DE2100685A1 - Pure 4-amino-5-halo-6-pyridazones sepn - from isomers by extraction with halohydrocarbons, alkanols or ethers - Google Patents

Abstract

Pure title cpds. of formula (I): are prepd. from their mixts. with isomers of formula (II): (where R1 is an aliphatic, cycloaliphatic, araliphatic or aromatic residue; R2 is H or an aliphatic residue, and X is halogen) by extracting (II) from the mixt. with aliphatic halohydrocarbons, alkanols and/or ethers. After the extraction, undissolved (I) can be sepd. off by filtration, and (II) can be isolated from the extract. (I) and (II) are plant-protection agents (herbicides) and inters. in synthesis of e.g. dyes and plant-protection agents.

Description

Process for the preparation of pure 4-amino-5-halopyridazonen- (6) The invention relates to a process for the preparation of pure 4-amino-5-halo-pyridazonen- (6) by separating the 4-amino compounds from mixtures with the isomeric 5-amino-4-halopyridazones- (6) by extraction of the isomers with aliphatic halogenated hydrocarbons, alkanols and / or ether.

It is known from German patent specification 1 105 252 that one by reacting 4,5-Dihalogenpyridazonen- (6) with ammonia or amine mixtures of 4,5- and 5,4-aminohalogenpyridazones- (6). For further processing These substances as intermediate products usually have to be separated from one another. The substances are also pesticides, with mostly only one isomer herbicide Has an effect or one isomer far exceeds the other in effectiveness. 1-phenyl-4-amino-5-chloro-pyridazon- (6) is e.g. a selective herbicide. In the amination of l-phenyl-4,5-dichloropyridazone a mixture of about 80% 1-phenyl-4-amino-5-chloropyridazon and about 20% of the isomeric 1-phenyl-4-chloro-5-amino compound. The latter connection only has half the selectivity of the 4-amino-pyridazone O A separation by e.g. fractionated Crystallization does not give satisfactory purity of the isomeric end products. Next to the isomers can also form by-products, e.g. 4-hydroxy-5-halo-pyridazone- (6) in the case of using water in the reaction.

German Offenlegungsschrift 1 620 186 describes a process for separating the isomeric 4,5- and 5,4-amino-chloro-1-phenyl-pyridazone- (6) by extracting the 5-amino compound and other by-products with non-polar solvents the group of aromatic or hydroaromatic hydrocarbons. The 4-amino compound is thus obtained in yields of approximately 95% according to the information in the laid-open specification. It has now been found that pure 4-amino-5-halo-pyridazone- (6) of the general formula can be obtained where R1 denotes an aliphatic, cycloaliphatic, araliphatic or aromatic radical, R2 denotes a hydrogen atom or an aliphatic radical and X denotes a halogen atom, by separation from its isomeric 5-amino-4-halo-pyridazonen- (6) of the general formula where R1, R2 and X have the aforementioned meaning, advantageously obtained from mixtures of the two substances with the aid of extraction with solvents, if the 5-amino-4-halopyridazone- (6) II is obtained by extraction with aliphatic halogenated hydrocarbons, alkanols and / or Separates ether.

It has also been found that it is advantageous after the extraction separates the 4-amino-5-halogen-pyridazone- (6) II from the extract in a known manner.

Compared to the known processes in which the isomeric end products are separated from one another without extraction, provides the process according to the invention the two isomers 4,5- and 5, 4-amino-halogen-pyridazone- (6) each in better Yield and purity. With regard to the aforementioned publication, the both isomers described there also in better purity, e.g. above 97% of theory can be obtained.

In addition, the method according to the invention allows a simpler one ways the preparation of further and numerous isomeric pyridazones (6) from corresponding Mix. Compared to those mentioned in the examples of the laid-open specification Information can include lower extraction temperatures and lower amounts of solvent be used. These beneficial results are surprising with polar or in comparison to the teaching of the laid-open specification, much more polarizable Solvents achieved.

The starting mixtures are mixtures of the two pyridazones (6) I and II in any quantitative ratio, advantageously in a weight ratio of 1 Up to 80% by weight of pyridazone- (6) II, based on pyridazone I, into consideration.

Isomer mixtures are preferably used which consist of corresponding Reactions, e.g. the reaction of 4,5-Dihalogenpyridazonen- (6) with ammonia or Amines. The work-up of such reaction mixtures to give the mixture of produced isomers can be designed in any way, for example according to the in DP 1 105 232 described mode of operation. The mixture of isomers can be further, through the reaction or work-up of the reaction mixture formed by-products, e.g. corresponding 4-hydropy-5-halogen compounds, and optionally residual solvents, e.g. up to 10% by weight of water. Inorganic substances are expediently removed before the extraction Compounds by washing the mixture of isomers with water.

Preferred tyridazone- (6) I and II are those of the general formulas I and II, in which R1 is an alkyl radical with 1 to 6 carbon atoms, a cycloalkyl radical with 5 or 6 carbon atoms, an aralkyl radical with 7 to 12 carbon atoms or denotes a phenyl radical, R2 denotes a hydrogen atom, an alkyl radical with 1 to 6 carbon atoms or an alkenyl radical with 2 to 6 carbon atoms and X represents a chlorine atom or a bromine atom. The remnants mentioned can still get through groups and / or atoms inert under the reaction conditions, see B. Chlorine atoms, hydroxy groups, Trifluoromethyl groups, alkyl groups, alkoxy groups each with 1 to 4 carbon atoms, be substituted.

For example, there are mixtures of the following 4,5-amino-halopyridazones and their 5,4 isomers: 4-amino, 4-methylamino, 4-isopropylamino, 4-tert-butylamino-, 4-ethylamino-, 4-allylamino-, 4-β-oxyethylamino-, 4-y-oxypropylamino-5-chloro-1 -phenyl-pyridazon- (6), corresponding 5-bromo compounds and analogous 1-methyl-, 1-cyclohexyl, 1-benzyl, 1-o-chlorophenyl, 1-i-propyl, 1-m-trifluoromethylphenyl, 1-p-toluyl, 1-r-methoxypropyl compounds.

The solvent is generally used in the extraction In an amount from 100 to 3,000, preferably from 200 to 1,500% by weight, based based on the weight of the two isomers in the isomer mixture. As preferred solvents there are alkanols with 1 to 4 carbon atoms such as methanol, ethanol, isopropanol, n-butanol, tert-butanol; 5- or 6-membered cyclic ethers such as tetrahydrofuran, Dioxane; Dialkyl ethers with 4 to 6 carbon atoms such as diethyl ether, di-n-propyl ether, Diisopropyl ether; and especially haloalkanes and haloalkenes, preferably Chloroalkanes and chloroalkenes, with 1 to 3 carbon atoms and 1 to 6 halogen atoms such as methylene chloride, chloroform, carbon tetrachloride, monofluorotrichloromethane, Difluorodibromo-methane, trifluor-trichloro-ethane, tetrafluor-dibromo-ethane, perchlorethylene, Trichlorethylene, dichloroethane, dichloropropane, tetrachloropropane; and corresponding Mixtures in question. The extraction is carried out at a temperature between -10 ° C and +10000, preferably between 15 and 350C, unpressurized or under pressure, continuously or carried out discontinuously. When using carbon tetrachloride works one advantageous at 50 to 800C.

The extraction can be carried out as follows: If necessary Isomer mixture washed with water is mixed with the solvent and during Extracted for 5 to 60 minutes with thorough mixing at the extraction temperature. The extraction can be carried out in any way using equipment, e.g. by shaking, Floating, repeated passage of the solvent through the extraction material, in rotating extractors, in standing extractors in battery circuit, Extraction presses. In this context it is referred to Ullmanns Encyclopedia der technical chemistry, Volume 1, pages 678-686. After the extraction will be the undissolved pyridazone- (6) I separated off by filtration.

The pyridazone- (6) II can be separated from the extract in a known manner, e.g. by cooling the extract and fractional crystallization, by distribution between the solvent used and another solvent or by precipitation the extract with the aid of a solvent that is miscible with the extraction medium. Are the starting mixtures of the two isomers not too strong, e.g. not over 15 % By weight, contaminated by by-products, it is usually sufficient to add the solvent to distill off the extract and the remaining pyrid azon- (6) II if necessary recrystallize from a suitable solvent such as one of the above.

The compounds preparable by the process of the invention are Plant protection products and valuable starting materials for numerous syntheses, e.g. the production of dyes and pesticides. Regarding the use reference is made to the publications mentioned.

The parts and percentages given in the following examples are Parts and percentages by weight. The percentages of the pyridazone are through UR spectroscopy determined.

Example 1 100 parts of crude 1-phenyl-4-amino-5-chloro-pyridazon- (6) (87 SS 4-amino-5-chloro compound; 13% 4-chloro-5-amino compound) that by reaction the corresponding 4,5-dichloro compound is prepared with ammonia mixed with 300 parts of chloroform for 15 minutes at 25 to 30 C. After filtering off 82 parts of 1-phenyl-4-amino-5-chloropyridazon- (6) (99- bis) are obtained as residue 100 percent) with a melting point of 199 to 201 ° C.

By distilling off the chloroform from the filtrate, 11.5 is obtained 1-Phenyl-4-chloro-5-aminopyridazon- (6) with a melting point of 139 ° to 1400 ° C. (recrystallized from ethanol).

Example 2 When carrying out the separation as in Example 1 with crude 1-phenyl-4-amino-5-bromo-pyridazõn- (6) (85 ffi 4-amino-5-bromo compound; 9% 4-bromo-5-amino compound) 84.5 parts of 1-phenyl-4-amino-5-bromo-pyridazon- (6) with a melting point of 213 ° to 215 ° C. are obtained (97 to 98 percent) and 8 parts of 1-phenyl-4-bromo-5-aminopyridazon- (6) from the filtrate of melting point 126 to 1270 ° C. (recrystallized from methanol).

Example 3 When the separation is carried out as in Example 1 with 50 Parts of crude 1-phenyl-4-amino-5-bromo-pyridazone- (6) (76% 4-amino-5-bromo compound; 17% 4-bromo-5-amino compound) and 120 parts of methanol as an extractant 33.9 parts of 1-phenyl-4-amino-5-bromo-pyridazon- (6) of melting point 212 to 2140 ° C. (95 percent contaminated with 1 to 2% of the isomeric compound).

Example 4 When the separation is carried out analogously to Example 3 with 120 Parts of tetrahydrofuran as extractant give 31.9 parts of 1-phenyl-4-amino-5-bromopyridazon- (6) from m.p. 211 to 213 0C (95 percent).

Example 5 When the separation is carried out analogously to Example 3 with 170 Parts of trichlorethylene as the extractant give 38 parts of 1-phenyl-4-amino-5-bromopyridazon- (6) from m.p. 210 to 212 ° C. (95 percent).

Example 6 When the separation is carried out analogously to Example 3 at 20 up to "50C with 170 parts of ethyl bromide as the extractant, 40.9 parts are obtained 1-Phenyl-4-amino-5-broia-pyridazon- (6) of m.p. 206 until 2090C (91 percent; contaminated with 3% of the isomeric compound).

Example 7 When the separation is carried out analogously to Example 5, with it is extracted with 200 parts of carbon tetrachloride for 10 minutes at 70 to 75 0C, 38.9 parts of 1-phenyl-4-amino-5-bromopyridazon- (6) of melting point 210 ° to 2120 ° C. are obtained (95 percent).

Example 8 When the separation is carried out as in Example 1 with 50 Parts of crude 1-phenyl-4-amino-5-bromo-pyridazon- (6) (83% 4-amino-5-bromo compound; 4% 4-bromo-5-amino compound) and 120 parts of diethyl ether as the extractant 42.3 parts of 1-phenyl-4-amino-5-bromo-pyridazon- (6) of melting point 215 to 217 are obtained 0C (97 to 98 percent).

Example 9 When the separation is carried out analogously to Example 8 with 130 Parts of dioxane as the extractant give 42 parts of 1-phenyl-4-amino-5-bromo-pyridazon- (6) from m.p. 216 to 2180C (98 to 99 percent).

Example 10 When the separation is carried out analogously to Example 8 with 130 Parts of isopropanol as the extractant give 42 parts of 1-phenyl-4-amino-5-bromo-pyridazon- (6) from m.p. 216 to 2180C (98 to 99 percent).

Example 11 When the separation is carried out analogously to Example 8 with 120 Parts of tetrafluorodibromoethane are obtained 43.3 parts of 1-phenyl-4-amino-5-bromopyridazon- (6) of melting point 204 to 2120C (95 percent; contaminated with 1 ffi of the isomeric compound).

Example 12 When carrying out the separation as in Example 1 with crude 1-Methy1-4-amino-5-chloro-pyridazon- (6) (90% 4-amino-5-chloro compound; 10% 4-chloro-5-amino compound) 84.8 parts of 1-Methy1-4-amino-5-chloropyridazon- (6) of melting point 203 to 2040 ° C. are obtained (98 to 99 percent). Distillation of the filtrate gives 8 parts of 1-methyl-4-chloro-5-aminopyridazon- (6) of melting point 111 to 1130 ° C. (recrystallized from ethanol).

Example 13 When carrying out the separation as in Example 1 with crude 1-Benzyl-4-amino-5-chloro-pyridazon- (6) (75% 4-amino-5-chloro compound; 23% 4-chloro-5-nmino compound) 72.8 parts of 1-benzyl-4-amino-5-chloro-pyridazon- (6) of melting point 220 to 2210 ° C. are obtained (98 to 99 percent). Concentration of the filtrate gives 18 parts of 1-benzyl-4-chloro-5-aminopyridazon- (6) of melting point 107 to 1080C (recrystallized from ethanol).

Example 14 When the separation is carried out as in Example 1 with crude 1 -Cyclohexyl-4-amino-5-chloro-pyridazon- (6) (75 * 4-amino-5-chloro compound; 19 % 4-chloro-5-amino compound) one receives 63.5 parts of 1-cyclohexyl-4-amino-5-chloropyridazon- (6) from m.p. 219 to 2210C (98 percent). Concentration of the filtrate gives 15 Parts of 1-cyclohexyl-4-chloro-5-aminopyridazon- (6) of melting point 96 to 980 ° C. (recrystallized from cyclohexane).

Example 15 When the separation is carried out as in Example 1 with crude 1 - (m-Trifluoromethyl-phenyl) -4-amino-5-bromo-pyridazone- (6) (79% 4-amino-5-bromo compound; 9% 4-bromo-5-amino compound) one receives 73.2 parts of 1- (m-trifluoromethyl-phenyl) -4-amino-5-bromopyridazon- (6) of m.p. 174 to 1760C (99 percent).

By concentrating the filtrate, 7 parts of 1- (m-2rifluoromethyl-phenyl) -4-bromo-5-aminopyridazon- (6) are obtained of melting point 146 to 1470 ° C. (recrystallized from ethanol).

Example 16 When carrying out the separation as in Example 1 with crude 1- (p-Methylphenyl) -4-methylamino-5-chloro-pyridazon- (6) (88 to 90% 4-methylamino-5-chloro compound; 10 to 12% 4-chloro-5-methylamino compound) gives 79.2 parts of 1- (p-methylphenyl) -4-methylamino-5-chloro-pyridazon- (6) from m.p. 208 to 21,000 (99 percent). Concentration of the filtrate gives 8.5 Parts 1 - (p-methylphenyl) -4-chloro-5-methylamino-pyridazon- (6) from m.p. 175 to 17600 (recrystallized from ethanol).

Claims (2)

Claims (; Process for the preparation of pure 4-amino-5-halopyridazones- (6) of the general formula where R1 denotes an aliphatic, cycloaliphatic, araliphatic or aromatic radical, R2 denotes a hydrogen atom or an aliphatic radical and X denotes a halogen atom, by separation from its isomeric 5-amino-4-halo-pyridazonen- (6) of the general formula wherein R1, R2 and X have the aforementioned meaning, from mixtures of the two substances with the aid of extraction with solvents, characterized in that the 5-amino-4-halo-pyridazone- (6) II is obtained by extraction with aliphatic halogenated hydrocarbons, alkanols and / or separates ether. 2. The method according to claim 1, characterized in that according to the extraction of the 4-amino-5-halogen-pyridasone- (6) II from the extract in known Way.