CN101219977A - CLT acid production method without acid waste discharge - Google Patents

Abstract

The invention relates to a method for producing 6-chloro-3-aminotoluene-4-sulfonic acid (hereinafter referred to as CLT acid). In the production of CLT acid, toluene azeotropic dehydration method is used to prepare toluene with p-toluenesulfonic acid as the main product. Sulfonic acid; after chlorination and nitration of toluenesulfonic acid, the precipitation method in 45-60% sulfuric acid in the original process is abolished, and the nitrates are directly reduced; the method of reduction and post-treatment is based on 1 mole of toluenesulfonic acid Use 1000-2500 ml of water to dissolve the nitration product, take 1/10 of the nitrate solution to activate the iron powder, adjust the remaining 9/10 solution to pH=5-7 with sodium carbonate, and drop it into the activated iron powder mixture carry out the reduction reaction. After the reduction is complete, adjust the pH to 9-11 with sodium carbonate, filter, wash the iron sludge with 500-2000 ml of the heat recovery liquid (I) from the previous time, combine the filtrate and washing liquid (if the color is darker, fade the color), and use dilute Adjust pH=1-1.5 with sulfuric acid to precipitate crude CLT acid, cool the filtrate below 10°C, and filter out sodium bisulfate crystals. The CLT acid filter cake is washed with the last recovered solution (II), and this filtrate is combined with the filtrate after filtering sodium bisulfate, and neutralized with sodium carbonate to obtain the recovered solution (I). Add 500-1000 milliliters of water to the CLT acid filter cake washed with the last recovery solution (II), stir and filter to obtain the recovery solution (II), and dry the obtained CLT acid filter cake at 80°C. The remaining recovery liquid (I) is mixed with coal and burned, so that no waste liquid is discharged, and CLT acid is produced with a high yield under environment-friendly conditions.

Description

CLT acid production method without acid waste discharge

[technical field] the present invention relates to the manufacture method of 6-chloro-3-aminotoluene-4-sulfonic acid (hereinafter referred to as CLT acid), specifically refer to toluene and sulfuric acid in the presence of excess toluene to carry out sulfonation reaction, continue to Toluenesulfonic acid is chlorinated, nitrated and reduced, and the waste acid salt solution is recycled to produce CLT acid. The present invention is characterized in that: no waste sulfuric acid and no waste acid salt solution are discharged, and the CLT acid is produced under environment-friendly conditions.

[Background technology] There are many synthesis routes of CLT acid: toluene sulfonation route, m-toluidine route, o-chlorotoluene route, m-xylene route, etc. However, the toluene sulfonation route has the advantages of wide sources of raw materials, low production costs, simple operation, and low requirements for equipment. The disadvantages are that many isomers are formed, the product yield is low, the consumption of sulfuric acid is large, and a large amount of waste sulfuric acid and a large amount of acidic saline solution are produced during the acid analysis process. If it can be further improved to reduce the three wastes and increase the yield, the toluene sulfonation route is still the best process route for producing CLT acid.

West Germany BASF (BASF) company patent EP57889 (1982) used 2.65-2.75 moles of concentrated sulfuric acid/mole of toluene to carry out sulfonation at 105-110 ° C, passed 1.1-1.3 moles of chlorine at 60-80 ° C, added at 60-70 ° C Nitrate with 98-100% nitric acid, dilute with water to make the concentration of sulfuric acid become 50-60% to precipitate nitrates, and then reduce to obtain the target compound. People such as Sun Chunguang [dye industry, 1990,27 (3) 29-32) have improved the processing condition of toluene sulfonation route, make product yield be had greater improvement, reduced sulfuric acid consumption substantially simultaneously, got rid of salt analysis, the three wastes are greatly reduced. But this method uses 2.88 mole concentrated sulfuric acid/mole toluene, adopts the waste sulfuric acid acid analysis method mechanically.

People such as Cui Yumin [Chemical Reaction Engineering and Technology, 2001,17 (1) 94-96] in order to overcome CLT acid yield low (42.8%), purity is low (96.7%), calcium sulfate residue is many, the problem of serious pollution, The original process has been improved. The neutralization method is replaced by acid analysis, so that the yield of CLT acid can reach 53.8%, and the purity can reach more than 98.0%, which greatly reduces the amount of sulfuric acid.

In the above-mentioned methods, 3-5 tons of 50-60% waste sulfuric acid and 15-30 tons of salty waste liquid with a pH of 1-1.5 will be discharged for every ton of CLT acid produced, causing serious environmental pollution. One of the reasons for producing a large amount of waste sulfuric acid and acid salt solution is the use of a large excess of sulfuric acid (2.64-3 moles of concentrated sulfuric acid/mole of toluene) in the sulfonation process; the second reason is the use of Lots of water. Therefore, to solve the problem of discharging a large amount of waste sulfuric acid and acid salt solution, two aspects of work need to be done:

(1) change the technology that uses excessive sulfuric acid into the technology that uses excessive toluene in the former sulfonation reaction, reduce the consumption of sulfuric acid as much as possible, simultaneously will abolish the waste sulfuric acid acid analysis method that uses in above-mentioned all documents; (2) after suitably handling Recycling and utilization of acidic waste salt solution produced during the production of CLT acid.

There are existing literatures on the preparation of p-toluenesulfonic acid hydrate under the condition of excess toluene. For example, British Patent GB967874 uses excess toluene for sulfonation, so that the sulfonate is precipitated in the form of hydrate, and the hydrate is filtered in air and dried to obtain p-toluenesulfonic acid hydrate. Japanese Patent Publication Ping 2-1457 uses 50-100% sulfuric acid to carry out sulfonation in the presence of excess toluene, and an appropriate amount of water is added to the toluenesulfonic acid mixture produced, and the precipitated hydrate crystallizes in dry air with a moisture content≤1g/ ^m3 Filter and dry to obtain p-toluenesulfonic acid hydrate with high purity. However, these methods have strict process conditions, and the process route for obtaining anhydrous p-toluenesulfonic acid is relatively long, so they are not suitable for direct application in the production of CLT acid.

There is no literature description about the process of recycling acidic waste salt solution in the production process of CLT acid.

[Summary of the invention] The object of the present invention is to provide an improved CLT acid production method, which is characterized by high yield, no discharge of waste sulfuric acid, and no discharge of salty waste liquid with pH=1-1.5.

To achieve the above object, the sulfonation reaction of the present invention is carried out in the presence of excess toluene. The molar ratio of toluene to sulfuric acid is 1.5-3.0, the sulfonation temperature is 110-115°C, the amount of dehydration is 70-100% of the sum of the water in sulfuric acid and the theoretical amount of water generated by sulfonation reaction, and the dehydration time generally takes 2-15 Hour. After the dehydration is over, toluene is recovered, a small amount of sulfuric acid is added, and then chlorination and nitration are carried out according to the traditional method.

In the present invention, in order to achieve the purpose of no waste sulfuric acid and acid waste liquid discharge, most of the salt solution with pH=1-1.5 after filtering and washing CLT acid is recycled, and a small amount of remaining acid salt solution is processed to achieve no waste liquid discharge. For this purpose, use 1000-2500 milliliters of water to dissolve the nitration product as a benchmark for 1 mole of toluenesulfonic acid, get 1/10 of its solution or 100-200 milliliters of recovery solution (I) to activate the iron powder, and the remaining 9/10 solution Or the whole nitrate aqueous solution is adjusted to PH=5-7 with sodium carbonate, and then dropped into the activated iron powder mixture to carry out the reduction reaction. When the reduction is complete, adjust the pH to 9-11 with sodium carbonate, filter, wash the iron sludge with 500-2000 ml of the neutralized heat recovery liquid (I), and combine the filtrate and washing liquid (if the color is darker, fade the color) , use dilute sulfuric acid to adjust PH=1-1.5 to precipitate crude CLT acid, filter, cool the filtrate to below 20°C, and filter to remove sodium bisulfate crystals. The CLT acid filter cake is washed with the hot concave recovery solution (II) last time, and the washing solution and the filtrate produced by filtering sodium bisulfate are combined to obtain the recovery solution (I), which is used for the next reduction and iron sludge washing. Add 500-1000 ml of hot water to the CLT acid filter cake washed with the heat recovery solution (II) last time, stir and filter to obtain the recovery solution (II), and dry the obtained CLT acid filter cake at 80°C . The remaining recovered liquid (I) is burned directly or mixed with coal after being concentrated.

In the present invention, the purity of toluenesulfonic acid content, sulfuric acid content and water content and the final product etc. in the sulfonate are determined by chemical analysis; 214nm to measure.

[Detailed ways]

Example 1

Fill the water separator with toluene, add 79.46g (0.75mol) 92.58% sulfuric acid to the dropping funnel, add 110g 98% toluene to a 250ml weighed four-necked bottle, heat to reflux the toluene, then drop in After the sulfuric acid in the dropping funnel was dropped, the azeotropic dehydration was continued until the water yield was 14.55ml, and then excess toluene was evaporated to obtain 127.9g of sulfonated compound. The results of chemical analysis showed that the product contained 6.556g of sulfuric acid, 3.64g of water and 117.7g of toluenesulfonic acid. HPLC analysis showed that the para-isomer content in toluenesulfonic acid was 88.18%, the ortho-isomer content was 11.82%, and the other products were trace amounts that could not be detected by HPLC.

Example 2

Dissolve the nitrated compound obtained after chlorination and nitration of the sulfonated compound of 0.3416mol toluenesulfonic acid in 512 milliliters of water, take 1/10 of its volume and add it to a four-neck flask containing 70 g of cast iron powder, and heat up to 100-102 °C After activating for 30 minutes, add 9/10 volume of the remaining solution neutralized to PH=5-7 dropwise at 100-102°C. After the drop is complete, continue to stir the reaction until the reaction is complete (about 3-5 hours). Use sodium carbonate to adjust PH=9-10, filter while hot, wash the iron sludge twice with 200ml of neutralized last heat recovery solution (I) each time, combine the filter solution and washing solution (if the color is dark, fade), Use dilute sulfuric acid to adjust PH=1.2-1.3 to precipitate CLT acid, cool down to 55°C, filter, compact, cool the filtrate to below 10°C, and filter to remove sodium bisulfate crystals. The CLT acid filter cake is washed with about 170 milliliters of last heat recovery solution (II), and this filtrate is combined with the filtrate after filtering to remove sodium bisulfate, neutralized with sodium carbonate to obtain recovery solution (I), and the iron sludge is washed next time used when. Add 170 milliliters of hot water to the CLT acid filter cake washed with the last heat recovery solution (II), stir and filter to obtain recovery solution (II), and dry the resulting CLT acid filter cake at 80°C to obtain 46.2-48.4 g of CLT acid with a purity ≥ 98% (the yield calculated from toluenesulfonic acid is 59.8-62.6%). The remaining recovered liquid (I) is 100-270 milliliters, which is directly or concentrated and burned together with coal.

Example 3

The nitrated compound obtained after the sulfonated compound of 0.3416mol toluenesulfonic acid was chlorinated and nitrated was dissolved in 337 ml of water, and the pH was adjusted to 5-7 with sodium carbonate. Add 346ml of the last recovered solution (I) into a four-necked bottle containing 70g of cast iron powder, raise the temperature to 100-102°C for activation for 30 minutes, and drop in the After the nitrate solution is dropped, continue to stir the reaction until the reaction is complete (about 3-5 hours). Use sodium carbonate to adjust PH=9-10, filter while it is hot, wash the iron sludge twice with the last heat recovery solution (I) of 116ml PH=8-10 each time, combine the filtering solution and washing solution (if the color is deep, carry out fading ), use dilute sulfuric acid to adjust PH=1.2-1.3 to precipitate CLT acid, cool to 55°C, filter, compact, cool the filtrate to below 10°C, and filter to remove sodium bisulfate crystals. The CLT acid filter cake is washed with about 170 milliliters of last heat recovery solution (II), and this filtrate and the filtrate after filtering to remove sodium bisulfate are combined to obtain recovery solution (I), which is used for the next reduction and washing of iron sludge. Add 170 milliliters of hot water to the CLT acid filter cake washed with the last heat recovery solution (II), stir and filter to obtain recovery solution (II), and dry the resulting CLT acid filter cake at 80°C to obtain 47.1-49.3 g of CLT acid with a purity ≥ 98% (the yield calculated from toluenesulfonic acid is 61.3-63.8%). The remaining recovered liquid (I) is about 80-120 milliliters, which is burned together with coal directly or after being concentrated.

Claims (4)

1. the method for toluene sulfonation manufactured 6-chloro-3-phenylmethylamine-4-sulfonic acid (being designated hereinafter simply as CLT acid), it is characterized in that toluene and sulfuric acid carry out sulfonation reaction under the existence of excess toluene, continuation is carried out chloro and nitrated with toluenesulphonic acids, directly itrated compound is reduced, under no discharging of waste liquid condition, make CLT acid.

2. the method for manufacturing CLT according to claim 1 acid, it is characterized in that process for sulfonation in the presence of the excess sulfuric acid discarded traditional in CLT acid is made and use methylbenzene azeotropic dehydration process for sulfonation, making with the tosic acid is the toluenesulphonic acids mixture of principal product.Toluene and vitriolic mol ratio are 1.5-3.0, and sulfonation temperature is 105-115 ℃, and dehydrating amount is water and the theoretical 70-100% that generates water yield sum of sulfonation reaction in the sulfuric acid.Dehydration finishes, and reclaims excess toluene, adds a small amount of sulfuric acid, carries out chloro and nitrated by traditional method then.

3. the method for manufacturing CLT according to claim 1 acid is characterized in that toluenesulphonic acids is carried out chloro and 45-60% sulfuric acid precipitation method in the former technology is abolished in nitrated back, directly itrated compound is reduced.

4. the method for manufacturing CLT according to claim 1 acid, it is characterized in that reducing and aftertreatment in recycle the waste liquid that 70-90% produces in reduced liquid preparation and last handling process, direct or the concentrated back of 10-30% residual waste solution is mixed together with coal and is burnt, thereby makes CLT acid under no discharging of waste liquid condition.