DE1543020A1 - Process for the preparation of monochlorotoluenes with a high content of p-chlorotoluene by chlorination of toluene - Google Patents

Description

Registration-Hr _β 394 069

The invention relates to a process for the preparation of monochlorotoluenes with a high content of p-chlorotoluene by concentration of toluene in the presence of a catalyst, which thereby characterized eats that the chlorination in the presence of a complex, sulfur-containing iron halide catalyst is carried out, wherein the sulfur component of the complex catalyst consists of sulfur or a sulfur halide,

The chlorination products of toluene have a wide range of applications as chemical intermediates in the manufacture of chemicals, for example, for agricultural and pharmaceutical purposes. 5 ^{1 For} these purposes the pure isomers, sometimes in a purity of more than 96%, are required. Relatively pure isomers bind more valuable than mixtures _c if toluene

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in the present a · »herkönmiiohen
is chlorinated, one obtains a mixture of the derivatives chlorinated in the ring, namely, ta · -, p ~ and o -chlorofcoluene. ₃ So if chemically pure aoluene is present in the presence of a catalyst such as ferric chloride with a certain amount of chlorine is chlorinated, which is theoretically sufficient. To convert all of the toluene into monochiotoluene, the typical composition of the product is the following: 13% unreacted toluene, 48% o-chlorotoluene, 22% p-chlorotoluene. 3i » Bt-chlorotoluene and

polychlorinated toluene. In practice, is it usually customary _? the preparation \ ^r on monochlorotoluene to favor by using lower amounts of chlorine ,. Even with this process, however, considerable quantities of polychlorinated products are formed, and larger quantities of unreacted toluene are obtained, which must be separated from the product and circulated back into the reactor.

In the known process for the chlorination of toluene is obtained one in relation to the para-isomer more o-chlorotoluene, what a can be a costly disadvantage if the market demand for p-Ohlortoluene is greater.

The difficult isolation of the para isomer from the ortho and ileta isomer can be done by distillation. There; but the boiling points very close to each other? lie, the mela isomer is also distilled the para-isomer over, whereby an additional purification is required viirdp uiu daa Para-Jaomer in überor ^ 8 ^ iga: c Kel.nb.eit su obtained

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The above disadvantages of the herköarolichan. Chlorier u & gß procedures are carried out by άβιο erfindiuag £ gei & älten procedures "baaeitetr

As the following examples illustrate, the combination can be ^e fm erfindungegemäßen process catalyst used depending on the required percentage of isomers may be varied. In general, the complex, sulfur-containing elene halide catalyst is composed of about 1 to 10 parts of an iron (III) halide to about 1 part of sulfur or about 1 to 2 parts of a sulfuric acid. Larger or smaller amounts of iron halide and sulfur halide can be used, e.g. from 0.5 to 20 Cevs praises α parts of an iron halide3 to 0.5 to 5 (parts of an iron halide. In a preferred embodiment of the process according to the invention, the complex consists catalyst is generally from 0.01 to 1 $ # Eieenohlord -and- O Ol ₁ to ljt'.der echwefelhaltigen compound. the Halogenidantoil the KatelrsatorB may consist of chlorine or bromine, for example. Therefore, £ _»Β β ΒΙβοη (ϊΙΙ) -ohlorid, EisenClIIJ-bromid, Eiaen (II) -ohlorid, Schwefelohlorid, Schwefölbromid or sulfur zitaanimen with chlorine and! Toluene as reactants can be used »

The other reaction conditions of the process according to the invention generally depend on the reactants used, don the products you want and the required ones Reaction speed. In general, the

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Reaktionoteniperatiir between about 40 bia about 90 ⁰ _O} Kwisoher preferably about 45 "C to 60" iißtürlich can httnere auofc "or wsräen employed lower temperatures, vcrau3g3setsi;. _F that they do not adversely affect de" ßelrationsmochanismus, Usually at ifomaldruclc if ,. required but also with atmospheric over- or-under &ruo.'j: ge

ψ Eao chlorine can be introduced and used either in its own or in the gaKfÖrioigen, whereby Ohlorgas the "bc—

Porin is. Similarly, the complex may be prepared either catalyst before the actual implementation used by tei each other a temperature between about 25 and about 200 ⁰ C misoht its Beatandteile and umsottrt, or is to Reaktionegemisoh in its individual Beetandteilen in the required proportions *

The proportion of iron (III) chloride to sulfur chloride or sulfur has a significant influence on the isomers » relationship. If the quantitative ratio is high and is outside the specified range, the effect is predominant Eieen (III) chloride and the results are approximately the same as when using Eieen (III} -ohlorid alone

If the quantitative ratio is low, the rate of chlorination can be reduced decrease and side chain substitution take place. The concentration defi kompwvcezj catalyst in the

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Reactions ka »n of ρ ra V; I see λ considerations about certain advertise. Too low a concentration leads to slow chlorination? In fact, it proves to be too high a "fore-pleasure Cl ¹ Sr catolytic effect if impurities destroy the catalyst". Concentration of the catalytic converter results in additional coats for the catalytic converter and later difficulties, "in the work-up and purification, which are made more difficult by the presence of the excessive amount of catalytic converter.

The product obtained after the process according to the invention is generally a mixture of o- and p-chlorotoluene, as well as a small proportion of m-chlorotoluene and polyohlotoluene. If necessary, the p-gilortoluene can be separated off in a manner known per se, for example by distillation. As described above, the para- and meta-isomers ββ difficult to separate, but this is in the implementation eriindung dee ·:. Proper procedure not necessary since eioh only EIAO * small, insignificant. Amount of m-chlorotoluene forms,

The examples illustrate the invention. Unless otherwise stated, leilo refer to the weight.

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Examples. 2i, 3.a.

In de "examples below a plunger sufficient Crüfie was used as fteaKtor to the required fitenge the toluene receive (generally 1..3 Idter) _t * Dei flask was equipped with a Einlaj3rchr for Color" ended below the Plüseigkaitaspiegele, an agitator , a thermometer and a hot water cooler. Inconsistent Substance3 as Were in a Weae & rfalle

The reactor is filled with toluene (according to Höntgenanalyco containing less than 20 parts / 1 million parts of sulfur - the required amount of the catalyst is added; the chlorine is now poured in with stirring. The temperature is quickly set and the reaction continued for so long , "is erreioiit until the required Chlorierungsgradi. in the examples ^v · 3pie.len the ratio of chlorine to toluene zwisohon used is 1.50 to 1.55. Me in the table specified reactions lasted etv.a 5 bio 12 hours. Eas specific weight of the reaction mass is a suitable * measure for the degree of Ohlorieruogßgrad, which ends the conversion of Tolucl in Mccochlortoluol iet in the case of a speci ^ schea weight vori: ij08 ( corrected to 20 ⁰ C)? If did Ohlorieru? G naofr öoii invention »· Geicässer.u Veri'aliron ej-fol§t _r samples can evolve dox reactioninaBae during the implementation wevden- uia on these wines üi.a

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to determine the product and its degree of chlorination. Reaction temperature, type υ.ηά Kenge the vc-iiv / ended catalyst and the results obtained are shown in Table I. The quantitative ratio of oil to chlorine can change
1 and 2 are and the reading room; it can last for 12 hours, whereby the latter is partly determined by the pressure with which the chlorine is incorporated and is shortened with increasing pressure.

bath

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Q table I.

Seiepiel Hr, 1 2 3 4 5 6 7

Participation in participation 0.06 0.10 0.10 0.01 0.03. 0 _s 04 O ₄ .04

to 100 parts of toluene

awn, ι, ο ι, ο o.io 0.30 0.50 0.10 0.0 » ^0> ° \ ° ^'05 °' ⁰⁵ ° ^'01 °> ⁰²⁴ °' ^{01 0} ^ ⁰⁰⁵

Sulfur (added, --- «.-.-

ben ale S ₂ Cl ₂ ) - 0.24 0.005 0.005 ₆₀ 25 85 45 45 60 60

Water - -.-. «- ^ ~«.

Reection temperature ° C 40 75 75 60 45 45 45

Infraroi-analyee "~ *" "" "" '

of the products, wt. %. 43.0 45.5 5O ₉ I 48.9 20 51.2? 0 _f 6 ^:

Sa ¹ OlUOl 5.2 3.5 11.9 44.1 - - 2.5 45, X) 35.0 41.1 43Γ1 £ l5? 46.5f45, -7!

go ~ cniortoluene 48.5 49.8 46.0 34.7 51.7 50.5 50.2 έΡ? 5 - ^ 0.3 <0 _? 4 ^ 0 _? 3 / * / ' t $

- p-Cblor-fcoluene 24.1 21.3 24.0 Il6.8 43.7 42.5 45.5 ⁸⁸ * 5 80.8 91 _S 6 92.3 35 97 * 7 96.3

^ tt-chlorotoluene 2.7 3.6 2 _f 6 / ^ 0.3 ^ T0.5 ^ 0.5 - " ¹ S ^ ⁵ " \

it © p .-., in-Ghlortoluole 75 3 74.7 72.6 51.5 95.7 93.5 96.2 11.3 2.8 7.7 7.8 4 _? 5 1.7 3-7

^ ßeozy.T cblorid ~ ._ - ... ^ =. ... -.

3? .I.chlortauf> Ucand .. 19.5 21.9 35.3 4.3 4.4 6.4 1.2 higher chlorinated

Px products l, o 1.3 1? 2 1.1 - - »-

Quantity ratio of

c-chloroiuol see below

p-chlorotcluene 2.0 2.3 1.9 - 1.2 1.2 1.1 _0f 011 0.009 0.010 0..00? - - - ^

Volume ratio of · ^

jr: -cBlortoluene au CaJ

p-Ohlortoluene 0, -11 0.17 0.11 - 0 _? 007 0.011 0.011 _o

ro - character for "less than" °

Testing and analysis of the products produced by the process according to the invention show that the catalyst leads to the formation of a product that has an unusually high content of p-chlorotoluene and that the catalyst practically completely suppresses the formation of egg-chlorotoluene Used in the process of the invention - Kaf.alyaalior di® selective chlorination of toluene to monochlorotoluene and prevents the formation of diehlortoluene and polyohlortoluene even in the presence of! doluene in reaction mixture. It is of course possible to produce dichlorotoluenes and polychlorotoluenes in the presence of this catalyst by continuing to add chlorine at a suitable temperature until the required degree of chlorination has been reached

The data in Examples 5-11 indicate that only a little m-chlorotoluene is formed when the catalyst is used in the appropriate quantitative ratio, and that the ratio of o-chlorotoluene to the p-chlorotoluene obtained is only 1.2 or we- ! ^ niger beträft _c If the catalyst is added in the form of the separated connection, oo are preferably used the catalyst in a weight ratio Aryan lsi to 8: 1 of iron halide su sulfur, but ^G are ewiehtsverhältniase 8 * 1 (example 6) also wirkungavoll. If, if this proportion is significantly less than 1, example 12, then larger amounts of side canals can be formed and polychlorotoluenes can be produced. Venmreii by minimal amounts of water (example S) öeelRT.

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normally do not affect the effect of the catalyst.

By chlorination in the presence of the catalyst used in the process, the toluene with which the reactor is charged is almost completely converted into mono-ortoluene and at the same time only an insignificant amount of poly-chloro-toluene is formed, as Examples 7, 13 and 14 illustrate. If the conventional bis (-) chloride catalyst is used alone, the chlorination is measured to be terminated when about half of the deo toluenes have not yet reacted (Example 4) if the simultaneous formation of dichloro- and polychlorotoluenes is observed wants to limit the small amount that is obtained when using the catalyst according to the invention.

If the toluene is fed continuously to a reactor and the product is continuously weighed off, the product contains a higher proportion of unconverted toluene and polyolotoluene than if the chlorination is carried out discontinuously with the same chlorination force. The difference swieohen the results in discontinuous and continuous process is, however, much lower in the new catalyst Verwendimg, since the difference of the zwisohen Chlorifc ungBg6Bohwi £ * 1st} substantially larger iiigk'3it of toluene and its Chlorierungeprcdukt ^ r ^ B at avm UEN catalyst ala at the known catalyst. Εε is therefore apparent that hot koaöinuierlicher Work whiteness of the hoho

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3.3.

The degree of selectivity that is achieved in the chlorination with the new catalyst represents an even greater advantage over the herkb'mialionen catalyst than in the case of the discontinuous process. Similarly V / else as described in Example 1-14, is Issen £ (II) ~ clilorid was used instead of iron (IH) -OhIorid that transforms praktlsoh completely under the Reaktionebedingungen in Eisen'ni) -ehlorid w ± rd ₀ Likewise, For example, ferrous sulfate can be used alone and sulfur can be used in place of a sulfur halide.

In the continuous chlorination of the reactor described above is so auogeotattet, DAFL toluene continuously metered into the reactor and product gas is continuously withdrawn from the R _e akt ± on3geiaisck "The Reaktionsmaeee is kept at 60 ⁰ C. Iron (III) chloride and sohulphur chloride are added directly to the reactor at intervals of 24 hours and in amounts of 0.3 $ each of the reaction mass. Since the catalyst is somewhat soluble in the material flowing out of the reactor, additional amounts of catalyst must be added from time to time. In which Zeitabatänden this is done is not of importance, provided that the concentration and composition of the catalyst in the reactor remain within the limits indicated above for the discontinuous method ^l. After 80 hours of continuous work, the following results were achieved

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Product analysis, Gaw .- »#

ToluoX 9.0

o-chlorotoluene 45.6

p-chlorotoluene 40.6

Diohlor and polyol toluene 4.3

m <chlorine-oluene "* £ 0.5

Amount ratio of o-chlorine toluene sp ~ * chlorine toluene »1 _? 1 t 5.

Quantity ratio of m-chlorotoluo! s p-chlorotoluene * 0.012 t 1

When carrying out the process according to the invention on an industrial scale, doluene is chlorinated in a bending vessel with a volume of about 2840 liters, since it is equipped with a reflux cooler _for a cooling jacket and a chlorine plate which is located below the liquid level at the bottom of the vessel »Iron (III) Chloride and sulfur monoxide in amounts of 0.06 and 0.03 percent by weight, based on the toluene used, are used as the catalyst. The temperature is kept at 60 ^° C. during the chlorination. In this case, the inflow of chlorine and the evolving hydrogen chloride and the temperature gradient cause movement. This process has proven to be satisfactory, but it is preferable, especially in the case of a continuously operating reactor *, to provide mechanical stirring so that the catalyst components and the reactants are evenly distributed «

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4 3020

(Toluene ---

o-Ohloptolttol 48.0

p-Chloptoluene 45.0

m-chlorotoluene ^ O _? 3

Total amount of poly

ohloi'toluenes 5.7

Ratio of c-Ohlortoluol ι p-Chloitoluol * I O _8: 1 ratio of si-Chlorioluol: p-Ohlortoluol "0 _f 006. 1

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Claims (3)

1) Process Eur production of MouoohlortoXuo3 en mil; high salary of p-chlorotoluene by chlorination of iüoluene in the presence of a catalyst, characterized in that the chlorination takes place against a complex, sulfur-containing iron halide catalyst is carried out, whereby the sulfur proportion of the complex catalystB made up of sulfur or a Sulfur halide * 2) The method according to claim 1, characterized in that the reaction between about 40 to about 90 ⁰ C is carried out. 3) Method according to claim 1 _F daiux-eä characterized in that the complex catalyst from 1 to 10 ropes elnua iron halides and 1 to 2 ropes of a sulfur halide is produced north., 2098 17/1493