DD298237A5 - METHOD FOR PRODUCING PURE ETHYLENE CHLOROBYDRINE FROM ETHYLENE OXIDE AND CHLORIDE HYDROGEN - Google Patents

Abstract

The preparation of pure ethylene chlorohydrin from ethylene oxide and hydrogen chloride in a continuous or discontinuous Prozesz succeeds in a reaction stage without corrosion-causing excess of hydrogen chloride and without significant by-product formation with good control of the resulting reaction heat, by adding a solution of ethylene oxide in ethylene chlorohydrin with an ethylene oxide concentration of 0.017 kg / kg a stoichiometric amount of hydrogen chloride is introduced into ethylene oxide. {ethylene chlorohydrin; ethylene oxide; Hydrochloric; continuous process; discontinuous process; stoichiometric ratio of the reactants; By-product formation; minimization; Reaktionswaerme; Corrosion; minimizing}

Description

The invention relates to a process for the preparation of pure ethylene chlorohydrin from ethylene oxide and hydrogen chloride in a batch or continuous process. The ethylene chlorohydrin serves as a synthesis base for dyes and sulfide rubber and as a solvent for the production of photographic materials.

Characteristic of the known state of the art

Anhydrous ethylene chlorohydrin {2-chloroethanol-1) is prepared from ethylene oxide and hydrogen chloride in all practical processes. The problem occurring is the formation of higher ethoxylated Chlorh'ydrine as by-products, which not only reduce the yield, but also occur as a non-recyclable residue and also complicate the distillative purification of ethylene chlorohydrin.

In the known embodiments of the Ethylene Chlorohydrin synthesis, the temperature control and the use of excess hydrogen chloride are used as measures against by-product formation. The synthesis is usually carried out in a condensed phase. Ethylene chlorohydrin itself is suitably used as the solvent. CS-PS 100737 describes this application as a non-aqueous solvent which reacts neither with ethylene oxide nor with hydrogen chloride.

DD-PS 142185 gives good yields of ethylene chlorohydrin by using as solvent a mixture of ethylene chlorohydrin with the residue from its distillative purification.

In SU-PS 422241 an embodiment of the synthesis is described in which the production of ethylene chlorohydrin is coupled to the hydrolysis of organochlorosilanes in yields of 88 to 92%.

A solvent-free synthesis is described in DD-PS 146040. This is reacted in gaseous form ethylene oxide with hydrogen chloride and operates at high temperatures (above 13O ⁰ C) and pressures below 20 bar, preferably with a 3 to 6facnen excess of hydrogen chloride.

The disadvantages of known processes with ethylene oxide and hydrogen chloride are generally that the excess hydrogen chloride in the majority of applications of pure ethylene chlorohydrin must be removed beforehand.

This requires either a second stage of the synthesis, in which the acid is neutralized with an excess of ethylene oxide, or other stages which complicate the process with oils, strippers and compressors.

The stoichiometric feedstock application described in DD-PS 146040 requires a special reactor, e.g.

in the effect of a steam generator. This synthesis always threatens the risk that the reaction temperatures come close to the ignition temperatures for ethylene chlorohydrin or ethylene oxide due to the high heat of reaction, since there are technical problems to dissipate the heat of reaction.

The use of the distillation residue as a solvent for the synthesis is disadvantageous because elevated temperatures are required for the separation by distillation of the ethylene chlorohydrin from a highly cxethyiierten residue which arises in the continuous process, which lead to the formation of decomposition products such. B. 1,4-dioxane, which deteriorates the quality of the pure product.

Object of the invention

The aim of the invention is to improve the synthesis of anhydrous ethylene chlorohydrin so that the known disadvantages are avoided and can be worked in a synthesis stage with high reliability. At the same time, hazards to the system due to acidic corrosion should be limited to a short reaction distance.

Presentation of the essence of the invention

The invention has for its object to develop a process for the preparation of pure ethylene chlorohydrin from ethylene oxide and hydrogen chloride in a batch or continuous process at usual temperatures for this reaction, which is charged with minimal by-product formation, wherein the heat of reaction with Kühlwassc and not with Cooling brine can be removed and in which no acidic, corrosive media occur.

According to the invention, a stoichiometric amount of hydrogen chloride is introduced into a solution of ethylene oxide in ethylene chlorohydrin having an ethylene oxide concentration of not more than 0.017 kg / kg. The essence of the invention is therefore that ethylene oxide is reacted in very high dilution with hydrogen chloride. As a result, the heat dissipation is very well controlled. It is surprising that, when the proposed mild reaction conditions are used, the measures required to avoid or minimize the formation of higher ethoxylated chlorohydrins according to the prior art are not required and the disadvantages associated with these measures are avoided.

The reaction can be in all dilution ratios of ethylene oxide to ethylene chlorohydrin greater than 1 -.60 or at all Ethylene oxide concentrations less than 0.017 kg / kg are performed. An upper or lower limit only results

technological or economic point of view.

The reaction can be carried out batchwise by gaseous hydrogen chloride while stirring in a long

diluted solution of ethylene oxide in ethylene chlorohydrin is introduced until the ethylene oxide is completely reacted. The

The concentration of ethylene oxide is initially 0.3 to 0.8%. There is also the possibility of adding dilute solutions of ethylene oxide in ethylene chlorohydrin and of Hydrogen chloride in ethylene chlorohydrin combined with stirring. The object is achieved by a continuous process in that via a wash column and a condenser Ethylene chlorohydrin of any purity is recycled. The circulation amount must be at least 6 u daa> surface of Forming amount of ethylene chlorohydrin. In the wash column are added as starting materials hydrogen chloride and Ethylene oxide in the stoichiometric ratio, so that no free starting materials are enriched in the cycle product,

wherein the ethylene oxide is fed in via the point of introduction of the hydrogen chloride. The new formation of ethylene chlorohydrin

runs out of an overflow continuously.

The problem is solved for a continuous process also by passing a wash column with a

a separate hydrogen chloride absorber and via a cooler a divided product stream passes, wherein the ethylene oxide is fed via the feed of the hydrogen chloride solution to the wash column. The spatial separation of

Hydrogen chloride injection from the ethylene oxide feed into the wash column has technical advantages. embodiments example 1 In a vessel equipped with a stirrer, a thermometer, a probe for determining electrical conductivity and

is equipped with an inlet tube for hydrogen chloride, are added 100 g of technical grade ethylene chlorohydrin with a content of free ethylene oxide of 0.54%.

The electrical conductivity is determined to be 2uS / cm. The solution becomes a hydrogen chloride stream over 30s

initiated that the conductivity increases to 9uS / cm and does not change further. 1 g of ethylene chlorohydrin has formed.

The content of the technical grade ethylene chlorohydrin to diethylene glycol chlorohydrin has increased during the addition of ethylene oxide

and hydrogen chloride increased from 0.16% to 0.17%.

Example 2 An apparatus consisting of a wash column with sieve plates and distributor plates, a circulation pump and a Cooler, which is operated with cooling water, which is available at a temperature of 25 ⁰ C, becomes continuous Production of ethylene chlorohydrin used. The wash column has a free diameter of 200mm. The influx of hydrogen chloride is in the middle of the Column height. In the upper half of the column are 9 sieve bottom, the inlet for ethylene oxide is between the fifth and

sixth sieve tray arranged. In the lower part of the column are 9 distributor bases with alternately centric and peripheral outlet.

The column drain for the product regeneration is 1000 mm above the bottom of the wash column. The circulatory product is running Recirculation pump from a central bottom outlet to and then back to the top of the column via the radiator. The Column is suitably operated at a pressure of 75 kPa (abs). In the process for the new product is a measuring probe for determining the electrical conductivity with the amount of Hydrogen chloride feed is controlled so that the conductivity is 6uS / cm. In the column 25 liters of ethylene oxide are introduced continuously hourly after the apparatus with technical Ethylene chlorohydrin filled and the circuit with cooler was put into operation. The column expires hourly 34.61 Ethylenchloridan, with a Giaiialt of 1.5% diethylene glycol chlorohydrin. Example 3

In a vessel equipped as in Example 1, 50 g of ethylene chlorohydrin are added, were dissolved in the 0.54 g of ethylene oxide. Hydrogen chloride is introduced into the vessel with stirring and cooling with external ice water. After the ethylene oxide is consumed, an increase in the content of diethylene glycol chlorohydrin is found to be 0.04%.

Bolsplel4

In the vessel according to Example 1, 50 g of ethylene chlorohydrin with 0.54% free ethylene oxide with 50 g of ethylene chlorohydrin with

0.46% free hydrogen chloride given. The increase in diethylene glycol chlorohydrin is determined to be 0.017%.

Claims (1)

Process for the preparation of pure ethylene chlorohydrin from ethylene oxide and hydrogen chloride in a batch or continuous process at usual temperatures for this reaction, characterized in that introduced into a solution of ethylene oxide in ethylene chlorohydrin having an ethylene oxide concentration of not more than 0.017 kg / kg stoichiometric amount of hydrogen chloride to ethylene oxide becomes. Field of application of the invention