US3077502A

US3077502A - Process for the nitration of halobenzenes

Info

Publication number: US3077502A
Application number: US42A
Authority: US
Inventors: Robert I Leib
Original assignee: Monsanto Chemicals Ltd
Current assignee: Monsanto Chemicals Ltd; Monsanto Chemical Co
Priority date: 1960-01-04
Filing date: 1960-01-04
Publication date: 1963-02-12
Anticipated expiration: 1980-02-12

Description

BJBTLSZ Patented Feb. 12, 1953 $377,502 PROCE FGR TEE NITRATIUN F IEA'LOBENZENES Robert I. Leib, Kirkwood, Mm, assignor to Monsanto Chemical Company, St. Louis, Mo, a corporation of Deiaware No Drawing. Fiied Ean 4, 1960, Ser. No. 42 20 Qlairns. (fl. 266-646) This invention relates to an improved process for the preparation of nitrohalobenzenes by the nitration of the corresponding halobenzene, whereby a more favorable isomer distribution is obtained. I

The present methods used in the preparation of nitrochlorobenzene, for example yield a mixture of the para and ortho isomers, in which the para/ortho ratio is generally around 1.7 or 63% para to 37% ortho. Because of the current and projected demand for the para isomer, a great oversupply of the ortho isomer will result, if this need forthe para isomer is fulfilled by using the current methods of making nitrochlorobenzene.

It has been found that the isomer distribution in the nitrohalobenzene product is influenced when the nitration of a halobenzene compound is carried out in the presence of a sulfonic acid. The presence of even small amounts of a sulfonic acid markedly influences the isomer distribution in a nitrohalobenzene product and this eifect is still obtained when a high concentration of sulfonic acid is employed, i.e. where 3 moles of sulfonic acid per mole of halobenzene are used. Moreover, the amount of the desired isomer obtained when the nitration is carried out in the presence of a sulfonic acid is greater than the amount obtained in the absence of a sulfonic acid'regardless of the nitrating agent or nitrating temperature employed.

The halobenzenes which can be employed in the process of this invention include monochlorobenzene as well as the other monohalogenated benzenes, e.g. monobromobenzene, monoiodobenzene and monofluorobenzene.

Any nitrating agent which is capable of effecting the nitration of an aromatic ring can be used in the process of this invention, e.g. mixed acid, concentrated nitric acid, nitric anhydride, nitrogen tetraoxide, ethyl nitrate, etc. Generally, the nitrating agent is employed in stoichiometric quantities, or slightly in excess of the amount required to effect the mononitration of the monohalobenzene. Concentrated nitric acid, which contains 90% or more by weight of HNO is a preferred nitrating agent. By the term a sulfonic acid as used herein through out the specification and claims is meant any organic sulfonic acid which contains one or more sulfonic acid groups, e.g. organic monosulfonic acids, organic disulfonic acids, organic trisulfonic acids or other organic polysulionic acids or mixtures thereof, which are at least partially soluble in water. The organic residue of the sulfonic acid can be an aliphatic group such as an alkyl group, a cycloaliphatic group such as a cycloalkyl group, an aromatic group such as an aryl group, or a heterocyclic group.

As illustrative of the aliphatic sulfonic acids there may be mentioned methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, propanedisulfonic acid, butanesulfonic acid, hexanesulfonic acid, Z-ethylhexanesulfonic acid, dodecanesulfonic acid, tridecanesulfonic acid, pentadecanesulfonic acid, octadecanesulfonic acid, etc., as well as the mixture of sulfonic acids obtained by the sulfonation of kerosene or a mixture obtained by the sulfonation of a high boiling mixture of hydrocarbons from the Fischer-Tropsch process. Illustrative examples of mo matic sulfonic acids contemplated are benzenesulfonic acid, toluenesulfonic acid, benzenedisulfonic acid, benzenetrisulfonic acid, ethylbenzenesulfonic acid, diethylbenzenesulfonic acid, dodecylbenzenesulfouic acid, tetradecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, phenylmethylsulfonic acid, phenylpropylsulfonic acid, alphanaphthalenesulfonic acid, betanaphthaleuesulfonic acid, 1,S-naphthalenedisulfonic acid, 1,6-naphthalenedisulfonic acid, naphthalene 1,3,6-trisulfonic acid, naphthalene 1,3,5,7-tetrasulfonic acid, etc. Illustrative examples of cycloaliphatic sulfonic acids contemplated are cyclobutanesulfonic acid, cyclopentanesulfonic acid, cyclohexanesulfonic acid, cycloheptanesulfonic acid, cyclohexanedisulfonic acid, methylcyclohexanesulfonic acid, ethylcyc1o hexanesulfonic acid, butylcyclohexanesulfonic acid, cycloheptane sulfonic acid. Illustrative examples of heterocyclic sutfonic acids are pyridine-3-sulfonic acid, picoline sulfonic acid, pyrrole sulfonic acid, quinoline-S-sulfonic acid, quinoline-S-sulfonic acid, methylacridinetetrasulfonic acid, imidazole sulfonic acid, 3,5-dimethyloxaz0le sulfonic acid, 3-sulfonic-5-methylfuroic acid, 1,2,8-trisulfonic acid-dibenzofuran, Z-thienyl sulfonic acid, thiophone-2,4-disulfonic acid, thiophene-2,5-disulfonic acid, carbazole-2,7-disulfonic acid, carbazole-1,3,6,7-tetrasulfonic acid, etc.

The aforementioned sulfonic acids may be further substituted by one or more substituents. Typical but not limitative of such substituents are the halogens, such as chlorine, bromine, iodine and fluorine; nitro; carboxy and other non-reactive substituents. Illustrative examples of such as sulfoacetic acid, chloromethane sulfonic acid, trichloromethane sulfonic acid, 3-chloro-thienyl-5-sulfonic acid, 2,8-dicarboxylic acid-4-sulfonic acid dibcnzofuran, etc.

The lower alkane sulfonic acids, i.e. those which contain l to 4 carbon atoms such as methane sulfonic acid, ethane sulfonic acid, propane sulfonic acid and butane sulfonic acid, constitute a preferred class of aliphatic sulfonic acids. A preferred class of aromatic sulfonic acids are the sulfonic acid derivatives of aromatic hydrocarbons of the benzene series, i.e. benzene and alkyl substituted benzenes in which the alkyl group contains from 1 to 18 carbon atoms.

In cases where the nitrohalobenzene product crystallizes from the reaction medium it may be advantageous to employ an excess of the halobenzene reactant to act as a solvent, or another solvent may be employed, such as a petroleum ether; a saturated aliphatic hydrocarbon, such as hexane, octane, cyclohexane, etc.; or a liquid chlorinated hydrocarbon such as chloroform, carbon tetrachloride or tetrachloroethane.

Effective concentrations of the sulfonic acid in the process of this invention vary in wide ranges depending upon the result desired, in that extremely low amounts, e.g. 0.05 mole of monosulfonic acid per mole of halobenzene to be nitrated -will produce the para directive efiect. Moreover, as the number of sulfonic acid groups er molecule of sulfonic acid is increased, the amount required to produce a given result is reduced proportionately. Higher yields and higher para isomer content are achieved when the concentration of sulfonic acid is within the range of from about 0.5 to about 2 moles per mole of halobenzene to be nitrated. It is even more preferred to employ from about 1.0 to about 2.0 moles of sulfonic acid per mole of halobenzene to be nitrated. Amounts greater than three moles of sulfonic acid per mole of halobenzene to be nitrate'd can be used, however no significant increase in either para isomer content or yield results.

A preferred embodiment of this invention is the process for the preparation of paranitrochlorobenzene which comprises reacting concentrated nitric acid with mono chlorobenzene in the presence of a mixture consisting essentially of a major portion of a sulfonic acid and a minor portion of sulfuric acid, the quantity of sulfonic acid added being within the range of from about 0.5 to about 2 moles per mole of monochlorobenzene added. It is preferred that the mixture contain at least about 1.5 parts by. weight of sulfonic acid per part of sulfuric acid. It is even more preferred to use a mixture which contains at least 3.0 parts ofv sulfonic acid per part by Weight of sulfuric acid. Expressed on a percentage basis the concentration of the two compounds should be within the range of from about 60% to 90% of sulfonic acid and-correspondingly from 40% to 10% sulfuric acid. Such mixtures are desirably obtained from a process for the sulfonation of benzene employing 25-35% oleum, wherein a mixture containing approximately 72% by weight of benzene sulfonic acid, 2 2% sulfuric acid, water, and- 1% of a mixture. of suIfoneSQbenzene. and benzenedisulfonic acid is obtained. l i

Those skilled in. the. art will recognize that. the process of this. invention is not limitedv to specific reaction. tern.- peratures, since the process canbe carried out at temperatures of from 130 to temperatures of; 160 C;. or more. 'A reactioii' temperature. of .-30 C. can be main tained, for. example, by employingacooling bath com' prising. a slurry of solid. carbonf dioxide. inacetone. and using chloroform as a r'eactio n diluent. Aswillbe appreciated, the rate of reaction at temperatures of from --3 0 C. to 0 C. will besomewhatslow. The. minimum temperature for. the process of this invention istherefore. that temperature just above thatat. which noreaction between the nitrating agent and the halobenzene will. take place. The maximum temperature is. only of economic importance, fer. it isdependentonv economic factors rather than technical factors. For example, the aromatic sulfonic acids will begin to. decompose at temperatures above 160 C. and it is, of course, necessary to supplyconsiderable.

amounts of heatto achieveand maintain reaction temp'eratur'es above. 90 C. Temperatures within the range of from about 30 C. to about 90 C. aredesirably used, While temperatures within the. range of from 50."- C. to 60 C. are especially preferred.

After the nitration r'eaction is complete, theproduct can be. recovered from the reactionv by any method well known to 'tho se skilled in the art. For example, the. reaction mixture is permitted to settle into two phases, i.e.

an organic phase and an aqueous phase. The organic phase is then separated and the aqueous phase is cooled to precipitate the product and the product is removed by filtration. This method can be varied by employing a solvent extraction technique to remove the residual product from the aqueous phase. Preferably, the reaction mixture is diluted with water before the organic phase is separated from the aqueous phase.

The manner of carrying out the process of this inven tion and the excellent results achieved therefrom will be further apparent from the following specific examples in which all parts and percentages are by weight unless otherwise specified.

' EXAMPLE 1 To a well stirred mixture of 176 parts (1.0 mole) of benzenesulfonic acid monohydrate and 112 parts of chlorobenzene there is slowlyadded 72 parts (1.0 mole) of 90% nitric acid. The temperature is maintained at C. to C. by cooling and the acid is added over-a 25 minute period. After all of the acid is in, the reaction mixture ismaintained at- 50-55 C. for approximately two hours. The resulting mixture is then diluted with 200 parts of water, permitted to separate into two phases and the bottom oillayer is drawn 0E. The product oil is washed at C. to C. with two aliquots containing 200 parts of water, two aliquots containing-200 parts by weight of a 5% sodium carbonate solution and finally with two additional aliquots of water. The washed oilis then heated at reduced pressure to remove the residual waterv and any unrea'cted chlorobenzene. There is obtained. 114. parts of nitrochlorobenzene representing a yield of 72%. The product contains about 71% para isomer andabout.29% orthoisomer.

The following table represents additional examples of the present invention, wherein the apparatus, procedure and ingredients of Example 1 are utilized except as speci tied inthe table. Generally, the temperature of the reac tion, the reaction time, and the molar ratio of monochloro benzene to nitric acid are the same as in Example 1, exceptions to this appear in the column headed Remarks. The quantity of sulfonic. acid and the specific sulfonic acid are varied as indicated therein, the percentage of yield beingbased on the monochlorobenzene reactant.

Tabie I Moles 8111- Amount, tonic Acid, Percent, Percent. Example Sult'onlc- Acid Parts per mole of Yield Para Remarks dblcrobenisomer zene 2 'Benzenesulfonic acid 176 0.45 38 70 monohydrate. 3 do 20.3 0.083 j 43.5 66.2 4 179 0.5 69 Nitrattng agent-33% HNO /55% H2804; 1.03 moles I-INO ImoIe of chlorobenzene. 178 2.02 72 a 70.6 355 4. 27 79. 5 70. 8 184 1. 05.. 77.2 69.1 Reaction time, 2.7 hours. Last 30 minutes reaction carried out at 80 0. d0 179 1.02 84 66 Reaction temperature, 123 C.-146 C. 9 Benzenesulfonie acid- 163.8 0.71. 71.4. 71.2

(anhydrous). 10 p-toluenesultonic aicd 104' 0.52 50.5 67.4 11..- do 400.2 1.17 72 69.7 12 Dodieizyzlshenzenesultonic 188 0.25. 37.3. 73.4

ac 0 13 p-nitaobenzenesulfonic' 40.3 0 198 42.1- 67.4.

8.01 14 .Benggnfdisulfonicacid. 142; 0 535 98 72.6 15 178.5 0.675 96.4 72.1 16 p-chlorobenzenesulionic 192 1.0 68.8

' acid.

methanesulf0nicacid 1. O4 86 69. 7 o 198 2.05 72.6 Mixed C -C alkanesul- 1. 0 67. 4 70 ionic: acid' (94%. 5111- tonic acids) a 'do 220 2.0 70 71.3

Technicalproduct containing 94% sulfonic acids (mixture'ot'iriethenesulionie. ethane sulionic and propanesulionlc acids), 1% su lfurieacid and'5% water;

EXAMFLE 21 The procedure of Example 1 is repeated except that 248 parts of a mixture containing 71.1% benzenesulfonic acid, 22.1% sulfuric acid and 4.9% Water (the balance the presence of a sulfonic acid in an amount which is sufficient to produce a para directive effect.

2. In a process for the production of nitrohalobenzene by the nitric acid nitration of the corresponding halobeh madam b V ions sulfoms bmzena and benzene 5 benzene compound, the improvement which comprises 3 m n g) fluted for a benzelvlesuiforic acid carrying out the nitration in the presence of a sulfonic 1 c s 1 acid in an amount which is sufficient to produce a para mononydrate and 129 parts (1.15 mores) of chiorobendirective effect zen? 15 provldes approxmzately 1 mole of 3. A process of claim 2 wherein the halobenzene is benzenesulfonic acid per mole of monocnlorobenzene and 3 t b ht r r a pa t of sulfuric momchmmbenzene' "1 par 5 Xwelg 0 f per a 4. A process of claim 3 wherein the sulfonic acid is acid. There is obtained 24: parts (99% yield) of mtroch orobe'i ne This roduct "ontain 69 1% ara isomer an 31 Oman" sulfonic all-(130 g iscmper b p 5. A process of claim 4 wherein the sulfonic acid is The followinn' {3151c repmsents additional evamples a sulfonic acid derivative of an aromatic hydrocarbon of c A a wherein the apparatus, procedure and ingredients of Ex- 10 the benzen" senes' ample 21 are mind except as specified In this table 6. A process of claim 4 wherein the sulfonic ac1d is an the benzenesulfonic acid mixture is identified as PBSA." ahphatlc sulfpmc ac1d- The quantity of PBSA and the quantity of chlorobenzene A P Pl'odllctlofl 0f IHU'OCNOYOPBHZEH are varied as indicated therein, the variation in chloroo Whlch compl'lses Teactlng monocfllol'obfinlene Wlth C0 benzene being indicated by the mole ratio of the benzene, centrated nitric acid at a temperature w1th1n the range of sulfonic acid to chlorobenzene. from about 0 C. to about 160 C. in the presence of a Table II Moles Benzene- Example PBSA" sulfonic acid Percent Percent Remarks Parts per mole of Yield Para chlorobenzene 24s 1.0 99 69.1 111 0.5 so 68.7 166 0.75 97 69.9 445 2.02 96.3 69 667 30. s 93. 7 69.5 225 1.02 95.2 67.8 Reaction temperature,

70 0.-75 0. 225 1.02 95.5 72.5 Reagtion temperature, 166 0.37 81.9 74 Reaction temperature, 0 0.; 1 mole excess of chlorobenzene employed. 225 1.02 97.7 69.8 Water added to reaction mixture before starting nitration to give 8.2% H instead of 4.9%.

EXAMPLE 31 To a weil stirred mixture of 176 parts (1 mole) of benzenesulfonic acid monohydrate and 225 parts of cbiorobenzene previously heated to 0., there is slowly added 97.5 parts (1.06 moles) of liquid nitrogen tetraoxide (N 0 The N 0 is added over 1 /2 hour period. After the addition is complete, the reaction mixture is maintained at a temperature of 45 C. C. for two hours. The reaction mixture is then diluted with 200 parts of Water, allowed to settle into two phases and the bottom spent acid layer is drawn oil. The oil layer is washed with two 400 part aliquots of water, one 400 part aliquot of 5 sodium carbonate solution and again With two 400 part aliquots of Water. The excess chlorobenzene is removed at reduced pressure leaving a product having a crystallizing point of 61.8 C. The product contains 73.8% para-nitrochlorobenzene and 26.2% ortho-nitrochlorobenzene.

EXAMPLE 32 The procedure of Example 1 is repeated except that an equivalent amount of bromobenzene is substituted for the chlorobenzene of said example. The nitrobromobenzene is recovered in good yield and contains approximately 70% para isomer.

While this invention has been described with respect to certain embodiments, it is not so limited and it is to be understood that variations and modifications thereof which are obvious to those skilled in the art may be made without departing from the spirit or scope of this invention.

What is ciaimed is:

1. in a process for the nitration of halobenzene, the improvement which comprises carrying out the reaction in mixture comprising a major portion of a sulfonic acid and a minor portion of sulfuric acid, the quantity of sulfonic acid added being from about 0.5 mole to about 2 moles per mole of chlorobenzene.

8. A process for the production of nitrochlorobenzene which comprises reacting monochlorobenzene with at least a stoichiometric quantity of concentrated nitric acid at a temperature within the range of from about 30 C. to about C. in the presence of a mixture comprising a major portion of an aromatic sulfonic acid and a minor portion of sulfuric acid, the quantity of sulfonic acid added being from about 0.5 mole to about 2 moles per mole of monochlorobenzene.

9. A process of claim 8 wherein the sulfonic acid is benzenesulfonic acid.

10. A process of claim 8 wherein the sulfonic acid is toluenesulfonic acid.

11. A process of claim 8 wherein the sulfonic acid is benzenedisulfonic acid.

12. A process of claim 8 wherein the sulfonic acid is dodecylbenzenesulfonic acid.

13. A process of claim 8 wherein the sulfonic acid is a mixture of lower alkanesulfonic acids.

14. A process for the production of nitrochlorobenzene which comprises adding a stoichiometric quantity of concentrated nitric acid to a reaction zone containing monochlorobenzene and a mixture comprising a major portion of an aromatic suiionic acid and a minor portion of sulfuric acid, the quantity of sulfonic acid added being within the range of from about 1 to about 2 moles per mole of monochlorobenzene and maintaining the temperature within the range of from about 50 C. to 60 C. throughout the nitration.

15. A process of claim 14 wherein the sulfonic acid is benzenesulfonic acid.

16. A process of claim 14 wherein the mixture contains at least 3 parts by-weight of benzene'sulfonic acid per part of sulfuric acid.

17. A process of claim 16 wherein the mole ratio of sulfonic acid to monochlorobenzene is about 2.0.

18. A process for the production of nitrochlorobenzene which comprises adding a stoichiometric quantity of concentrated nitric acid to a reaction zone containing monochlorobenzene and a mixture consisting essentially of a major portion of an aliphatic sulfonic acid and a minor portion of sulfuric acid, the quantity of sulfonic acid being within the range of from about 1 to about 2 moles per mole of monochlorobenzene and maintaining the temperature within the range of 50 C. to 60 C. throughout the nitration.

19. A process of claim 18 wherein the aliphatic sulfonic acid is a lower alkanesulfonic acid.

20. A process for the production ofnitrochlorobenzone which comprises adding a-stoichiometric; quantity of References Cited in the file of this patent UNITED STATES PATENTS 1,586,253 Livingston et a1 May 25, 1926 2,370,558 Mares Feb. 27, 1945 FOREIGN PATENTS 102,216 Great Britain Nov. 12, 1915 OTHER REFERENCES Heertjes: Rec. Trav. Chem., vol. 77 (1958), pp. 693, 694, 695, 713'.