NO151547B - RELATIONSHIPS WITH HERBICID ACTIVITY - Google Patents

Description

The present invention relates to new O-aryl-N-phosphonomethyl-glycinonitriles with herbicidal activity.

According to US patent 3,923,877, N-phosphonomethylglycine can be prepared by reacting a dihydrocarbyl phosphite with 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine in the presence of a catalyst, such as hydrogen halide, a Lewis acid , a carboxylic acid halide or a carboxylic acid anhydride, and then hydrolyzing the product formed. The yields of this method are very low. The patent states that the reaction takes place between the sulfite and the triazine to form an intermediate product, an ester of N-phosphonomethylglycinonitrile. The convenient esters according to the patent are aliphatic with 1-6 carbon atoms or phenyl-substituted aliphatic groups such as benzyl and preferably alkyl with 1-6 carbon atoms. These esters are hydrolysed, whereby N-phosphonomethylglycine is obtained,

a post-emergent herbicide. It has been shown that the 0,0-diethyl-N-phosphonomethylglycinonitriles produced according to the method in the patent have no post-emergent herbicidal activity at 4.48 kg/ha and no pre-emergent herbicidal activity at 5.60 kg/ha.

It has now been shown that 0,0-diaryl-N-phosphonomethylglycinonitriles can be prepared by reacting a diaryl phosphite with 1,3,5,-tricyanomethyl-hexahydro-1,3,5-triazine without the need for any catalyst. It has further been shown that these glycinonitriles prepared in this way, as well as the corresponding monoaryl esters prepared by mild hydrolysis of the diester compounds have pre- and post-emergent herbicidal activity which is completely unexpected due to the inactivity of the diethyl-N-phosphonomethylglycinonitrile.

The N-phosphonomethylglycinonitriles according to the invention are distinctive in that they have the formula:

where Aryl is phenyl or naphthyl, each X is a substituent on Aryl and selected from halogen, alkyl with 1-4 carbon atoms, alkoxy and alkylthio with 1-3 carbon atoms, methylenedioxy, trifluoromethyl or nitro, Z is oxygen or sulfur, a is 0 , 1, 2 or 3, b is 0 or 1, R is a strong acid having a pKa in water of 2.5 or less, and x is 0 or 1, with the proviso that x must be 0 when b is 1 .

According to the above caveat, the strong acid salts are only formed with a diester. When a strong acid is added to a monoester (see formula IV), the single aryl ester group can be hydrolysed from the molecule.

The N-phosphonomethylglycinonitriles of formula I where x and b are zero are formed by forming a mixture consisting essentially of a phosphoric acid ester of the formula: where X, Z and a are as above, and 1,3,5-tricyanomethyl-hexahydro -1,3,5-triazine (also called N-methyleneglycinonitrile trimer) with the formula:

and heating the mixture to a sufficiently high temperature

to initiate the reaction, and maintain a temperature sufficient to maintain the reaction of the phosphoric acid ester with the triazine to form the aforementioned N-phosphonomethylglycinitrile of formula I.

Although a solvent is not required by

this procedure, it is sometimes desirable to use a solvent for convenience and to facilitate the reaction. A solvent is also useful to regulate the reaction temperature. The solvent used is one in which the triazine is soluble and which does not react with any of the reactants. Such inert solvents include acetonitrile, ethyl acetate, tetrahydrofuran and the like.

It has been shown that the reaction temperature can be so

as low as 25° C to 110° C. Higher temperature can be used, but no corresponding advantages are gained thereby as the reaction is essentially complete by the time the temperature reaches approx. 85°C.

As will be seen from the above formulas II and III, should

the ratio of phosphoric acid ester to triazine should be 3 to 1 for best results. Higher or lower ratios could be used, but no corresponding advantages are thereby obtained, since at higher ratios, excess phosphoric acid esters will have to be separated, and at lower ratios of ester to triazine, by-product formation is possible.

The reaction is generally carried out at atmospheric pressure for economic reasons. However, higher and lower pressures can be used, but no advantages are thereby achieved.

To prepare the compounds of formula I where b is

1 and x is 0, i.e. compounds with the formula:

where X, Z and a are as stated above, only a solution of a compound with the formula is prepared:

where X, Z and a are as above, in a solvent

containing at least one molar equivalent of water, and the solution is kept at the ambient temperature at which one of the groups

(X ri Aryl-O) is hydrolyzed. The preferred solvent for the hydrolysis is acetone. The desired material is isolated by usual methods such as fractional crystallization or vacuum evaporation of the solvent and other volatile hydrolysis products, after which the desired material can be crystallized from a suitable solvent.

To prepare the compounds of formula I where b is 0 and x is 1, i.e. compounds of the formula:

where X, Z and a are as indicated above, a compound of formula V is dissolved in an anhydrous solvent such as chloroform, and a strong acid is added to the solution, either in a solvent or in some cases the acid itself is added, while stirring at the ambient temperature for a time sufficient to allow the compound of formula V and the acid to react to form the compound of formula VI. In many cases, the desired product precipitates in crystalline form from the reaction solution. In the second case, a 50-50 volume mixture of chloroform and diethyl ether is added to cause the product to crystallize or to separate it from the reaction solution as an oil.

The compounds of formula VI are salts of the diester of formula V and can also be represented by the formula:

where X, Z and a are as above, and is the anion of the strong acid.

The groups substituted on the phenyl or naphthyl group and represented by X are halogen, such as chlorine, fluorine and bromine, methyl, ethyl, propyl and butyl, methoxy, ethoxy and propoxy, methylthio, ethylthio and propylthio, as well as methylenedioxy, trifluoromethyl and nitro. It is obvious from the formula that the groups represented

at X may be the same or different on the same aryl ring.

The strong acids which are useful in the preparation of the strong acid salts of formula I, VI and VII are those which have a pKa in water of 2.5 or less, and include e.g. p-toluenesulfonic acid, p-chlorobenzenesulfonic acid, trichloroacetic acid, oxalic acid, fluoroboric acid, hydrogen chloride, hydrogen bromide, hydrogen iodide, trifluoroacetic acid, pentafluoropropionic acid, heptafluorobutyric acid, trifluoromethanesulfonic acid, nitric acid, sulfuric acid, phosphoric acid, trichloromethanephosphonic acid, perchloric acid, methanesulfonic acid and the like.

When preparing the strong acid salts with the formulas I, VI and VII, it is preferred to use the diester of the phosphonic acid and the strong acid in equal molar proportions to facilitate the isolation of the salt of the strong acid. Higher or lower ratios of ester to acid can be used, although isolation of the product can be made difficult due to the presence of an excess of one of the reactants.

The compounds of formula I are useful as herbicides for both pre-emergent and post-emergent applications.

The following general procedures show the preferred methods for preparing the various compounds according to the invention.

The diarylesters of formula V are preferably prepared by one of the the following two methods.

(A) 50 ml of an acetonitrile solution of 3.4 g (0.0167 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine and

0.050 mole of diaryl phosphite is mixed in a reaction vessel and heated from 45° C. to 85° C. for from 1 to 90 hours until all phosphite or triazine is consumed as determined by n.m.r. analysis. If the n.m.r. spectral analysis indicates that no impurities are present, the product is isolated by vacuum evaporation. If impurities are present, the product is isolated and purified by crystallization or chromatography. In some cases, the diester product can be difficult to isolate in very pure form because hydrolysis occurs during the attempted isolation.

(B) A mixture of 0.05 mole of a diaryl phosphite and

3.4 g (0.0167 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine

introduced into a reaction vessel and heated to 60 - 100° C for 20 minutes to 1 hour, until all phosphite or triazine is consumed as determined by n.m.r. spectral analysis. The products are purified by crystallization or chromatography.

The monoaryl esters of N-phosphonomethylglycinonitrile are prepared by dissolving the diaryl ester in acetone containing a small amount of water (usually about 2% by weight of water) and stirring the reaction mixture for from 18 to 72 hours. The monoesters are usually crystalline and are collected by filtration, washed with acetone and air-dried.

The strong acid salts of the diaryl esters are preferably prepared by the following general procedure. 0.01 mol of a solution of the strong acid (or the acid itself) is added dropwise to a chloroform solution of the diester at ambient temperature and allowed to stand. If crystals form, they are collected by filtration, washed with a 50% by volume chloroform-ether mixture and air dried. Otherwise, a 50% by volume chloroform-ether mixture is added to cause the salt to crystallize or come out of solution as an oil. .The following experiments serve to further illuminate the invention. All parts are parts by weight unless otherwise specifically stated.

Example 1

23.32 g, 78% pure (0.06 mol) di-(p-chlorophenyl)-phosphite and 4.08 g (0.02 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5- triazine was mixed in a reaction vessel at room temperature and the mixture was heated to 100°C for 20 minutes whereby 27 g of 0,0-di-(p-chlorophenyl)-N-phosphonomethylglycinonitrile were obtained in 100% yield,

n^<1> = 1.5747.

Example 2

10 ml of an acetonitrile solution of 8.7 g (0.03 mol) of di-(3,4-dimethylphenyl)-phosphite was added to 50 ml of an acetonitrile solution of 2.04 g (0.01 mol) of 1, 3,5-tricyanomethyl-hexa-hydro-1,3,5-triazine and the mixture was heated at 55° C. for 90 hours. Filtration of the solid material present and evaporation of the solution gave a burgundy colored oil which, by n.m.r. analysis, contained the desired product and the aminal of this product. Chromatography of the oil (8.0 g) over 450 g silica gel with 60 ml fractions 50% cyclohexane/50% ethyl acetate gave 0,0-di-(3,4-dimethylphenyl)-N-phosphonomethylglycinonitrile in fractions 30 - 41 which melted at 61 - 64° C after removal of the solvent. The solid was recrystallized from carbon tetrachloride-isooctane, whereby 3.1 g (40% yield) with melting point 63 - 66° C was obtained.

Example 3

A stirred mixture of 0.02 mol di-(p-methylthiophenyl)-phosphite and 0.006 7 mol 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine was heated to 80° C. for 1.0 hour which led to a dark red-brown oil. Half of the sample was then placed in a refrigerator for 8 days, which gave a semi-solid mass. The sample was then recrystallized from 70 ml of carbon tetrachloride which gave a pale pink solid. The solid was dissolved in 100 ml of hot carbon tetrachloride and filtered through "Celite" covered with 5.0 g of silica gel. The filtrate was evaporated to 50 ml and placed in a refrigerator overnight. The suspension was filtered to give 1.8 g (45%) of a white solid which was identified as O,0-di-(p-methylthiophenyl)-N-phosphonomethylglycininitrile with a melting point of 64-65°C and the following analysis:

Calculated: C 51.8, H4.9, N7.1

Found: C 51.7, H 4.9, N 7.1

Example 4

A solution of 8.05 g, 91% pure (0.025 mol) di-(o-methoxyphenyl)-phosphite and 1.7 g (0.0083 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5 -triazine was heated at 55°C for 73 hours and then filtered. The filtrate was evaporated to give 9.6 g of a dark brown oil. 5.8 g of the oil was applied to 8 g of silica gel and extracted with 80 ml of ethyl acetate. The ethyl acetate solution was evaporated and the resulting oil applied to 4.0 g of silica gel. This silica gel was extracted with 70 ml of ethyl acetate and the solution evaporated under vacuum to give a pale yellow oil,

nD 22 = 1.5542. The yellow oil was found to be O,O-di-(o-methoxyphenyl)-N-phosphonomethylglycinonitrile containing a small amount of o-methoxyphenol.

Example 5

A solution of 13.6 g (0.066 mol) 1,3,5-tricyano-methyl-hexahydro-1,3,5-triazine and 46.8 g (0.2 mol) diphenylphosphite in 100 ml acetonitrile was heated at 55° C for 48 hours. N.M.R. of the crude reaction mixture indicated complete conversion to 0,O-diphenyl-N-phosphonomethylglycinonitrile. The acetonitrile was removed in vacuo to give 57 g (94.4%) of a viscous black oil. The oil was dissolved in chloroform, 114 g of silica gel was added and the mixture evaporated to dryness in vacuo. The product-impregnated silica gel was then placed on a column containing a slurry of chloroform and 200 g of silica gel, and eluted until the product was no longer detectable in the eluent at n.m.r. The chloroform eluates were evaporated, dissolved with methylene chloride and washed twice with 100 ml of 5% potassium hydroxide, and then with water. The methylene chloride layer was dried over magnesium sulfate, filtered and evaporated to give 37.9 g of a light yellow oil which solidified on standing. The solid had a melting point of 64-67.5°C and was identified as O,O-diphenyl-N-phosphonomethylglycinonitrile. Yield 75%.

Example 6

A 100 ml acetonitrile solution of 10.7 g (0.04 mol) di-(m-tolyl)-phosphite and 2.72 g (0.0133 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5 -triazine was heated at 50°C for 3 days. The solution took on a burgundy color and the solvent was evaporated to give 12.4 g of a red oil (92.4% recovery). 9.0 g of the oil was chromatographed over silica gel eluting with 60% cyclohexane/40% ethyl acetate, collecting 60 ml fractions. Fractions 45 - 63 gave 1.25 g (14% yield) of pure 0,0-di-(m-tolyl)-N-phosphonomethylglycinonitrile, nD 25 = 1.5467, with the following analysis:

Calculated: C 61.81, H 5.80, N 8.48

Found: C 61.75, H 5.81, N 8.41

Example 7

A solution of 15.2 g, 83% pure (0.0392 mol) di-(m-nitrophenyl)-phosphite and 2.66 g (0.013 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5 -triazine in acetonitrile was heated at 50° C. for 20 hours. N.m.r. analysis indicated complete turnover. The solution was filtered and the solvent removed in vacuo to give 13 g of an amber oil which was identified as 0,0-di-(m-toyl)-N-phosphonomethylglycinonitrile which gave the following analysis:

Calculated: C 45.93, H 3.34, N 14.28

Found: C 45.80, H 3.39, N 14.27

Example 8

15.63 g of 94% pure (0.05 mol) di-(p-methoxyphenyl)-phosphite and 3.4 g (0.0167 mol) of 1,3,5-tricyanomethyl-hexahydro-1,3,5 -triazine was dissolved in acetonitrile and the solution was heated under reflux for 1 hour. The solvent was evaporated in vacuo to give 19.0 g of a bright pink oil. 5 g of this oil was subjected to high-pressure liquid chromatography using a mixture of cyclohexane and ethyl acetate.. (40/60% by volume) whereby 4.1 g of 0,0-di-(p-methoxyphenyl)-N- phosphonomethyl-25

glycinonitrile as an oil in 82% yield, nQ = 1.5541.

Example 9

A mixture of 2.04 g (0.01 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine and 8.8 g 91.6% pure (0.03 mol) di-(p -fluorophenyl)-phosphite in 50 ml of acetonitrile was heated at 55° C. for 70 hours. The reaction mixture was then filtered and the solvent removed under vacuum whereby a brown oil was obtained, nD 2 5 = 1.52 70 which was 92% pure 0,0-di-(p-fluorophenyl)-N-phosphonomethylglycinonitrile.

Example 10

9.93 g of 91.5% pure (0.03 mol) di-(m-chlorophenyl)-phosphite dissolved in 20 ml of acetonitrile was added to 2.04 g (9.01 mol) of 1,3,5- tricyanomethyl-hexahydro-1,3,5-triazine dissolved in 50 ml of acetonitrile and the mixture was heated at 55°C for 70 hours. The acetonitrile was removed in vacuo to give a pale pink oil, nQ 2 5 = 1.5656 which was 92% pure O,0-di-(m-chlorophenyl)-N-phosphonomethylglycinonitrile.

The following compounds can also be prepared by the above methods: 0,0-di-(p-cyanophenyl)-N-phosphonomethylglycinonitrile 0,0-di-(p-biphenylyl)-N-phosphonomethylglycinonitrile

Example 11

4.0 g (0.099 mol) of the diester prepared in Example 10 was dissolved in 100 ml of 2% aqueous acetone and the solution was stirred at ambient temperature for 6 days during which time a solid had formed. The solid was collected, washed with acetone and dried to give 1.55 g (60%) of O-m-chlorophenyl-N-phosphonomethylglycinonitrile as a solid with a melting point of 181-182°C and with the following analysis:

Calculated: C 41.5, H 3.9, N 10.8

Found: C 41.5, N 3.9, N 10.8

Example 12

2.38 g (0.069 mol) of the diester prepared in Example 9 was dissolved in 100 ml of 2% aqueous acetone and stirred at ambient temperature for 3 days. The resulting slurry was filtered and the solids washed with acetone to give 0.87 g of a leather-colored solid, m.p. 258-262°C. The mother liquor was allowed to stand for 6 weeks and the solids formed were collected and washed with acetone whereby a further 0.8 g of material with the same melting point was obtained, which was identified as 0-p-fluorophenyl-N-phosphonomethylglycinonitrile in a 98% yield and with the following analysis:

Calculated: C 44.3, H 4.1, N 11.5

Found: C 44.3, H 4.2, N 11.5

Example 13

1.51 g (0.005 mol) of 0,O-diphenyl-N-phosphonomethylglycinonitrile was stirred in 50 ml of 2N hydrochloric acid while heating until all material was dissolved (2 hours). An amber oil was observed at the bottom of the flask and proved to be phenol. The flask was cooled to room temperature and the hydrochloric acid solution was washed twice with 25 ml of methylene chloride to remove any starting material and the phenol formed in the reaction. The hydrochloric acid solution was then cooled in an ice bath during which crystals began to form. The crystals were collected, washed with cold water and air dried. The crystals were identified as O-phenyl-N-phosphonomethylglycinonitrile and had no apparent melting point. The crystals gave the following analysis:

Calculated: C 47.79, H 4.90, N 12.39

Found: C 47.52, H 4.93, N 12.12

Example 14

4.0 g (0.012 mol) of O,0-di-(m-tolyl)-N-phosphonomethylglycinonitrile was dissolved in 50 ml of acetone containing 1 ml of water and stirred for 60 days at ambient temperature. Three fractions of crystals were obtained. The first two fractions of crystals had a melting point of 161-166°C and were found to be impure. It

third fraction had a melting point of 179-179.5° and proved to be analytically pure 0-(m-tolyl)-N-phosphonomethylglycinonitrile which was obtained in 53% yield and had the following analysis:

Calculated: C 50.0, H5.5, N 11.7

Found: C 50.0, H 5.5, N 11.7

Example 15

3.15 g (0.008 mol) of O,0-di-(m-nitrophenyl)-N-phosphonomethylglycinonitrile was dissolved in 50 ml of acetone and 1 ml of water and stirred at room temperature for 16 hours. Solids formed which were collected and washed with acetone to give 1.1 g (51%) yield of a material identified as 0-(m-nitrophenyl)-N-phosphonomethylglycinonitrile with a melting point of 174 - 176°C during cleavage, and had the following analysis:

Calculated: C 40.0, H 3.4, N 15.6

Found : C 40.0, H 3.4, N 15.5

Example 16

100 ml of an acetone solution of 11.64 g (0.0314 mol) di-(m-trifluorotolyl)-phosphite and 2.15 g (0.0105 mol) 1,3,5-tri-cyanomethyl-hexahydro-1, 3,5-triazine was heated at 50°C overnight. The acetonitrile was evaporated under vacuum and solids began to form. The remaining material was dissolved in 50 mL of acetone and 1 mL of water and stirred overnight at ambient temperature during which time solids formed. The solids were collected and washed with acetone to give 3.5 g (39.5%) of a white solid, mp 195-196°C, which was identified as O-m-trifluorotolyl-N-phosphonomethylglycinonitrile by the following analysis :

Calculated: C 40.8, H3.4, N9.5

Found: C 41.0, H 3.5, N 9.7

Example 17

9.0 g (0.024 mol) of 0,0-di-(p-chlorophenyl)-N-phosphonomethylglycinonitrile was dissolved in 50 ml of acetone and 1 ml of water and stirred at room temperature for 2 days. A solid was formed which was collected and weighed 2.35 g. The solid had a melting point of 170°C during cleavage and was identified as O-p-chlorophenyl-N-phosphonomethylglycinonitrile. The mother liquor was set aside for several weeks and a further 0.85 g was collected. The total yield of the product was 3.2 g (51% yield).

Example 18

21 g of a solution containing 83.8% by weight of di-(3-methyl-4-nitrophenyl)-phosphite (0.05 mol) and 3.4 g (0.0167 mol) of 1,3,5-tricyanomethyl-hexahydro -1,3,5-triazine was dissolved in 100 ml of acetonitrile and heated at 70° C. for 1 hour. The acetonitrile solvent was then removed under vacuum and the residue dissolved in 50 ml of acetone containing 1 ml of water and stirred at room temperature. The crystals, 4.3 g, 30% yield, were identified as 0-(3-methyl-4-nitrophenyl)-N-phosphonomethylglycinonitrile with a melting point of 181 - 182° C. The material had the following analysis:

Calculated: C 42.1, H 4.2, N 14.7

Found: C 42.2, H 4.3, N 14.7

Example 19

3.0 g (0.0082 mol) of 0,0-di-(p-methoxyphenyl)-N-phosphonomethylglycinonitrile was dissolved in 50 ml of acetone and 1 ml of water and stirred at ambient temperature for 3 months. During this time, solids formed. The solids were removed by filtration, washed with acetone and dried. The solid was identified as O-p-methoxyphenyl-N-phosphonomethylglycinonitrile and had a melting point of 185-195°C during cleavage. The material provided the following analysis:

Calculated: C 46.9, H 5.1, N 11.0

Found: C 47.1, H 5.2, N 10.8

Example 2 0

19.5 g (80% by weight, 0.05 mol) of di-(o-chlorophenyl)-phosphite was

added to 50 ml of an acetonitrile solution of 3.4 g (0.01640 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine and heated at 70° C. for 2 hours. A 15 ml portion of the reactant solution was evaporated and dissolved in 50 ml acetone and 1 ml water and stirred overnight during which time solids formed. The solids were collected, washed with acetone and dried to give 3.2 g (82% yield) of a material identified as O-S-chlorophenyl-N-phosphonomethylglycinonitrile with a melting point of 170-171°C and with the following analysis:

Calculated: C 41.5, H 3.9, N 10.8

Found: C 41.4, H 3.9, N 10.7

Example 21

2.38 g (0.069 mol) of 0,0-di-(p-fluorophenyl)-N-phosphonomethylglycinonitrile was stirred in a 50% by volume mixture of carbon tetrachloride and methylene chloride, filtered and 0.67 g (0.069 mol)

methanesulfonic acid was added. The solution was allowed to stand overnight, the crystals formed were collected by filtration and washed with carbon tetrachloride to give 2.68 g of a white crystalline material which was identified as the methanesulfonic acid salt

of 0,0-di-(p-fluorophenyl)-N-phosphonomethylglycinonitrile. This salt had a melting point of 132 - 132.5° C and gave the following analysis :

Calculated: C 44.2, H4.0, N6.5, S7.4

Found : C 44.0, H4.0, N6.6, S7.5

Example 22

1.9 g (0.01 mol) of p-toluenesulfonic acid was refluxed in 100 ml of benzene and the water present was removed by azeotropic distillation with benzene. This benzene solution was added to 100 ml of a 50/50% by volume benzene-methylene chloride solution of 3.02 g (0.1 mol) of 0,O-diphenyl-N-phosphonomethylglycinonitrile. The mixture was stirred for 1 minute at room temperature during which crystallization occurred. The resulting slurry was stirred at room temperature overnight and then filtered to give 4.83 g (92.4% yield) of a white solid which was identified as the p-toluenesulfonic acid salt of O,O-diphenyl-N-phosphonomethylglycinonitrile, with a melting point of 152 - 153° C and with the following analysis:

Calculated: C 55.7, H 4.9, N 5.9

Found: C 55.4, N 4.9, N 5.7

Example 23

A chloroform solution of 1.92 g (0.01 mol) of p-chlorobenzenesulfonic acid was added to a chloroform solution of 3.0 g (0.01 mol) of 0,O-diphenyl-N-phosphonomethylglycinonitrile. The mixture was stirred and after 10 minutes crystallization began. The slurry was then stirred overnight, filtered and the solids washed with chloroform to give 4.0 g of a white solid (81%), mp 149-151°C, which was identified as the p-chloro-benzenesulfonic acid salt of O,O-diphenyl-N-phosphonomethylglycinonitrile, with the following analysis:

Calculated: C 51.0, H4.1, N5.7

Found : C 50.7, N 4.1, N 5.7

Example 24

20 ml of a chloroform solution of 1.63 g (0.01 mol) trichloroacetic acid was added to 100 ml of a chloroform solution of 3.0 g (0.01 mol) 0,O-diphenyl-N-phosphonomethylglycinonitrile and stirred overnight at room temperature. Crystallization could not be effected and the solvent was removed in vacuo which

25

gave 3.75 g (80%) of a light yellow oil nQ = 1.5410, which was identified. fised as the trichloroacetic acid salt of 0,O-diphenyl-N-phosphonomethylglycinonitrile with the following analysis:

Calculated: C 43.9, H3.5, N6.0

Found : C 43.9, H 3.5, N 5.9 .

Example 25

25 ml of an acetone solution of 1.26 g (10 mol) of oxalic acid dihydrate was added to an acetone solution of 3.02 g (10 mol) of 0,0-diphenyl-N-phosphonomethylglycinonitrile. After 10 minutes, the salt began to crystallize from the solution. The solution was stirred overnight, cooled and 1.9 g of solid was collected and washed with acetone. Another crop of 0.8 g was obtained by concentrating the mother liquor. The yield was 2.7 g, 69%, with melting point 165° C during cleavage. The crystals were identified as the oxalic acid salt of O,O-diphenyl-N-phosphonomethylglycinonitrile, and had the following analysis:

Calculated: C 52.1, H 4.4, N 7.1

Found : C 52.1, H4.4, N7.1

Example 26

An ether solution of perchloric acid was added to a chloroform-ether solution of 3.0 g (10 mol) of 0,0-diphenyl-N-phosphonomethylglycinonitrile. The perchlorate salt crystallized slowly as white prisms. The solid, identified as the perchloride salt of the O,O-diphenyl-N-phosphonomethylglycinonitrile, was collected and washed with ether-chloroform to give 0.73 g, 18% yield, mp 166-168°C. The salt had the following analysis:

Calculated: C 44.7, H4.0, N7.0

Found: C 44.8, H 4.0, N 7.0

Example 2 7

A chloroform-methanol solution of 1.99 g (0.01 mol) of trichloromethanephosphonic acid was added to a chloroform solution of 3.0 g (10 mol) of O,O-diphenyl-N-phosphonomethylglycinonitrile. After 10 minutes ether was added but no crystals formed. Petroleum ether was then added until just before the flash point. After 10 minutes, crystals began to form and the mixture was allowed to stand for another 10 minutes. The crystals were collected in two harvests, 2.9 g, 58% yield, melting point 145 - 146° C. The crystals were identified as the trichloromethanephosphonic acid salt of O,O-diphenyl-N-phosphonomethylglycinonitrile and had the following analysis:

Calculated: C 38.3, H 3.4, N 5.6

Found : C 38.3, H 3.5, N 5.6

Example 28

An ether solution of fluoroboric acid was added to a chloroform-ether solution of 3.0 g (10 mol) of 0,0-diphenyl-N-phosphonomethylglycinonitrile. The solution was stirred overnight, the solid was filtered off, washed with ether-chloroform (50/50) to give 1.1 g of white crystals, 28% yield, mp 156 - 158°C, identified as the fluoroboric acid salt of 0.0- diphenyl-N-phosphonomethylglycinonitrile, with the following analysis:

Calculated: C 46.2, H 4.1, N 7.2

Found: C 46.0, H 4.2, N 7.2

Example 29

Gaseous hydrogen bromide was bubbled into a chloroform solution of 3.0 g (10 mol) O,O-diphenyl-N-phosphonomethylglycinonitrile. The solution was left overnight while the hydrobromide crystallized. The crystals were collected and washed with ether to give 3.0 g, 78% yield, identified as the hydrogen bromide salt of O,O-diphenyl-N-phosphonomethylglycinonitrile, with the following analysis:

Calculated: C 47.0, H 4.2, N 7.3

Found: C 47.1, H 4.3, N 7.4

Example 30

2 ml of a 57% solution of hydrogen iodide was added to a chloroform solution of 3.0 g (10 mol) of 0,0-diphenyl-N-phosphonomethylglycinonitrile. The solution became cloudy and took on a golden color. After 2 hours no solid had formed, so ether was added to the boiling point and crystallization began. The solution was stirred for a further 1 hour and the solid, identified as the hydrogen iodide salt of O,0-diphenyl-N-phosphonomethylglycinonitrile, was collected as pale yellow plates, mp 163 - 164°C, in an amount of 2.4 g, 56 % dividend. The salt had the following analysis:

Calculated: C 41.9, H 3.8, N 29.5

Found C 41.8, H 3.8, N 29.3 ..'

Example 31

1.14 g (10 mol) of trifluoroacetic acid was added to a chloroform solution of 3.0 g (10 mol) of 0,O-diphenyl-N-phosphonomethylglycinonitrile. The solution was stirred overnight and the solvent evaporated in vacuo to give 4.0 g of a pale yellow oil, 96% yield, n^25 = 1.5172, identified as the trifluoroacetic acid salt of O,0-diphenyl-N- phosphonomethylglycinonitrile.

Example 32

1.50 g (10 mol) vapors of trifluoromethanesulfonic acid were added to a chloroform solution of 3.0 g (10 mol) 0,0-diphenyl-

N-phosphonomethylglycinonitrile. The reaction mixture was stirred at room temperature for 2 hours and ether was added to the boiling point. The product crystallized. After standing for 1 hour, the solid was collected and washed with chloroform-ether (50%) to give 3.8 g, 84% yield, mp 119 - 120°C, and identified as the trifluoromethanesulfonic acid salt of O,O-diphenyl -N-phosphonomethylglycinonitrile, with the following analysis:

Calculated: C 42.5, H3.6, N6.2

Found: C 42.7, H 3.6, N 6.2

Example 33

To a chloroform solution of 15.1 g (0.05 mol) of 0.0-diphenyl-N-phosphonomethylglycinonitrile was added 5.0 g (0.051 mol) of methanesulfonic acid and the solution was stirred for 2 hours at ambient temperature. A solid precipitated and was collected, washed with ether and dried. The solid weighed 15.9 g and was identified as the methanesulfonic acid salt of 0,0-diphenyl-N-phosphonomethylglycinonitrile, with a melting point of 147-150° C. The yield of the salt was 82.1%. The salt had the following analysis:

Calculated: C 44.2, H4.0, N6.5, S7.4

Found : C 44.0, H4.0, N6.6, S7.5

Example 34

10 ml of an ether solution of 0.9 g (0.01 mol) nitric acid (70% by weight) was added to 100 ml of a chloroform solution containing 3.0 g (0.01 mol) of 0,O-diphenyl-N -phosphonomethylglycinonitrile. No bleeding occurred. Additional diethyl ether was added, followed by 20 mL of isooctane at which point solids began to crystallize out of solution. The mixture was stirred for 1 hour at ambient temperature, the crystals were collected, washed with chloroform and air dried. The crystals weighed 2.66 g and were identified as the nitric acid salt of 0,0-diphenyl-N-phosphonomethylglycinonitrile, with melting point 116 - 116.5° C. The yield was 72% of the theoretical. The salt had the following analysis:

Calculated: C 49.32, H 4.42, N 11.5

Found: C 49 .2 , H. 4 .42, N .11.6

Example 35

To a solution of 3.0 g (0.01 mol) of 0.0-diphenyl-N-phosphonomethylglycinonitrile in 100 ml of chloroform was added an ether solution of 1.01 g (0.01 mol) of 98% sulfuric acid. Additional chloroform was added and the mixture was stirred for 2 hours. The solid was removed by filtration and washed with chloroform, then with ether, and dried to give 3.9 g of a material identified as the sulfuric acid salt of 0,O-diphenyl-N-phosphonomethylglycinonitrile, mp 151-151 .5° C. The salt was obtained in 100% yield and had the following analysis:

Calculated: C 45.0, H 4.28, S 8.01

Found: C 44.90, H 4.27, S 8.05

Example 36

An ethereal solution of 0.01 mol phosphoric acid was added to a chloroform solution of 3.0 g (0.01 mol) 0,0-diphenyl-N-phosphonomethylglycinonitrile at ambient temperature with stirring. The resolution was immediately broken. An oil was present at the bottom of the flask. After cooling, the solvent was decanted, evaporated to dryness and dried over anhydrous magnesium sulfate. The solid was identified as the phosphoric acid salt of 0,0-diphenyl-N-phosphonomethylglycinonitrile with a melting point of 74.5 - 78.5° C. The salt was obtained in 25% yield and had the following analysis:

Calculated: C 45.0, H4.5, N 7.0

Found: C 44.8, H 4.6, N 7.1

Example 37

A heterogeneous solution of 60.4 g (0.2 mol) of 0,0-diphenyl-N-phosphonomethylglycinonitrile in 500 ml of ethanol was cooled in an ice bath and dry hydrogen chloride was bubbled through. The solution was allowed to stand, ethyl ether was added and a white solid was collected by suction filtration. More white solid formed by bubbling dry hydrogen chloride through the ethanol-ether mother liquor at approx. 0° C, and was collected and washed with ether. The yield was 62.7 g (93%) of the hydrochloride salt of 0,0-diphenyl-N-phosphonomethylglycinonitrile, with a melting point of 112 - 123° C. The salt had the following analysis:

Calculated: C 53.19, H 4.79, N 8.27

Found: C 53.51, H 4.78, N 8.30

Example 38

17.8 g (0.05 mol) of di-(2,4,6-trimethylphenyl)-phosphite was added to 50 ml of acetonitrile solution of 3.4 g (0.0164 mol) of 1,3,5-tricyanomethyl- hexahydro-1,3,5-triazine, and the mixture was heated at 80° C. for 18 hours. The black solution that formed was filtered and evaporated to an oil. A 7 g portion was chromatographed over 450 g silica gel with 70% cyclohexane/30% ethyl acetate (60 ml fractions) whereby 1.0 g (14%) of 0,0-di-(2,4,6-trimethylphenyl)- N-phosphonomethylglycinonitrile, with a melting point of 118 - 120° Ci the fractions 28 - 40 which crystallized on standing. The product had the following analysis:

Calculated: C 65.27, H 7.04, N 7.25

Found: C 65.38, H 7.07, N 7.18

Example 39

A solution of 0.025 mol of the diester product from Example 3 in 50 ml of wet acetone was heated under reflux for 2 hours and then left at ambient temperature for 5 days. The suspension was filtered to give 0.9 g of an impure pale pink solid. The filtrate was placed in a corked flask and left at room temperature for a further 30 days. The resulting suspension was filtered and the solid was washed with 50 ml of acetone. 4.5 g (66%) of O-p-methylthio-N-phosphonomethylglycinonitrile were obtained as a white solid with! melting point 250 - 253° C (decomposition). The product had the following analysis:

Calculated: C 44.12, H 4.81, N 10.29

Found: C 44.26, H 4.86, N 10.22

Example 40

8.2 g (0.0246 mol) of diphenyl thiophosphite and 1.68 g (0.00823 mol) of 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine were dissolved in 50 ml of acetonitrile and heated at 60 - 65° C for 2 hours. The resulting oil was chromatographed over 450 g of silica gel eluting with 60% cyclohexane/40% ethyl acetate (60 mL fractions) to give 1.6 g (20%) of 0,0-diphenyl-N-thiophosphonomethylglycino-25

nitrile, nD = 1.584 7, in fraction 30. The product had the following

analysis:

Calculated: C 56.60, H 4.75, N 8.80, S 10.07

Found : C 56.40, H 4.80, N 8.73, S 10.26

Example 41

100 ml acetnitrile solution of 33.5 g (0.1 mol) di-(3-naphthyl)-phosphite and 20.4 g (0.1 mol) 1,3,5-tricyanomethyl-hexahydro-1,3,5- triazine was heated under reflux for 1 hour and then evaporated to a reddish brown oil. A 10 g sample was purified by high pressure liquid chromatography over silica gel eluting with 60% cyclohexane/40% ethyl acetate (20 ml fractions). Fractions 45 - 64 were combined and evaporated, and the resulting oil was crystallized from carbon tetrachloride which gave 1.1 g of 0,0-di-(3-naphthyl)-N-phosphonomethylglycinonitrile as a tan solid with a melting point of 104 - 105° C. The product gave the following analysis:

Calculated: C 68.65, H 4.76, N 6.96

Found: C 68.58, H 4.79, N 6.92

Oak sample 42

A stirred solution of 0.05 mol of di-(3,4-methylenedioxy-phenyl)-phosphite and 0.0167 mol of 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine in 75 ml of acetonitrile was heated at 75° C for 3 hours and then left at room temperature overnight. The resulting solution was evaporated to an amber oil. To a 100 ml chloroform solution of 7.6 g (0.02 mol) of the oil obtained, 1.92 g (0.02 mol) methanesulfonic acid was added dropwise. After stirring for 15 minutes, 200 ml of ether was added and a white solid precipitated. The solid was recrystallized twice from acetone whereby 4.6 g (47%) of the methanesulfonic acid salt of 0.0-di-(3,4-methylenedioxyphenyl)-N-phosphonomethylglycinonitrile with a melting point of 135 - 136.5° C was obtained. The product had the following analysis:

Calculated: C 44.44, H 3.94, N 5.76

Found: C 44.26, H 3.94, N 5.71

Example 43

A solution of 0.01 mole of the amber oil from Example 42 in 70 ml of wet acetone was refluxed for 4 days. The amber solution was then allowed to stand for 1 day at ambient temperature. The resulting suspension was filtered whereby 1.7 g of 0-(3,4-methylenedioxyphenyl)-N-phosphonomethylglycinonitrile was obtained as a white solid with a melting point of 160 - 161°C.

Example 44

A stirred solution of 0.04 mol of di-(3,4-dichlorophenyl)-phosphite and 0.013 mol of 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine in 40 ml of acetonitrile was heated to 80°C and kept at this temperature for 18 hours. The resulting solution was evaporated to an oil, 80 ml of wet acetone was added and the mixture was refluxed for 80 hours. The resulting suspension was filtered to give a white solid which was washed with 50 ml of acetone to give 6.3 g (53%) of O-(3,4-dichlorophenyl)-N-phosphonomethylglycinonitrile with melting point 169-170°C.

Example 45

234 g (1.0 mol) of diphenyl phosphite was added to a 300 ml acetonitrile solution of 68 g (0.333 mol) of 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine and heated at 75-82°C for 3 hours. The solution was cooled and evaporated in vacuo, whereby a black oil was obtained which was mainly the product from example 5. A sample of 101 g of this oil was applied to silica gel (which had been dissolved in chloroform, more silica gel was added and the solvent was evaporated ), and this material was chromatographed over 1.1 kg of silica gel eluting with chloroform (1 liter fractions). Fractions 13 and 14 were combined, evaporated and recrystallized

from dichloromethane-cyclohexane whereby 51 g of 0,0-diphenyl-N-phosphonomethylglycinonitrile were obtained.

The discovery that O-aryl-N-phosphonomethylglycinonitriles can be prepared in high yields by reaction of a diaryl phosphite with 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine in the absence of a catalyst was highly unexpected in light of what is disclosed in US Patent 3,923,877. This publication discloses the use of acid catalyst as a hydrogen halide, a Lewis acid, a carboxylic acid anhydride or acid halide. According to the only example in this publication, a calculated yield of only 6.12% of the diethyl ester of N-phosphonomethylglycinonitrile was obtained by the reaction of a solution of diethyl phosphite and 1,3,5-tricyano-methyl-hexahydro-l , 3 , 5-triazine saturated with hydrogen chloride. In contrast to such low yields, the present method is characterized by yields of the diaryl esters of N-phosphonomethylglycinonitrile between 45% and 100%. When the example in US patent 3 92 3 877 was carried out with stoichiometric amounts of the reactants and with a looping of the hydrogen chloride catalyst, surprisingly no reaction could be detected at 40° C, nor even for a 24-hour reaction at 100° C. the same negative result was obtained when the experiment was carried out as above (no acid catalyst) using acetonitrile as solvent for the reactants and the reaction was carried out for 24 hours at 100°C.

In another experiment which was carried out as the example in the said patent, but using chloroform as a solvent for the reactants, no reaction was observed at 40°C or at 100°C.

When an acid catalyst of the type disclosed in US patent 3,923,877 was used in the reaction of a diaryl phosphite, i.e. diphenyl phosphite, with 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine in the presence of hydrogen chloride according to the procedure described in the example in the publication, a yield of only 15% of the desired diester was obtained compared to the 75% yield shown in Example 5. These results show that there are considerable differences between the reaction of dialkyl phosphites and of diaryl phosphites with 1,3,5-tricyanomethyl-hexahydro-1,3,5-triazine.

Example 46

The post-emergent herbicidal activity of various compounds of the invention is demonstrated as follows. The active ingredients are applied in spray form to 14 - 21 day old specimens of different plant species. The spray, a water or organic solvent-water solution containing active ingredient and a surfactant (35 parts butylamine salt of dodecylbenzenesulfonic acid and 65 parts tall oil condensed with ethylene oxide in a ratio of 11 mol ethylene oxide to 1 mol tall oil), is applied to the plants in different sets of dishes in several amounts (kg/ha) of active ingredient. The treated plants are placed in a greenhouse and the effects are observed and recorded after approx. 2 weeks or approx. 4 weeks. Data are given in Tables I and II.

The post-emergence herbicidal activity index used in Tables I and II is as follows:

In the tables, WAT indicates weeks after treatment, and the treated plant species are each represented by a code letter as follows:

Example 47

The pre-emergent herbicidal activity of various compounds of the invention is demonstrated as follows. A good quality topsoil is placed in aluminum trays and compacted to a depth of 9 - 13 mm from the top of each tray. A predetermined number of seeds or vegetative shoots of each of several plant species are placed on top of the soil in each bowl and then pressed down. Herbicidal preparations (as described in example 46)) using active ingredients according to the present invention are applied by mixing with or incorporating into the top layer of soil.

In this method, the soil required to cover is weighed

the seeds and shoots and mixed with a herbicide preparation containing a known amount of active ingredient. The bowls are then filled with the mixture and leveled. Watering is carried out by allowing the soil in the bowls to absorb moisture through openings in the bowl bottoms. The bowls containing the seeds and shoots are placed on a wet sand bench and kept for approx. 2 weeks under normal sunshine and watering conditions. At the end of this period, the number of sprouting plants of each species is noted and compared with an untreated control. Data are given in Table III.

The pre-emergent herbicide activity index used below is based on the average percent control of each species as follows:

The plant species are indicated in table III with the same code letters as used in example 46.

From the test results indicated in Tables I and II, it can be seen that the post-emergent herbicidal activity of the compounds according to the invention is mostly of a general nature. In certain specific cases, however, some selectivity is exhibited. On the other hand, the test results for pre-emergent herbicidal activity clearly show the selective effect on field thistle and a few other species. In this regard, it should be remembered that each individual species selected for the above samples is a representative member of a recognized family of plant species.

The herbicidal preparations, including concentrates that require dilution before application to the plants,

contains from 5 to 95 parts by weight of at least one active ingredient and from 5 to 95 parts by weight of an auxiliary substance in liquid or solid form, e.g. from 0.25 to 25 parts by weight of wetting agent, from

0.25 to 25 parts by weight of a dispersing agent and from 4.5 to 94.5 parts by weight of inert liquid extender, e.g. water, all parts being parts by weight of the total preparation. If necessary can from

0.1 to 2.0 parts by weight of the inert liquid extender is replaced with a corrosion inhibitor or an antifoam agent, or both. The preparations are prepared by mixing the active ingredient with an auxiliary substance including diluents, extenders, carriers and conditioners to obtain preparations in the form of finely divided particulate solids, pellets, solutions, dispersions or emulsions. The active ingredient can thus be used with an auxiliary substance such as a finely divided solid, a liquid of organic origin, water, a wetting agent, a dispersing agent, an emulsifying agent or any suitable combination of these. From an economic and convenience point of view, water is the preferred diluent.

The herbicidal preparations, particularly liquids and soluble powders, preferably contain as a conditioning agent one or more surfactants in quantities sufficient to make a given preparation easily dispersible in water or in oil. The incorporation of a surfactant into the preparations greatly increases their effectiveness. The term "surfactant" is used herein to include wetting agents, dispersing agents, suspending agents and emulsifying agents. Anionic, cationic and non-ionic agents can be used with

equal ease.

Coated wetting agents are alkylbenzene and alkylnaphthalene sulfonates, sulfated fatty alcohols, amines or acid amides, long-chain acid esters of sodium isothionate, esters of sodium sulfosuccinate, sulfated or sulfonated fatty acid esters, petroleum sulfonates, sulfonated vegetable oils, polyoxyethylene derivatives of phenols and alkylphenols (especially isooctylphenol and nonylphenol) and polyoxyethylene derivatives of mono-higher fatty acid esters of hexitolanhydrides (eg sorbitan). Preferred dispersants are methyl cellulose, polyvinyl alcohol, sodium lignin sulfonates, polymers, alkyl naphthalene sulfonates, sodium naphthalene sulfonate, polymethylene bis naphthalene sulfonate, and sodium N-methyl-N-(long chain acid) taurates.

Water-dispersible powder preparations can be prepared containing one or more active ingredients, an inert solid extender and one or more wetting and dispersing agents. The inert solid extenders are usually of mineral origin such as natural clays, diatomaceous earth and synthetic minerals derived from silicon oxide and the like. Examples of such extenders include kaolinites, attapulgite clay and synthetic magnesium silicate. The water-dispersible powder

usually contains from 5 to 95 parts by weight of active ingredient, from 0.25 to 25 parts by weight of wetting agent, from 0.25 to 25 parts by weight of dispersing agent and from 4.5 to 9 4.5 parts by weight of inert solid extender, all parts being calculated by weight of the total preparation. If necessary, from 0.1 to 2.0 parts by weight of the solid inert extender may be replaced with a corrosion inhibitor or an antifoam agent, or both.

Aqueous suspensions can be prepared by mixing and grinding an aqueous slurry of water-insoluble active ingredient in the presence of dispersing agents to obtain a concentrated slurry of very finely divided particles. The concentrated aqueous solution formed is characterized by its extremely small particle size, so that when diluted and sprayed, the coverage is uniform and usually contains from 5 to 95 parts by weight of active ingredient, from 0.25 to 25 parts by weight of dispersant, and from 4.5 to 94.5 parts by weight of water.

Emulsifiable oils are usually solutions of active ingredients in water-immiscible solvents that are partly or completely immiscible together with a surface-active agent. Suitable solvents for the active ingredient according to the present invention include hydrocarbons and water-immiscible ethers, esters or ketones. The emulsifiable oil preparations generally contain from 5 to 95 parts of active ingredient, 1 to 50 parts of surface-active agent and 4 to 94 parts of solvent, all parts being by weight calculated on the total weight of emulsifiable oil.

Although the preparations can also contain

the other additions, e.g. fertilisers, phytotoxic and plant growth regulating agents, pesticides and the like used as auxiliary substances or in combination with any of the above-mentioned auxiliary substances, it is preferred to use the preparations alone with independent treatments with other phytotoxic

sic agents, fertilizers and the like to get maximum effect. A field could e.g. sprayed with the preparations either before or after treatment with pesticides,

other phytotoxic agents and the like. The preparations can also be mixed with other materials, e.g. qiødninqs-

substances, other phytotoxic agents, etc, and are applied in a single application. Chemicals which are useful in combination with the active ingredients according to the invention, either simultaneously or separately, include e.g. triazines, ureas, carbamates, acetamides, acetanilides, uracils, acetic acids, phenols, thiocarbamates, triazoles, benzoic acids, nitriles and the like.

Fertilizers that are useful in combination with the active ingredients include e.g. ammonium nitrate, urea, pot ash and superphosphate.

When employed, effective amounts of the gicinomtriles are applied to the plants or to the soil containing the plants, or incorporated into aqueous media in any convenient manner. The application of liquid or particulate solid preparations to plants or soil can be carried out by conventional methods, e.g. powder dusters, boom and hand sprayers and spray dusters. The preparations can also be applied from aircraft as a dust or a spray due to their effectiveness in low doses. The application of herbicidal preparations to aquatic plants is usually carried out by adding the preparations to the aqueous medium in the area where control of the aquatic plants is desired.

Applying an effective amount of the preparations to the plant is essential and critical. The exact amount of active

component that should be used depends on the response desired in the plant as well as such other factors as the plant species and its stage of development, and the amount of rainfall as well as the specific glycine used. In foliar treatment to control vegetative growth, the active ingredients are applied in quantities from 0.112 to 22.4 or more kg per have. In the pre-emergence treatment, the application amount can be from 0.56 to 22.4

or more kg/ha. When applied to combat aquatic plants, the active ingredients are used in amounts from 0.01 ppm to 1000 ppm, calculated on the aqueous medium. An effective amount for phytotoxic or herbicidal control is the amount necessary for total or selective control, i.e. a phytotoxic or herbicidal amount.

Claims (5)

1. Compounds with herbicidal activity, characterized in that they have the formula: where Aryl is phenyl or naphthyl, each X is a substituent on Aryl and selected from halogen, alkyl with 1-4 carbon atoms, alkoxy and alkylthio with 1-3 carbon atoms, methylenedioxy, trifluoromethyl or nitro, Z is oxygen or sulfur, a is 0 , 1, 2 or 3, b is 0 or 1, R is a strong acid having a pKa in water of 2.5 or less, and x is 0 or 1, with the proviso that x must be 0 when b is 1 . 2. Connection according to claim 1, characterized in that Aryl is phenyl and Z is oxygen. 3. Compound according to claim 1 or 2, characterized in that it is 0,0-di-(p-fluoro-phenyl)-N-phosphonomethylglycinonitrile. 4. Compound according to claim 1 or 2, characterized in that it is O-phenyl-N-phosphonomethylglycinonitrile. 5. Compound according to claim 1 or 2, characterized in that it is the hydrogen bromide salt of 0,O-diphenyl-N-phosphonomethylglycinonitrile.