DE2120641A1 - Process for the preparation of secondary or tertiary aromatic amines - Google Patents

Description

SUMITOMO GHELIICAL COMPANY, LIMITED
Osaka, Japan

"Process for the production of secondary or tertiary aromatics:
high amines "

Priority: April 28, 1970, Japan, No. 37 013/70

The invention relates to a new method for the production of secondary or tertiary aromatic amines from nitro compounds.

Various processes are known for the preparation of secondary or tertiary aromatic amines. The reaction of aniline with an alcohol in the presence of sulfuric acid (Unit Process in Organic Chemistry, 1958, page 580), of concentrated phosphoric acid (US Pat. No. 2,991,311) or of aluminum
'Nium oxide (Chemisches Zentralblatt, 1953, page 2579) as a catalyst and a process for converting aromatic nitro-

109846/1956

compounds with an aldehyde in an alcoholic solvent in the presence of Raney-Liickel (Journal of American Chemical Society Gg (1940) 69).

The abovementioned processes have the disadvantage that the catalysts are difficult to handle and that the starting compounds aniline and the aldehyde are expensive,

The object of the invention was therefore to overcome the aforementioned disadvantages and to create a technically simpler and more economical process for the production of secondary or tertiary aromatic amines. This problem is solved by the invention «

The invention thus relates to a method for producing secondary or tertiary aromatic amines of the general formula (I)

in the Ύ. a hydrogen or halogen atom ,, a C, ..- alkoxy or C ^ .Q-alkyl radical, Z a hydrogen or halogen atom or the methyl group and η denotes 2 _a hl 1 or 2 and Y denotes the radical -NHR, - NHR «, -NHR", -NR ₂ , -NR ^, -MRg or -NR ¹ R "represents, where R is a CL ^ -alkyl radical or phenyl group and R ¹ and R" represent different CL _r -alkyl radicals, which thereby is characterized in that an aromatic nitro compound of the general formula (II)

109848 / 1S58

(II)

(Z)

in which X, Z and η have the aforementioned meaning, with 'a Alcohol of the general formula R-OH, in which R has the aforementioned meaning, or a mixture of aliphatic alcohols general formulas R'-0H and R "-OH, in which R 'and R" have the aforementioned Have meaning, and brings hydrogen in the presence of a copper chromite catalyst for implementation.

In the process of the invention, the reduction and the alkylation of the nitro compound of the general formula (II) take place simultaneously according to the following reaction scheme, in which R, R ¹ , R ", X, Z and η have the aforementioned meaning:

NO ₂ H ₂ , RAW

NHR +

N (R) ₀ + 4H _o 0

109846/1956

-H-

(R'OH + R "OH)

(Z)

M'R "+ 4H _o 0

The copper chromite catalyst used for the process of the invention can be in a simple manner ^ .B. according to a method described in "Organic Reaction" 8 (1954) page 9 _/ by neutralizing a solution of copper nitrate and a dichromate with ammonia and then heating the reaction mixture. Small amounts of one or more of the elements iron, nickel, cobalt, zinc, barium, calcium, magnesium, manganese, aluminum, phosphorus, ger, thorium or other elements can be incorporated into the copper chrome as a promoter. In addition, the catalysts can contain, for example, coagulated amounts of diatomaceous earth, sodium silicate, kaolin, graphite, pumice stone or activated carbon as carrier substances. In general, these catalysts are commercially available in powder or tablet form.

109 846/1956

Nitro compounds suitable for the process of the invention. general formula (II), which can be prepared by known processes, are e.g. nitrobenzene, 3-chloronitrobenzene, 2,4-diohlonitrobenzene, 3-bromonitrobenzene, 2,4,6-trichloronitrobenzol, 4-methylnitrobenzene, 4-n-propylnitrobenzene, 2-l-ethyl-4-fluoronitrobenzene, 2-methyl-3,4-dichloronitrobenzene, 2,4-dimethyl-nitrobenzene, 2,4,5-trimethylnitrobenzene, 3-methoxynitrobenzene, 4-ethoxynitrobenzene, 2-methoxy-4-chloronitrobenzene or .3-methoxy-5-methylnitrobenzene.

The aliphatic or aromatic alcohols of the general formulas R-OH, R'-OH and R "-OH can be prepared by known processes and are commercially available. Specific examples are methanol, ethanol, n-propanol, isopropanol, isoamyl alcohol, n-butanol, isobutanol, sec-butanol or phenol.

Whether you get a secondary or tertiary according to the method of the invention Amine or a mixture of these amines obtained depends on the nature and the molar ratios of the starting compounds. in the in general, the secondary amine is preferably obtained at lower molar ratios of alcohol to nitro compound and at The tertiary amine is preferred for larger molar ratios.

The molar ratio of aliphatic or aromatic alcohol to aromatic nitro compound cannot be arbitrary assume below 1. At a molar ratio of around 20: 1 the reaction is in a state of equilibrium. Therefore, a molar ratio of 1: 1 to 20: 1 is preferably used. Following the reaction, the unreacted alcohol can be recovered and reused.

109846/1956

* The Mo .verhältnis of alcohols of the general Poj ¹ Mel R'-0II to the alcohol of general formula R "-0H may preferably be selected freely, it is 1% 0.7 to 1:. 1.5.

The process of the invention can be carried out either under pressure or in the gas bubble. The gas phase process is preferred there sioh any secondary after this procedure or tertiary amines due to the wide scope in the mixture ratio from aromatic ifitro compound to aliphatic or aromatic alcohol can be produced and there the reaction continuously imports.

The reaction temperature is in the printing process and when Gaepha3enverfahren preferably 150 to 400 ⁰ C. The printing process is preferably carried out at pressures of 20 to 100 atmospheres for 5 to 60 hours.

After the reaction has ended, the oily layer is subjected to fractional distillation. The compounds thus obtained are pure enough for practical purposes. If necessary, they can be further purified by recrystallization, rectification, column chromatography or by treatment with formic acid (see Industrial and Engineering Chemistry 20 (1936) 33).

The secondary or tertiary aromatic compounds which can be prepared according to the invention Aiaine are valuable intermediates for the cheraisehe Industry, especially for the dye, agricultural and rubber sectors.

■ The examples illustrate the invention.

109848/1956

example 1

A reaction tube made of iron suitable for the catalytic gas phase reaction with a diameter of 2 cm and a height of 50 cm is charged with 80.0 g of a copper chroraite catalyst in tablet form b (and heated to about 270 ° C. An evaporator is added dropwise at a feed rate A mixture of nitrobenzene and ethanol in a weight ratio of 1: 4 is fed in at a rate of 3.0.7 g / hour 10 hours after the start of the reaction, after the reaction product has been separated off, the oily layer is dried over sodium sulfate and subjected to fractional distillation. This gives a distillate with a boiling point of 190 to 194 ^° C. which, after cooling to - 5 C and filtering off the precipitated crystals gives 52.0 g Ν, Ν-dimethylaniline with a P. 2.5 ° C. The yield is 86 μS, based on nitro benzene.

Analysis: ber .: 79 C. 9 H N found : 79 , 3 9 , 09 11.5 ,1 - , 07 11.2

The filtrate obtained on filtering off the crystals is purified by column chromatography using silica gel and η-hexane as the solvent. This gives 6.0 g of N-Ye thy! Aniline.

Analysis: ber .: C. 5 H 13th N found: 79 2 8.4 13th ,1 79 8.3 , 2

109846/1956

Example 2

A 500 ml autoclave with an electromagnetic stirrer is mixed with 10.0 g of a powdery! Copper chromite catalyst, 137 g of 3-methylnitrobenzene and 140 g of ethanol are charged. This The reaction mixture is heated to 250 C for 20 hours, during which 'The pressure was kept at 50 atmospheres with the introduction of hydrogen will.

After the reaction has ended, the reaction product is distilled. This gives 27.5 g of N-ethyl-3-niethylaniline with a boiling point of 219 to 222 ⁰ O. This product is purified by column chromatography using silica gel and carbon tetrachloride as solvent.

Analysis: ber .: G H N found s 80.0 9.6 10.4 79.8 ' 9.3 10.2

B e i s ρ i e 1 3

A Reaktionsrolir for katalLytische (Jasphasenreaktion is with 80 g of a ^ s copper chromite catalyst Irr fablettenform bescMcfct and a ^ f about heated 260 ⁰ C., A (xäsgeiaisen oma EitTQVet & oil un € methanol in frewiehtsverhältnis ti i mti is a ^ In the Katalysatorschiciit ufuhjrgesc ^ vvlndigicei% of 24.6 g / Stä. initiated in a hydrogen stream of 00 Üter / gtd *.

5 hours after the start of the reaction, the reactant brittle is removed and worked up according to Example 1. Here mail receives 4S, gg f-Ketfcy! Aniline from Kp * °

ber .; C. 5 - ⁹ - H 2 120641 Analysis: found: 79 4th 8.4 N 79 8.1 13, 1 13, 2

By means of gas chromatography it is established that at the same time 5.4 g Ν, Ν-dimethylaniline formed as a by-product to have.

Example 4 ' ^x

A suitable for the gas phase catalytic reaction reaction tube is with- ^ 2 g of a copper chromite catalyst charged in tablet form and heated to about 270 ⁰ C.

A gas mixture of nitrobenzene and ethanol in a weight ratio of 1: 5 is fed into the catalyst layer at one speed of 60.0 g / h in a hydrogen flow of 96 liters / hour. initiated.

10 hours after the start of the reaction, the reaction product is isolated and separated into an oil layer and an aqueous layer. After drying over sodium sulfate and distilling off the ethanol, the oil layer is treated with 21 g of an 85 percent strength aqueous formic acid. The resulting reaction mixture is refluxed for about 1 hour and then distilled. In this case, one obtains 109 g of N, N-diethylaniline, bp. 215-216 ⁰ C.

After purification by column chromatography using Silica gel and η-hexane as solvents give a product with the following analysis values:

109846/1956

Analysis: G HN

calc .: 67.1 10.1 9.4

found .; 67.4 10.4 9.6

The gas chromatographic analysis shows that at the same time 5.0 g of N-monoethylaniline were formed as a by-product.

Example 5

Am a reaction tube suitable for the catalytic gas phase reaction is made with 72 g of a copper chromite catalyst in tablet form charged and heated to about 260 C. In the catalyst layer is a gas mixture of nitrobenzene and ethanol in a weight ratio of 1: 1.5 with a feed rate of 25.0 g / hour in a hydrogen flow of 96 liters / hour. initiated.

5 hours after the start of the reaction, the reaction product is isolated and worked up as in Example 1. Here one obtains 45.3 g of N-ethylaniline, b.p. 206-207 ° C.

Analysis: CHN

calc .: 79.3 9.1 11.6

found: 79.0 9.2 11.7

Example 6

Example 4 is repeated with a mixture of nitrobenzene, methanol and ethanol in a weight ratio of 1: 2: 3 .. Here a reaction product is obtained with the following gas chromatograph Analysis:

1 0

- 11 - 2120641 component Proportion of (#) N-methylaniline 4.2 N-ethylaniline 5.7 N, N-Dimethy! Aniline 30.0 N, N-diethylaniline 45.0 Ii-Me thy 1-N-ethylaniline 15.1

After purification of the reaction product of N-methyl-H-ethylaniline 202 is obtained by Kp. To 206 ⁰ C.

Analysis: C H. N

ber ;: 80.0 9.6 10.4

found: 79.6 9.7 10.7

Example 7

Example 4 is With a mixture of 4-methylnitrobenzene, Repeatedly methanol and ethanol in a weight ratio of 1: 2.5: 2.5. This gives a reaction product with the following gas chromatography Analysis:

Component portion (ji) N-methyl-4-methylaniline "9.2

N-Xthyl-4-methylaniline 15.3

K, H-dimethyl-4-methy! Aniline 31.0 " N, N-diethyl-4-methylaniline 22.9 N-methyl-H-ethyl-4-methylaniline 21.6

After the "cleaning of the reaction product 216 is obtained K-K RethyÜr-ethyl-4-methylaniline, bp. To 219 ⁰ C.

109846/1956

212064t

Analysis; C-H Ii

calc .: 80.5 10.0 9.3

found: 80.9. 9.8 9.3

Example 8

Example 4 is with a, mixture of 2,4-dichloronitrobenzene,
Repeated methanol and ethanol in a weight ratio of 1: 2 i 3. This gives a reaction product with the following gas chromatographic analysis:

component

K _r M-siffiethyl-2,4-dichloroanilite

proportion of 3 21 6th 9, t 37,

purification of the reaction product gives K-methylr

from the K © * 25? Ma 266 ° C.

Q H Cl N

52.9 5.3 "'""54.8 6» 8
1 53 HA 6 _t 6

Be i 8 ρ 1 e 3. q 9 b i a 3 6

1 becomes with üsn in, dej? listed in the table
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109846/1958

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109846/1956

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109846/1956

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109846/1956

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Claims (14)

- 22 claims 1 / method of making secondary or tertiary aromatic amines of the general formula (I) (D in which X is a hydrogen or halogen atom, a C. ^ - alkoxy or C ._. jQ-alkyl radical, Z is a hydrogen or halogen atom or the methyl group and η is the number 1 or 2 and Y is the radical -NHR, - NHR ', -NHR ", -NRg, -NR £ _t -NRJ or -NR ¹ R" represents, where R is a C ^^ - alkyl radical or the phenyl group and R ¹ and R "represent different C, - alkyl radicals, characterized in that an aromatic nitro compound of the general formula (II) (II) with an alcohol having in the X, Z and η as defined above, of the general formula R-OH, in which H has the abovementioned meaning, or a mixture _i aliphatic alcohols of the general formula R'-0H and R ^ -OH, in which E ^f and R "the given 109846/1356 have mentioned meaning, and hydrogen in the presence of a copper chromite catalyst brings to implementation. 2. The method according to claim 1 for the preparation of secondary or tertiary aromatic amines of the general formula (I), in which Y is the radical -HIIR or -NR ₂ , where R has the aforementioned meaning, characterized in that the nitro compound of the general Brings formula (II) with an alcohol of the general formula R-OH, in which R has the aforementioned meaning, to implement. 3. The method according to claim 1 for the preparation of tertiary aromatic amines of the general formula (I), in which Y denotes the radical -NR ¹ R " , where R ¹ and R ^{H have} the aforementioned meaning, characterized in that the nitro compound of the general Reacts formula (II) with the mixture of aliphatic alcohols of the general formulas R'-OH and S ^M -OH, in which R ¹ and R "have the aforementioned meaning . 4. The method according to claim 1 to 3 »characterized in that the reaction is carried out as a gas phase reaction. 5. The method according to claim 1 to 3, characterized in that the reaction is carried out under pressure. 6. The method according to claim 1 to 5, characterized in that 1 to 20 moles of the aliphatic or aromatic alcohol are used per mole of the aromatic nitro compound. 7. The method of claim 1 to 6, characterized in that one carries out the reaction at temperatures of 150 to 400 ⁰ G. 10S846 / 1986 8. The method according to claim 3, characterized in that one maintains a pressure of 20 to 100 atmospheres during the reaction by supplying hydrogen. 9. The method according to claim 1 to 8, characterized in that that a copper chromite catalyst is used which contains small amounts of a proinotor. 10. The method according to claim 1 to 9, characterized in that k that the reaction with a nitro compound of the general Formula (II), in which X is a C1, -Alkoxyreet, carries out . 11. The method according to claim 1 to 10, characterized in that the reaction with a nitro compound of the general Formula (II), in which Z is a halogen atom, carries out. 12. The method according to claim 11, characterized in that a compound of the general formula (II) in which Z is a Represents chlorine, bromine or fluorine atom is used. 13 · Method according to claim 1, 2, 4 to 7 and 9 to 12, thereby characterized in that the reaction with an alcohol of the general formula R-OH, in which R is a C, .. Q-alkyl group, performs. ... 14. The method according to claim 1 and 3 to 12, characterized. draws that the reaction with alcohols of the general Formulas E '»OH and R" -0H, in which R' and R "are Met" hyl- or Xthy! Group mean carries out. 109846/1956