DE1961449A1 - Process for the preparation of dichloroalkanes - Google Patents

Description

1961U9

Qr, ir. ' f

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68/59

LI ο Ivay .c Oi e.

35, Rue du Prince Albert, Brussels 5, Belgium

Process for the preparation of dichloroalkanes.

Priority: Belgian patent application

I ¹ Jr ₀ 07 637 from 18 December 1968

The Urfinviung betrifxt a process for the preparation of dichloro iik; uien and high purity, in particular of dichloroethane untj: · filing out the corresponding Ülefinen _o

Yes i>. t, known, the dichloroalkanes and especially dichloroethane by chlorinating the corresponding olefin in liquid! ■ • to manufacture «

Dieüfi reaction has some Lüelstände, Gaseous ethylene r-Jaji3rt with garjförmi ^ eir chlorine, to give liquid 1 ₀ 2-Dichlorüthan unte .. · very grower / heat development (51.5 kcal / mol). The same applies to the chlorination of other olefins, • i, ic ι rop./lon (53.1 kcal / mol), na is consequently notwenii: · ;, xiüo.v stance [jüilsysteme to use to maintain a constant iiuHkt; iunsfce; i: f. In addition, since the Di.ci; xur: -iikan is kept in a liquid state, it must be withdrawn from aeiü RöL.L'tor and the impurities removed

yi ea contains, Z ₀ B ₀ the reaction catalyst,

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the other chlorinated hydrocarbons and the like «) This cleaning is known to be expensive and causes considerable losses *

In order to reduce these disadvantages, it has been proposed that the olefin in a solvent under normal pressure or at To chlorinate pressures below atmospheric and at such a temperature that the dichloroalkane formed evaporates and the reaction medium leaves α The dichloroalkane obtained is free of catalyst and heavy products «In addition This process enables the alkaline Y / Äsehe and the azeotropic drying of the dichloroalkane formed to be saved «

Since the evaporation of dichloroalkane consumes 7.8 kcal / mole for dichloroethane, 1.6 kcal / mole for dichloropropane, etc., some of the calories generated by the chlorination are removed. However, there is still a considerable excess of heat which is not recovered , and which was eliminated by cooling

On the other hand, we know that the recovery äev dichloroalkanes which are intended to undergo partial pyrolysis to Konochloralkenen, either by chlorination or by oxychlorination of the corresponding olefin or by these two combined methods are used "</ ie their Herstellungsvieise Seij it is appropriate to oesondare to purify the dichloroalkane prior to pyrolysis in order to remove the heavy chloroalkanes, which on the one hand can inhibit the pyrolysis and on the other hand can form undesirable by-products during the pyrolysis. Therefore, the various liquid fractions of the chlorination, dichloralicans obtained in oxychlorination and partial pyrolysis

Jas has now been determined that within the framework of a general agreement

3.11 F.

for the production of monochloroalkene / the corresponding Olefin and especially in the production of vinyl

off. _n .

chloride / ethylene or allyl chloride / propylene it is possible

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was, the entirety of the dichloroalkane by distillation to clean heavy products without it being necessary to provide any heat source for this distillation to perform

The invention therefore relates to a process for obtaining purified dichloroalkane which is suitable for pyrolysis, to obtain the corresponding monochloroalkene, going out of crude dichloroalkane obtained by several processes, at least one of which is the additive chlorination of the corresponding olefin in a liquid kept at the boiling point of the dichloroalkane To effect soil phase. It is characterized in that the dichloroalkane vapors obtained in the aforementioned chlorination stage in and through a distillation column

go, which also with crude dichloroalkane, which was obtained by oxychlorination of the corresponding olefin, and / or by impure dichloroalkane, which is separated from the llonochloroalkene obtained by pyrolysis of the dichloroalkane was fed, ^ obei the calories required for the distillation by the chlorination reaction of the corresponding olefins and delivered to the distillation column by the vapors of the resulting from this chlorination Dichloroalkane, while the liquid arm, v.which ar.siselt in the distillery oil, constantly in the chlorination zone for the olefin is recycled "

The process according to the invention is preferably useful, to obtain 1 «2-dichloroethane of high purity from ethylene, which is suitable for pyrolysis to vinyl chloride »In the Technology makes it possible to use a single de-oiling column Hindering the by chlorination or oxychlorination of the correspondent. Olefin formed diohloralkane and the diohloralkane, which not in LSonoohioralk in the pyrolysis furnace was transferred to use © The product obtained has a high degree of unity and can be pyrolysed after disposal the light components such as jhlor and unreacted Ethylene, hydrogen chloride and the like sent will"

BATH

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The process according to the invention is very economical: the energy required for the distillation of the dichloroalkane, which comes from the chlorination and oxychlorination of the corresponding olefin, and the dichloroalkane not converted in the pyrolysis furnace is supplied by the chlorination reaction of the olefin.This advantage is twofold, on the one hand it is not necessary to cool the liquid bottom phase in which the olefin is chlorinated, because all the heat of reaction is consumed for the distillation, on the other hand it is not necessary to supply external energy to the distillation column. The method according to the invention is therefore particularly simple in its mode of operation _e

However, it is not excluded that a minimum of external energy can be supplied to the column, especially if In addition to the hydrogen chloride resulting from the pyrolysis of dichloroalkane, there is also a significant amount of hydrogen chloride used, which comes from a different technical process «The same applies if the degree of pyrolysis of the dichloroalkane is very low, or if the reflux level of the distillation column is very high; it can sometimes be useful to supply a smaller amount of external energy "

The working diagram shown describes a plant according to the invention for the production of 1,2-dichloroethano. A reactor 4, which contains boiling 1,2-dichloroethane and a catalyst, ferric chloride, is supplied with gaseous chlorine through line 1 and with gaseous ethylene through line 2 The vapors obtained from 1,2-dichloroethane v- ^ rlas- a er. Λ en reactor through newspaper 5 and enter a distillation column 6. This distillation colony * .v is also fed with T o2-Dichiorätr.an, which through oxychlorination is formed by iithyien, and has not been reacted with 1 .2-dichloroethane, -Which in the pyrolysis zone 11 _β A portion of the effluent from the Destilxierkolonr.e is recycled to the reactor through line 17 in order under the 7 / MPACT the Chlorierungswii ' The vapors from pure dichloroethane leave the distillation column at 7 o'clock, cleaned of light components in the column 8. Die-aase

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such as hydrogen chloride, air, unreacted ethylene and the like are eliminated at 9. The dichloroethane distilled off goes into the pyrolysis zone 11 via line 10 »Vinyl chloride is obtained, which is obtained at 12, unconverted 1 <. ? -Mchloroethane, which is returned to the distillation column 6 via line-, and hydrogen chloride, which is sent via line 13 to the oxychlorination 15. Line 2 feeds the oxychlorination with ethylene, while oxygen (or Jjuft) is introduced therein at 3. The dichloroethane obtained in the oxychlorination is sent to the distillation column 6 via line 16.

It goes without saying that a similar system applies, with the distillation column being an integral part of the reactor makes up, also in the area of the invention,

Other olefins, for _t B, propylene and butylene can be used to prepare the corresponding dichloroalkanes high purity AEM invention. The working scheme is then the same as that described for the production of 1.2-dichloroethane «

The following example further explains the invention Procedure without limiting it,

example

The experiment was carried out according to a reaction scheme similar to that described above. The chlorination reactor for ethylene in the liquid phase is followed by a distillation column, fed with the dichloroethane formed by the oxychlorination of ethylene and with the dichloroethane which has not reacted in the pyrolysis furnace Bubbling moles of gaseous chlorine and 20.6 moles of gaseous ethylene through the chlorination reactor »This reactor contains liquid dichloroethane and 5.4 g of ferric chloride per kg of solvent. The temperature is 85 ° 0Ό The dichloroethane vapors obtained go into a distillation column, where at the same time 20 moles of dichloroethane, which was formed by oxychlorination and 40 moles of dichloroethane, which has not reacted in the pyrolysis, are introduced ₀ one part

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The effluent is returned to the chlorination reactor to be evaporated under the action of the heat of chlorination. The distillate after removing the light components contains more than 99.9 % dichloroethane and is free from water and hydrochloric acid. The dichloroethane obtained in this way can be sent to the pyrolysis furnace without further purification «

009827/2064

Claims (1)

1961U9 - 7 - Claims 1) Process for the production of pure dichloroalkane, which Cileh is suitable for pyrolysis in order to obtain the corresponding monochloroalkene, starting from crude dichloroalkane, which was obtained by several processes, at least one of which consists in the auditory chlorination of the corresponding olefin in to effect a liquid bottom phase kept at the boiling point of the dichloroalkane, characterized in that the dichloro-alkane vapors obtained in the aforementioned chlorination stage go into and through a distillation column, which is also fed by crude dichloroalkane, which comes from other production or recovery sources, the ones for the Calories required for distillation are supplied by the chlorination reaction of the corresponding olefin and carried to the distillation column by the vapors of the dicliloroalkane resulting from this chlorination, while the liquid phase which collects in the distillation column i n the chlorination ^ ones for the olefin continuously returned ^T .vird _a 2. The method according to claim 1, characterized in that that the crude dichloralkane introduced into the distillation column from the oxychlorination of the corresponding Olefins originates " 3 · Method according to claim 1, characterized that the rche introduced into the Jestilli jr column Dichloroalkane from that in the pyrolysis of the dicx ^ ioralkane to the corresponding lüonochloralkene not converted Part sta: n: .. t » 4. The method according to claim 1, characterized in that that the distillation column for the dichloroalkane obtained by chlorination also with crude M-chioralKan, -.velches by oxychlorination of the corresponding Olefins was obtained, and also by impure dichloroalkane, which is obtained from the aurch pyrolysis of the dichloroalkane 0 0 9 6 ..7 2 Monochloralkene was separated, is fed 5ο method according to the preceding claims, d a through characterized in that the dichloroalkane is 1o2-dichloroethane and the corresponding olefin is ethylene is used o 6 »Process according to claims 1-4, characterized in that daf3 as dichloroalkane 1,2-dichloro propane and propylene is used as the corresponding olefino 7 * Today commercial products resulting from the application one of the methods of the preceding claims result in « 8.7 / 206 /,