Way to obtain the diethyl ester of phthalic acid

 

(57) Abstract:

The present invention relates to the production of esters of carboxylic acids, namely, to obtain diethyl ether phthalic acid diethylphthalate. The method of producing diethylphthalate lies in the interaction of phthalic anhydride and ethyl alcohol in film mode in the presence of the solid catalyst is aluminum oxide impregnated with sulfuric anhydride at least 15% at a temperature of 120-130oC. Technical result is simplification. 2 C.p. f-crystals, 1 tab., 1 Il.

The invention relates to the field of organic chemistry, in particular the production of esters of carboxylic acids containing esterified carboxyl group attached to a carbon atom of six-membered aromatic nuclei, namely to obtain diethyl ether phthalic acid diethylphthalate. Diethylphthalate widely used as a plasticizer for plastics, solvent, and in various fields of perfumery, cosmetics and medicine.

Known methods for producing diethylphthalate interaction of ethyl alcohol with phthalic anhydride or phthalic acid or its acid chloride.

A known method of producing diethylphthalate interaction CFT is of alcohol vapor through the reaction mixture of phthalic anhydride and sulfuric acid at a temperature of 120-130oC. While diethylphthalate remains in the molten phthalic anhydride and water vapor and a pair of unreacted ethyl alcohol are condensed and collected in the form of aqueous solution. The resulting diethylphthalate contains from 3 to 5% sulfuric acid. Further diethylphthalate raw washed from sulfuric acid and dried. The disadvantages of this method are:

high consumption of ethyl alcohol, the return in which the process is carried out after dehydration;

washing diethylphthalate wool from a sulfuric acid;

as waste large amounts of sewage.

The present invention is to identify a more optimal conditions for the esterification of phthalic anhydride vapors of ethyl alcohol, the creation of a more simple process used in industrial production with a great economic effect.

To solve this problem is proposed to carry out the esterification of phthalic anhydride vapors of ethyl alcohol in film mode in the presence of the solid catalyst is granulated-alumina, impregnated with sulfuric anhydride at least 15%. The process is carried out at a temperature of 120-130oC.

The use of solid catalyst-op at the same time as the nozzle, which provides the interaction of phthalic anhydride with ethyl alcohol in film mode. This allows you to avoid the disadvantages that are present when using a liquid catalyst is concentrated sulfuric acid in the method prototype. The proposed solution allows to simplify the technological process of obtaining diethylphthalate and make it more economical in industrial production at the high end results of commercial products.

The method developed in pilot production in continuous mode.

Example

For carrying out the method of producing diethylphthalate interaction of phthalic anhydride with ethyl alcohol in the presence of the solid catalyst is granulated-Al2O3soaked in sulfuric anhydride, pre-prepare the catalyst of esterification.

In cylindrical device placed granular - Al2O3pre-dried and freed from dust scattering. Through an apparatus containing - Al2O3miss a controlled flow of dry air containing 6-7% wt. sulfuric anhydride. The amount of bypass air determined from the calculation of total p is Lenna thus the catalyst is unloaded in the dry atmosphere, weighing and overload in a column type reactor for esterification, which is represented in the drawing.

A cylindrical reactor made of stainless steel, the inner diameter of the reactor 6,0 see charged To the reactor the catalyst to a height of 60 cm, the volume located in the reactor catalyst 1,7 DM3. In the reactor, in its upper part through fitting A metered molten phthalic anhydride (To= 130-140oC). Under a layer of molten phthalic anhydride metered ethyl rectified spirit. The desired temperature in the reactor (13010oC) support the heaters (coil) located on the outer wall of the reactor. The resulting pairs of ethyl alcohol interact with molten phthalic anhydride in for him on the catalyst nozzle in the form of a film. The process proceeds according to the reaction:

C6H4(CO)2O + 2C2H5OH ---> C6H4(COOC2H5)2+ H2O

The resulting diethylphthalate flows into the lower part of the reactor and after cooling comes in the collection of commercial product and vaporous reaction products of water and unreacted alcohol is removed from the reactor through the nozzle D, located in the lower part of the reactor.

For comparison, in the same reactor experiments were conducted to obtain diethylphthalate interaction of phthalic anhydride with ethyl alcohol in the presence of a catalyst - granulated - alumina, impregnated with sulfuric anhydride in bubble mode.

In the reactor (see drawing) to create a bubbling regime changed the flow of the reactants on the ascendant. Molten phthalic anhydride and ethyl alcohol were dosed out through the socket C, and D, located at the bottom of the reactor. Through the nozzle A and nozzle B, located in the upper part of the reactor, withdraw the liquid reaction mixture vapors of water and ethyl alcohol.

During the process of esterification speed and dosing time of phthalic anhydride and ethanol were determined by means of a dosing pump and hours. Samples of reaction mixtures was performed after passing through the reactor 1.5 l total reaction mixture of phthalic anhydrides mixture was determined by gas chromatography (GC). The process parameters of the experiments are presented in the table.

The table shows that carrying out the esterification of phthalic anhydride with ethyl alcohol in the presence of the solid catalyst is granulated Al2O3soaked in sulfuric anhydride in film mode, has significant advantages over the bubbling regime as a result of the process: the output of diethylphthalate, its content in the finished product, as well as the ethanol content in the condensate.

The proposed method of obtaining diethylphthalate more simple, technological and economical.

Sources:

1. Oil and fat industry, 1985, N 5 "Obtaining methyl and ethyl esters high boiling carboxylic acids".

1. Way to obtain the diethyl ester of phthalic acid esterification of phthalic anhydride with ethyl alcohol in the presence of a catalyst at elevated temperature, characterized in that the interaction of phthalic anhydride with ethyl alcohol is carried out in a film mode, as the catalyst used granulated-alumina impregnated with sulfuric anhydride.

2. The method according to p. 1, characterized in that the interaction of phthalic anhydride by-alumina contains at least 15% of sulfuric anhydride.

 

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where:

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EFFECT: improved preparing method.

9 cl, 3 dwg, 5 ex

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