RU2061676C1 - Process for preparing 2,6-dichlorodiphenylamine - Google Patents

Abstract

FIELD: as semiproduct in the synthesis of drugs. SUBSTANCE: product: 2,6-dichlorodiphenylamine. Reagent 1: 2,2,6,6- tetrachlorocyclohexanone. Reagent 2: aniline. Reaction conditions: aromatic hydrocarbon, titanium tetrachloride, 5-20 C, molar ratio of 2,2,6,6-tetrachlorocyclohexanone, aniline, titanium tetrachloride of 1: (5.5-7.0):1.5. EFFECT: more efficient preparation process. 9 ex, 3 tbl

Description

Соединение I является ключевым соединением в производстве N-хлорацетил-2,6-дихлорфениламина формулы

который, в свою очередь, является промежуточным продуктом в синтезе высокоэффективного противовоспалительного лекарственного препарата ортофена /1/, производство которого осуществлено на производственном объединении "Олайнфарм".The invention relates to the chemistry of aromatic amines, specifically relates to an improved method for producing a known compound of 2,6-dichlorophenylamine of the formula

Compound I is a key compound in the manufacture of N-chloroacetyl-2,6-dichlorophenylamine of the formula

which, in turn, is an intermediate product in the synthesis of the highly effective anti-inflammatory drug ortofen / 1 /, the production of which was carried out at the production association "Olainfarm".

 On the filing date, a number of methods for preparing the compound 1 / 2-6 / are known, but only two methods / 7, 8 / are most important for practical application.

 One of them / 7 / is used in industry. Industrial synthesis of 2,6-dichlorophenylamine consists in the fact that 2,6-dichloroacetanilide (III) is condensed with bromobenzene in the presence of a copper powder by the Ulmann reaction.

The reaction is carried out at a temperature of 160,170 ^o With the simultaneous distillation of water and adding to the reaction mass of bromobenzene in an amount equal to distilled with water. The duration of the reaction is 30 33 hours.

The reaction mass containing N-acetyl-2,6-dichlorodiphenylamine (IV) is cooled, filtered. Bromobenzene is distilled off with a sharp steam at 120 ^° C. The bottom residue containing product IV is cooled, the water is decanted, isopropyl alcohol is added and the residue is dissolved (90-100 ^° C), and the solution is cooled.

 The precipitated N-acetyl-2,6-dichlorodiphenylamine (IV) is filtered off and subjected to hydrolysis with 8 10% solution of potassium hydroxide in isopropyl alcohol at boiling (3 h).

Получают 2,6-дихлордифениламин (I) с выходом 62% (считая на исходный 2,6-дихлоацетанилид) и содержанием основного вещества 86 94%
Данный способ имеет ряд существенных недостатков:
трудность исходного соединения III (2,6-дихлорацетанилида).Scheme of an industrial method for producing compound I

Get 2,6-dichlorodiphenylamine (I) with a yield of 62% (counting on the original 2,6-dichloacetanilide) and a basic substance content of 86 94%
This method has several significant disadvantages:
difficulty of starting compound III (2,6-dichloroacetanilide).

 Compound III is prepared from 2,6-dichloro-4-nitroaniline (V) by multi-step synthesis according to the scheme.

с низким входом (26,5% считая на 2,6-дихлор-4-нитроанилин (V);
низкий выход целевого продукта 1/22% считая на V, или 62% считая на III/;
взрывоопасность производства соединения I в связи с использованием порошка меди, приготовление которого необходимо проводить в отдельном помещении с соблюдением мер предосторожности, т.к. при его производстве выделяется водород;
необходимость проведения отгонки бромбензола с острым паром, что повышает опасность производства I;
высокая температуры процесса (160 170^oC);
длительность процесса (30 33 ч).The scheme of the method of obtaining the starting compound III (2,6-dichloroacetanilide)

with a low input (26.5% based on 2,6-dichloro-4-nitroaniline (V);
low yield of the target product 1/22% counting on V, or 62% counting on III /;
explosion hazard in the production of compound I in connection with the use of copper powder, the preparation of which must be carried out in a separate room with the observance of safety measures, as hydrogen is released during its production;
the need for distillation of bromobenzene with hot steam, which increases the risk of production I;
high process temperature (160 170 ^o C);
the duration of the process (30 33 hours).

где R атом водорода, линейные или разветвленные алкильные группы, а также замещенные или незамещенные ароматические группы;
Х атом галогена: хлора, брома, фтора, иода,
заключающийся в том, что 2,2,6,6-тетрагалоидциклогексанон (VI) подвергают взаимодействию с аммиаком или первичным амином в присутствии кислоты Льюиса при температуре (-10) 50^oC, образующееся соответствующее производное 2,2,6,6-тетрагалоидциклогексанимина общей формулы Б

где R и Х имеют вышеуказанные значения,
выделяют и подвергают дегидрохлорированию в присутствии основного катализатора в среде растворителя при нагревании /8/.A known method of producing derivatives of 2,6-dihaloalines of the general formula A

where R is a hydrogen atom, linear or branched alkyl groups, as well as substituted or unsubstituted aromatic groups;
X halogen atom: chlorine, bromine, fluorine, iodine,
consisting in the fact that 2,2,6,6-tetrahalocyclohexanone (VI) is reacted with ammonia or a primary amine in the presence of a Lewis acid at a temperature of (-10) 50 ^o C, the corresponding derivative of 2,2,6,6-tetrahalocyclohexanimine is formed general formula B

where R and X have the above meanings,
isolated and subjected to dehydrochlorination in the presence of a basic catalyst in a solvent medium under heating / 8 /.

According to the description of the patent / 8 /, halogen or alkoxide metals are used as the Llis acid;
the condensation stage is carried out in an environment of solvents: halocarbons, aliphatic, aromatic hydrocarbons;
carbonates, bicarbonates, oxides, hydroxides of alkali or alkaline-earth metals, organic bases are used as the main catalyst.

 The group of compounds of general formula A also includes a compound of the formula 1-2,6-dichlorodiphenylamine.

 Below is a synthesis scheme for compound I.

 The synthesis scheme of compound l according to the patent / 8 /.

и табл. 1 и 2, где приведены условия синтеза, выхода и качество промежуточных соединений общей формулы Б (производных 2,2,6,6-тетрагалоидциклогексаниминов, в том числе и соединения VII) и конечных продуктов общей формулы А (производных 2,6-дигалоиданилинов, в том числе соединения I). В общей части описания патента (с. 7) указано, что молярное соотношение соответственно
исходного соединения VI анилина 1: (1 5)
исходного соединения VI катализатора 1 (0,25-2,0) (преимущественно 1: (0,75-1,2).

and table 1 and 2, which show the synthesis conditions, yield and quality of intermediate compounds of the general formula B (derivatives of 2,2,6,6-tetrahalocyclohexanimines, including compounds VII) and end products of the general formula A (derivatives of 2,6-dihaloidanilines, including compound I). In the general part of the patent description (p. 7) it is indicated that the molar ratio, respectively
starting compound VI of aniline 1: (1 5)
starting compound VI of catalyst 1 (0.25-2.0) (preferably 1: (0.75-1.2).

However, it should be noted that during the reproduction of the preferential conditions (VI aniline TiCl ₄ 1 4 1.1) for synthesis of l (in the patent Example 1), intermediate VII was obtained in low yield (note in Table 1).

As can be seen from the table. 1 (condensation step) the synthesis of intermediate VII, although shown by the large group (12) of examples (1 to 3 and 13 to 21), but in all these examples a limited range of its conditions is given, namely:
the molar ratio of VI and aniline as 1 4;
- the use of a catalyst (Lewis acids) / it should be noted that intermediate VII with a high yield was obtained only when TiCl ₄ / was used as a catalyst;
the ratio of compound VI and Lewis acid (catalyst) as 1 1.1;
-use only toluene as a solvent;
- the weight ratio of VI and solvent as 1 2.2;
temperature 5 105 ^o C (mainly 5 20 ^o C).

From the table. 2 (dehydrochlorination step) it can be seen that the main group of examples (NN 22 52) is given for the synthesis of compound l, where the necessary conditions for the dehydrochlorination of intermediate VII are:
the presence of a basic catalyst;
the ratio of the main catalyst and the intermediate compound VII stoichiometric;
temperature 20 150 ^o C;
carrying out the process in a solvent environment;
aromatic polar solvents, aliphatic nitriles, aliphatic amides, aprotic polar solvents are used as a solvent.

Thus, as a result of the analysis of the data of the prototype, we concluded that, according to patent / 8 /, the possibility of synthesizing compound l in high yield is possible under the following specific conditions:
l stage (condensation VI + aniline)
the molar ratio of starting VI to aniline 1 4;
TiCl ₄ catalyst;
the molar ratio of the starting compound MI and TiCl ₄ 1 1.1;
toluene medium;
the weight ratio of compound VI to toluene 1 2.2;
temperature range 5 to 20 ^o C;
purification of intermediate VII by recrystallization.

Stage II (dehydrochlorination VII)
main catalyst;
solvent: aromatic polar solvents, aliphatic nitriles, aliphatic amides, aprotic polar solvents;
temperature 95 100 ^o C.

 These conditions for the synthesis of compound I are the closest in technical essence to the conditions of the proposed method for producing compound l, and therefore this synthesis method l is accepted by us as a prototype.

The prototype method / 8 / is as follows: to a mixture of 2,2,6,6-tetrachlorocyclohexanone (VI), toluene (weight ratio of VI and toluene 1 2.2) and titanium tetrachloride catalyst (molar ratio of VI and TiCl ₄ 1 1 , 1), cooled to 5 ^o C, add aniline dropwise (molar ratio of VI to aniline 1 4) at such a rate that the temperature does not exceed 20 ^o C, followed by exposure at this temperature (2 h). The resulting reaction mixture was poured into cold water (10 ^° C.). The water and toluene layers are separated. The aqueous layer was extracted with toluene, the extract was added to the basic toluene solution, and the toluene was evaporated. The residue containing N-phenyl-2,2,6,6-tetrochlorocyclohexanimine (VII) as a black solid is recrystallized from methanol.

Thus obtained N-phenyl, 2,2,6,6-tetrachlorocyclohexanimine (VII) (in the form of yellow needles, mp 71.8 72.6, 89.6% yield) is subjected to dehydrochlorination in a solvent medium (as which uses an aromatic polar solvent, aliphatic nitrile, aliphatic amide, aprotic polar solvent) at a temperature of 95 ^o C in the presence of a basic catalyst (which is used as carbonates, bicarbonates, oxides, hydroxides of alkali and alkaline earth metals and organic bases).

Get the technical target product l with a yield of 67.2 87.8% (counting on the initial IV *) (* the calculation of the yield of compound 1 was made by the authors of this application without taking into account the content of the main substance). and with a basic substance content of 99.5%
The output of purified l is not shown.

 Information on the use of this synthesis l in industry is not available in the literature.

The main disadvantages of the prototype method / 8 / are:
the need for purification of intermediate VII, because the product is black;
relatively low yield of intermediate VII.

As indicated above (table. 1), according to the extreme data obtained by us when reproducing the conditions of example 1 of the patent / 8 /, the yield of compound VII does not exceed 65%
We studied the mother liquors after filtration of compound VII (obtained from crystallization from methanol) and the technical product VII itself by gas-liquid chromatography and polarography.

It was found that they contain a significant amount of the starting compound VI, namely:
in technical product VII 16%
in its mother liquors 50 65%
In connection with the foregoing, we affirm that the yield of the unitary enterprise given in the patent is significantly overestimated;
the difficulty of transporting the reaction mass in the UP / t separation operation. K. the reaction mass is dense, hardly mixing and pouring it into water is not possible.

 The purpose of the invention is to simplify the process and increase the yield and quality of the intermediate N-phenyl-2,2,6,6-tetrachlorocyclohexanimine (UP).

The goal is achieved by the proposed improved method for producing 2,6-dichlorodiphenylamine (I), which consists in the fact that 2,2,6,6-tetrachlorocyclohexanone (Vl) is reacted with aniline (molar ratio, respectively, 1: (5.5-7) * (* excess aniline is recovered with a yield of 81 84%), (predominantly 1: 6) in the presence of a titanium tetrachloride catalyst (molar ratio, respectively 1: 1.5) at 5 20 ^o С in a medium of 4 10-fold excess of aromatic hydrocarbon (mainly toluene )

Water was added to the reaction mass, the organic layer containing N-phenyl-2,2,6,6-tetrachlorocyclohexanimine (UP) was separated, the solvent was removed, and the residue was a tan solid (N-phenyl-2,2,6, 6-tetrachlorocyclohexanimine (UP)) is heated (subjected to dehydrochlorination) to 95-100 ^° C in the presence of a basic catalyst (mainly triethylamine) in an aprotic polar solvent (e.g. dimethylformamide, dimethylacetamide).

 The target product is isolated in a known manner.

Get the technical target product l with a yield of 88 90% (counting on the original VI without taking into account the content of the main substance) in the form of a crystalline powder from beige to brown in color with so pl. 42-43 ^o With and the content of the main substance of 96.3%
Since the product has a low melting point and is readily soluble in most solvents, it is difficult to clean it by recrystallization. However, obtained by the claimed method, the technical product l is quite clean (high content of the main substance) and meets the requirements of the regulation for the production of the orthophene drug / 7 / (according to which the content of the main substance in the product should be at least 92%), which is the main indicator of the product’s shelf life l .

Distinctive features of the proposed method are:
the molar ratio of VI to TiCl ₄ as 1: 1.5;
the molar ratio of VI to aniline as 1: (5.5-7);
4-10 times the amount of aromatic hydrocarbon as a solvent in the condensation stage of VI and aniline in the presence of TiCl ₄ ;
the processing order of the reaction mixture containing the UP compound with water (water is added to the reaction mixture, and not vice versa (see prototype));
the introduction of the connection UP at the stage of dehydrochlorination without purification (in the prototype UP before dehydrochlorination is subjected to recrystallization).

As indicated above (see table. 1), satisfactory yield of intermediate ketimine UP obtained only with TiCl ₄ ; other Lewis acids (AlCl ₃ , SnCl ₄ , etc.) give significantly worse results.

These data are consistent with the pioneering work on the use of TiCl ₄ in the synthesis of ketimines / 9 /, where it is shown that for sterically hindered ketones (which include compound VI), only the use of titanium tetrachloride is optimal.

The examples of the synthesis of ketimines (for example, from 2,6-diisopropylcyclohexanone) presented in this work actually confirm the possibility of producing ketimines in satisfactory yields only in the presence of TiCl ₄ .

 Given the foregoing, the inapplicability of the use of other Lewis acids to obtain the intermediate compound UP (the condensation product of starting VI and aniline) is obvious.

The claimed molar ratio of the starting VI and catalyst (TiCl ₄ ) is a necessary and sufficient condition for increasing the yield of VII / used in the prototype method / 8 /, the preferred ratio of the starting VI and the Lewis acid catalyst is close to equimolecular (1: 1.1) /.

In an experimental study of the condensation reaction of VI and aniline, we noticed that even the claimed preferential ratio of the starting VI and aniline (1: 6) in combination with the predominant (patented) ratio of VI and TiCl ₄ (1: 1.1) do not provide ketimine VII sufficiently high quality (table. 3, example 4, where the yield of compound VII is 90%, the content of starting compound VI in product VII is 15%).

In addition, the increase in the amount of catalyst (TiCl ₄ ) to 1.5 moles when using the predominant (patented) ratio of the starting VI and aniline (1: 4) also does not allow to obtain satisfactory quality VII (table 3, example 5, where the content of the starting Compound VI in product VII is 14%).

Only an increase in the amount of catalyst (TiCl ₄ ) and aniline, namely aniline (5.5-7) moles, and catalyst up to 1.5 moles relative to the original VI, allowed the condensation process to be carried out purposefully and to obtain VII with a significantly higher yield and satisfactory quality (table. 3, examples 1 to 3).

 The improvement in the quality of intermediate VII is confirmed by GLC analytical data, according to which technical product VII obtained under the claimed conditions contains impurities of the initial VI of not more than 0.7 2.37% (according to the prototype, the technical (crude) product VII contains up to 16% of the initial VI, which, when dehydrochlorination gives an admixture of 2,6-dichlorophenol to 11% of table 3, example 7).

 A decrease in the amount of aniline (5.5 moles) leads to a decrease in the content of the main product VII (i.e., a deterioration in the quality of VII, table 3, example 5).

 An increase in the amount of aniline (> 7.0 moles) is impractical because the yield and quality of product VII does not increase (table. 3, example 6).

 In the prototype, the condensation reaction is carried out in an aromatic, aliphatic and halocarbon medium.

 In the inventive method at this stage only aromatic hydrocarbon is used.

 The use of other solvents for the synthesis of l at the stage of condensation indicated in the prototype is impractical for the following reasons. Thus, compound VII in an aliphatic hydrocarbon medium is obtained of unsatisfactory quality and with a low yield (as we found in the experiment, the starting VI and ketimine VII are slightly soluble in this solvent).

 Halocarbons are environmentally hazardous and are prohibited by the World Health Organization (WHO), as when they are neutralized, toxic dioxin substances are formed.

 It is important to note that the ratio VI solvent of 1: 2.2 proposed in the prototype at the stage of condensation creates significant technological complications due to the difficulty of mixing the thick reaction mass, its transportability, the inability to take an average sample for analysis, but since these operations are necessary in industrial production , then an increase in the amount of solvent (the solvent is almost completely regenerated) up to 4 10-fold excess in relation to the initial VI is one of the significant factors, ensuring This creates a homogeneous suspension and, therefore, a more complete implementation of the condensation process.

 In addition, an increase in the amount of solvent, along with the procedure for treating the reaction mixture containing VII with water, allows us to solve the problem of transportation of the above reaction mixture, facilitates the isolation of VII under industrial conditions, and the preparation of VII with improved yield and quality.

All of the above improvements in the condensation stage allow:
to obtain an intermediate product VII of high quality (the content of the main product according to polarography is 92 99%) and practically with a quantitative yield (98 99%) / table. 3, examples 1 3 /;
eliminate the need for purification of product VII / in the prototype, product VII is necessarily recrystallized, because it is formed as a black solid and contains up to 16% of the impurity of the starting compound VI, which is converted by dehydrochlorination (see examples 1 to 3, Table 3) into 2,6-dichlorophenol (up to 11%), which in subsequent syntheses leads to contamination of the drug orthophene /;
due to the exclusion of purification of intermediate VII, the number of technological operations was reduced at the stage of condensation, the list of technological equipment was reduced, the need to use additional solvent for recrystallization of VII and the introduction of additional stages for the registration of this solvent were eliminated.

 The dehydrochlorination step, as indicated above, in the prototype is carried out in polar aromatic solvents, aliphatic nitriles or aprotic polar solvents.

 We settled on the last group of solvents, aprotic polar solvents.

 Our attempt to reproduce the dehydrochlorination step in chlorobenzene (polar aromatic solvent) according to the method described in detail in the prototype did not lead to product l (even product G1 was not detected even by GLC analysis) (Table 2, examples 22 and 23).

It should be noted that the use of aliphatic nitriles (for example acetonitrile, bp 82 ^° C) at the dehydrochlorination stage is impossible, since the boiling point of these solvents is much lower than the temperature of the dehydrochlorination process (95 ^° C).

 And only the use of a polar aprotic solvent allowed dehydrochlorination of technical VII obtained under the claimed conditions (without special purification) in the presence of triethylamine and to obtain the target product 1, and with a high yield (table. 3, examples 1 3).

It should be reiterated that dehydrochlorination of technical VII under the same conditions (the main catalyst is triethylamine, 95-100 ^° C, but in an aromatic polar solvent (chlorobenzene), did not lead to the desired product l (table 3, example 10).

Thus, the claimed combination of conditions of the proposed method of obtaining l creates a number of advantages compared with the prototype, namely, as described above, allows:
to obtain intermediate product VII of improved quality without purifying it (in product VII obtained by the present method, the impurity of the starting compound is not more than 2.37% and according to the prototype 16%);
eliminate the need for purification of product VII and, as a result, reduce the number of technological operations in industrial production, the list of technological equipment, eliminate the need to use additional amounts of solvent for its recrystallization and introduce additional operations related to the regeneration of this solvent;
get the target product with a yield of 88 90% (counting on the original VI, excluding the content of the main substance), which is 30% higher than the yield of the target product l, reproduced in the conditions of the prototype (according to the description of example 1 of the patent / 8 / result, see table. 1 )

 The technical target product l obtained by the present method meets the requirements for the production of ortofen.

 Example A confirms the possibility of using the above target product l for the synthesis of N-chloroacetyl-2,6-dichlorodiphenylamine intermediate used in the synthesis of orthophene.

 Example A. The use of l obtained by the present method for the synthesis of N-chloroacetyl-2,6-dichlorodiphenylamine.

A mixture of 17.3 ml (0.23 mol) of chloroacetyl chloride and 31.36 g (0.13 mol) of dichlorophenylamine is slowly heated with stirring to 108 ± 2 ^° C. The mixture is held at this temperature for 2 hours. Then, the heating is removed and at 105 ^{° C.} 40 ml of toluene is added to the reaction mass, maintaining the temperature at a mass of 80 83 ^o C. Then 14 ml of isopropyl alcohol are added and boiled for 1 h. The reaction mass is cooled to 5 ± 2 ^o C, incubated for 2 hours, the precipitate is filtered off, washed with 21 ml of isopropyl alcohol are dried.

 Obtain 34 g of technical N-chloroacetyl-2,6-dichlorodiphenylamine, which is recrystallized from 476 ml of isopropyl alcohol with 2.4 g of activated carbon.

 Obtain 27.85 g of pure N-chloroacetyl-2,6-dichlorodiphenylamine.

 The isopropanol mother liquor was evaporated by 80% to give an additional 3.12 g of pure N-chloroacetyl-2,6-dichlorodiphenylamine.

 The total yield of 30.97 g (76.9%), based on the starting 2,6-dichlorodiphenylamine.

Mp 144 145.5 ^o C. According to GLC, the content of the main substance is 99%
The yield of N-chloroacetyl-2,6-dichlorodiphenylamine, laid down in the industrial regulation, is 73%
Mp not lower than 144 ^o C not higher than 148 ^o C within 2 ^o C.

The content of the basic substance is not lower than 99%
The following examples illustrate the claimed method of obtaining l.

 Example 1. Obtaining 2,6-dichlorodiphenylamine (I).

 a) preparation of the intermediate N-phenyl-2,2,6,6-tetrachlorocyclohexanimine (VII).

To a solution of 15 g (0.06 mol) of 2,2,6,6-tetrachlorocyclohexanone in 130 g of toluene was added 17 g (0.09 mol) of TiCl ₄ . The mixture is cooled to 10 ^{° C.} and 36.4 g (0.36 mol) of aniline are added dropwise over 1.5 hours so that the temperature in the reaction mass does not exceed 20 ^° C. The mixture is held at this temperature for 2 hours, after which it is added. 90 ml of water cooled to 10 ^o With, stirred until complete dissolution of the reaction mass. Then the layers (aqueous and organic) are separated. The organic layer was evaporated. 19.6 g (99%) of N-phenyl-2,2,6,6-tetrachlorocyclohexanimine are obtained, which is used in the dehydrochlorination step (Example 1, Table 3).

 b) obtaining the target product l.

A mixture of 19.54 g (0.063 mol) of N-phenyl-2,2,6,6-tetrachlorocyclohexanimine, 98 ml of dimethylformamide and 19.5 ml (0.14 mol) of triethylamine is heated for 5 hours at 95-100 ^° C. The mixture is cooled , triethylamine hydrochloride is filtered off, washed with dimethylformamide. The filtrate was evaporated, 5 ml of water was added to the residue and stirred. The precipitate formed is filtered off, washed with water and dried.

 13.8 g (91%) of 2,6-dichlorodiphenylamine are obtained. TTT1 TTT2 TTT3 TTT4 TTT5 TTT6

Claims (1)

The method of obtaining 2,6-dichlorodiphenylamine of the formula

by condensation of 2,2,6,6-tetrachlorocyclohexanone and aniline in the presence of titanium tetrachloride in an aromatic hydrocarbon medium in the temperature range of 5-20 ^o With the subsequent separation of N-phenyl-2,2,6,6-tetrachlorocyclohexanimine from the reaction mass using water and its dehydrochlorination in the presence of a basic catalyst in an aprotic polar solvent at 95-100 ^o C, characterized in that the condensation of the original 2,2,6,6-tetrachlorocyclohexanone and aniline in the presence of titanium tetrachloride is carried out at their molar a ratio of 1 (5.5-7.0) 1.5, respectively, in a medium of 4-10 times an excess of aromatic hydrocarbon with respect to 2,2,6,6-tetrachlorocyclohexanone, the resulting condensation product of N-phenyl-2,2,6, 6-tetrachlorocyclohexanimine is isolated from the reaction mixture by adding water to it, separating the organic layer containing the condensation product, followed by removal of the solvent from the organic layer and dehydrochlorination of the obtained technical N-phenyl-2,2,6,6-tetrachlorocyclohexanimine.

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