 molar ratios) of one reagent relative to another is possible, in practice it is more advantageous to approach stoichiometric amounts as much as possible and not deviate by more than 20 mol% from said stoichiometry. Indeed, one of the important advantages of this invention is that it does not require an excess of one reagent over another. Another advantage of the invention is that it gives good yields in the preparation of the compounds according to the invention.

Formaldehyde is used in one of its conveniently available forms. According to the most common embodiment, it is used as an aqueous solution with a concentration between 1% and impregnation, preferably 30-40%.

The reaction may be carried out in the presence of an inert solvent; sometimes such a solvent is useless, but the reaction mixture usually contains water, especially since formaldehyde is used as an aqueous solution.

The reaction product is isolated by any means known per se.

The products of formula (I) may be converted into known herbicides of the formula:

OR

O = P - CH - NH - CH - CO - OH (IV)

112 2 OR

by simple hydrogenolysis of the group R. Debenzylation is most commonly used. This debenzylation is preferably carried out in an aqueous or alcoholic medium at or above ambient temperature and at a pressure greater than or equal to atmospheric pressure. As the catalyst, ordinary Rs of the radicals in question can be used

II

5,75831 hydrogenolysis catalysts. Suitable catalysts include palladium, platinum and Raney nickel. This catalyst can be used with or without an inert support. It is also possible to use the abovementioned metals, in particular palladium and platinum, in the form of salts, hydroxides or oxides which are converted into the corresponding metal by the action of hydrogen. Palladium-based catalysts such as palladium on activated carbon or palladium on barium sulfate or palladium hydroxide on activated carbon are used as the primary catalysts for debenzylation. Upon completion of the reaction, the catalyst can be separated by filtration and the filtrate evaporated; this forms the product of formula (IV) in substantially pure form. An important advantage of the invention is that the reaction time of this debenzylation is relatively short, which makes it possible to use small amounts of catalyst.

When it is desired to prepare known non-esterified forms of herbicides, such as N-phosphonomethylglycine itself, the product of formula (IV) can be completely or partially hydrolysed in a known manner, for example by heating with an acidic or alkaline reagent solution, especially an alkali metal or earth. with an alkali metal hydroxide or carbonate, or with hydrochloric, sulfuric, phosphoric, perchloric or arylsulfonic acid. This hydrolysis may also involve salt formation or conversion to other herbicidal derivatives. Thus, the hydrogenolysis of the invention may be followed by hydrolysis and / or salt formation.

The following examples illustrate the invention and show how it can be applied in practice.

Example 1

39 g of N-benzylglycine, 80 ml of water, 20.3 ml of aqueous formaldehyde solution (0.248 mol) are stirred. At ambient temperature, 58 g (0.248 mol) of diphenyl phosphite (C, H, -O) -PH (O) are poured drop by drop. After 30 minutes, allow the temperature to rise to 30 ° C and stir for another hour. Filter, wash with water and dry. After recrystallization from isopropyl / isopropanol ether, 10/1 by volume, 57.4 g of a white powder with a melting point of 91 [deg.] C. (yield: 59.1%) are obtained, consisting of a product of the formula:

CcH, -O CH0-C, Hc 65, 265 I i O = P - CH2 n - CH2 - COOH (V) C6h50

Example 2

16.5 g of N-benzylglycine, 28 ml of water, 13.8 g of diethyl phosphite (C2H2O) 2PH (O) are stirred. At 20 [deg.] C., 9 ml of a 37% aqueous solution of formol (0.11 mol) are poured. No exotherm is observed at all. Heat at 50 ° C for 5 h. Cool and add 40 mL of CH 2 Cl 2 · The organic phase is separated and 40 mL of water and then 100 mL of aqueous NaOH are added. The aqueous phase is decanted, extracted with CH2Cl2 and acidified. The organic phase is dried and evaporated. 23.5 g (74% yield) of the formula: C-H-O CHO-CcH are obtained.

2 51 j 2 6 5 O = P - CH- N - CH ~ - COOH (VI) l 1 1 c2h50

Example 3

Saponification of ethyl N-benzylglycinate is performed in situ. Mix 0.5 l of 30% aqueous NaOH (5 moles) and 1 liter of water; 965 g of ethyl N-benzylglycinate are gradually poured into this solution over one hour. The temperature rises to 45 ° C. The ethanol is removed by distillation, cooled and 0.82 l of 6N aqueous hydrochloric acid is added. N-benzylglycine precipitates. 690 g of diethyl phosphite and 0.45 l of a 37% aqueous solution of formol (5 mol) are added. is considered

II

75831 for 5 h 30 min at 50 ° C. Then proceed as in Example 2. 1116 g (71% yield) of the product of formula (VI) are obtained.

Claims (2)

8 75831 1. For use in the preparation of phosphonium radiators with a form in OR R 0. P - CH - N - CH - CO - OH (I) 112. OR color R is a hydrogenolyser group, a fatty acid aryl alkyl group, and a R is a hydrolyser group, which is converted to a phosphonium ester with a form of (R 0) ^ P (0) H is a formaldehyde and a form of a form R NH-CH 2 -COOH, color R and R har ovan angiven bety-delse. 1 I O = P - CH - N - CH - CO - OH (i) 1 2 2 OR wherein R is a hydrogenolysable group, preferably an arylalkyl group, and R is a hydrolyzable group, characterized in that the phosphonic acid ester of the formula (R 0) ^ P (O) H is reacted with formaldehyde and the formula R-NH-CH 2 - A nation of a compound of COOH wherein R and R are as defined above. Process according to Claim 1, characterized in that the radical R is a radical of the formula 4 R Ar - C - (II) 13 R in which Ar is an aromatic group, preferably aryl, which is optionally substituted, and 3 R and R each represent a hydrogen atom or a radical Ar or an alkyl group, preferably containing up to 6 carbon atoms. Process according to Claim 2, characterized in that R is a benzyl radical. Process according to any one of Claims 1 to 3, characterized in that R is an alkyl phenyl radical which is optionally substituted and contains up to 12 carbon atoms. li 9 75831 Process according to Claim 3 or 4, characterized in that R is an alkyl radical containing 1 to 6 carbon atoms or a phenyl radical. Process according to any one of Claims 1 to 5, characterized in that the reaction is carried out at a temperature of 0 to 100 ° C and that each reagent is present in an amount which does not differ from the stoichiometric by more than 20%. Process according to any one of Claims 1 to 6, characterized in that the reaction is carried out in an aqueous step. A process for the preparation of phosphonic acid diesters of the formula OR R 2. A patent according to claim 1, comprising a radical R or a radical of formula 4 R Ar - C - (II) 13 R