Technology for purifying 2, 4-diaminotoluene by recrystallization method

A technology of diaminotoluene and recrystallization, applied in the direction of amino compound purification/separation, organic chemistry, etc., can solve the problems of environmental pollution, serious environmental pollution, a large amount of acidic wastewater, waste residue, etc., to avoid secondary pollution, process and device Simple, low production cost effect

Active Publication Date: 2015-03-11
CANGZHOU FENGYUAN ENVIRONMENTAL PROTECTION SCI & TECH
View PDF3 Cites 4 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Domestic manufacturers of 2,4-diaminotoluene mostly use 2,4-dinitrotoluene to reduce with iron powder under acidic conditions to produce 2,4-diaminotoluene. This process will produce a large amount of acidic wastewater, Waste residue, causing serious environmental pollution, this method is gradually being eliminated
At the same time, after extracting 2,4-diaminotoluene, a large amount of mixture of 2,4-diaminotoluene and 2,6-diaminotoluene will remain, and the ratio of the two components is about 50% each. The waste residue, the environmental pollution is also very serious

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Technology for purifying 2, 4-diaminotoluene by recrystallization method
  • Technology for purifying 2, 4-diaminotoluene by recrystallization method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Add 1000kg of 2,4 and 2,6-diaminotoluene mixture (isomerization ratio 2,4 / 2,6=(80±5) / (20±5)), 500kg of distilled water and 500kg of methanol into the reactor, Stir while heating, and reflux at a temperature of 65°C to dissolve and mix the above materials evenly; stop heating, cool down to 10-15°C with water through the jacket of the crystallizer, and precipitate crystals; separate with a centrifuge, and obtain The crystals were washed and separated with water, and the washed crystals were vacuum-dried at 65-75°C with a vacuum degree greater than 0.080MPa to obtain 600kg of 2,4-diaminotoluene with a yield of 60% (relative to 2,4 and 2,6-diaminotoluene mixture), the purity of the product (detected by gas chromatography (GC method)) is 99.78% (see figure 2 ). The washing liquid separated by centrifugation is returned to the reaction kettle through the liquid pump as raw material for recycling.

Embodiment 2

[0036] Add 1000kg of 2,4 and 2,6-diaminotoluene mixture (isomerization ratio 2,4 / 2,6=(80±5) / (20±5)), 1500kg of distilled water and 1500kg of ethanol into the reactor, Introduce nitrogen for protection, stir while heating, and dissolve and mix the above materials evenly under the reflux state of 50°C; stop heating, cool down to 10-15°C with water through the jacket of the reaction kettle, and stir to precipitate crystals; Separation, washing the crystals obtained after separation with water, separation, vacuum-drying the washed crystals at 65-75°C, the vacuum degree is greater than 0.080MPa, to obtain 580Kg of 2,4-diaminotoluene, the yield is 58% , the purity (GC method) of the product is 99.72%. The washing liquid separated by centrifugation is returned to the reaction kettle through the liquid pump as raw material for recycling.

Embodiment 3

[0038] Add 500g of 2,4 and 2,6-diaminotoluene mixture (isomerization ratio 2,4 / 2,6=(80±5) / (20±5)), 500g of distilled water and 500g of ethylene glycol into the reactor In the process, pass nitrogen protection, stir while heating, dissolve and mix the above materials evenly at a temperature of 85°C; stop heating, pass through the crystallizer jacket, cool down with water by 10-15°C, stir and precipitate crystals; use a centrifuge to separate , washing the crystals obtained after separation with water, separating, and vacuum-drying the washed crystals at 65-75° C., with a vacuum degree greater than 0.080 MPa, to obtain 325 g of 2,4-diaminotoluene with a yield of 65%. The purity of the product (GC method) is 99.57%; the washing liquid separated by centrifugation is used as raw material for recycling.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

No PUM Login to view more

Abstract

The invention discloses a technology for purifying 2, 4-diaminotoluene by a recrystallization method. The technology comprises the following steps: a) mixing the mixture of 2,4-diaminotoluene and 2,6-diaminotoluene, distilled water and an organic alcohol solvent or a ketone solvent at the mass ratio of 1:(0.5-1.5):(0.5-1.5) in a reactor, stirring the materials under a regurgitation state at the temperature of 50-90 DEG C to enable the materials to be uniformly mixed; b) stopping heating, cooling the mixed materials to the temperature of 5-25 DEG C in a crystallizer, and separating out crystals; c) performing centrifugation and washing; d) drying the washed crystals so as to obtain the pure product 2,4-diaminotoluene. Through the adoption of the technology disclosed by the invention, the content of the 2,4-diaminotoluene in products exceeds more than 99.5%, the product quality is improved, and the additional value is increased; besides, washed raffinate can be circularly utilized and can be used for replacing about 60% of raw material water and a solvent, so that the production cost is reduced, requirements of energy conservation and emission reduction are met, and secondary pollution is avoided.

Description

technical field [0001] The invention relates to a process for purifying 2,4-diaminotoluene from mixed diaminotoluene (TDA). technical background [0002] 2,4-diaminotoluene is an important dye intermediate and an important raw material for the production of toluene diisocyanate (TDI). The method of industrially synthesizing TDA is usually to first nitrate toluene to obtain mixed dinitrotoluene, and then obtain meta-position mixed dinitrotoluene after rectification and separation to remove ortho-position dinitrotoluene, and then reduce to obtain mixed TDA, 2,4- There are mainly two ratios (mass ratio) of TDA and 2,6-TDA content, 80:20 or 65:35. Because the dyes synthesized from pure 2,4-TDA have better color and the performance of polyurethane is better, so the economical and efficient production process of purifying 2,4-TDA has broad industrial prospects. [0003] At present, there are few domestic reports on the preparation of 2,4-diaminotoluene by mixing TDA. Domestic m...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/84C07C211/50
Inventor 苏德水段利黄津王长飞
Owner CANGZHOU FENGYUAN ENVIRONMENTAL PROTECTION SCI & TECH
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap