LOW-VOLATILE SALT OF DICAMBA AND HERBICIDES

Abstract: There is disclosed the 2-(2-aminoethoxy) ethanol salt of dicamba. This compound has herbicidal utility, and the advantages of a lower volatility and excellent solubility in water and organic solvents.

Description: DESCRIPTION NEW SALT OF DICAMBA This invention relates to a new salt of dicamba. In particular, this invention relates to the 2-(2-aminoethoxy) ethanol salt of dicamba. Dicamba (3,6-dichloro-2-methoxybenzoic acid) has proven to be a highly beneficial herbicide. It is normally applied as the dimethylamine salt. Unfortunately, this salt has a volatility that causes the product, under certain conditions of application, to come into contact with desirable plants, such as soybeans, that it can damage. This is caused by its volatility. It is therefore an object of the present invention to find a derivative of dicamba that will maintain or improve the beneficial properties of the product while lowering the volatility. It is another object of the present invention to locate a compound that has the herbicidal properties of dicamba with enhanced solubility characteristics. Other objects of the present invention will be seen-from the ensuing description. It has been found that the 2-(2-aminoethoxy) ethanol salt of dicamba (3,6-dichloro-2-methoxy benzoic acid) decreases the volatility and improves other less advantageous properties of dicamba without detracting from its beneficial herbicidal properties. Dicamba was described and patented in United States Patent Number 3,013,054 issued December, 12, 1961. Since that time it has become a valuable herbicidal product, particularly in the control of weeds in corn. While it is safe to corn plants, it does harm certain other beneficial crops, such as soybeans. Consequently, care must be ten so that it does not come into contact with such plants. Dicamba is normally applied as the dimethylamine salt. Unfortunately, this salt is sufficiently volatile that the product applied to a corn crop can come into contact and injure adjacent crops, such as soybeans. This problem cannot be readily solved by the use of additives or other means except very careful application procedures under specified weather conditions. This is often very difficult to accomplish. It has now been found that by using the previously unknown 2-(2-aminoethoxy) ethanol salt of dicamba that the product has a sufficiently low volatility so as to prevent the product from volatilizing onto undesired valuable crops1 and improved solubility without any loss of herbicidal properties. The invention therefore includes: 1. The 2-(2-aminoethoxy) ethanol salt of dicamba; 2. A method of making same which comprises admixing dicamba and 2-(2-aminoethoxy) ethanol; 3. A herbicidal composition comprising a herbicide and a carrier, characterised in that the herbicide is the 2-(2-aminoethoxy) ethanol salt of dicamba; and 4. A method of killing weeds by use of the compound or composition of this invention. The new compound can be prepared as follows: EXAMPLE 1 Dicamba (22.1 grams; 0.10 mole) and water (100 ml) were placed into a beaker. 2-(2-aminoethoxy) ethanol (10.5 grams; 0.10 mole) was added to the mixture, which was stirred until the solids were dissolved. The cloudy solution was washed two times with methylene chloride, filtered, rotoevaporated and stripped under vacuum to yield the desired product, the 2-(2-aminoethoxy) ethanol salt of dicamba (32.3 grams). It had a melting point of 76 - 78 C. Its elemental analysis was: Theory Found C 44.19 43.87 H 5.25 5.28 N 4.29 4.30 C1 21.74 21.09 H20 0 0.74 In actual use, the salt is used as a solution containing four pounds of the 2-(2-aminoethoxy) ethanol salt of dicamba per gallon of water. This is readily prepared by following the procedure of the foregoing example of mixing the dicamba, 2-(2-aminoethoxy) ethanol and water. The necessary concentration of the salt is obtained by adding sufficient water to the solution. In order to demonstrate the herbicidal effectiveness of the new compound of this invention, a series of tests were performed in comparison with the use of the known dimethyl ammonium salt of dicamba ("DMA"). In each instance the test materials were sprayed onto the plants by standard post-emergence herbicidal test procedures. The results were as follows: EXAMPLE 2 CONTROL OF PENNSYLVANIA SMARTWEED IN CORN RATE CONTROL (%1 COMPOUND (Pounds/Acre) 12 Days After Application Claimed Salt 0.125 85 Claimed Salt 0.25 85 Claimed Salt 0.50 90 Claimed Salt 1.0 100 DMA 0.125 40 DMA 0.25 85 DMA 0.50 93 DMA 1.0 98 EXAMPLE 3 CONTROL OF SMOOTH PIGWEED IN GRAIN SORGHUM RATE OF APPLICATION CONTROL (%) COMPOUND (Pounds/Acre) Days After Application 10 31 49 Claimed 0.125 84 40 31 Claimed 0.25 98 92 84 Claimed 0.50 97 85 79 Claimed 1.0 98 84 86 DMA 0.125 73 0 0 DMA 0.25 72 26 43 DMA 0.50 88 60 71 DMA 1.0 98 89 77 Control O 0 0 EXAMPLE 4 CONTROL OF SMOOTH PIGWEED IN GRAIN SORGHUM RATE OF APPLICATION CONTROL (%) COMPOUND (Pound/Acre) Days After Application 43 92 Claimed 0.125 89 88 Claimed 0.25 91 93 Claimed 0.50 97 95 Claimed 1.0 99 98 DMA 0.125 83 75 DMA 0.25 82 89 DMA 0.50 87 88 DMA 1.0 94 94 Control O 0 EXAMPLE S CONTROL OF REDROOT PIGWEED IN GRAIN SORGHUM RATE OF APPLICATION CONTROL (X) COMPOUND (Pounds/Acre) Days After Application 7 51 Claimed 0.125 70 99 Claimed 0.25 90 98 Claimed 0.50 87 96 Claimed 1.0 90 99 DMA 0.125 57 91 DMA 0.25 80 99 DMA 0.50 83 96 DMA 1.0 90 99 Control O 0 In order to demonstrate the reduced volatility of the 2-(2-aminoethoxy) ethanol salt of dicamba in comparison to the volatility of the commercial dimethylamine salt of dicamba, experiments were performed on these compounds. EXAMPLE 6 Dimethylamine salt of 14e-dicamba ("DMA") and 2-(2-aminoethoxy) ethanol salt of 14c-dicamba were prepared. The materials were applied to glass petri dishes at a rate of about one pound per acre and maintained at 30 C and 70% to 90 relative humidity. Samples were taken at 0, 2, 5, 15, and 30 days to determine the amounts of radiocarbon remaining on the petri dishes as follows: Half Life DAYS: 0 2 7 15 30 (Days3 Claimed Compound () 99.42 99.25 97.63 100.71 97.01 1 DMA (%) 91.52 87.16 90.35 90.42 79.86 1' The chemical stability of the 2-(2-aminoethoxy) ethanol salt of dicamba was determined at 1220F with the following results: TIME DICAMBA (Days) (%) 0 39.6 7 40.1 14 39.9 28 39.5 56 39.4 84 39.5 It can be seen that the compound ofthe present invention has a lower volatility than the previously used salts of dicamba, excellent chemical stability and herbicidal utility. In addition, the 2-(2-aminoethoxy) ethanol salt of dicamba is unique in having a high solubility in water. In fact, solution containing six pounds of the salt per gallon of water are readily prepared. This permits the ready preparation of high concentration solutions without the need for additives or solvents. Also, the 2-(2-aminoethoxy) ethanol salt of dicamba is readily soluble in organic solvents such as butyl cellosolve, 2-ethyl-l-hexanol and cyclohexanone. This permits the formulation of emulsifiable concentrates containing up to four pounds of the salt per gallon of solvent. Of equal value is the fact that the salt of this invention has no odour.

Claims: CLAIMS 1. The 2-(2-aminoethoxy) ethanol salt of dicamba. 2. A method for the preparation of this 2-(2aminoethoxy) ethanol salt of dicamba, characterised by admixingdicamba and 2-(2-aminoethoxy) ethanol. 3. A method as claimed in claim 2, characterised in that the dicamba and 2-(2-aminoethoxy) ethanol are admixed in water and the resulting solution is washed with methylene chloride, filtered, rotoevaporated and stripped under vacuum. 4. A herbicidal composition comprising a herbicide and a carrier, characterised in that the herbicide is a compound as claimed in claim 1. 5. A method of killing weeds characterised by applying to said weeds a compound as claimed in claim 1, or a composition as claimed in claim 4.

Inventors: BURNS, JOHNNY L., CHIRCHIRILLO, MICHAEL T., JONES, RITA S.
Applicants: SANDOZ LIMITED
Application year: 1985
Main classification: C07C65
IPC codes: C07C51, C07C65, C07C63, A01N37, A01N33