CA1189057A - Catalyst mixture and process for making 1,2- dichloroethane - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The disclosure relates to a catalyst mixture consisting of anhydrous iron(III)chloride and a further mixing component, for making 1,2-dichloroethane by subjecting ethylene to reac-tion with chlorine in a solvent at atomospheric or elevated pressure. The mixture is more particularly characterized in that the further mixing component is a nitrogen base or a salt thereof, which is used in a proportion approximately equivalent to the iron(III)chloride proportion.

Description

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It is known that 1,2-dichloroethane can be made by reacting ethylene with chlorine in 1,2-dichloroethane as a solvent and reaction medium. The principal by-product ob-tained in this reaction is 1,1,2-trichloroethane which ori-ginates from a substitution reaction 1,2-dichloroethane is subjected to~ In order to obviate this substitution re-action9 use is made of catalysts which comprise chlorides of the elements belonging to groups IV to VI of the Peri~-dic System, and are partially used in the presence of oxy-gen; more especially, anhydrous iron(III)chloride which isreadily accessible and inexpensive is used.
The resulting crude catalyst-containing dichloroethane is normally taken from the reaction ~essel, treated with water or aqueous alkali metal solution so as to be ~reed from catalyst and hydrogen chloride, and distillati~ely worked up in known manner.
The use of FeCl3 as a catalyst in the addition chlori-nation of ethylene entails certain adverse effects. In the presence of water, for example, FeCl3 has corrosiveness for metallic mate~ als such as those normally used for making reactors, columns or heat exchangers provided of course that these come into contact ~herewith. Needless to say, chlorine of commercial purity which is normally used for e~fecting the chlorination always contains traces of water and hy~rogen chloride origi~ating from undesirable side reactions, Whene~er it is desirable for the heat energy set free during the chlorination of ethylene to be utilized9 it is ~.

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invariably necessary for the reaction to be carried out at temperatures higher than the boiling point of dichloro-ethane at atmospheric pressure. In ~iew of the fact that corrosiveness increases considerably with increasing tem-peratures, it is indispensable to effect the chlorinationreaction in apparatus lined with corrosion-resistant mate-rials which naturally affect the commercial at-tracti~eness of the entire process.
We ha~e now ~ound that FeC13 which is used as a cata-lyst in the production of 1,2-dichloroethane is of consi-derably reduced corrosi~eness .~or reactor materials which are not corrosionproof provided that the ~eCl3-catalyst is used in admixture with certain addends. In addltion to this, the addends have been found favorably to influence by-pro-duct formation which is reduced.
The present invention relates more particularly to acatalyst mixture consisting o~ anhydrous iron(III)chloride and a further mixing component, for making 1,2-dichloro-ethane by subjecting ethylene to reaction with chlorine in a solvent at atmospheric or elevated pressure, which is cha-racterized in that the fur-ther mixing component is a n$tro-gen base or salt thereof which is used in a proportion appro-ximately equivalent to the iron(III~chloride proportion.
The nitrogen base is selected ~rom NH3, a primary, se-condary or tertiary alkyl, aralkyl, aryl or alicyclic amine or polya~ine; The salt of the nitrogen base preferably is ahalogen salt, e.g. ammonium chloride.
The in~ention also relates to a process for making 1,2-dichloroethane with the use o~ the present catalyst mixture.

5~7 The invention provides a process for makiny 1,2-dichloroethane by subjecting ethylene to reaction with chlorine in a solvent at a-tmospheric or elevated pressure in the presence of a catalyst mixture consistinc~ of anhydrous iron (III) chloride and a nitrogen base or a salt thereof, which is used in a proportion approximately equivalent to the iron(III)chloride proportion.
The process of the present invention for making 1,2-dichloroethane by subjecting ethylene to reaction with chlorine in a solvent in the presence of a catalyst mixture consisting of anhydrous iron(III)chloride and a further mixing component and, if desired, an agent inhibi-ting the formation of by-products at a temperature of about 20 to 200C, at atmospheric or elevated pressure and distil.la-tivel~ separating the 1,2-dichloroet~ane from the chlorination mixture, is more particularly characterized in that a) the further mixing component is a nitrogen hase or a salt thereof;
b) the further mïxing component is used in a propo.rtion approximately equivalent to the proportion of iron (III)chloride, and c~ the iron(III)chloride is used in a concentratio.n of O.OQ5 to about 0.5 weight ~, based on the quantity of solvent.
In describing the catalyst mixture, it has already been mentionsd that the nitrogen base should be selected from NH3~ a primary, secondary or tertiary alkyl, aralkyl, aryl or alicyclic amine or polyamine. The salt of the nitrogen base preferabl-y is a halogen salt, especially ammonium chloride.

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A preferred feature of the present process provides for 1,2-dichloroethane to be used as the solven-t and for oxygen to be used as inhibitor.
The following sta-tements are intended further to illus-trate the process of this invention.
The catalyst should generally be clissolved or suspended in the solvent placed in a reactor. It is also possible how-- 3a -ever for the catalyst to be prepared outside ~he reactor i.e. by suspending anhydrous FeC13 together with the further catalyst component in 1,2-dichloroethane, for example, and for the suspension to be introduced into the reactor St~ll further, it is possible to introduce a~hydrous FeC17 and NH3 or an amine int~ the solvent placed in the reactor, and ini-tiate a reaction during which hydrogen chloride sufficient ~or the formation o~ the corresponding ammonium salt is set free.
The present catalyst can be said to compare fa~orably with the prior art catalysts inasmuch as it is of conside-rably reduced corrosiveness for reactors made up of not cor-rosionproof metals, compared with the corrosiveness in the prior art methods for making 1,2-dichloroethane. It was also found that apart ~rom minor proportions of 1,1,2-trichloro-etha~e (as the first substitution product) and a correspon-dingly minor proportion of hydrogen chloride, practically no further by-products are being formed under the process conditions selected in accordance with this invention. The reaction solution remains~clear e~en after reaction over a prolonged period provided that the solution contains the addends of this invention in proportions approximately equi-valent to the iron chloride present. It is even possible for reaction mixture rendered dark during reaction to re-assume a lighter coloration during the Iurther course of the reac-tion, upon the addition o~ the addends specified hereinabo~e.
Further desirable results of the present process reside in the almost quantitative conversion rate at high space/time-yields.

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The process of this invention can be carried out, for e~ample, in the loop reactor described in DE-OS 24 27 045 or any other suitable reactor.
The following Examples illustrate the invention.
Example 1

2.0 kg 1,2-dichloroethane and 4 g anhydrous iron(III) chloride were placed in a loop reactor which had a capacity of about 2 liters. Next, 0.42 g ammonia which was in the form of an O.67 weight ~ solution in dichloroethane was in-troduced at 30 - 40C. The ascending portion of the reactor loop was provided with a layer of packing material. Disposed below the layer of packing material so as to open into the reactor were ethylene, chlorine and air inlets for the in-troduction of about 60 l/h each of ethylene and chlorine and 15 l/h air. The reactor liquid was circulated in the reactor system in accordance with the principle underlying a mammouth pump and the catalyst mixture was thereby homo-geneously suspended in the liquid phase. During the reaction, a temperature of about 77C was found to establish in the reaction mixture. The concentration of the catalyst mixture, determined as FeCl3, which was dissolved in the reactor li-quid, was 0,13 weight % after se~eral days. Dichloroethane in vapor form which came from the reactor was condensed in a water cooler arranged above the reactor. 3y means o~ a con-densate distributing means, a condensate portion correspond-ing to the quantity produced was ~aken from the cooler whilst condensate in excess was recycled to the reaction zone. By means of a cooling trap, a further dichloroethane p~rtio~
was separated from issuing gas which consisted substantially ~ 8 ~

of inert gases. After continuous operation over 2 period o~ several days, the catalyst mixture was found to have been extensively dissolved in the reactor liquid; the Fe-content in the reac~or liquid was determined colorimetrical-ly and f~und to be about 0.13 weight %. The experiment wasr~n o~er a period o~ 14 days and 1,2-di.chloroethane was ob-tained at an hourly rate of 262 g.
Product A which was obtained in the condenser and Pro-duct B which was reactor liquid were analyzed a~ter the re-action had been terminated, and the following results wereobtained:

Product A Product B
wgt % wgt %
_ _ ~

C2H5 l < 0.002 ~0.002 1,2-EDC 99.94 99.82 1,1,2-ETC ~.04 0.14 HCl ~ 0.001 r~r-~-r ~o-~r~ o o~ 0.04 EDC = 1,2-dichloroethane ETC = 1,1 7 2-trichloroethane Ex~mple 2 The procedure was as in Example 1 but the reaction mixture circulated through the reactor was ad~itionally ad-mixed dropwise by means of a dropptng funnel with 50 ml/h 1,2-dichl~roe~hane con~aining 0.4 weight % 1,1j2-trichloro-ethane. 1,2-dichloroethane was obtained at an hourly rate of ~26 g. The experiment was run over a period of 8 days~ Pro-duct A obtained in the condenser and reactor liquid B~ wereanalyzed after the reaction had been terminated, and the following results were obtained:
__ Product A Product B
_ wgt % wgt % .
. .. . . . _ C2H5Cl ~ 0.002 ~0.002 1,2-EDC 99.87 99.61 1,1,2-ETC 0.10 0.34 HCl ~ 0.001 Further components O.03 O.05 Example 3 The procedure was as in Example 1 but the concentration of FeCl3 in the reaction mixture and the molar ratio of FeCl3 to ammoni~ were varied. The followi~g Table indicates the va-riatio~ and its effect upon the proportions of 1,1,2-ETC and HCl in the product obtained in the condenser:

. .. . . _ . . , ., , ,,, , . , . _ Concentration Molar ratio Wgt% 1,1,2-ETC Wgt % HCl FeC1~5 (wgt%)' Fc 13 3 , ;~ .

0.07 1 : 2 0.2 0~004 0.34 1 : 2 0.6 0.002 0.45 1 : 1.5 0.1 0.001 0.32 1 : 1 0.06~ 0.001 In the experiment run with 0.32 wgt % FeC13-concen-tration over a period of 19 days, 1,2-dichloroethane was obtained at an hourly rate of 260 g. Product A obtained in the condenser and reactor liquld B were analyzed a~ter the reaction had been terminated, and the ~ollowirlg re-sults were obtained:

Pr~duct A Product B
wgt % wgt %
.. .. . . . .

C2H5Cl ' 0,002 0.002 'I,2-EDC 99.93 99.78 1,1,2-ETC 0.06 __ .0,19 HCl 0.001 Further components O.01 O.03 .. . ... . _...

Example 4 The procedure was as in Example 1 but 1.~5 kg 1,2-di-chloroethane was used and the reaction solution was admixed with 1.3 g trimethylamine dissolved in 30 ml 192-dichloro-ethane, which replaced ammon~a, The experimen~ was run over a peri~d o~ 6 days and 1,2-dichloroethane ~as obtained at an hourly rate o~ 276 g. The FeCl3-content in the solution was determined colorimetrlcally; it averaged 0.13 weight %.
Pr~duct A obtained in the condenser was analyzed after the reaction had bee~ terminated and the following results were obtained:

Product A (wgt %) 1,2-EDC 99.86 1,1,2-ETC 0.13 HCl 0.01 Fbrther ~om~e~t~ O.006 Example 5 The procedure was as in Example 4 but the catalys-t added to the reaction solution was 1.7 g FeCl3 and 0.65 g diamino-ethane. The FeCl3-content in the solution was determined colo-rimetrically; it averaged 0.07 wgt %. The experiment was run over a period of 3 days a~d dichloroethane was ~btained at an hourly rate of ~68 g, Product A obtained in ~he conde~ser was analyzed and the ~ollowing results were obtalned.

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Product A (~Ygt %j ___ _ ~

1~2-EDC 99,1 1,1,2-ETC 0.85 HCl 0,02 EIr~l~e- ~o~ =0 01 Example 6 The procedure was as in Example 1 but 1.5 kg 1,2-dichlo-roethane and 3.3 g ~eCl~ and 3.0 g triethanolamine (catalyst) were used. The FeC13-content determined colorimetrically in the reaction solution averaged 0.25 wgt ~. m e experiment was run over a period of 6 days and dichloroethane was ob-tained at an hourly rate of 268 g.
Product A obtained in the condenser was analyzed and the following results were obtained:

~-od~ t ~_ . . . , ... . _ .
C2H5Cl < 0.002 1,2-EDC 9~.65 1,1,2-ETC 0.~3 HCl 0.007 Further components O.01 , Example 7 a) 2 kg 1,2-dichloroethane and 2.1 g iron(III)chloride were placed in a 2 liter round flask provided ~ith an agita-tor, dropping ~unnel and reflux condenser, The mixture was heated ~o boiling while stirring and admixed drop-wise with 002 g ammonia which was dissol~ed in 58 g dl-5i7 chloroethane; this corresponded to a total catalyst quantity of 2.3 g. The mixture was boiled ~wnder re-flux for a further 5 hours and the FeCl3-content in the solution was determined colorimetrically; it was 0.11 wgt %.
b) The mixture of dichloroethane and catalyst was intro-duced into the loop reactor described in Example 1.
Next, about 60 l/h each o~ chlorine and ethylene were introduced together with about 5 l/h air. The experi-~ent was run over a period of 8 days ~nd dichloro-ethane was obtained at an hourly rate of 273 g.
Product A obtained in the condenser was analyzed and the following results were obtained:

Product A (Wgt ~) . , .. - . . I
C2H5Cl < 0.002 1,2-EDC 99.51 1,1,2-ETC 0.48 HCl 0.002 Further compo~ents OffOO9 Example 8 a) The procedure was as in Example 7 a) but 1.5 kg 1,2-di-chloroethane and 12 g FeCl3 were heated to boiling while stirring. Next, the mixture was admixed dropwise first with a solution of 2.7 g hydrogen chloride in 750 g di-chloroethane and then with a solution of 1.26 g ~H3 in 273 g dichloroethane~ After cooling, the reaction mix-ture was ~iltered and the filter residue dried. 14.4 g dry catalyst was obtained.

a~ 7 b) To produce 1~2-dichloroethane, 4 g of the catalyst made as described under a~ and 2 g ~eC13 were sus-pended in 2.7 kg 1,2-dichloroethane, the suspension was concentrated to a volume o~ about 2 liters and introduced into the loop reactor described in Example 1.
The loop reactor was ~ed per hour with about 60 liters each o~ chlorine and ethylene and 15 liters air and the reaction was initiated under the conditions des-cribed in Example 1. The experiment was run over a period of 6 days and 1,2-dichloroethane was obtained at an hourly rate of 266 g. The ~eCl3-content in the reaction solution determined colorimetrically averaged 0~15 wgt %.
Product A obtained in the condenser and reactor liquid B
were analyzed after the reaction had been terminated and the ~ollowing results were obtained.

Product A (Wgt %) Product B (Wgt %) ~_ C2H5 l 0.004 0.006 1,2-EDC 99.93 99.74 1,1,2-ETC 0.06 0.23 HCl 0.002 0.03 rur~her c~m~e.tsO.003 _ . _ _ Example 9 Steel specimens were tested for corrosion under the condi-tions of the process of this invention. To this end, 4 speci-mens were exposed at 4 places in a co~mercial rsactor for mak-ing 1,2-dichloroethane. The specimens were taken from the re-actor at intervals of 20 days and the material removed there-from by corrosion was determ~ned.
~ The average corrosion rate determined for unalloyed steel was less than 0.05 mm per annum in the pro-cess carried out with the FeCl3/NH3-catalyst of this in-vention at a reaction temperature maintained at 100-110C, In the prooess carried out in known marmer with the use exclusively of ~eCl3 as the catalyst, the average corro-sion rate determined for unalloyed steel was 0.43 mm per annum.

Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for making 1,2-dichloroethane by subjecting ethylene to reaction with chlorine in a solvent at atmospheric or elevated pressure in the presence of a catalyst mixture con-sisting of anhydrous iron(III)chloride and a nitrogen base or a salt thereof, which is used in a proportion approximately equi-valent to the iron(III)chloride proportion.

2. A process for making 1,2-dichloroethane by subjecting ethylene to reaction with chlorine in a solvent at atmospheric or elevated pressure in the presence of a catalyst mixture con-sisting of anhydrous iron(III)chloride in a concentration of 0.005 to about 0.5 weight %, based on the quantity of solvent and a nitrogen base or a salt thereof, which is used in a pro-portion approximately equivalent to the iron(III)chloride pro-portion, and, if desired, an agent inhibiting the formation of by-products at a temperature of about 20 to 200°C.

3. The process as claimed in claim 1 or 2, wherein the nitrogen base is NH3, a primary, secondary or tertiary alkyl, aralkyl, aryl or alicyclic amine or polyamine.

4. The process as claimed in claim 1 or 2, wherein the salt of the nitrogen base is a halogen salt.

5. The process as claimed in claim 1 or 2, wherein the salt of the nitrogen base is ammonium chloride.

6. The process as claimed in claim 1 or 2, wherein the solvent is 1,2-dichloroethane.

7. The process as claimed in claim 2, wherein the inhibit-ing agent is oxygen.