DE3241114A1 - Process for the preparation of 1-amino-1,3,5-triazine- 2,4-[1H,3H]diones - Google Patents

Abstract

Herbicidally active 1-amino-1,3,5-triazine-2,4-[1H,3H]diones of the general formula <IMAGE> are obtained by a novel process in high yields in the following ways: 1st step <IMAGE> 2nd step <IMAGE> 3rd step <IMAGE> In step 3, apart from by hydrolysis, the alkylidene protective group of the intermediates (V) can also be removed by transfer to isothiosemicarbazides of the formula <IMAGE> the starting substances (III) being obtained again. In the general formulae I-VI, the radicals R<1>, R<2>, R<3>, R<4> and X have the meanings given in the description.

Description

Process for the preparation of 1-amino-1,3,5-triazine

2,4 (1H, 3H) -diones The present invention relates to a new process for the production of widely known 1-amino-1,3,5-triazine-2,4- (1H, 3H) -diones, which can be used as herbicides.

It has already become known that 1-amino-1,3,5-triazine-2,4 (1H, 3H) -diones through implementation of N-substituted imidodicarboxylic acid dichlorides with Hydrohalides of isothiosemicarbazones and subsequent acid-catalyzed hydrolysis of the 1-alkylideneamino derivatives initially formed as intermediates can (see. DE-OS 22 54 200). However, this method has a number of disadvantages on. For example, imidodicarboxylic acid dichlorides are used as starting materials a considerable technical effort, since their production only after multi-stage Procedure (cf.

DE-OS 23 51 556) or about difficult to access starting products (cf. DE-OS 12 98 095) is possible and, moreover, the yields are unsatisfactory.

It has also become known that 1-amino-1,3,5-triazine-2,4 (1H, 3H) -diones obtained by N-substituted imido-dicarboxylic acid diaryl esters with isothiosemicarbazones converts and the 1-alkylideneamino derivatives formed in turn first accordingly hydrolyzed by the first-mentioned process (cf. DE-OS 3 006 263 / EP-A2-0 034 751). However, this process can only be carried out on a larger scale with considerable technical effort Scale feasible, since initially the imido-dicarboxylic acid diaryl ester required as starting materials in an upstream reaction stage by means of a high-temperature reaction Conversion of carbamic acid aryl esters or primary amines with carbonic aryl ester chlorides with elimination of HCl at temperatures between 100 and 300 "C, preferably between about 170 and 2500C - have to be produced (cf. DE-OS 3 006 226 / EP-A2-0 034 750; DE-OS 3 035 392 / EP-A-0 048 376; DE-OS 3 035 393 / EP-A1-0 048 377). The high Reaction temperatures require a high expenditure of energy, but especially occur Significant corrosion problems due to the hydrogen chloride released at the high temperatures on. In addition, the cyclization stage also requires higher temperatures (preferably around 100 ° C).

According to two other known methods, it is possible to replace the aforementioned N-substituted imidodicarboxylic acid dichloride or diaryl ester either N-chlorocarbonyl-carbamic acid-O-aryl ester (cf. DE-OS 3 106 724 / EP-A1-0 058 895) or 1-cyano-N-aryloxycarbonylformamides (cf. DE-OS 3,147,735) with isothiosemicarbazides implemented in order to ultimately arrive at the same end products.

All known methods have the disadvantage that their large technical Realization for cost reasons seems uneconomical and in any case only would be possible with a very substantial investment, since the process is multi-stage and individual stages - in some cases with only unsatisfactory yields, and there the safe and inexpensive handling of the inevitable by-products (Hydrogen chloride at high temperatures, phenol or hydrocyanic acid) additional difficulties prepares.

For the reasons mentioned, there was an urgent technical need after an economical, technically simpler manufacturing process that too the desired group of substances.

It has now surprisingly been found that the 1-amino-1,3,5-triazine-2,4 (1H, 3H) -diones of the general formula I in which R1 stands for aliphatic and cycloaliphatic hydrocarbon radicals, araliphatic hydrocarbon or aryl radicals and R2 stands for aliphatic hydrocarbon radicals, in high yields and in pure form, if isocyanates of the general formula II R1 ~ NC0 (11), in which R1 the above has given meaning, with an isothiosemicarbazone of the general formula III (which exist in the following tautomeric forms or

can react): where R2 has the meaning given above and R3 and Rd are identical or different and each stand for hydrogen, alkyl, cycloalkyl, aralkyl or aryl, optionally in the presence of a diluent and optionally in the presence of a catalyst at temperatures between 0 and 1000C ( 1st stage) and the resulting new urea derivatives of the general formula IV (which are present or can react in the following tautomeric forms): in which R1, R2, R3 and R4 have the meaning given above, reacted with phosgene (C0Cl2) in the presence of an organic base and in the presence of a diluent at temperatures between -50 and OOC, at least 2 moles of phosgene per mole of urea derivative (IV) and at least 2 moles of the organic base are used (2nd stage), and the partially new 1-alkylideneamino-1,3,5-triazine-2,4 (1H, 3H) -diones of the general formula V formed in this process in which R1, R2, R3 and R have the meaning given above, to remove the alkylidene protective group, optionally without intermediate isolation, either hydrolyzed in a manner known per se in an acidic medium or with S-alkylisothiosemicarbazides or their hydrohalides or monoalkyl sulfates of the formula VI where X is chlorine, bromine or the monoalkylsulfate radical R²OSO3- and R² has the meaning given above, optionally in the presence of a diluent and optionally in the presence of a catalyst at temperatures between 0 ° and 100 "C (3rd stage), in addition to the Compounds of the formula (I) - after conversion of the initially formed hydrohalides or

Monoalkyl sulfates into the free bases - the isothiosemicarbazones Formula (III) wins, which are used again in the 1st stage of the process can.

The method according to the invention is characterized by a surprising uniform course of the reaction and thus leads - under mild conditions - too high yields of the desired end products. Especially in the second Process stage (cyclization reaction) had to be expected that the polyfunctional intermediates (IV) with phosgene in various directions would react, synonymous with an inconsistent course of the reaction and low to vanishing yields of the desired end products. But also with the first stage of the process (isocyanate addition to isothiosemicarbazone) could not excluded from the outset that in addition to those required for this synthetic route Urea derivatives (IV) produce undesirable by-products to a considerable extent would. In fact, the reaction conditions found are essential for the success of the Synthesis of vital importance.

A key technical advantage of the new process is its significantly improved economic efficiency compared to the previously known processes, because in the new process the desired principle of building the desired End products from the smallest synthesis building blocks is realized and the disadvantages the known method can be avoided.

If, for example, neopentyl isocyanate and benzaldehyde-S-ethyl-isothiosemicarbazone are used as starting materials, pyridine as the organic base in the second stage and S-ethyl-isothiosemicarbazide-monoethyl sulfate in the third stage for variant b), the course of the reaction can be represented by the following equation : 1st stage: 2nd stage 3rd stage The isocyanates to be used as starting materials are generally defined by formula (II). In this formula, R¹ preferably stands for a straight or branched alkyl radical having 1-12 carbon atoms, with the exception, however, of those alkyl radicals which have a tertiary branch on the atom C1 (such as, for example, tert-butyl); furthermore for a cycloalkyl radical with 5-8 ring carbon atoms, with the exception of those radicals which are, for example, alkyl-substituted on the ring atom C1 (such as, for example, 1-methylcyclohexyl) i furthermore for benzyl or phenyl.

The isocyanates of the formula (II) are known or can be prepared according to known Process are produced (cf. e.g.

Houben-Weyl, Methods of Organic Chemistry, 4th Edition, Volume 8, P. 119 ff, Georg Thieme Verlag, Stuttgart, 1952).

As examples of the isocyanates which can be used according to the invention Formula (II) may be mentioned in detail: methyl, ethyl, propyl, isopropyl, sec-butyl, Isobutyl, pentyl, isopentyl neopentyl, 1-ethylpropyl, 1,2,2-trimethylpropyl, Cyclopropylmethyl, cyclopentylmethyl -, Cyclohexylmethyl-, (2,5-methano-cyclohexyl) -methyl-, Cycloheptylmethyl, 2-methylpentyl, 2-ethylpentyl, 2-methylhexyl, 2-ethylhexyl, Cyclopentyl, cyclohexyl, 2-methylcyclohexyl, benzyl and phenyl isocyanate.

The isothiosemicarbazones to be used as starting materials are generally defined by the formula (III). In this formula, R² is preferably for a straight or branched alkyl radical with 1 - 6 carbon atoms.

The radicals R³ and R4 can be identical or different and can stand in formula (III) preferably in each case for hydrogen, alkyl with 1 - 4 carbon atoms, Cycloalkyl with 5 - 7 carbon atoms, benzyl or aryl radical with 6 - 10 carbon atoms. R³ and R4 can also preferably together with the alkylidene C atom have a 5-7 membered structure form carbocyclic ring. R3 particularly preferably stands for hydrogen and R4 for phenyl or t-butyl.

The isothiosemicarbazones of the formula (III) are known or can be prepared by known methods, for example by S-alkylation of the corresponding thiosemicarbazones (cf. Houben-Weyi, Methods of Organic Chemistry, 4th ed. Volume 9, p. 912). The following isothiosemicarbazones are known in detail: Table 1: No. R R3 R4 Literature 1) -C2H5 -H 4 Canad. J. Chem. 53, 610 (1975) 2) -CH3 -CH3 e Chem. Soc. 1950, 452 3) -CH3 -H e Canad. J. Chem. 53, 610 CH3 -H 6i0 (1975) 4) -CH2 t -H e lt 5) -CH-H -C3H7 6) -CH3 -CH3 -CH3 acc 7) -CH3 ¼ 8) -CH3 -H -C2H5 Bull. Soc. Chim. (Japan) 51, 1846 (1978) Table 1: (continued) No. R2 R3 R4 Literature 9) -CH3 -H-Cl Bull. Soc. Chim. (Japan) 54, 1767 (1981) 10) CH3 Suitable diluents for the first process stage are all industrially interesting solvents which are inert under the reaction conditions. These include hydrocarbons such as benzene, toluene and the xylenes, chlorinated hydrocarbons such as chlorobenzene; Ethers such as di-n-butyl ether, esters such as ethyl acetate, ketones such as methyl isopropyl ketone; the reaction can also be carried out in water. Hydrocarbons are preferably used as diluents, and toluene is particularly preferred.

The catalyst used in this process stage is that of isocyanate reactions conventional catalysts can be used, for example tertiary amines such as pyridine or triethylamine; dibutyltin dilaurate is preferably used.

The first process stage is carried out at temperatures between 0 and 1000C, preferably carried out between 20 and 600C. The reaction times are generally between 0.5 and 24 hours, in particular between 1 and 8 hours.

When carrying out the first stage of the process, the starting materials are used of the formulas (II) and (III), preferably in equimolar amounts. Appropriately one proceeds in such a way that one in a solution of the isothiosemicarbazone (III) the Isocyanate (II) enters and, after the reaction has ended, the urea derivatives formed (IV) isolated by stripping off the solvent; the yields of the thus obtained Urea derivatives are between 85-95% of theory.

The urea derivatives which can be prepared according to stage 1 of the process according to the invention (IV) are new. You can, if desired, in the usual way, e.g. by recrystallization, further cleaned; However, you can in any case directly, without further purification, are used in stage 2 of the process according to the invention.

Certain are used as diluents for the second stage of the process organic solvents in question. Suitable solvents are methylene chloride, 1,2-dichloroethane, chloroform, toluene, the xylenes, chlorobenzene, ethyl acetate, Butyl acetate, acetonitrile or mixtures of these solvents. Particularly preferred solvents are methylene chloride and toluene.

The second stage is in the presence of an organic base (hereinafter referred to as auxiliary base) carried out. Suitable auxiliary bases are in particular pyridine and certain substituted pyridines, where as substituents Halogen atoms and / or lower alkyl radicals come into question. Also the use of others tertiary amines such as dimethylbenzylatin is possible. Particularly beneficial is the use of pyridine as an auxiliary base.

The reaction temperature must be between 0 and -50 ° C, preferably between -10 and -30 ° C. One works most appropriately under normal pressure. Implementation is quick and practical with bringing them together the reaction components ended.

When carrying out the second stage of the procedure, one relies on 1 Moles of urea derivative (IV) at least 2 moles of phosgene and at least 2 moles of the auxiliary base a. If you use smaller amounts of phosgene and auxiliary base, e.g. only equimolar Quantities, there is a significant reduction in the yield. Generally on 1 mole of urea derivative (IV), 2 to 10 moles of phosgene and 2 to 10 moles of the auxiliary base, preferably 2-4 moles of phosgene and 2-4 moles of the auxiliary base are used. The most favorable molar ratio between phosgene and auxiliary base is there always 1: 1. With it ergbit that it is particularly advantageous when carrying out process stage 2, urea derivatives (IV), phosgene and auxiliary base in a molar ratio of 1: 2: 2 to 1: 4: 4.

The most convenient way to go is to carry out the second stage of the process according to the invention so that a solution of phosgene in the chosen Submitted solvent and with cooling the auxiliary base, optionally dissolved in same solvent, adds.

The urea derivative is also poured into the suspension obtained in this way with cooling (IV) either in solid form or as a solution or suspension in the same solvent registered.

But one can also proceed in this way - without loss of yield occurring - that either the auxiliary base and the urea derivative (IV) together and at the same time enters into the submitted phosgene solution, or that a solution of the auxiliary base and the urea derivative (IV) and introduces the phosgene therein, or that you only submit the urea derivative (IV) and the phosgene and the auxiliary base together and at the same time.

For work-up - in the case of the batchwise described here Procedure - to be proceeded in the same way in all cases: After a After stirring for about 30 minutes, the reaction mixture is brought to room temperature and with vigorous stirring in Water entered. After another After stirring for a further 15 minutes, the organic phase is separated off and washed with water. The organic solvent is removed in vacuo and it remains in most Precipitate an oily residue, which crystallizes after stirring with a little petroleum ether solidifies and the 1-alkylidene-amino-1,3,5-triazine-2,4 (1H, 3H) -diones of the formula (V) in yields of approx.

80-90% of theory results.

Since the cyclization reaction (IV) H (V) occurs at a sufficiently high rate expires, the second process stage can also in a special embodiment be designed as a continuous process.

The third process stage is used to remove the alkylidene protective group or release of the amino function in the 1-position of the triazine ring.

For this purpose, the intermediates of the formula (V) - if appropriate without intermediate isolation - hydrolyze in an acidic medium in a manner known per se (see e.g.

DE-OS 2 254 200; U.S. Patent 4,056,527; EP-A2-0 034 751).

It is particularly useful to use the intermediates (V) for this purpose to dissolve in an alcohol such as isopropanol and at temperatures between about 40 and 70 ° C, optionally under reduced pressure, with a mineral acid such as sulfuric acid or an organic sulfonic acid such as p-toluenesulfonic acid ver set and the formed carbonyl compounds of the formula R3-CO-R4 together with part of the alcohol used as a diluent to distill off the reaction mixture. The end products (I) are isolated in a known manner by crystallization and filtering off; for further cleaning the end products (I) can easily be recrystallized.

According to the present invention, however, it is also possible - and in the case of technical Procedure particularly advantageous - the protective group on isothiosemicarbazide derivatives of the formula (VI) given above.

All inert diluents are suitable for this reaction organic solvents, especially hydrocarbons such as toluene. as acidic catalyst has proven particularly useful p-toluenesulfonic acid.

The reaction temperatures are generally between 0 ° and 100 °, preferably between 20 and 80ob. The reaction components (V) and (VI) are preferably used in approximately equimolar amounts. The one for splitting off the protective group The isothiosemicarbazide derivatives (VI) required are known in part from the literature (see e.g.

Chem. Soc. 1927, page 2530 ff.) Or are according to known methods manufacturable (see example part).

The isothiosemicarbazones obtained by this process variant (III) are after conversion of the initially formed salts into the free bases in very easily soluble in non-polar solvents, while the tri- zindione of structure <1), due to their low solubility in these solvents, can be filtered off and isolated. The isothiosemicarbazones remaining in the filtrate (III) can then be used again in process stage 1 without intermediate isolation will.

The 1-amino-1,3,5-triazine-2,4 (1H, 3H) -diones which can be prepared according to the invention (I) are mostly known and have excellent herbicidal properties (see e.g.

DE-OS 2 254 200; U.S. Patent 4,056,527; also DK-PS 136 067 and EP-A2-0 034 751).

The following preparation examples serve for further explanation detr invention.

Example 1 stage 1: 169.5 g (1.5 mol) of neopentyl isocyanate are introduced into a solution of 310.5 g (1.5 mol) of S-ethylbenzaldehyde isothiosemicarbazone (111-1) in 2 liters of toluene. The mixture is stirred for 6 hours at 50 ° C., cooled to room temperature and the urea derivative (IV-1) which has precipitated is filtered off with suction. Concentration of the mother liquor gives further pure product with a melting point of 140-1410C. Yield 451.2 g (94% of theory).

Level 2: 59.4 g (0.6 mol) of phosgene are introduced into 230 g of methylene chloride at + 100 ° C. Then 47.5 g (0.6 mol) of pyridine, dissolved in 100 ml of methylene chloride, are added with cooling at -200C. 64.0 g (0.2 mol) of urea derivative (IV-1), dissolved in 160 ml of methylene chloride, are introduced into the suspension thus obtained. After a further stirring time of 30 minutes, the reaction mixture is brought to room temperature and introduced into 300 ml of water with vigorous stirring. After a further 15 minutes of stirring, the organic phase is separated off, washed with 100 ml of water and the methylene chloride is removed in vacuo. A yellowish oil remains, which solidifies in crystalline form after stirring with a little petroleum ether. Yield 62.4 g (# 90% of theory) of 1-benzylideneamino-6-ethylthio-3-neopentyl-1,3,5-triazine-2,4 (1u-, 3H) -dione (V-1) of melting point 1040C.

Stage 3 / variant a: (hydrolysis) To a solution of 34.1 g (0.114 mol) of 1-isopropylideneamino-6-ethylthio-3-neopentyl-1,3,5-triazine-2,4 (1H, 3H) -dione (V-2) in 150 ml 1.1 g of p-toluenesulphonic acid and 5.4 ml of water are added to isopropanol at 60.degree. C. and the mixture is stirred for one hour at 60.degree. C., the majority of the reaction product crystallizing out. About 80 ml are distilled off at 200-300 mbar, cooled to 0 ° C., filtered off with suction and washed with a little methanol. 26.8 g (91% of theory) of 1-amino-6-ethylthio-3-neopentyl-1,3,5-triazine-2,4 (1H, 3H) -dione (1-1) with a melting point of 202 are obtained -204 ° C.

Stage 3 / variant b: A) X = 5.2 g (0.015 mol) of 1-benzylideneamino-6-ethylthio-3-neopentyl-1,3,5-triazine-2,4- (1H, 3H) -dione (V-1), 3 g (0.015 mol) of S-ethylisothiosemicarbazide hydrobromide (VI-1, X = Br) and a spatula tip of p-toluenesulfonic acid in 80 ml of toluene are stirred for 12 hours at 50-55 ° C. After cooling, 0.6 is added dropwise g (0.015 mol) of sodium hydroxide in 5.4 g of water are added and the mixture is stirred for 1 hour at room temperature, the precipitated solid is filtered off and dried, giving 3.75 g (= 95% of theory) 1-amino-6-ethylthio-3 -neopentyl-1,3,5-triazine-2,4 (1H, 3H) -dione (I-1) of melting point 204-2050C.

4.1 g (# 95% of theory) of S-ethylbenzaldehyde isothiosemicarbazone hydrobromide are obtained as a by-product (III-1) x HBr. The free S-ethylbenzaldehyde isothiosemicarbazone can be obtained from the hydrobromide in a known manner (III-1) regenerate, which can be used again in stage 1.

B) X = 12.25 g (0.05 mole) S-ethyl isothiosemicarbazide monoethyl sulfate (VI-1, X = C2H5OSO3) are suspended in 80 ml of toluene. Then you give a spatula tip p-toluenesulfonic acid and 15.57 g (0.045 mol) of 1-benzylideneamino-6-ethylthio-3-neopentyl-1,3,5-triazine-2,4 (1H, 3H) -dione (V-1) and heated to 50 ° C. for 12 hours while stirring. After cooling down, give Add 2 g (0.05 mol) of sodium hydroxide in 78 ml of water. The insoluble part is sucked off and dried. 11.1 g (# 95.7% of theory) of 1-amino-6-ethylthio-3-neopentyl-1,3,5-triazine-2,4 are obtained (1H, 3H) -dione (I-1) of melting point 204-205 ° C.

14.3 g (-95.4% of theory) are obtained as a by-product. S-ethyl benzaldehyde isothiosemicarbazone monoethyl sulfate, (VI-1) x C2H50S03H. From this salt can be in the same way as in the case of Hydro bromids the free S-ethyl-benzaldehyde-isothiosemicarbazone (III-1) regenerate, which can be used again in stage 1.

The following new urea derivatives (IV) can be prepared analogously to Example 1 / Step 1: Table 3: Example R¹ R² R³ R4 Melting Point No. (° C) IV-2 # -C2H5-H # 134 IV-3 # -C2H5 -CH3 -CH3 131 IV-4 # -C2H5-H # 142 IV-5 # -C2H5 -CH3 -CH3 121 IV-6 -C (CH3) 3 -C2H5 -H # 154 IV-7 -C (CH3) 3 -C2H5 -CH3 -CH3 120 IV-8 -CH3 -C2H5 -CH3 -CH3 133 IV-9 -CH3 -C2H5 -CH3 -CH3 144 IV-10 -C3H7-i -C2H5 -CH3 -CH3 137 IV-11 -C3H7-i -C2H5 # 139 IV-12 -CH2C (CH3) 3 -C2H5 # 115 IV-13 -CH2C (CH3) 3 -C2H5 -H # 148 IV-14 -CH2C (CH3) 3 -C2H5 -H -C (CH3) 3 150 IV-15 -CH2C (CH3) 3 -C2H5 -H -C3H7-i 107 Table 2 (continued) Example R¹ R² R³ R4 Melting Point No. (° C) IV-16 -CH2C (CH3) 3 -C2H5 -CH3 # 152 IV-17 -CH-C (CH3) 3 -C2H5-H # 141 CH3 -CH3 IV-18 -C3H7-i -CH3 -CH3 -CH3 125 IV-19 # -CH3 -CH3 -CH3 128 IV-20 # -CH3 -CH3 -CH3 130 IV-21 -CH3 -CH3 -H # 144 IV-22 -CH3 -CH3 -CH3 # 151 IV-23 -CH2CH (CH3) 2 -CH3 -CH3 -CH3 148 IV-24 -CH2C (CH3) 3 -C2H5 -CH3 -CH3 102 Analogously to example 1 / step 2, the following, partly new 1-alkylideneamino-1,3,5-triazine-2,4 (1H, 3H) -diones (V) can be prepared: Table 3 Example R1 R2 R3 R & hmelz- known / No. point (° C) new V-2 -CH2C (CH3) 3 -C2H5 -CH3 -CH3 101 known. V-3 to -CH3 -CH3 -CM3 111 known. V4 q -CH3 -CM3 -CH3 107 bek. V-5 -CH3 -CM3 -CM3 -CH3 130 beck. V-6 -CM3 -c2H5 -CM3 -CM3 121 be V-7 -C3Hri -Hs -CM3 -CM3 110 bek. V-8 -CM2c (C'M3> 3 -CM3 -CM3 -CM3 122 be. V-9 -CW2C (CH3) 3 -C2H5 H t 104 new Table 3 (continued) Example R1 R2 R3 4 melting known / No. R point (0C) new V-10 -CM2C (CH3) 3 -C2H5 -H -C (CH3) 3 62 new V-1 1 -CH2C (CH3) 3 -C2H5 5 O 182 new V-12 -CH2CH (CH3) 2 CH3 -CM3 -CH3 125be. V-13 -CH3 -CM3 -H 4 94 new V-14 -C3H7-i -CM3 -H 4 90 new V-15 for -CM3 -H 98 new Analogously to Example 1 / Step 3, the following (known) 1-amino-1,3,5-triazine-2,4 (1H, 3H) -dinoe (I) can be prepared: Table 4 9 Example R1 R2 melting point No. (0C) 1-2 k -C2H5 141-142 I-3 -CH3 -C2H5 133-134 I-4 -CH3 -CH3 174-175 I-5 -C3H7-i -C2H5 147-148 I-6 -C 3H7 -i -CH3 148-150 I-7 "c3 177-179 I-8 71 '-CH3 158-159 1-9 -CH2CH (CH3) 2 -CH3 167-169 I-10 -CH2C (CH3) 3 -CH3 229-231 1-11 -CH2 -CH3 127-128 I-12 -C4H9sec. -CH3 151-152 I-1343 -C2H5 172-273 I-14 -.C2H5 -CH3 199-201 I-15 -C3H7-n -CH3 131-132 Example R1 R2 melting point No. ('C) I-16 -C4H9-n -CH3 133-134 1-17 2H25 -CH3 116-118 I-18 4 -CH3 205-208 Example VI-1B 4.55 g (0.05 mol) of thiosemicarbazide, 7.7 g (0.05 mol) of diethyl sulfate and 80 ml of toluene are stirred for 4 hours at 80 "C. After the solvent has been stripped off, the salt formed, S-ethyl- isothiosemicarbazide monoethyl sulfate, returned as an oil; the yield is quantitative (12.25 g).

Claims (10)

Process for the preparation of 1-amino-1,3,5-triazine-2,4 (1H, 3H) -diones of the general formula I. in which R1 stands for aliphatic and cycloaliphatic hydrocarbon radicals, araliphatic hydrocarbon or aryl radicals and R2 stands for aliphatic hydrocarbon radicals, characterized in that isocyanates of the general formula II R1 ~ NCO (11) in which R1 has the meaning given above, with an isothiosemicarbazone of the general formula III (which can exist or react in the following tautomeric forms): where R2 has the meaning given above and R3 and R4 are identical or different and each represent hydrogen, alkyl, cycloalkyl, aralkyl or aryl, optionally. in the presence of a diluent and optionally in the presence of a catalyst at temperatures between 0 and 1000C (1st stage) and the urea derivatives of the general formula IV formed in the process (which are present or can react in the following tautomeric forms): wherein R1, R2, R3 and R4 have the meaning given above, with phosgene (COCl2) in the presence of an organic base and in the presence of a diluent at temperatures between -50 and 0 ° C, at least 2 per mole of urea derivative (IV) Mol of phosgene and at least 2 mol of the auxiliary base are used (2nd stage), and the 1-alkylideneamino-1,3,5-triazine-2,4 (1H, 3H) -diones of the general formula V formed in this way in which 1 R2, R3 and R4 have the meaning given above, to remove the alkylidene protective group, optionally without intermediate isolation, either hydrolyzed in a manner known per se in an acidic medium or with S-alkyl-isothiosemicarbazides or their hydrohalides or monoalkyl sulfates of the formula VI where X is chlorine, bromine or the monoalkylsulfate radical 2 -R²OSO3 and R² has the meaning given above, optionally in the presence of a diluent and optionally in the presence of an acidic catalyst at temperatures between 0 ° and 1000C (3rd stage), where in addition the compounds of formula (I) - after conversion of the initially formed hydrohalides or monoalkyl sulfates into the free bases - wins the isothiosemicarbazones of formula (III), which can be used again in the 1st stage of the process. 2) Method according to claim 1, characterized in that the first process stage at temperatures between 20 and 600C, the second process stage at temperatures between -10 and -30 ° C and the third process stage at temperatures between 20 and 800C. 3) Method according to claim 1, characterized in that one in the second process stage to 1 mole of urea derivative (IV) 2 - 10 moles of phosgene and 2 -10 moles of auxiliary base is used. 4) Method according to claim, characterized in that in the second Process stage phosgene and auxiliary base are used in a molar ratio of 1: 1. 5) Method according to claim 1, characterized in that in the second Process stage urea derivative (IV), phosgene and auxiliary base in a molar ratio of 1: 2: 2 to 1: 4: 4 can be used. 6) Method according to claim 1, characterized in that in the first Process stage as isocyanate (II) neopentyl isocyanate and as isothiosemicarbazone (III) Benzaldehyde-S-ethyl-isothiosemicarbazone can be used. 7) Method according to claim 1, characterized in that as a diluent in the first stage toluene and in the second stage methylene chloride or toluene can be used 8) Method according to claim 1, characterized in that in the second process stage is used as an auxiliary base pyridine. 9) Urea derivatives of the formula IV wherein R¹, R2, R3 and R4 have the meaning given in claim 1. 10) urea derivative according to claim 9 of the formula (IV), wherein R1 is for Neopentyl, R2 for ethyl, R3 for hydrogen and R4 for phenyl.