JPH01106850A - Manufacture of n-acyl-n-alkyl-2,6-dialkyl-3- chloroaniline - Google Patents

Abstract

PURPOSE: To easily obtain N-acyl-N-alkyl-2,6-dialkyl-3-chloroanilines including some having bactericidal activity in a good yield by acylating 2,6-dialkylanilines and allowing the resultant N-acyl-N-alkyl-2,6-dialkylanilines to react with chlorine atoms.

CONSTITUTION: 2,6-Dialkylanilines of formula I (where R₁ is methyl or ethyl) are allowed to react with a halide of formula II (where R₃ is alkoxymethyl, carboxyl, etc.; R₄ is H or methyl; R₃ and R₄ together may form a ring; and X is Cl or Br). The resultant N-alkyl-2,6-dialkylanilines of formula III are allowed to react with an acylating agent of formula IV [where X₁ is Cl, Br or O-CO-R₂ (R₂ is alkoxymethyl, chloromethyl, etc.)], and the resultant compds. of formula V are allowed to react with chlorine to obtain the objective compds. of formula VI, e.g. N-methoxyacetyl-N-(2-oxotetrahydro-3-furyl)-3-chloro-2,6- dimethylaniline.

COPYRIGHT: (C)1989,JPO

Description

[Detailed description of the invention] The present invention is based on the linear formula ■: (In the formula, 几! represents a methyl group or an ethyl group.

for an alkoxymethyl group, a chloromethyl group, or a 2-
Tetrahydrofuryl foundation, RI3 represents an alkoxymethyl group, carboxyl group or alkoxycarbonyl group, and R4 represents a hydrogen atom or a methyl group.

bird represents a carboxyl group or an alkoxycarbonyl group, and R4 further represents a 2-alkoxyethyl group and a 2-
When representing an alkoxypropyl group, HJs and 几4 together with the carbon atoms bonded to both groups further represent 2
-Oxotetrahydro-3-furyl group or 2-oxo-5-methyltetrahydro-6-furyl group may be formed. ) N-acyl-N-alkyl-2
, 6-dialkyl-5-chloroaniline.

Some of the compounds of formula I have fungicidal activity, and some of the compounds have herbicidal activity. Compounds of this type are described, for example, in U.S. Pat.
No. 64629, Lay and No. 3933860, British Patent No. 1455471, European Patent Publication No. 0028011 and British Patent Publication No. 2006.783.

From British Patent Publication No. 2098210,
N-alkoxycarbonylmethyl-2,6-dialkyl-aniline and N-(1-alkoxycarbonylethyl)-2,6-dialkylaniline r, N-alkoxycarbonylalkyl-2,6- corresponding to a halogen atom
1 mol of dialkylaniline followed by at least 2 mol of Lewis acid
mol and subsequently obtained n9N-alkoxycarbonylmethyl-2,6-dialkyl-3-
N-acylated N-alkoxycarbonylmethyl-2,6-dialkyl-6-haloaniline and N-( 1-alkoxycarbonylethyl)-2,6-
It is known to produce dialkyl-6-haloanilines. A suitable Lewis acid is aluminum chloride.

These are aluminum bromide, boron trifluoride, tin tetrachloride, and titanium tetrachloride. This method is disadvantageous in that a Lewis acid must be used to obtain the desired effect, e.g.

9 parts of N-alkoxycarbonylalkyl-2,6-dialkyl ayu is required followed by 2 parts by weight of aluminum chloride. Since this large amount of aluminum chloride must first be decomposed together with water before working up the reaction oil, the process is not only expensive in terms of starting materials and auxiliaries required, but also requires further implementation. make it complicated.

Furthermore, by chlorinating 2,6-dimethylacetanilide, 3-chloro-2,6-
It is also known to produce dimethylacetanilide (
8ynthsis, 1971.

467 Sada). According to this method, N-acyl-N-alkyl-2,6-dialkyl-6- of formula I
Chloroaniline is obtained by acylating the corresponding λ6-dialkylaniline and chlorinating 6-dialkylacetanilide to obtain 3-chloro-2,6-dialkylaniline. Hydrolyzing acetanilide and acylating the compound.

Then, the product is obtained by carrying out acylation according to the following reaction formula. : According to this method, N-acyl-N- expressed by the formula
Alkyl-2,6-dia,-roxy-5-chloroanilines can be prepared in yields of about 40% of theory based on the starting material 2,6-dialkyldianiline.

This process is complex due to the large number of reaction steps required and is unsatisfactory with respect to the yields that can be obtained.

It is therefore an object of the present invention to provide N-acyl-N-alkyl-6- of the formula I in a simple manner and with good yields.
A method is provided which makes it possible to produce dialkyl-3-chloroaniline.

This purpose is achieved by alkylating the corresponding 2,6-dialkylaniline and subsequently acylating the corresponding N
-acyl-N-alkyl-λ6-dialkylaniline, and then by reacting the vaginal compound with a chlorine atom, N-acyl-N-alkyl-Otsu6 represented by the formula
It has been found that this can be carried out advantageously by converting it into -dialkyl-6-chloroaniline.

Therefore, according to the present invention, the linear equation ■: (During the ceremony.

R1 has the meaning defined in formula I. ) expressed as nru2
, 6-dialkylaniline and the following formula ■: (wherein R3 and 1 (4 represents the meaning defined in formula ■, and X represents a chlorine atom or a bromine atom) n
The following formula ■: (in the formula.

R1t　3 and 几4 represent the meanings defined in the formula!.

) to obtain an N-alkyl-λ6-dialkylaniline represented by the following formula (1): Xl-CU-R2(V) (in the formula.

Bird represents the meaning defined in formula (■), and X is a chlorine atom, a bromine atom, or 10-CO-R.

represents. ) is reacted with an acylating agent, and the following formula is obtained: (wherein.

几i, bird, & and 几4 have the meanings defined in the formula ■.

) to produce N-acyl-he-alkyl-2,6-dialkyl-3-chloroaniline represented by formula I by reacting N-acyl-N-alkyl-2,6-dialkyl-3-dialkylaniline represented by formula I with chlorine. Suggest that you do.

A suitable 2,6-dialkylaniline represented by the formula
Y, 2,6-dimethylaniline and 2,6-dinitylaniline. 46-dimethylaniline is particularly suitable.

Suitable halides represented by formula (2) include 2-alcokyneethylchloride, 2-alkoxyethylbromide,
2-alkoxypropyl chloride, 2-alkoxypropyl bromide, 2-chloroacid m, 2-bromoacetic acid, 2-
Chloropropionic acid, 2-bromopropionic acid% 2-chloroacetic acid alkyl ester, 2-bromoacetic acid alkyl ester, 2-talolopropionic acid alkyl ester, 2
-bromopropionic acid alkyl ester, 2-chloroo-
4-Alkoxybutyric acid, 2-bromo 4-alkoxybutyric acid, 2-chloro-4-alkoxyvaleric acid% 2-bromo 4-alkoxypareric acid, 2-bromo 4-
Alkoxybutyric acid alkyl ester % 2-bromo-4-alkoxybutyric acid alkyl ester, 2-chloro-4-alkoxyvaleric acid alkyl ester.

These are 2-bromo 4-alkoxyvalerian alkyl ester, α-chloro-r-butyrolactone, α-bromo-r-butyrolactone, α-chloro-γ-valerolactone, and α-bromo-γ-valerolactone. The alkoxy and alkyl ester groups present in the above halide represented by 2 and 3 each have 1 to 4 carbon atoms.
Contains alkyl funds. In particular, the alkyl groups may be methyl, ethyl, propyl, isopropyl, butyl, nibutyl, tert-butyl and isobutyl.

When using a halide represented by the formula 2 (wherein, X represents a chlorine atom), 2,6-
The reaction of the dialkylaniline with the halogenide of the formula (1) is advantageously carried out in the presence of an alkali metal iodide, especially potassium iodide, as a catalyst.

Preferred halides represented by 2.

2-methoxyethyl chloride, 2-ethoxyethyl chloride, 2-methoxy-1-methylethyl, 11/riolJ
l-”, methyl-2-chloroacetate.

Ethyl 2-chloroacetate, methyl-2-bromopropionate, ethyl 2-bromopropionate and α-
Chloro-r-butyrolactone. A particularly preferred halide represented by ① is α-bromo-γ-butyrolactone.

Suitable acylating agents of the formula (2) are the chlorides and bromides of chloroacetic acid, alkoxyacetic acid and tetrahydrofuran-2-carboxylic acid and the anhydrides of these acids.

Alkoxyacetic acid.

Methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, sec-butoxy group.

In particular, all radicals containing C1 -C4 alkoxy radicals, such as tertiary-butoxy and isobutoxy, are to be understood.

Preferred acylating agents are methoxyacetyl chloride, chloroacetyl chloride and tetrahydrofuran-2-carboxylic acid chloride, with methoxyacetyl chloride being particularly preferred.

The reaction of the 2,6-dialkylaniline of the formula with the halide of the formula 2 is advantageously carried out in the presence of an inert solvent intermediate acceptor. Suitable inert solvents are aromatic and hydrogenated hydrocarbons such as benzene, toluene, xylene, chlorobenzene and 0-dichlorobenzene, and N,N-dimethylformamide and N,N-dimethylacetamide. ,
2,6-dialkylaniline represented by an N-disubstituted carboxamide and an excess of 2. Preferred solvents are toluene and xylene. Suitable acid acceptors include inorganic acids such as alkali metal hydroxides, alkali metal carbonates, alkali metal bicarbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates and alkaline earth metal bicarbonates. Bases and organic bases such as triethylamine, pyridine or excess 2,6-dialkylaniline of the formula (2). A preferred base is sodium carbonate. The reaction temperature generally ranges from 80° C. to the reflux temperature of the reaction medium. It is advantageous to carry out the alkylation at the reflux temperature of the reaction medium. The reaction between a 6-dialkylaniline represented by the formula (■) and a halide represented by (2) is carried out in toluene or xylene as a solvent and in the presence of sodium carbonate as an acid acceptor as a reaction medium. Preference is given to carrying out at reflux temperature.

The reaction of the N-alkyl-λ6-dialkylaniline of formula (II) with the acylating agent of formula V is advantageously carried out in an inert solvent in the absence or presence of an acid acceptor. . Suitable inert solvents are water-immiscible solvents, such as in particular aliphatic and aromatic hydrocarbons and halogenated hydrocarbons. Examples of suitable solvents are hexane, benzene, toluene, xylene, chlorobenzene, methylene chloride, chloroform, carbon tetrachloride and ethylene chloride. Preferred solvents are toluene and hoxylene.

Suitable acid acceptors in which the reaction of N-alkyl-2,6-dialkylaniline represented by the formula (2) with the acylating agent represented by the formula (2) is carried out in the presence of an alkali metal hydroxide, an alkali Inorganic and organic bases such as metal carbonates, alkali metal bicarbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, alkaline earth metal bicarbonates, triethylamine and pyridine. Represented by the formula ■
-The reaction between an alkyl-2,6-dialkylaniline and an acylating agent represented by formula V.

Preferably it is carried out in toluene or xylene under reduced pressure in the absence of a base. A suitable pressure at which the reaction between the N-alkyl-λ6-dialkylaniline of the formula (2) and the acylating agent of the formula (2) can be carried out is from 50 to 150 mbar, preferably from 60 to 100 mbar.
It is in the range of bar.

N-acyl-N-alkyl represented by the formula ■2.6-
The chlorination of dialkylanilines can additionally be carried out advantageously in an inert solvent. What is a suitable solvent?

Sometimes lower aliphatic carboxylic acids such as formic acid and acetic acid. A further suitable solvent is chlorobenzene.

Chlorinated aromatic and aliphatic hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and ethylene chloride.

The carboxylic acid used as a solvent may have a total water content of up to 60% by weight.

N-acyl-N-alkyl-2,6- represented by formula ■
A preferred solvent in which the chlorination of dialkylanilines is actually carried out is formic acid with a water content of up to 40% by weight.

The chlorination is advantageously carried out in the temperature range from 20°C to 40°C, although the chlorination can also be carried out either at even higher n'fc temperatures, or at cold or lower temperatures.

However, at temperatures above 40°C, the formation of diatomic products increases, whereas at temperatures below 20°C, the reaction does not start immediately after the initiation of chlorine introduction, resulting in relatively high chlorine concentrations. It must be kept in mind that there is a possibility that it will start only when it is formed. This delayed starting reaction is often so violent that it is difficult to control the temperature of the reaction mixture. In this context, the formation of di-primed products must also be expected.

Furthermore, the chlorination is advantageously carried out in the presence of a hydrochloric acid such as aluminum chloride, iron chloride), boron trifluoride and titanium tetrachloride. Iron chloride (110 is the preferred Lewis acid. The Lewis acid is.

N-acyl-N-alkyl-2,6-sialylaniline represented by the formula ■ for chlorination? 1 as a base
5% to 5% by weight, preferably 1.5 to 2.5% by weight
Use in the amount of Lewis acids themselves do not have a substantial effect on chlorination, but they chlorinate N-acyl-N-alkyl-2,6- Significantly increases the solubility of dialkylaniline in aqueous formic acid or acetic acid solutions. Therefore, when using formic acid or acetic acid as a solvent to obtain a tube cap, it is advisable to add the entire Lewis acid to the load. Therefore, the chlorination of N-acyl-N-alkyl-2,6-dialkylanilines of the formula -N-alkyl-2,6-dialkylaniline as a pace and 1.5 to 2.5% by weight of iron chloride (lII)
) is preferably carried out.

Chlorination is usually carried out under normal pressure. When using formic acid or acetic acid as a solvent, the reaction may be carried out under slight pressure, since no gas escapes from the reaction mixture while using the solvent.

The method of the present invention enables the production of N-acyl-N-
This makes it possible to produce all alkyl-2,6-dialkyl-6-chloroanilines. In comparison to the process described in GB 2089210, i.e. a process based on the chlorination of N-alkyl-2,6-dialkylanili in the presence of at least 2 mol of Lewis acid. , the use of large amounts of Lewis acid and the attendant disturbances during processing can be avoided. N-acetyl-2,6
- Easy to chlorinate dialkylanilines, compared to the first described method, with the exception of two reaction steps, i.e. the introduction of acetyl groups before chlorination and the removal of acetyl groups after chlorination. It can be implemented. N-alkylation of 2,6-dialkylanilines can give better yields than N-alkylation of corresponding 2,6-dialkyl-6-chloroanilines. Furthermore, it is surprising that the chlorination of N-acyl-N-alkyl-2,6-dialkylanilines of formula (1) can give better yields than the chlorination of known 2,6-dialkyl acetanilides. . The idea of the invention is to make it possible for the first time to fully exploit these advantages. The introduction of a chlorine atom into the 5-position of the fenyl group in the final stage means that
This is an undeniable feature of this idea.

The method of the invention will be explained in more detail by the following examples.

Example 1: Preparation of he-methoxyacetyl-N-(2-oxotetrahydro-6-furyl)-3-chloro-6-dimethylaniline a) Anhydrous carbonic acid solution 64 f (0.6 mol) ) is suspended in a solution of 2,6-dimethylaniline 1219 (1,0 mol) in 500 d of xylene.

α-Bromo-r-butyrolactone (3-bromo-2-oxotetrahydrofuran) 2067 (1,
25 mol) are added to this suspension at reflux temperature (approximately 140° C.). After the addition of α-promo-γ-butyrolactone is complete, the reaction mixture is stirred at room temperature for 4 hours. The reaction water was added during the addition of α-bromo-γ-butyrolactone, and
K is removed during subsequent stirring. The reaction mixture was then heated to 50°C.
first with 200% water and then with 5% hydrochloric acid 200%
Wash with IIL.

Subsequently, 50 to 60 rrtlf of the solvent is distilled off to dry. Gas chromatography analysis showed that the reaction mixture was N-(2-oxotetrahydro-3-furyl)
-2,6-dimethylaniline 174p (85% of theoretical
)i jointly owned.

When the reaction mixture is cooled, some of it precipitates. The resulting suspension can be further processed directly in the next step.

However, the product may also be recovered by distilling off the solvent and total crystallization of the residue from the Improper Tool. Melting point is 82-84°C.

b) Methoxyacetyl chloride 116 diluted over 2 hours (
1,04 mol) at 60-70°C, 70-80 mbar
N-(2-
Add to a suspension of oxotetrahydro-6-furyl)-2,6-dimethylaniline 205 P (1,0 mol). Hydrogen chloride gas is evolved as the reaction mixture begins to boil at the end of the methoxyacetyl chloride addition. After the addition of methoxyacetyl chloride is complete, the reaction mixture is heated under mild reflux at 60-65 °C to 70-80 mb.
The mixture was stirred under ar pressure for 5 hours to remove hydrogen chloride generated during the first reaction. Subsequently half of the xylene is distilled off, the reaction mixture is cooled to 20°C, the precipitated product is filtered, washed with xylene and dried to give N-methoxyacetyl-N-(, mp 118-120°C). 2-oxotetrahydro-3-furyl) -2,6-dimethylaniline 265
9 (95% of the theoretical value) is obtained.

c) Chlorine 74.69 (LO5 mol) after 2 hours
85q6 of N-methoxyacetyl-N-(2-oxotetrahydro-5-furyl)-2 in 300 m of formic acid/2,
6-dimethylaniline is introduced at 25-30 DEG C. into a solution of 2 fufu (1.0 mol) and 5 t of iron chloride (IIT). The reaction is exothermic and virtually no gas is evolved. After the addition of chlorine is completed.

The reaction mixture is stirred at 25° C. for 50 minutes, then the formic acid is distilled off under vacuum, the residue is taken up in 50 ml of toluene (bxJ and the toluene solution is washed with 100 ml of water. The toluene is evaporated off. The resulting oily residue is crystallized from a mixture of isopronochlorinol and hexane and has a melting point of 8.
N-Methoxyacetyl-N-(2-oxotetrahydro-3-furyl)-5-chloro-2,6-dimethylaniline at 0-82°C 287? (92% of the theoretical value) is obtained.

Patent applicant Civer Geigy akchengesell shaft

Claims (27)

[Claims] (1) The following formula II: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (II) (In the formula, R_1 represents the meaning defined in the following formula I.) 2,6-dialkylaniline and the following formula III : ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) (In the formula, R_3 and R_4 represent the meanings defined in the following formula I, and X represents a chlorine atom or a bromine atom.) The reaction produces the following formula IV: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (IV) (In the formula, R_1, R_3 and R_4 represent the meanings defined in the following formula I.) N-alkyl-2, 6-dialkylaniline is obtained and then N of formula IV above is obtained.
-Alkyl-2,6-dialkylaniline and the following formula V: X_1-CO-R_2(V) (wherein R_2 represents the meaning defined in the following formula I, and CO-R_
Represents 2. ), and the following formula VI is obtained: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(VI) (wherein, R_1, R_2, R_3 and R_4 are the following formula I) By reacting N-acyl-N-alkyl-2,6-dialkylaniline represented by the following formula I with chlorine, N-acyl-N-
The following formula I is obtained by converting to alkyl-2,6-dialkyl-3-chloroaniline: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, R_1 represents a methyl group or an ethyl group, R_2 represents an alkoxymethyl group, chloromethyl group, or 2-tetrahydrofuryl group, R_3 represents an alkoxymethyl group, carboxyl group, or alkoxycarbonyl group, and R_4 represents a hydrogen atom or a methyl group, but R_3
represents a carboxyl group or an alkoxycarbonyl group, and R_4 further represents a 2-alkoxyethyl group and a 2-alkoxypropyl group, R_3 and R_4 together with the carbon atoms bonded to both groups further represent a 2-alkoxyethyl group and a 2-alkoxypropyl group,
-Oxotetrahydro-3-furyl group or 2-oxo-5-methyltetrahydro-3-furyl group may be formed. ) N-acyl-N-alkyl-2 represented by
, 6-dialkyl-3-chloroaniline manufacturing method. (2) The method according to claim 1, wherein the 2,6-dialkylaniline represented by the above formula II is 2,6-dimethylaniline or 2,6-diethylaniline. (3) The method according to claim 2, wherein the 2,6-dialkylaniline represented by the above formula II is 2,6-dimethylaniline. (4) The halide represented by the above formula III is 2-methoxyethyl chloride, 2-ethoxyethyl chloride, 2
-methoxy-1-methylethyl chloride, methyl 2-chloroacetate, ethyl 2-chloroacetate, methyl 2-bromopropionate, ethyl 2-bromopropionate or α-bromo-γ-butyrolactone. The method described in paragraph 1. (5) The halide represented by formula III is α-bromo-
5. The method according to claim 4, wherein the γ-butyrolactone is γ-butyrolactone. (6) The method according to claim 1, wherein the acylating agent represented by formula V is methoxyacetyl chloride, chloroacetyl chloride, or tetrahydrofuran-2-carboxylic acid chloride. (7) The method according to claim 6, wherein the acylating agent represented by formula V is methoxyacetyl chloride. (8) Claim 1, wherein the reaction between a 2,6-dialkylaniline represented by formula II and a halide represented by formula III is carried out in an inert solvent in the presence of an acid acceptor. the method of. (9) The method according to claim 8, wherein the inert solvent is benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, N,N-dimethylformamide or N,N-dimethylacetamide. (10) The method according to claim 8, wherein the inert solvent is toluene or xylene. (11) The acid acceptor is an alkali metal hydroxide, an alkali metal carbonate, an alkali metal bicarbonate, an alkaline earth metal hydroxide, an alkaline earth metal carbonate, an alkaline earth metal bicarbonate, triethylamine or pyridine. The method according to claim 8. (12) The method according to claim 8, wherein the acid acceptor is sodium carbonate. (13) Claim 1, characterized in that the reaction between the 2,6-dialkylaniline represented by formula II and the halide represented by formula III is carried out in the range from 80°C to the reflux temperature of the reaction medium. the method of. (14) Claim 13 comprising carrying out the reaction of the 2,6-dialkylaniline represented by formula II with the halide represented by formula III at the reflux temperature of the reaction medium.
The method described in section. (15) The reaction of a 2,6-dialkylaniline represented by formula II with a halide represented by formula III is carried out in toluene or xylene as a solvent in the presence of sodium carbonate as an acid acceptor at the reflux temperature of the reaction medium. A method according to claim 1, comprising the following. (16) The method according to claim 1, which comprises carrying out the reaction of the N-alkyl-2,6-dialkylaniline represented by formula IV and the acylating agent represented by formula V in an inert solvent. . (17) Hexane, benzene, toluene, xylene,
17. The process according to claim 16, comprising carrying out the process in chlorobenzene, methylene chloride, chloroform, carbon tetrachloride or ethylene chloride. (18) Claim 16, wherein the reaction between the N-alkyl-2,6-dialkylaniline represented by formula IV and the acylating agent represented by formula V is carried out in toluene or xylene as a solvent. the method of. (19) The reaction between the N-alkyl-2,6-dialkylaniline represented by formula IV and the acylating agent represented by formula V is carried out under reduced pressure in the presence of a base and in the presence of toluene or xylene as a solvent. A method according to claim 1, comprising: (20) N-acyl-N-alkyl- represented by formula VI
A process according to claim 1, characterized in that the chlorination of the 2,6-dialkylaniline is carried out in an inert solvent. (21) The method according to claim 20, wherein the inert solvent is formic acid, acetic acid, chlorobenzene, methylene chloride, chloroform, carbon tetrachloride or ethylene chloride. (22) The method according to claim 20, wherein the inert solvent is formic acid or acetic acid with a water content of up to 40% by weight. (23) N-acyl-N-alkyl- represented by formula VI
Chlorination of 2,6-dialkylaniline from 20℃ to 40℃
A method according to claim 1, characterized in that it is carried out in a temperature range up to .degree. (24) N-acyl-N-alkyl- represented by formula VI
2. A process according to claim 1, wherein the chlorination of the 2,6-dialkylaniline is carried out in the presence of 1 to 5% by weight of a Lewis acid. (25) Lewis acid is aluminum chloride, iron(III) chloride
, boron trifluoride or titanium tetrachloride. (26) The method according to claim 24, wherein the Lewis acid is iron (III) chloride. (27) N-acyl-N-alkyl- represented by formula VI
Chlorination of 2,6-dialkylaniline from 20℃ to 40℃
N-acyl-N-alkyl-2 of the formula VI to be used in formic acid with a water content of up to 40% by weight in the temperature range of
, 6-dialkylaniline in the presence of 1.5 to 25% by weight of iron(III) chloride.