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Method for synthesizing p-nitrotoluene-ortho-sulfonic acid from p-nitrotoluene adopting mother liquid circulation style

A p-nitrotoluene, recycling technology, applied in the direction of sulfonic acid preparation, organic chemistry, etc., can solve problems such as difficult recycling and reuse, high COD and chroma of waste acid, and does not meet the requirements of modern clean production, and achieve reduction Sulfuric acid dosage, effect of reducing emissions

Inactive Publication Date: 2006-04-26
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage is that after the sulfonation reaction is completed, water must be added to the reaction completion solution to adjust the sulfuric acid concentration to 55-60% to separate the product NTS, thereby producing a large amount of 55-60% waste sulfuric acid, usually producing about 2 tons of waste acid per ton of NTS; The COD and chroma of the waste acid are very high, so it is difficult to recycle and reuse
Therefore, from an economic and environmental point of view, it does not meet the requirements of modern clean production.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0008] 1. Add 137g of p-nitrotoluene into a 1L glass four-neck flask, heat and melt; adjust the stirring rate at 500 rpm, add 440g of 20% oleum within 1h, and keep the reaction temperature at 90- within 95°C. After the oleum is added dropwise, keep warm to make the p-nitrotoluene react completely, and the temperature is controlled at 100-105°C. After the reaction is complete, cool to 10°C, crystallize, and filter with suction to obtain NTS and sulfuric acid mother liquor.

[0009] 2. Add 137g of p-nitrotoluene into a 1L glass four-neck flask, heat and melt; adjust the stirring rate at 500 rpm, and add 127.3g of sulfuric acid mother liquor within 0.5h. After p-nitrotoluene and sulfuric acid mother liquor are fully mixed, heat to 90°C. Then 176g of 50% oleum was added dropwise within 1 hour, and the sulfonation temperature was controlled at 90-95°C. After the addition of fuming sulfuric acid is completed dropwise, keep warm for 1 hour to completely convert p-nitrotoluene, and...

example 2

[0013] Prepare sulfuric acid mother liquor with the method for step 1 among the example one and recycle.

[0014] Add 68.5g of p-nitrotoluene into a 1L glass four-necked flask, heat and melt. Adjust the stirring rate at 500 rpm, add 102.8 g of sulfuric acid mother liquor within 0.5 h as a diluent, and control the reaction temperature at 100-105 ° C during the process. Then 88g of 50% oleum was added dropwise within 0.5h, and the reaction temperature was always controlled within 100-105°C during the dropwise addition. After the oleum is added dropwise, keep warm for 0.75h to completely convert p-nitrotoluene, and keep the temperature at 110-115°C during the keep warm. After complete conversion of p-nitrotoluene, cool to 10°C, crystallize, and filter with suction to obtain NTS103.5 and 155.5 sulfuric acid mother liquors.

[0015] Get 102.8g next time sulfonation use from gained sulfuric acid mother liquor. The remaining spent acid was diluted with 40 g of water, filtered with...

example 3

[0018] Prepare sulfuric acid mother liquor with the method for step 1 among the example one and recycle.

[0019] Add 137g of p-nitrotoluene into a 1L glass four-neck flask, heat and melt; adjust the stirring rate at 500 rpm, add 133.3g of sulfuric acid mother liquor within 0.5h as a diluent, and control the temperature at 80-85°C during the process. Then, 160 g of 55% oleum was added dropwise within 0.75 hours, and the reaction temperature was always controlled within 100-105° C. during the dropwise addition. After the oleum is added dropwise, keep warm for 0.5h to completely convert p-nitrotoluene, and keep the temperature at 110-115°C during the keep warm. After complete conversion of p-nitrotoluene, cool to 10°C, crystallize, and filter with suction to obtain 209.8g of NTS and 220.5g of sulfuric acid mother liquor.

[0020] Get 133.3g next time sulfonation use from gained sulfuric acid mother liquor. The remaining 87.2g of spent acid was diluted with 64.8g of water, filt...

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Abstract

The present invention discloses mother liquid circulating p-nitrotoluene sulfonating process of preparing p-nitrotoluene sulfonic acid. The process includes the following steps: adding fuming sulfuric acid in 20 % into molten p-nitrotoluene, sulfonation, and maintaining the temperature until completing reaction; cooling to crystallize, filtering to obtain sulfuric acid mother liquid; mixing molten p-nitrotoluene and sulfuric acid mother liquid, dropping fuming sulfuric acid in 50-65 %, sulfonation, and maintaining the temperature until completing reaction; cooling, crystallizing, filtering to obtain filter cake as NTS and filtrate as sulfuric acid mother liquid; reusing parital sulfuric acid mother liquid, adding water into residual filtrate to regulate sulfuric acid concentration, and filtering to obtain NTS crystal; and circulating so on. The present invention adopts fuming sulfuric acid as sulfonating agent, circulating partial sulfuric acid mother liquid, and has the advantages of reduced sulfuric acid consumption and decreased waste acid exhaust.

Description

technical field [0001] The invention relates to a method for synthesizing p-nitrotoluene-o-sulfonic acid from p-nitrotoluene in a mother liquid circulation method, which belongs to the synthesis technology of p-nitrotoluene-o-sulfonic acid. Background technique [0002] p-Nitrotoluene sulfonic acid (NTS) is the raw material for the synthesis of dye intermediate 4,4'-diaminostilbene-2,2'-disulfonic acid (DSD acid). There are more than 100 kinds of fluorescent whitening agents based on DSD acid, more than 50 kinds of reactive dyes, and more than 70 kinds of direct dyes. As a substitute for benzidine dyes, dyes synthesized with DSD acid have received extensive attention in recent years due to their non-toxicity and non-accumulation in the human body, and their production scale has developed very rapidly. [0003] In industry, NTS is usually prepared by sulfonating molten p-nitrotoluene at high temperature. The sulfonating agent is 20% oleum, liquid sulfur trioxide and gaseous...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C309/40C07C303/06
Inventor 张凤宝秦丽红张国亮王淑兰
Owner TIANJIN UNIV
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