DE1493831C3 - Process for the preparation of a p-nitroso-N-phenylaniline - Google Patents

Description

This invention relates to a process for the direct conversion of aniline and other aromatic primaries Amines with p-nitrosophenol to form a corresponding p-nitroso-N-phenylaniline.

p-Nitroso-N-phenylanilines have special uses found as chemical intermediates, particularly in terms of ease of use which the nitroso group can be reduced to form the corresponding amine derivatives. So For example, p-nitrosodiphenylamine, which can easily be alkylated in a reducing manner, is an important one Intermediate product in the production of N-isopropyl-N'-phenyl-p-phenylenediamine, a well known antiozonant.

In the German patent specification 1211216 a process for the preparation of p-nitrosophenylamines by the indirect amination of p-nitrosophenol is described, according to this application p-nitrosophenol is first reacted with a primary or secondary alcohol to form the corresponding p-nitrosophenyl ether and the ether then reacted with a primary amine to form the p-nitrosophenylamine product. The use of the ether in the process of the above application is based on the finding that if one tries to react a primary amine with p-nitrosophenol directly to form the p-nitrosophenyl-N-substituted amine, an unacceptably low conversion of the p-nitrosophenol to p-nitroso-N-substituted amine is achieved.
The present invention relates to a process in which primary aromatic amines can be reacted directly with p-nitrosophenol, taking into account critical process conditions, to form a corresponding p-nitroso-N-phenylaniline as an amination product with conversion rates in the range from 60 to 70% and higher , with yield losses that often do not exceed 5 to 10%. According to the invention, to prepare p-nitroso-N-phenylaniline by reacting a primary aromatic amine with p-nitrosophenol, the procedure is that a mixture of aniline, o-toluidine, m-toluidine, p-anisidine, p-phenetidine or p- Chloraniline with p-nitrosophenol, in a molar ratio in excess of 1: 1, preferably in the range from 3: 1 to 12: 1, in the presence of pyridine, quinoline, isoquinoline or 4-picoline in a volume ratio of at least 0.2: 1 , expediently 0.2: 1 to 10: 1, based on the molar excess of the primary amine, and in the presence of hydrogen chloride, p-toluene sulfonic acid or boron trifluoride as a catalyst at 0 to 100 ^° C. for at least 2 minutes and preferably not more than 5 hours.

Procedures in which the mixture is used for 0.5 to 4 hours have proven particularly useful is kept at a temperature of 0 to 35 ° C. Preferably the molar ratio of the catalyst is to the p-nitrosophenol in the range of 0.25: 1 to 2.5: 1. The ratio of the liquid volume of the tertiary amines to the excess of pri- The moderate amine is generally no more than about 5: 1.

The primary aromatic amine reactant, based on the system in molar excess the p-nitrosophenol used is added, has the function of a solvent for the amination, so that both the excess primary reactant and the tertiary amine, with the latter referred to as a co-solvent, acts as a solvent for the amination reaction.

The unique effect of pyridine, quinoline, isoquinoline and 4-picoline, each as a cosolvent, in the amination process of the present invention is illustrated by a series of amination sequences, each of which is the reaction of aniline with p-nitrosophenol to form p-nitrosodiphenylamine , at 35 ^° C. in the presence of the hydrogen halide added as aniline hydrochloride as the catalyst. In each run, the amination reaction mixture contained 10 mmol of p-nitrosophenol, 10 mmol of aniline hydrochloride and 10 ml of aniline cosolvent. The results of these processes are summarized in the table below.

Table I.

solvent Aniline total
mmol ") tertiary amine
solvent
(mmol) reaction time
(Hours) % Conversion
for the formation of
p-nitrosodiphenyl
amine aniline 120 No 0.5
1.0
2.0 30th
32
34

") Includes the 10 mmoles of aniline introduced as aniline hydrochloride.

continuation

solvent Aniline total
mmol ") tertiary amine
solvent
(mmol) reaction time
(Hours) % Conversion
for the formation of
p-nitrosodiphenyl
amine Aniline-pyridine
Aniline pyridine
Aniline pyridine
Pyridine 98
65
32
10
65
65
65 25th
62
99
124
42
42
51 2.0
2.0
3.0
2.0
3.0
2.0
3.0
2.0
2.0
3.0 58
62-65
60-61
57
58 ·
31
34
61
65
61 Aniline quinoline ■
Aniline isoquinoline
Aniline-4-picoline

") Includes the 10 mmol of aniline which were introduced as aniline hydrochloride.

Table II lists the values indicating the unsatisfactorily low conversion results obtained in the presence of a tertiary amine instead of a tertiary amine cosolvent Invention can be obtained.

Table!!

solvent

tertiary amine
solvent
(mmol) reaction time
(Hours) % Conversion
for the formation of
p-nitrosodiphenyl
amine 51
43
39
63
79
36
58
38 2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0 41
8th
29-36
13th
4th
<1
<1
9 Aniline total
mmol °) 65
65
65
32
10
65
32
65

Aniline-2-picoline

Aniline-2,6-lutidine

Aniline-dimethylaniline

Aniline-dimethylaniline

Aniline-dimethylaniline

Aniline triethylamine ..

Aniline triethylamine ..

Aniline triethanolamine

") Includes the 10 mmol of aniline which were introduced as aniline hydrochloride.

The data in Tables I and II illustrate the conversion results of p-nitrosophenol to p-nitrosodiphenylamine in the range of 60 to 70%, if a solvent for the amination Combination of excess primary amine with one of the above-mentioned co-solvents used whereas with aniline alone or with the co-solvent alone or with aniline as Solvent in association with a tertiary amine cosolvent, outside the scope of these Invention, the conversion results are significantly lower and vary from about 0 to not more than about 35%. Of particular importance is the low conversion result that is obtained is used when using aniline as a solvent in conjunction with 2-picoline or with 2,6-lutidine, each as a "co-solvent," the structure of these compounds being that of pyridine, a co-solvent according to the present invention, more or less similar or related.

The tertiary aromatic amine co-solvent is used in a volume ratio to that as the solvent serving primary aromatic amine, d. H. the proportion of the primary aromatic amine that is present in a stoichiometric excess, based on the p-nitrosophenol, of at least 0.2: 1, im generally in the range from 0.20: 1 to 10: 1 and more, used. Equal parts by volume of co-solvent and excess primary aromatic Amines (solvents) are generally extremely beneficial.

The critical function of the choice of acid catalyst of the process of the invention is with reference to several different aminations, each in the presence of a different Acid catalyst is carried out, shown. Each run was made using aniline as the primary aromatic amine reactant and solvent carried out at 35 ° C. In Table III summarized the results of these processes.

Table III

catalyst mmol p-nitrosophenoI aniline Pyridine reaction time % Around
change (mmol) (mmol) (mmol) (Hours.) Aniline hydrochloride 10 10 55 62 2.0 62-65 3.0 60-61 10 10 110 - 0.5 30th 1.0 32 2.0 34 p-toluenesulfonic acid. . 10 10 66 62 2.0 62 3.0 65 4.0 61 10 10 121 - 2.0 48 *) 10 10 121 - 3.0 37 *) Boron trifluoride 10 10 66 56 2.0 60 3.0 70 *) 4.0 67 10 10 121 - 1.0 46 *) 10 10 121 - 2.0 45 *) Phosphoric acid .. 10 10 120 2.0 6th 10 10 66 62 2.0 2

*) Contains approximately 4 to 7% p-phenylazodiphenylamine.

The data in Table III show the high conversion results obtained when Hydrogen chloride, p-toluenesulfonic acid and boron trifluoride can be used as catalysts, as well as the Specificity of these acids, what the low conversion results, which are practically zero when using phosphoric acid as a catalyst Absence and presence of pyridine can be obtained as co-solvent.

Table IV lists a series of operations with conversion results ranging from 60 to 70% demonstrate that in practicing the invention using primary aromatic amine reactant solvent other than aniline. as well Table IV lists the results of similar runs in which reactant-solvent outside the scope of this invention were used with no conversion result with regard to p-nitroso-N-phenylaniline, which additionally increases the specificity of those primary Reactant solvents of the invention is illustrated. In those summarized in Table IV A primary aromatic amine reactant of the invention was added to processes in stoichiometric excess, with p-nitrosophenol at 35 ° C (excluding drain 7, 45 ° C) in the presence (Expires to 3, 5 to 6, 8 to 9, 11) and in Absence (runs 4, 7, 10) of pyridine as a tertiary amine cosolvent among those identified Process conditions implemented. Results of similar processes (processes 12, 13, 14), including o-, m- and p-nitroaniline "reactant solvents" listed for reasons of comparison.

Table IV

procedure
No. Primary aromat. Amine mmol p-nitroso
phenol Acid catalyst Pyridine (mmol) (10 mmol) (mmol) 1 o-toluidine 65 10 p-toluenesulfonic acid 62 2 m-toluidine 65 10 the same 62 3 the same 55 10 m-toluidine hydrochloride 62 4th the same 118 10 p-toluene sulfonic acid - 5 p-toluidine 65 10 the same 62 6th the same 56 10 p-toluidine hydrochloride 62 7th the same 121 10 p-toluene sulfonic acid - 8th p-anisidine 73 10 the same 62 9 p-phenetidine 65 10 the same 62 10 the same 123 10 the same - 11th ■ p-chloroaniline , 65 10 the same 62

continuation

procedure
No. Primary aromat. Amine mmol p-nitroso-
phenol
(mmol) Acid catalyst
(10 mmol) Pyridine
(mmol) 12th
13th
14th o-nitroaniline
m-nitroaniline
p-nitroaniline 65
65
65 10
10
10 p-toluidine hydrochloride
the same
the same 62
62
62

Λ Ul Γ Primary aromat. Amine mmol Reaction p-Nitroso-N-phenylaniline product Around ablaut
No. time conversion *) o-toluidine 65 (Hours.) o-methyl-p'-nitrosodiphenyl-amine (%) 1 m-toluidine 65 3.0 m-methyl-p'-nitrosodiphenyl-amine 56 2 the same 55 3.0 the same 60 3 the same 118 3.0 the same 61 4th p-toluidine 65 3.0 p-methyl-p'-nitrosodiphenyl-amine 50 5 . the same 56 3.0 the same 63 6th the same 121 3.0 the same 63 7th p-anisidine 73 2.0 **) p-methoxy-p'-nitrosodiphenyl-amine 44 8th p-phenetidine 65 3.0 p-ethoxy-p'-nitrosodiphenyl-amine 68 9 p-phenetidine 123 3.0 the same 66 10 p-chloroaniline 65 3.0 p-chloro-p'-nitrosodiphenyl-amine 35 11th o-nitroaniline 65 3.0 - 63 12th m-nitroaniline 65 3.0 - No 13th p-nitroaniline 65 3.0 - No 14th 3.0 No

*) Includes correspondingly substituted p-phenylazodiphenylamine (approx. 4 to 7%). *) Amination at 45 ^C C.

Although the primary amine in the reaction system in any molar ratio based on that used p-nitrosophenol, which is at least 1: 1, added will generally be in a range of about 1.5: 1 to 15: 1, usually about 3: 1 to 12: 1 and preferably from about 4.5: 1 to 7.5: 1 are used.

The concentration of catalyst in the amination system is not critical, but is catalytic Minimum quantity required to achieve a reasonable response rate. A molar ratio from acid to p-nitrosophenol greater than 2.5: 1 is generally not required. In one lower range of acid to p-nitrosophenol molar ratio, z. B. 0.25: 1 to 1: 1, the conversion results during a given reaction period are lower than those at a higher molar ratio obtained, e.g. B. from 1: 1 to 2: 1, and from an increase in the molar ratio within the 0.5: 1 to 1: 1 range, there is a slight increase in the conversion rate. However, occurs, though there is a slight increase in conversion during the given reaction time with a higher acidity p-nitrosophenol molar ratio, e.g. B. 1: 1, results in a very small increase in conversion when said molar ratio is increased beyond this limit, e.g. B. in the range from 1: 1 to 2: 1. So is in practicing the invention, the acid catalyst to p-nitrosophenol molar ratio generally very advantageous in the range of about 0.8: 1 to 1.2: 1, although the optimum values in to a certain extent depend on the reactants used and the reaction conditions.

The influence of the reaction time in the amination process of the invention is roughly similar to that which can be observed when the catalyst concentration is increased.

Longer reaction periods increase the consumption of p-nitrosophenol without an adequate increase in conversion with regard to p-nitrosodiphenylamine. However, the one used is more general Response time within the range of about 0.5 to 4 hours, and sometimes values are outside this range, it is advantageous depending on the reactants and the process conditions. Response times as short as approximately 2 minutes are and are advantageously used in the higher reaction temperature ranges sometimes justified at lower temperature ranges with a simultaneous low conversion rate with regard to the proportionally smaller extent by the formation of by-products. Response times longer than 5 hours are rare, though at all, of considerable advantage.

The reaction temperature is in the range of about 0 to 100 ⁰ C, and generally from 25 to 55 ° C and preferably does not exceed about 40 ⁰ C. The effect of reaction temperature seems to be the effect of the catalyst concentration and reaction time to be similar, wherein the consumption of the p -Nitrosophenols is higher at the higher temperature, but without a significant increase in conversion

409 626/271

in terms of the desired p-nitrosodiphenylamine product. Accordingly, in many cases the temperature used will be in the range of 15 to 35 ° C, because under these conditions, although somewhat smaller reaction dimensions are achieved, the final yield of the product is greater because of the lower level of runoff under these conditions Side reactions.

Although the volume ratio of tertiary amine cosolvent! to primary aromatic Amine, which is present in stoichiometric excess, is generally not above about 5: 1, higher ratios can be used, such as 10: 1 or higher.

Although the maximum conversion results are generally in the range of 60 to 70%, there is little loss of net yield in practicing the invention. About it In addition, essentially the only side reactions which occur are those caused by reaction of the primary aromatic reactant with (1) the nitroso group of the p-nitrosophenol reactant and (2) with the p-nitroso-N-phenylaniline product to form a corresponding p-phenylazophenol and p-phenylazodiphenylamine lead. Any of these by-products can be hydrogenated under Cleavage of the primary amine reactant for renewed circulation. When the primary amine reactant Is aniline, also results from the hydrogenation of p-phenylazodiphenylamine Formation of p-aminodiphenylamine, which is a precursor of N-isopropyl-N'-phenyl-p-phenylenediamine is a well known antiozonant. p-Nitrosodiphenylamine, the product of the reaction of Aniline, and p-nitrosophenol, is also a precursor of the antiozonant, which is why it is a by-product obtained p-aminodiphenylamine, which is formed by hydrogenation of p-phenylazodiphenylamine, can be attributed to the product yield due to its usability.

Claims (3)

Patent claims: 1. A process for the preparation of a p-nitroso-N-phenylaniline by reacting a primary aromatic amine with p-nitrosophenol, characterized in that a mixture of aniline, o-toluidine, m-toluidine, p-anisidine, p-phenetidine or p-chloroaniline with p-nitrosophenol, in a molar ratio in excess of 1: 1, preferably in the range from 3: 1 to 12: 1 in the presence of pyridine, quinoline, isoquinoline or 4-picoline in a volume ratio of at least 0.2: 1, expediently 0.2: 1 to 10: 1, based on the molar excess of the primary amine, and in the presence of hydrogen chloride, p-toluenesulfonic acid or boron trifluoride as a catalyst at 0 to 100 ^° C. for at least 2 minutes and preferably not more than 5 Hours. 2. The method according to claim 1, characterized in that the mixture is 0.5 to Reacts for 4 hours at a temperature of 0 to 35 ° C. 3. The method according to claim 1 or 2, characterized in that the molar ratio of the catalyst to the p-nilrosophenol is in the range of 0.25: 1 to 2.5: 1.