DE1618090A1 - Process for the preparation of herbicidally active esters of polyalcohols - Google Patents

Description

Process for the production of herbicidally active esters of polyalcohols The invention relates to processes for the production of trichloroacetic acid esters of polyhydric alcohols of the general formula Here, R denotes a lower alkyl radical, the NO2 group, the radical (CCl3-CO-O-CH2) 3C-CH2-O-CH2 or preferably the group CCl-3-CO-O-CH2-. The compounds show a good herbicidal action in leaf and soil treatment (for example, genetic couch grass) and are particularly suitable as total herbicides.

The compounds according to the invention are prepared by customary processes. by making a polyhydric alcohol of the general formula in which R 'is a lower alkyl radical, the NO2 group, the HOCH2 radical or the radical (HOCH203C-CH2-O-CH2-treated) with trichloroacetic acid, triohloroacetyl chloride or trichloractic anhydride.

The esterification with trichloroacetic acid is expedient in an inert Solvent such as toluene with azeotropic distillation of the water formed carried out. The addition of an acidic catalyst, z.H. p-toluenesulfonic acid. is although not necessary, it accelerates the reaction and improves the yield. The esterification can also be carried out using a solvent, for example in In the presence of gaseous hydrogen chloride. When esterifying with trichloroacetyl chloride I also recommend adding an acid acceptor.

In catalyzed esterification e.g. deo pentaerythrite with trichloroacetic acid in toluene one keeps the evaporation of the toluene and the washing of the evaporation rUcketandes with water and methanol an already pure, crystalline product. the is almost colorless and odorless.

The melting point is only slightly below that of the analytically pure substance, so that there is no further purification.

Trichloroacetic acid and its salts have long been used as weed killers known. The trichloroacetic acid itself is to be used because of its strong caustic effect not very suitable as a herbicide; therefore sodium eel (NATA or Na-TCA) is preferred used in weed control. however, sodium trichloroacetate also has significant application-independent disadvantages. by being highly corrosive to metals and thereby attacks storage vessels and spray equipment. Therefore one finds in the Patent literature numerous details about additives that can be corrosive Should reduce the properties of NATA solutions (e.g.

U.S. Patents 2,554,972, 2,728,652, 2,740,8 130, however, so far it is we did not succeed in completely eliminating the corrosive effects of the NATA The indifferent esters of trichloresaiga acid have been used as haricides several times recommended (trichloroacetic acid methylestex, Belgian PatO 826 426, trichloroacetic acid benzyl ester, US Pat. 2-581 852). has been used as an ester of a polyhydric alcohol in very recent times dae ethylene glycol bis trichloroacetate known The mentioned esters of trichloroacetic acid but have de Nachtel. under the influence of aqueous media and already at longer storage at room temperature, trichleracetic acid should be removed possesses the above-mentioned aggressive properties, this made the possibility The storage and use of TCA esters was previously restricted. It has now been restricted found that according to the invention can be produced baron compounds, especially that Pentaerythritol tetrakistrichloroacetate (= P (TCA) 4; R = CCl3-CO-O-CH20. A surprising one Have persistence. When compared with ethylene glycol bis @ trichloroacetate (A) resulted in the following value: 1 II III A; % Maturation: <2% 32 % 70% P (TCA) 4; % Saponification: <2% <2% 8% 1: immediately after production II: after 8 months of storage at 25 ° C III: after 2 hours of warming in aqueous media Fioxane at 70 ° C compared to the known trichloroacetic acid esters by a factor of ten greater resistance of the P (TCA) 4 enables long-term storage and the Use as a herbicide without the formation of the aggressive. free triobloroacetic acid must be feared.

In contrast to the well-known, liquid trichloroacetic acid esters P (TCA) 4 is a crystalline. relatively high-melting substance (f. 155 ° C), which is easy to handle. The other compounds of the general formula X as well aind kriatallin.

The compounds of the invention are in particular in a conventional manner processed into emulsion concentrates and suspension powders. Di. use as herbicides takes place preferably in the form of aqueous sprays and solid dusts. For formulation one uses the usual emulsifiers, adhesives and wetting agents as well as carriers per ilectar The amount of active ingredient to be used depends on several factors abo in particular on the type of plants to be destroyed. Example 1 Pentaerythritol Tetrakis (trichloroacetate a) A mixture of 39 g (0.28 mol) pentaerythritol and 220 g (1.35 Mol) triohloroacetic acid is heated to 180 ° C. while passing through HCl gas. To About 1 1/2 hours the formed Resktionewaseer is distilled off, the excess Trichloroacetic acid is distilled off at 10 mm and the Rtlokatand from methanol recrystallized. 133 g (66% of theory) of pentaerythritol are obtained. tetrakis (trichloroacetate). Pn 154-155 ° C. b) 34 g (0p25 mol) of pentaerythritol are suspended in 200 ml of toluene. After adding 171 g (1.05 mol) of trichloroacetic acid and 5 g (approx. 0.03 mol) of p-toluenesulfonic acid the mixture is boiled for 3 hours using a water separator warmed up; after this time 18 ml of water have separated after adding 2 g activated charcoal, the solution is filtered and evaporated in vacuo. The residue is washed thoroughly with water and then with 125 ml of methanol Yield of ester 163 g (9% of theory). 152-154 ° C c) 68 g (0.5 mol) of pentaerythritol are as described under b), but without the addition of p-Tcluenesulfonic acid. reacted with 408 g (2.5 mol) of trichloroacetic acid. After 7 hours, the din was calculated Amount of water separated off. 269 g (74.7% of theory) of pentaerythritol tetrakis are obtained (trichloroacetate). 151-153 ° C. d) To a suspension of 3.4 g (0.025 Gol) of pentaerythritol in 50 ml of dry tetrahydrofuran and 8.1 ml (0.1 mol) of pyridine, 181 g (0.1 Mol) trichloroacetic acid chloride added dropwise. The mixture is left at room temperature for 24 hours ture and then heated to the boil for 30 minutes. After filtration of the pyridine hydrochloride, the tetrahydrofuran solution is stirred with activated charcoal filtered and evaporated in vacuo. The residue is thoroughly with water and washed twice with 20 ml of methanol. 15.1 g (84% of theory) of the title compound are obtained. 152-154 ° C. e) 27.2 g (0.2 mol) of pentaerythritol and 130 g (0.42 mol) of trichloroacetic anhydride are used after adding 5 g of p toluenesulfonic acid in 200 ml of toluene a water separator heated to boiling for 3 hours The warm toluene solution is treated with 3 g of aktiv @ ohls, filtered and evaporated in vacuo, the residue it is washed with water and methanol, yield 118 g (82% of theory). 151-154 ° C.

Example 2 1 1 1-Tris (trichloroacetoxymetbyl) ethane A mixture of 12 g (0.1 mol) of 2-methyl-2-hydroxymethyl-1,3-propanediol and 59 g (0.36 mol) of trichloroacetic acid is while passing through HCl gas until sur complete distillation., lation of the formed Water at 160 ° C. The reaction mixture is after cooling in 100 μl of methylene chloride taken up, the solution washed neutral with saturated sodium bicarbonate solution and evaporated in a Vekuui. The residue is dissolved in 100 ml of methanol. After addition 8 g (75% of theory) of colorless crystals from the melting point crystallize from 25 ml of water 45-470 C Example 3 1,1,1 @ Tris (trichloroacetoxymethy10-propane A powdered mixture of 13.4 g (0.1 mol) of 2-ethyl-2-hydroxymethyl1-1, 3-propanediol and 59 g (0.36 mol) Trichloroacetic acid is obtained while passing through HCl and distilling off the resulting Wasaers heated to 180 ° for 30 minutes. The cooled reaction phase is mixed with water washed and recrystallized from 50 .1 methanol. You get 44 g (77%% of theory) colorless. Crystals with a melting point of 62 - 64 ° C., Example @ Nit @@ - tris (trichloroscetexymethyl) methane A solution of 15.1 g (0.1 mol) of tris (hydroxymethyl) nitromethane. 59 g (0.36 Nol0 trichloroetic acid and 3 g of p-toluenesulfonic acid in 75 ml of toluene is heated to boiling for 20 hours using a water separator.

The tolaol solution is washed three times with water. dried, with Throat treated and evaporated in vacuo. The semi-solid XUcketand is made with little cold methanol digerted. The extracted crystals crystallize very little Methanol or from gasoline (b.p. 80-110 ° C). Developed 27.1 g (46% of theory). F. 97 99 ° C, Example 5 2,2,2,2, 2, 2 '-Hexakia (trichloroacetoxymethyl) -dläthyläther Eine Suspenelon of 25.4 g (0.1 mol) of dipentaerythritol is mixed with 107 g (0.66 mol) of trichloroacetic acid esterified in toluene with aze @ troper distillation of the Rsaktionawassera.

The solution is treated with activated charcoal, filtered hot and in vacuo @@ evaporated to a viscous oil. The crude product is boiling as little as possible Methanol dissolved; the ester crystallizes out on cooling and trituration 80 e (71% of theory) colorless crystals from Melting point 120-123 ° C. The compound can be recrystallized from gasoline (bp 80-110 ° C).

Claims (1)

Patent claims: 1.) Process for the preparation of compounds of the general formula in which R denotes a lower alkyl radical, the NO2 group, the radical CCl3-CO-O-CH2- or the radical (CCl3-CO-O-CH2) 3C-CH2-O-CH2-, which means that one is polyvalent Alcohol of the general formula in which R 'is a lower alkyl radical, the NO2 group, the radical HOCH2- or the radical (HOCH2) 3C-CH2-O-CH2- is reacted with triohloroacetic acid, trichloroacetic anhydride or trichloroacetyl chloride 2.) Herbicide averages marked by a content of one or more compounds of general formula 1 as active ingredients. 3.) Herbicidal agent, characterized by a content of pentaerythritol tetrakis triohloroacetate as active ingredient 4.) Compounds of the general formula I. 5.) Pentaerythritol tetrakis trichloroacetate.