DE2555736C2 - Process for the production of halonitrobenzenes - Google Patents

Description

of sodium nitrite, 2,6-dichloro-4-nitro-aniline, sulfuric acid and ethanol by the following formulas be reproduced:

NO,

J \ + 2NaNO ₂ + H, SO ₄ + 2CH ₁ -CFl ₂ OH

NH,

Na ₂ SO ₄
4H, O

NO,

Cl- (j CI

f 2N, + 2CH, CHO

In view of the prior art, the process according to the invention provides halonitrobenzenes in a simpler and more economical way in better yield and purity, especially on an industrial scale. It is not necessary to add copper salts or other catalysts or large amounts of alcohol. Despite the high water content of the reaction mixture, the amount of halogenated nitrophenol formed is less than 0.06 percent by weight, based on the reaction mixture. The formation of resinous secondary substances cannot be observed to any significant extent. All these advantageous results are especially with regard to the teaching of the aforementioned publications, first in the cold in the usual procedure of diazotization to prepare the diazonium salt and then in the absence of water or in the presence of the smallest possible amounts of water, the reduction with alcohol using auxiliaries such as Performing copper salts, surprising. With regard to Houben - Weyl, too, it was not to be expected that the end product would be obtained in better yield and purity without prior preparation of the diazonium salt and in the presence of larger amounts of water at elevated temperature. Preferred starting materials II and correspondingly preferred end materials I are those in whose formulas R ¹ and R ^{2 can be} identical or different and each represent an iodine atom, advantageously a bromine atom or, in particular, a chlorine atom and R ^{2 can} also denote a hydrogen atom. For example, the following starting materials II are suitable:

2-chloro-4-nitro-aniline, 2-bromo-4-nitro-aniline,

2-iodine-4-nitro-aniline, 2,6-dichloro-4-nitro-aniline,

2,6-dibromo-4-nitro-aniline, 2,6-diiodo-4-nitro-aniline, 2-chloro-6-bromo-4-nitro-aniline,

2-chloro-6-iodine-4-nitro-aniline,

2-bromo-6-iodo-4-nitro-aniline, 4-chloro-2-nitro-aniline, 6-chloro-2-nitro-aniline, 4-bromo-2-nitro-aniline,

6-bromo-2-nitro-aniline, 4-) od-2-nitro-aniline,

4,6-dichloro-2-nitro-aniline,

4,6-dibromo-2-nitro-aniline, 4,6-diiodo-2-nitro-aniline, 4-chloro-6-bromo-2-nitro-aniline,

4-bromo-6-chloro-2-nitro-aniline,

4-chloro-6-iodo-2-nitro-aniline

4-iodine-6-chloro-2-nitro-aniline,

4-bromo-6-iodo-2-nitro-aniline,

4-iodo-6-bromo-2-nitro-aniline. Are preferred

2,6-dibromo-4-nitro-aniline,

2,4-dibromo-6-nitro-aniline, 2,6-dichloro-4-nitroaniline, 2,4-dich! Or-6-nitro-aniline.

The starting materials II are in a stoichiometric amount or with an excess of alcohol, preferably in an amount of 3 to 30, in particular 5 to 15 equivalents (mol. divided by the number of Hydroxyl groups in the molecule) alcohol per mole of starting material II, implemented. The alcohols can be aliphatic, be cycloaliphatic or araliphatic mono- or polyalcohols. Preferred alcohols are those of formula

R ¹ OlI

(IUl

wherein R 'an alkyl radical with 1 to 5 carbon atoms or a cyclohexyl radical or an aralkyl radical with 7 to 12 carbon atoms or the radical FIO-R ⁴ -, in which R ⁴ denotes an aliphatic radical, in particular an alkylene radical with 2 to 4 carbon atoms,

ίο or the rest

RO- (R ⁴ O) _n -R ⁴ -

in which the individual radicals R ^{4 can be the} same or different and represent an aliphatic radical, in particular an alkylene radical with 2 to 4 carbon atoms, and R ¹ denotes a hydrogen atom or an aliphatic radical, in particular an alkyl radical with 1 to 4 carbon atoms, and η stands for the number 4, 3, 2 or, in particular, 1, denotes. The above radicals may be substituted with in each case I to 3 carbon atoms or by inert groups under the reaction conditions, 2., alkyl groups or alkoxy groups.
As alcohols III come z. B.

Methanol, ethanol, n- and isopropanol, n-butanol,
Butanol-2, isobutanol, ethylene glycol,
Diethylene glycol, methylethylene glycol,
Benzyl alcohol, n-pentanol, phenylethanol,
so neopentyl glycol, p-methylbenzyl alcohol,
p-ethoxybenzyl alcohol, 1,3-propylene glycol,
1,4-butanediol, 1,2-propylene glycol, triethylene glycol, diethylene glycol mono-n-butyl ether;
or corresponding mixtures in question.
Ethanol, isopropanol, methylethylene glycol, n-propanol and isobutanol are preferred.

Furthermore, nitrosating agents are used in the reaction, e.g. B. nitrous acid and substances that are converted into nitrous acid under the reaction conditions, such as nitrous gases; Salts, preferably alkali metal salts, of nitrous acid, in particular potassium nitrite and sodium nitrite; Esters of nitrous acid, expediently cycloalkyl, aralkyl nitrites or, preferably, alkyl nitrites. In the case of the use of ds alkyl nitrites, the addition of alcohol can be completely or appropriately partially dispensed with, since under the reaction conditions such nitrites are a combination of nitrous acid and the corresponding one

Can replace alcohol; in such cases, a ratio of 1 to 5 equivalents of alcohol per mole of starting material II is expedient. The esters are preferably alkyl nitrites having 1 to 6 carbon atoms, e.g. B. ethyl, n-propyl, n-isoprop, 'initrite, n-butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl nitrite, benzyl nitrite, cyclohexyl nitrite and especially methyl nitrite into consideration . Nitrous gases are understood here as meaning the nitrogen oxides, nitrogen monoxide, nitrogen dioxide, nitrogen tetroxide, and dinitrogen trioxide known as nitrosating agents. They can be used individually or appropriately in an appropriate mixture, advantageously of nitrogen monoxide and nitrogen dioxide. In general there are amounts of 1.1 to 5 mol of alkyl nitrite, nitrous acid ester and / or nitrous gases per mole of starting material II, expediently 1.1 to 2.7, in particular 1.1 to 1.7 mol of alkyl nitrite or nitrous acid ester or 1.5 up to 5, in particular 2 to 4 moles of N ₂ Oj per mole of starting material II, are possible. The nitrogen oxides or gas mixtures mentioned can still be inert gases under the reaction conditions, e.g. B. nitrogen, are added.

Glycol esters of nitrous acid are also suitable as nitrosating agents. These esters of Nitrous acid can be used in any way, expediently according to that in the German Offenlegungsschrift 21 44 420 described process, by reaction of glycols or glycol derivatives with nitrous Acid or nitrogen oxides. Preferred esters of glycols and glycol derivatives are mono- or diglycol esters of nitrous acid of the formula

ONO - R ⁶ -X

(IV)

CH ₁ O-CH ₂ CH ₂ -OH

C ₂ H ₅ O-CH ₂ CH ₂ -OH

C ₃ H ₇ O-CH ₂ CH ₂ -OH

C ₄ H ₉ O-CH ₂ CH ₂ -OH

HO- (CH ₂ CH ₂ O) ₂ H

HO- (CH ₂ CH ₂ O) ₃ H

CH ₁ O (CH ₂ CH ₂ O) ₂ H

C ₂ H ₅ O (CH ₂ CH ₂ O) ₂ H

C ₃ H ₇ O (CH ₂ CH ₂ O) ₂ H

CJL) O (CH ₂ CH ₂ O) ₂ H

CH ₃ O (CH ₂ CH ₂ O) ₃ H

C ₂ H ₅ O (CH ₂ CH ₂ O) ₃ H

C ₃ H ₇ O (CH ₂ CH ₂ O) ₁ H

C ₄ H ^) (CH ₂ CH ₂ O) ₃ H

wherein R ^ is the radical —R ⁷ —O— or the radical

fCH -CH ₂ O

R ⁷ denotes an aliphatic radical and R ⁸ denotes a hydrogen atom or an aliphatic radical, π stands for the number 1, 2, 3 or 4 and X stands for the group

ίο —NO, means an aliphatic, araliphatic, cycloaliphatic or aromatic radical. Advantageously, R ⁷ denotes an alkylene radical with 3 to 12, in particular 4 to 9 carbon atoms, R ⁸ denotes a hydrogen atom or an alkyl radical with 1 to 4 carbon atoms, in particular the methyl group, η stands for the number 1, 2 or 3 and X denotes the group - NO, an alkyl radical with 1 to 4 carbon atoms, an aralkyl radical with 7 to 12 carbon atoms, a cyclohexyl radical, a cyclopentyl radical, a phenyl radical, an alkylcarbonyl radical with 2 to 5 carbon atoms, advantageously the acetyl group. The alkyl radicals and alkylene radicals mentioned can be straight-chain or branched. The aforementioned advantageous radicals can also be replaced by groups which are inert under the reaction conditions, e.g. B. alkoxy groups, alkyl groups each having 1 to 3 carbon atoms, may be substituted. In general, amounts of 1.1 to 5 moles of monoglycol ester per mole of starting material II, expediently 1.1 to 2.7, in particular 1.1 to 2.2 moles of monoglycol ester per mole of starting material II, are suitable. Correspondingly, amounts of 0.55 to 2.5, expediently 0.55 to 1.35, in particular 0.55 to 1.1 mol of diglycol ester per mole of starting material II are chosen. Suitable esters IV are, for example, mono- or diesters of nitrous acid with the following connections:

CH ₃
CH ₃ O-CH ₂ -CH-OH

CH ₃ CH ₃

HO-CH-CH ₂ OCH ₂ -Ch-OH

CH ₃ O- \ CH- CH ₂ O / ₂ H

Γ)

C ₂ H ₅ O-VCH-CH ₂ OJ ₂ H

CH ₃ COOCH ₂ CH ₂ Oh
C ₆ H ₅ OCH ₂ CH ₂ OH

H ₃ C

OCH, CH, OH

CH ₇ O (CH ₂ CH ₁ O) ₁ H

CH ₃ O-

OCH ₂ CH ₂ OH

H VQ (CH ₂ CH ₂ O) ₂ H

HV-O (CH ₂ CH ₂ O) ₂ H

CH ₅ O (CH ₂ CH ₂ O) ₄ H: diglycol esters, R "of which is the radical - R ⁷ , --Ο-, X is the group - NO and R ^{7 is} the alkylene group - (CH ₂ I ₃ -, - (CH ₂ I ₄ -

- (CH ₂ ), -

- (CH ₂ ) ,, -

C ₇ H,

C ₂ H ₅

-CH ₂ -C-CH ₂ - -CH-CH-CH, -C ₂ H ₅ C ₃ H ₇

CH ₃ CH ₃

-C-CH ₂ -CH-CH ₃

mean.

The reaction is carried out with the addition of water, advantageously in an amount of from 5 to 100, in particular carried out from 15 to 50 moles of water per mole of starting material II; the water can be separated and / or in Form of aqueous solutions of the reactants, e.g. B. of aqueous acid, of aqueous alkali metal nitrite solutions or mixtures of the alcohol with water. That which is formed in the reaction itself In this context, water is not defined as added water and is not included in the above contain advantageous amounts of water.

The reaction is carried out in the presence of acid, advantageously in an amount of from 1.5 to 15, in particular from 2.5 to 10 equivalents of acid, based on starting material II, carried out. There are inorganic ones Acids into consideration Instead of monobasic acids, equivalent amounts of polybasic acids can also be used Acids are used. For example, the following acids are suitable: hydrogen chloride, hydrogen bromide, Hydrogen iodide, perchloric acid, sulfuric acid, nitrous acid, phosphoric acid, nitric acid; boron containing acids such as boric acid, hydrofluoric acid; or corresponding mixtures. The acids can in concentrated form, mixed with one another and / or with a solvent, in particular Water. Sulfuric acid, nitric acid, phosphoric acid and perchloric acid are preferred.

The reaction is carried out at a temperature of at least 35 ° C, usually at a temperature of 35 ° C to the boiling point of the mixture, expediently from 40 to 200 ° C, preferably from 45 to 100 ° C, carried out without pressure or under pressure, continuously or discontinuously. As a rule, components are used of the starting mixture, e.g. B. water, alcohol or acid, or the entire starting mixture as the reaction medium.

The reaction can be carried out as follows: A mixture of starting material II, alcohol, nitrosating agent, The acid and water are kept at the reaction temperature for 1.5 to 5 hours. Expediently, the nitrosating agent, for. B. the Aqueous sodium nitrite solution or the nitrous acid ester run in to the mixture of the reactants.

CH ₃ CH ₃ -CH ₂ -CH-CH ₂ - -CH ₂ -C-CH ₂ - CH ₃ CH ₃ C ₂ H _{5 2} - -CH-C-CH ₂ - -CH ₂ -C-CH ₂ - CH ₃ C ₄ H ₉

C ₃ H ₇

40

The inflow can take place as quickly as desired over a wide area. The end of the reaction usually coincides with the End of the inflow of the nitrosating agent together. The end product is made from the reaction mixture in the usual way Way, e.g. B. by filtration, separated.

The novel compounds which can be prepared by the process of the invention are valuable starting materials for the manufacture of Pharmaceutica, dyes and pesticides. Regarding the use reference is made to the aforementioned publications and Ullmann's Encyklopadie der technischen Chemie, 3. Edition, Volume 12, pages 798 to 800, referenced.

The parts mentioned in the examples are parts by weight.

example 1

207 parts of 2,6-dichloro-4-nitro-aniline in 18C parts of isopropanol and 300 parts of water are introduced, and 200 parts of concentrated sulfuric acid (98 percent by weight) are then added to the mixture. The solution of 125 parts of NaNO ₂ in 175 parts of water is allowed to run in at 50 ° C., nitrogen being evolved. The mixture is cooled, 400 parts of water are added and the product is filtered off with suction. 192 parts (practically quantitative yield) of 3,5-dichloro-nitro-benzene with a melting point of 60 ° to 62 ° C. are obtained.

Example 2

If, as in Example 1, 130 parts of isopropyl nitrite are reacted instead of NaNO ₂ , 186 parts (97% of theory) of 3,5-dichloro-nitro-benzo with a melting point of 61 to 62 ° C. are obtained

Example 3

207 parts of 4,6-dichloro-2-nitro-aniline in 40 parts of ethanol and 900 parts of water are added and there is added; Then mixture with 400 parts of concentrated sulfuric acid (98 percent by weight). The solution of 105 parts of NaNO ₂ in 175 parts of water is allowed to run in analogously to Example 1 at 80.degree. The mixture is cooled and filtered off with suction. 182 parts (95% of theory) of 3 ^ -dichloro-nitro-benzene with a melting point of 56 ° to 59 ° C. are obtained.

Example 4

296 parts of 2,6-dibromo-4-nitro-aniline in 400 parts of isopropanol and 750 parts of water are added, and 130 parts of concentrated sulfuric acid (98 percent by weight) are then added to the mixture. At 70 ° C., the solution of 105 parts of NaNO ₂ in 150 parts of water is run in analogously to Example 1. The mixture is cooled, 300 parts of water are added and the mixture is filtered off with suction. 278 parts of 3,5-dibromo-nitro-benzo are obtained! (99% of theory) from melting point 102 to 104 ⁰ C.

Example 5

207 parts of 2,6-dichloro-4-nitro-aniline are introduced into 500 parts of glycol monomethyl ether, and 1000 parts of 50 percent strength by weight sulfuric acid are then added to the mixture. At 70 ° C., 90 parts of NaNO ₂ in 150 parts of water are slowly added for 7u. The mixture is cooled and filtered off with suction. 179 parts (92% of theory) of 3,5-dichloro-nitro-benzene with a melting point of 56 ° to 59 ° C. are obtained.

Example 6

103.5 parts of 2,6-dichloro-4-nitro-aniline and 103.5 parts of 2,4-dichloro-6-nitro-aniline in 180 parts of isopropanol and 300 parts of water are added, and 200 parts are then added to the mixture concentrated sulfuric acid (98 percent by weight). At 50 ° C., the solution of 125 parts of NaNO ₂ in 175 parts of water is run in analogously to Example 1. The mixture is cooled, 400 parts of water are added and the mixture is filtered off with suction. 192 parts (practically quantitative) of 3,5-dichloro-nitro-benzene with a melting point of 60 to 61 ° C. are obtained.

Example 7

172.5 parts of 2-chloro-4-nitro-aniline in 180 parts of isopropanol and 300 parts of water are introduced, and 200 parts of concentrated sulfuric acid (98 percent by weight) are then added to the mixture. At 50 ⁰ C the solution is allowed 125 parts of NaNO ₂ in 175 parts water in analogy to Example 1 run. The mixture is cooled, 400 parts of water are added and the mixture is filtered off with suction. 142 parts (90% of theory) of 3-chloro-nitro-benzene with a melting point of 40 to 42 ° C. are obtained.

Example 8

ίο One carries 207 parts of 2,6-dichloro-4-nitro-aniline in 500 parts of isopropanol and then mixed the mixture with 780 parts of 65 weight percent nitric acid. At 50 ° C., the solution of 125 parts of NaNO ₂ in 175 parts of water is run in analogously to Example 1. The mixture is cooled, 400 parts of water are added and the mixture is filtered off with suction. 172 parts (90% of theory) of 3,5-dichloronitro-benzene with a melting point of 55 to 57 ° C. are obtained.

Example 9

207 parts of 2,6-dichloro-4-nitro-aniline in 300 parts of isopropanol and 9 parts of water are introduced, and 200 parts of concentrated sulfuric acid (98 percent by weight) are then added to the mixture. At 5O ⁰ C is allowed to run 170 parts isopropyl, with nitrogen developed. The mixture is cooled, 800 parts of water are added and the product is filtered off with suction. 188 parts (98% of theory) of 3,5-dichloro-nitro-benzene with a melting point of 59 to 62 ° C. are obtained.

Example 10

207 parts of 2,6-dichloro-4-nitro-aniline in 1,800 parts of isopropanol and 18,000 parts of water are introduced, and 700 parts of concentrated sulfuric acid (98 percent by weight) are then added. At 60 ^° C., the solution of 140 parts of sodium nitrite in 240 parts of water is allowed to run in slowly. The mixture is cooled and filtered off with suction. 190 parts of 3,5-dichloro-nitrobenzene (99% of theory) with a melting point of 61 ° -62 ° C. are obtained.

Claims (1)

Claim: Process for the preparation of halonitrobenzenes of the formula (I) where R ¹ and R ^{2 can be the} same or different and each represent a halogen atom (halogen = chlorine, bromine, iodine) and R ^{2 can} also denote a hydrogen atom, by reacting halonitroanilines with alcohols and nitrosating agents at elevated temperature in the presence of acid, characterized in that one halonitroanilines of the formula NO R ² NH, (N) wherein R ¹ and R ^{2 have} the aforementioned meanings and the nitro group and the two halogen atoms are in the 2-, 4- or 6-position to the amino group, with aliphatic, cycloaliphatic or araliphatic alcohols at a temperature of at least 35 ° C with the addition of water (separately and / or in the form of aqueous solutions of the reactants). It is from Houben-Weyl, Methods of Organic Chemistry, 4th Edition, Volume 10/3, pages 116 ff., Known that aromatic diazonium salts can convert in alcohols in the heat to the corresponding aromatic hydrocarbons; it it is recommended to use the diazonium salt solution as concentrated as possible and to mix it with the alcohol 5 to 10 times the volume to be added. The alcohol is converted into the corresponding aldehyde, the so increasing content of aldehyde prevents the reuse of the unreacted portion of Alcohol. Depending on the constitution of the diazonium salt, anhydrous must be used, or it can also be one SO weight percent, aqueous ethanol solution used will. Organic Reactions, Volume II, page 274 (Wiley, N.Y.) also teaches that the reaction does not must absolutely be carried out anhydrous, but the amount of water to about 5 to 10% should be restricted. In addition to the hydrocarbons, the phenol ethers corresponding to the alcohol used and more or less large amounts of resin (Houben-Weyl, loacit, pages 123 and 124), especially in alcohol diluted with water, are formed as by-products. The yield and purity of the end products are mostly unsatisfactory in these processes, especially on an industrial scale. So z. B. for 2,4-dichloroaniline 46% and for anthranilic acid as starting amine 53% yield of end product indicated (Houben — Weyl, loc. Cit., Page 125). A work in Angewandte Chemie, Volume 70 (1958), page 211, teaches that one must use ethers such as dioxane instead of alcohols in order to avoid the formation of secondary substances and to improve the yield of the end product. Instead of the aqueous diazotizing solution, the diazonium salt itself can also be separated off and reacted with the alcohol (Saunders, "The Aromatic Diazo Compounds" [E. Arnold & Co. London 1949], page 271). All of these processes are unsatisfactory, especially on an industrial scale, in terms of economy and simple mode of operation with, at the same time, the best possible yield of end product. In a work in Science, Volume 117, pages 379 and 380 (1953), it is shown that the reaction of the benzene diazonium salt with an alcohol usually leads to the corresponding phenyl alkyl ethers and not or only in a smaller amount to that after the cleavage of the ίο diazonium group remaining benzene derivative leads. This teaching is also described in H. Z ο 11 i η g e r, Azo and Diazo Chemistry, Interscience Publishers New York and London, 1961, p. 141. Also Houben - Weyl points out (loc.cit., Page 124) that the Decomposition of numerous diazonium salts by heating in ethanol with exchange of the diazonium group runs against the ethoxy residue. Replacement of the diazonium group with hydrogen is required according to this teaching certain reaction conditions such as addition of zinc or -ίο irradiate with ultraviolet light. To achieve higher yields of benzenes in the reduction with alcohols, the addition of alkalis or copper or. Zinc compounds recommended (loc. Cit., Pages 119 and 127). Houben - Weyl points out (loc. Cit., Page 128) that with increasing temperature the ratio of the two reaction products, phenol ethers and hydrocarbon, shifts in favor of the former. Because the product mixtures are often difficult to work up are and the yield of the desired so hydrocarbon is bad, will use other reducing agents recommended (ZoI linger, loc. cit., page 168). It is known from Journal of the American Chemical Society, Volume 72, page 798 (1950) that one ss 2,6-dichloro-4-nitroaniline, ethanol and sodium nitrite in the absence of water and in the presence of concentrated sulfuric acid at boiling temperature in a yield of 84% to 3,5-dichloronitrobenzene can implement. A corresponding implementation for fio 3,5-dibromo derivative gives a yield of 91%. That Process is simple, reliable and economical with regard to yield and purity of the end product Operation unsatisfactory, especially on a large industrial scale. '' 5 The subject of the invention is the above Process for the production of halonitrobenzenes shown in claim. Implementation can use in case