GB2207915A - Preparation of pure fumaric acid - Google Patents

Description

1. 4) 2 PROCESS FOR THE PREPARATION OF PURE F 1IC ACID This invention

relates to the preparation of pure fumaric acid from by- products containing maleic acid whict were formed during tne production of phthalic anhydride, or anhydride of maleic acid, Fumaric acid la 5 a geometric isomer of maleic acid with similar chemical characteristcs. Prom these two isomers. fumaric acid Is a more stable compounds therefore, transformation of maleic acid to fumaric acid, starts at room temperature. in industrial processes isomerization is accelerated by lo increasing the temperature and using catalysts.

Fumaric acid is used to several purposes 20lyester resins. paints. lacquers, modified casting resins. electrochemical insulators. elastomers. plastisizers In the paper industry and others are produced from it and fumaric acid is also used to animal foods and as adclitive in the food industry to replace the more expensive tartaric acid and citric acid. Basic material of preparation oz fumaric acid is maleic acid and its anhydri'de, respectively, Yjaleic anhydride is prepared by catalytic oxidation of benzene but It also forms as byproduct In manufacturing of phthalic anhydride and catalytic oxidation of naphtalene and ortho -xylene,, respectively. In this latter case, maleic anhydride# formed during oxidation in vapor form is absorbed in water. This maleic anhyd=ide Is contaminated with by-products which mcke processing to fumaric acid difficult. -zuch a waste washing liquid contains. generally, lu-30 per ceni of maleic acid, as well as organic products of oxidation, namely acids$ aldehydes. quinones, etc., In addition to condensation and polymerization products.

These waste washing liquids are not utilized in many cases, therefore they flow to the sewage and increase the pollution of the environment. Their proceasing is recommended both from point of view of environment protection and "onomical considerations.

This Invention relates to the preparation of fumaric acid from i_ndustrial wastes. containing maleic aeld. which is formed during the production of phthalic anhydride either from naphtalene, or from ortho-xylene and also in the production of maleic anhydride from benzene, starting from pure maleic acid. isomerization runs smoothly, the developed fumarxic acid does not need additional purifying. If maleic acid-containing waste-water Is used as starting material# the following problems arise:

- by-products in sewage reduce the efficiency of Iso merization catalysts, In addition. they react with catalysts and further contamination arises; a certain part of contaminating materials from the waste water is mixed with the fumaric acid crystalsy k i e therefore the formed raw products should be purified.

In well known processes a bromine donor compound and an oxidizing agent are preferably used as catalyst. such as ammonium bromide and ammonium per-sulphate, In additions urea, thiourea and its derivatives. hydrogen chloride and nitrogen, or sulphur compounds are also applied, in the Polish patent NO, 57076 it has bem described that to produce fumaxic acid. 40 per cent of maleic acid solution was first discoloured with activated carbon in an autoclave, but if this treatment is not satisfactory an additional treatment with sodium hypochlorite is applied, Then isomerization is completed at a temperature of 100 OC in the presence of potassi= bromate ca.talyst. No data are available for the purity of prouct, In the US patent No. 2 704 296 a txeatment with chlorine and purifying with activated carbon is described before isomerization of tLe starting material then isomerization is run by boiling for two hours J= the presence of hydrogen chloride as catalyst. The coloux of fumaric acid can be in the range of from the pale yellow to white.

Air is the oxidizing agent during isomerization i.n the U.S. patent No. 3 256 327 and isomerization is completed at a temperature of 80 OC in the presence of ammonium bromide and ammonium persulphate catalysts.

2 W- Colour of the obtained product is No. 45 on the Hazen scale, In accordance with the following well-own pro- cesses L , finished Ciunaric acid Is jaujected to an extra purifying operaTlony afte-r isolation:

According to the Japanese patent No. 37-b.5u7/19b2, a 10 per cent water solution of fumaric acid is prepared which is treated in the presence of acj;ivated carbon and manganese oxides. A pure fumaric acid Is resulted but the colour number is not reported.

According to the Japanese patent No. 48-34.121/19731 raw fuma--ric acid is purified by sublimation, clarified with ac',.-,lvated charcoal and crystallization. The colour of the turified nroduct is No. 30 on the Hazen scale.

According to the Sovie-t Patent No. 163.174. maleic acid is isomerized first by urea., then with thiourea for three hou--s at a temperatture of 70 00. Fumaric acid is isolated and recrystallized with activated charcoal. No data on purity of the product are available.

According to the Italian patent application No.

21 766 A/81. maleic acid is heat treated at 100 0 a and clarified with activated charcoal. After filtering, isomerization Is performed with thiourea and the fumaric acid is Isolated. The raw fumaric acid is recrystallized with clarifying with activated charcoal.

nie object of the present Invention is to elaborate a process for the preparation of 'Ek'uma=ic acid from maleic 1 j i 11 acid containing solutiong with different grade of contaninationt said process providing an isomerization at a relatively low temperature resulting a pure end product.

According to this Invention. preparation of fiima!c acid from by-products. containing maleic acid Is performed in a way according to which a solution containing malelc acid is purified with activated char coal. then isomerized in the presence of thiou--9a,, hydrogen chloride and sodium bisulfite. Fumaric acid crystals, developing from the solution are white and after drying, correspond to No. 10 on Razen scale.

Du=Ing isomerizationg starting material Is wa--med at 60-60 00 In the presence o f additives for 30 minutes.

Advantages of this invention are as follows:

1, The process is simple, can be quickly completed and the isomerization runs at a relatively low te-pera ture within a short period.

2. Additives are available easily and effective even in the presence of contamination.

3. A pure product can be produced without recrystal.11 zation. having a colour corresponding to APEA number about No, 10 on the Hazen scale.

The following examples illustrate the detalls, of this Invention.

Example 1

Th=ee per cent of activated charcoal, calculated to maleic acid content. is added to 220 g coloured washing solutiony containing 25 per cent of maleic acid, which was obtained during phthalic anhydride production on naphtalene base. The mixture is stirred for 15 mlrutes at 90 00 and cooled to 30 0 a then filtered. Then 1,7 per cent of thio-urea, 3,5 per cent of NallSO 3 are added to the solution. calculated to its maleic acid content and ml 30 % hydrogen chloride are added. The solution is heated to 80 0 C and st4Lrred for 30 minutes at the said temperature, After cooling to 25 0 a, the solution is f:Llte-,e,-.'& and the wet fu=ic acid is dried at 80 0 C The yield is 49.5 gs 80 per cent of the theoretical value. The purity of the fumaric acid is 99.7-99.9 per cent, /maleic acid content only in tracesl. The colour of a 5 % solution. dissolved in absolute alcohol is No.

on Hazen scale, Heating residue is 0.01 %, Pe content is lower than 3 ppm. Melting point 286.5-288.5 0 a Exam.Dle 2 1,7 per cent activated charcoal is added to 220 g coloured washing solution which contains 27 per cent maleic acid. This solution was formed in the phthalic anhydride production based on orto-xylene. The solution jL is stirred f or 15 minutes at go 0 C then cooled to 30 00 and filtered. 1. 7 per cent of thiourea and 3,5 per cent NARSO 3 are added to the solution, calculated to the maleic acid content and 10 ml. 30 % hydrogen chloride are also added.

A.fter Isomerization for 30 minutes with continuous stirring at 80 OC, the solution Is cooled to 25 0 er fumaric acid separated is filtered and dried at 80 0 00 Yield 54 gg 91 per cent of the theoretical value. Colour of 5 % solution dissolved in absolute alcohol is No, 10 on Eazen scale. Purity of the end-product is 99.7-99.9 Meltin-g point is 276-288 0 0.

:.xam-ole 3 1R Five per cent activated charcoal is added to 220 g coloured washing solution which contains 27 per cent maleic acid. This solution was formed during maleic acid production on benzene base, The solution is stirred f or 30 minutes at 90 OC and cooled to 30 OC then filtered.

1,8 per cent of thiourea and 5 per cent of Na 2 so 3 are added to the solution. calculated on maleic acid con tent and 15 M1 30 % hydrogen chloride is also added.

isomerization was performed for 30 minutes with conti nuous sti=ing at 80 OC then the mixture is cooled to OC and the separated fumaric acid is filtered and dried at 80 OC. The yield is 53.5 gr 90 per cent of a the theoretical value. Colour of 5 5% solution. dissolved in absolute alcohol is No 10 on Hazen ecale. Purity 99.7-99.9 %. 1,'AelJ.."J.ng point 286-288 0 00 t S claims:

1, A process for the preparation of pure fumaric acid from maleic acid containing by-products of malele anhydride production based on benzene and phthalic anhydrid production based on naphtalene or orto-xylene characterized by using solutions having maleic acid content of 14-40 %, preferably 20-30 %, and isomerizing these solutions In the presence of activated carbon.

further thiourea,, hydrogen chloride and NaESo 3 or Na2SO Y_ at a temperature between 40 - 90 0 c 2. The process of Cla-4m 1, by adjusting the quantity of NaES0 3 or Na 2SO 3 to 2-8 % by mass, hydrogen chloride to 4-8 % by mass and thiou--ea to 1.2-2 % by mass based on the maleic acid content of the starting solution.

3. A process for the preparation of pure fumaric acid from a solution of maleic acid which comprises purifying the solution by contacting it with activated charmil and isomerising the maleic acid in the presence of thiourea and hydrogen chloride and either sodium bisulfite or sodium sulfite.

4. A process substantially as hereinbefore described in any one of Examples 1 to 3.

Published 1988 at 11e Patc,-.. O".ce. State Howe 66 71 High Holborn. London WC1R 4TP- Further copies may be obtamed from The Patent Office, Sales Branch. St Mam, Cray. Orpingtor. Kent. BR5 3RD Printed by Mulup'ex techniques ILd. S, Mary Cray. Kent Con 1 87