CN1785969A

CN1785969A - Semicontinuous method of preparing DSD acid by iron powder reducing DNS sodium salt

Info

Publication number: CN1785969A
Application number: CN 200510122439
Authority: CN
Inventors: 张凤宝; 范晓彬; 张国亮
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2005-12-20
Filing date: 2005-12-20
Publication date: 2006-06-14
Anticipated expiration: 2025-12-20
Also published as: CN1313444C

Abstract

The present invention discloses a semi-continuous method for preparing DSD acid by using iron powder reduced DNS sodium salt. Said method adopts two reactors, and its process includes the following steps: adding acetic acid and concentrated sulfuric acid as additive into first reactor in which the iron powder and water are held, after precorrosion, adding DNS sodium salt solution into said reactor, controlling pH value of reaction system and making it be 5.1-5.6; importing partial reaction solution into second reactor in which the iron powder and water are held from first reactor, supplementing iron powder and acetic acid into first reactor, then continuously adding DNS sodium salt solution; at the same time, after the reaction solution in the second reactor is continuously reacted, the solution can be completely discharged, then adding NaOH solution to regulate solution pH value, filtering to remove ferrous mud; adding sulfuric acid into the obtained filtrate to regulate pH value, then filtering so as to obtain DSD acid.

Description

The semicontinuous method of preparing DSD acid by iron powder reducing DNS sodium salt

Technical field

The present invention relates to a kind of semicontinuous method of preparing DSD acid by iron powder reducing DNS sodium salt, belong to the technology of preparation DSD acid.

Background technology

4,4 '-diaminobenzil-2,2 '-disulfonic acid (DSD acid) are the important intermediate of preparation toluylene type white dyes and StilbeneShi substantive dyestuff, reactive dyestuffs.The major industry production technique of DSD acid at present is the Bechamp reduction method, promptly in the presence of iron and ferrous salt from 4,4 '-dinitrobenzene toluylene-2,2 '-disulfonic acid (DNS) sodium salt directly reduces and obtains.Therefore this method produces a large amount of iron mud owing to need consume iron powder in process of production, and passivation iron powder surface, make speed of reaction along with the carrying out of reaction progressively descends, so corresponding D NS sodium salt adds limited speed, feeding intake needs long-time insulation after finishing, and the production cycle is long.And traditional technology is followed fluctuating widely of pH value at the initial stage that adds the DNS sodium salt, makes quality product restive.Andnon-continuous operation manner is all adopted in the restoring operation of the sour manufacturer of present domestic DSD, and not only labour intensity is big, and the time that reaction is finished is longer, and quality product is not high.

Summary of the invention

The object of the present invention is to provide a kind of semicontinuous method of preparing DSD acid by iron powder reducing DNS sodium salt.The easily control of pH value in process of production of this method, the reaction times is short, and the purity and the yield of the DSD acid of being produced are higher.

The present invention is realized by following technical proposals, a kind of semicontinuous method of preparing DSD acid by iron powder reducing DNS sodium salt, and this method adopts two reactors, and its feature comprises following process:

The first step: the mass ratio that adds by iron powder and water in first reactor is 1.5-1.8: 1 mixing solutions under violent stirring, adds the acetic acid of 0.05-0.06 mole and the vitriol oil of 0.047-0.048 mole to this reactor by every premium on currency again.Be heated to 95-100 ℃ and made the iron powder pre-etching 1-2 hour.At 95-100 ℃, adding above-mentioned mixeding liquid volume 4.5-5 mass concentration doubly in reactor is the DNS sodium salt solution of 15-20%.Control pH value of reaction system at 5.1-5.6 by the feed rate strictness.

Second step: in second reactor, add with first reactor in be 1.5-1.8 with the iron powder of volume and the mass ratio of water: 1 mixing solutions, with second reactor of 2/3-3/4 reaction solution importing of the reaction solution volume in first reactor.Add 0.2-0.3 kilogram iron powder and 0.05-0.06 molar acetate to first reactor by every liter of residual reaction liquid afterwards.And to continue to add its residual reaction liquid volume 4.5-5 mass concentration doubly to first reactor be the DNS sodium salt solution of 15-20%.The pH value of progressively accelerating rate of feeding and keeping reaction solution is at 5.1-5.6; Simultaneously, the reaction solution in second reactor continues insulation after 1-1.5 hour under 95-100 ℃ and violent stirring, and reaction solution in second reactor all being derived and add mass concentration to this derivations reaction solution is that 30% NaOH solution adjustment pH value is to 9-11.Filter the back and remove de-iron mud, gained filtrate adds sulphuric acid soln and adjusts the pH value to 1-2, filters and obtains DSD acid.

The 3rd step: continuously repeat third step 5-6 time, stop also iron mud in the purge reactor at last.

The invention has the advantages that, replace traditional single reactor, the step that feeds intake is carried out separately in two reactors with incubation step, shorten the production cycle, raising DSD acid yield with double-reactor.And in order to adapt to the decline of system speed of reaction, the speed that adds of traditional DNS sodium salt needs progressively to reduce, and the present invention takes different dosing methods, and the speed that adds of DNS sodium salt is progressively quickened for slow back is fast earlier.Solved the initial reaction stage pH value problem that fluctuates widely, gained DSD acid product quality is higher.

Embodiment

Example one:

Turbine stirring is being housed, thermometer, reflux condensate device, charging opening, pack in 2 liters of stainless steel reduction reaction stills of first of pH meter and heating unit 200ml water and 300 gram iron powders.The acetic acid additive that under the strong mixing condition, successively adds 0.95 gram sulfuric acid (98%) and 0.01mol.Begin to be heated to reflux temperature and kept 30-60 minute.When the pH value reaches 5.1-5.6, dropwise add mass concentration and be 1 liter of DNS sodium salt solution of 17%, and slowly accelerate rate of feeding.Strict control pH value is 5.1-5.6.Charging time is 1.5-2.5 hour.First reactor is reinforced finish after, the reaction solution of wherein 800ml volume is entered second stainless steel reduction reaction still that 100 gram iron powders and 200ml water are housed by overflow.In first reactor, add acetic acid additive and the 50 gram iron powders of 0.01mol afterwards in the remaining 400ml reaction solution, continue to add mass concentration and be 1 liter of 17% DNS sodium salt solution.Progressively accelerate rate of feeding and make the pH value stabilization at 5.1-5.6; Simultaneously, reaction solution continues reaction and all derives after 1 hour in second reactor.The adding mass concentration is 30% NaOH solution in the mixed solution after deriving, adjusts the pH value to 9-11, removes by filter iron mud, adds the vitriol oil (98%) and adjust the pH value to 1-2 in gained filtrate, filters and obtains the DSD acid product.Repeat to stop behind the aforesaid operations five times and purge reactor in iron mud.Through high pressure liquid chromatographic analysis, the DSD acid content of five batches of products on average reaches 98.2%, is 97.3% of theoretical yield in the average yield of DNS.

Example two:

Mass content is 17% DNS sodium salt solution 7.5m ³At 20m ³Have in the stainless steel reactor of agitator and bottom discharge device and add 2m ³Water and 3000 kilograms of iron powders.The additive acetic acid that under the strong mixing condition, successively adds 10 kilo sulfuric acid (93%) and 100mol.Begin to be heated to 95 ℃ and kept 30-60 minute.When the pH value reaches 5.1-5.6, begin to add mass concentration and be 17% DNS sodium salt solution, slowly accelerate rate of feeding, strict control pH value is 5.1-5.6.Charging time is 4-5.5 hour.First stainless steel reduction reactor 10m that feeds in raw material ³After, will about 8m ³Reaction solution enter the stainless steel reduction reactor that the next one is equipped with 1000 kilograms of iron powders and agitator by overflow.Remaining 4m in first reactor afterwards ³Add acetic acid and the 500 gram iron powders of 100mol in the solution, continue to add DNS sodium salt solution 10m ³Progressively accelerate rate of feeding and make the pH value stabilization at 5.1-5.6; Simultaneously, reaction solution continues reaction and derives by overflow after about 1 hour in second reactor.The adding mass concentration is 30% NaOH solution in the mixed solution of deriving, and adjusts the pH value to 9-11, removes by filter iron mud, adds the vitriol oil (98%) and adjust the pH value to 1-2 in gained filtrate, filters and obtains the DSD acid product.After repeating aforesaid operations five times, stop and removing iron mud.Through high pressure liquid chromatographic analysis, the DSD acid content of five batches of products on average reaches 98.1%, is 97.5% of theoretical yield in the average yield of DNS.

Claims

1. the semicontinuous method of a preparing DSD acid by iron powder reducing DNS sodium salt, this method adopts two reactors, and its feature comprises following process:

(1) mass ratio that adds by iron powder and water in first reactor is 1.5-1.8: 1 mixing solutions under violent stirring, adds the acetic acid of 0.05-0.06 mole and the vitriol oil of 0.047-0.048 mole to this reactor by every premium on currency again; Be heated to 95-100 ℃ and made the iron powder pre-etching 1-2 hour, at 95-100 ℃, adding above-mentioned mixeding liquid volume 4.5-5 mass concentration doubly in reactor is the DNS sodium salt solution of 15-20%, controls pH value of reaction system at 5.1-5.6 by the strictness of control feed rate;

(2) in second reactor, add with first reactor in be 1.5-1.8 with the iron powder of volume and the mass ratio of water: 1 mixing solutions, with second reactor of 2/3-3/4 reaction solution importing of the reaction solution volume in first reactor; Add 0.2-0.3 kilogram iron powder and 0.05-0.06 molar acetate to first reactor by every liter of residual reaction liquid afterwards, and to continue to add its residual reaction liquid volume 4.5-5 mass concentration doubly to first reactor be the DNS sodium salt solution of 15-20%, and the pH value of progressively accelerating rate of feeding and keeping reaction solution is at 5.1-5.6; Simultaneously, reaction solution in second reactor continues insulation after 1-1.5 hour under 95-100 ℃ and violent stirring, reaction solution in second reactor all being derived and add mass concentration to this derivations reaction solution is that 30% NaOH solution adjustment pH value is to 9-11, filter the back and remove de-iron mud, gained filtrate adds sulphuric acid soln and adjusts the pH value to 1-2, filters and obtains DSD acid;

(3) continuous 5-6 repeating step (2) stops also iron mud in the purge reactor at last.