DE2300990A1 - PROCESS FOR THE PRODUCTION OF 1,4DIOXANE - Google Patents

Description

Badische Anilin- & Soda-Fabrik AG

Our reference: O.Z. 29 6jl Mu / UB

6700 Ludwigshafen, 8.1.1973

Process for the production of 1,4-dioxane

The invention relates to an improvement of a process for the production of 1,4-dioxane from diethylene glycol and its homologues by splitting off water by means of acidic ion exchangers.

The ring closure reaction of diethylene glycol by means of acids (e.g. Sulfuric acid) to 1,4-dioxane has been known for a long time.

From French patent 1,086,977 is also known that polyethylene glycols (ie, di- and triethylene glycol) merge with elimination of water in dioxane, when heated an acidic ion exchanger at 150 to 200 ⁰ G in the presence of a suspension. A mixture of dioxane and water is distilled off and contains about 18 % of water; the given explanation there, in the dioxane-water mixture if it were an azeotrope, but does not apply because this mixture should boil already below 100 ⁰ C, namely at about 88 ⁰ G. Rather, the condensation of diethylene glycol to dioxane produces water in a weight ratio of the molar weights, ie 88:18. Dioxane and water are distilled off at the reaction temperature of 180 to 200 C to the extent that they are formed.

It is found that such a method can only work-time yield room with technically satisfactory, when the reaction temperature is greater than but 16O ⁰ G. Higher reaction temperatures lead to a higher by-product levels in the distillate and reduced service life of the ion exchanger; There is therefore a need for a process which delivers high-purity dioxane with a high space-time yield by heating diethylene glycol and its homologues in the presence of a strongly acidic ion exchanger and which is gentle on the catalyst.

According to the invention, the need is remedied if the

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Reacting polystyrene sulfonated in the presence of an ion exchanger based on an optionally cross-linked "under reduced pressure, and - in at aioh bekannter.Weise while simultaneously distilling off the dioxane-water mixture at a temperature below 17O ⁰ C and even below performs 15O ⁰ C .

Surprisingly, it has been shown that for the new Only the ion exchangers which belong to the class of sulfonated polystyrenes are practically suitable for the process and which have very strongly acidic properties. These ion exchangers but do not withstand higher temperatures.

The temperature is set to a value in the range of HO to 170 ⁰ C, preferably to values below 16O ⁰ C, adjusted and reduced pressure in the range between about 50 bi3 700 Torr (ie 60-930 mbar), preferably 200 to 500 Torr ( 270 to 670 mbar) are used. Even a pressure reduction of 100 mm Hg compared to normal conditions causes a significant increase in the space-time yield.

The weight ratio of di- or polyglycol to exchange resin should be at least 2: 1, with the oligomers under polyglycol of ethylene glycol with a degree of polymerization between 3 and 6 should be understood. Diethylene glycol and its Homologues occur in the manufacture of ethylene glycol, so that a systematic synthesis of these compounds in many Cases can be dispensed with.

A preferred embodiment is the continuous mode of operation. In this case, the filling level of the reactor, which contains a suspension of the exchanger, is increased by constant inflow kept constant by di- or polyglycol.

In another continuous mode of operation of this process one draws from the discharge of a continuously flowing through, filled with lumpy Ausauacherharz (featbett) Reactor the dioxane-water-G-emisch by distillation from un-l carries out the distillation residue, mixed with fresh di- or Polyflykol, to the reactor again.

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In order to accelerate the reaction, according to the invention Ion exchange resins based on sulfonated, optionally crosslinked polystyrene is used. These ion exchangers are commercially available and are, if necessary, before use converted into the acidic form (Η-form). They have the advantage that they do not attack the reactor materials, even in large quantities and do not cause sewage problems. Suitable sulfonated Polystyrenes are also described, for example, by Helfrich "Ionenaustauscher", Weinheim (1959).

The procedure according to the invention under moderately reduced Pressure and in the presence of a polystyrene sulfonic acid exchange resin can indicate the most effective possible disruption the reaction equilibrium cannot be adequately described; for a good space-time yield is namely compliance of an only moderately reduced pressure (e.g. 350 mm Hg, corresponding to about 470 mbar), while after more professional Consideration - it is essentially anhydrous Solution worked and only the water formed is continuously removed with the dioxane - another reduction in pressure is another Increase the implementation speed would have to bring about.

In the following examples, "parts" mean parts by weight; they relate to "parts by volume" as kilograms to liters.

example 1

In a stirred tank with a capacity of 250 parts by volume, which is provided with a feed vessel and a descending cooler including a receiver is, 106 parts of ethylene glycol and 30 parts of ion exchange resin of the type ^ Dowex 50WX3 filled and stirring brought to reaction temperature. With a vacuum pump, any desired pressure below atmospheric pressure can be created in the device can be set. A mixture is distilled off which consists essentially of dioxane and water. The pro The amount of the mixture that passes over time unit depends on the reaction conditions; it is constantly being replaced by new diglycol replaced so that the level of the boiler does not change.

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In the table is the stationary distillation rate shown together with the associated reaction conditions.

Mean:

a = temperature ( ⁰ O)

b = pressure (Torr)

c = amount per hour (parts by volume / h)

Tabel

a b O 145 760 10 145 300 17th 160 760 42 160 300 75 170 760 70

The Destillationsgeschwindiglreit at 145 and at 160 ⁰ O each by 70 is increased to 80 i 'by reducing the pressure from 760 to 300 Torr, so that for example at 160 ⁰ O and 300 Torr distilled off more dioxane as at 170 ⁰ O and atmospheric pressure. This result allows the conclusion that the rate of formation of the dioxane on the chosen exchanger resin is greater than the possible rate of distillation at atmospheric pressure.

Example 2

In a 6-liter stirred flask, equipped with a feed vessel and a descending cooler and template, 4000 g of diethylene glycol and 400 ml Ionenaustauacherharz type Iewatit ^ S are filled 100 and heated with stirring to 150 ⁰ G. The apparatus can be evacuated with a vacuum pump. A mixture is distilled off which consists essentially of dioxane and water. The filling level of the flask is kept constant by constantly flowing in Diglvkol. The steady-state distillation rate is 250 g / h at 760 Torr and 500 g / h at 300 Torr.

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Example 3

318 parts of diethylene glycol and 90 parts are placed in a stirred tank with a capacity of 1000 toluene parts, which is provided with a feed vessel and a descending condenser including a receiver
Filled ion exchange resin of the ® Amberlite 200 (Η form) and heated ^{to 142 0 O with stirring.} The apparatus can be evacuated with a water jet pump. A mixture is distilled off which consists essentially of dioxane and water. The filling level of the flask is kept constant by constantly flowing diglycol. The steady-state distillation rate is 15 parts per hour at 760 torr, 28 parts at torr and 45 parts per hour at 100 torr.

Example 4

In a 1000 Tolumenteile comprehensive stirred tank, which is provided with a feed vessel and a descending cooler and template, 400 parts of triethylene glycol and 100 parts of ion-exchange resin to be filled and of the type Lewatit ® S 100 heated with stirring to 15O ⁰ O. The apparatus can be evacuated with a water jet pump. A mixture is distilled off which consists essentially of dioxane and water. The filling level of the boiler is kept constant by constantly flowing triglycol. The steady-state distillation rate is 30 parts per hour at 760 mm Hg and 60 parts per hour at 500 mm Hg.

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Claims (3)

- 6 -. O.Z. 29 claims 230133 i3 U 1. Process for the production of dioxane by. Heating of diethylene glycol or its homologues in the presence of an acidic ion exchanger, characterized in that the reaction is carried out in the presence of an ion exchanger based on - optionally crosslinked - sulfonated polystyrene under reduced pressure and - in a manner known per se with simultaneous distillation of a3 Dioxane-water mixture - at a temperature below 17O ⁰ C carried out. 2. Continuous implementation of the process according to claim 1, characterized in that an amount of di- or polyethylene glycol which is equivalent by weight to the distillate is constantly fed to the reaction space. 3. The method according to claim 1, characterized in that the reaction is carried out at a pressure between -600 and 50 Torr. Badische Anilin- & Soda-F-abrik AJJ A09828 / 1082