CN103936623B - Process for preparing toluene diisocyanate (TDI) by using toluenediamine and dimethyl carbonate - Google Patents
Process for preparing toluene diisocyanate (TDI) by using toluenediamine and dimethyl carbonate Download PDFInfo
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Abstract
The invention relates to a process for preparing toluene diisocyanate (TDI) by using toluenediamine and dimethyl carbonate. According to the process, a deactivation catalyst, namely zinc oxide (ZnO), of a reaction, which is used for synthesizing toluene dicarbamate (TDC) through catalyzing toluenediamine and dimethyl carbonate by zinc acetate, is used as a catalyst of a reaction for TDC decomposed TDI preparation, the deactivation catalyst, namely ZnO, of the reaction is not required to be separated from the product TDC and is directly applied to the reaction for TDC decomposition catalyzed TDI preparation, and a TDC decomposed TDI preparation process adopts that decomposition reactors of two stages are in series connection and a fractional condenser is arranged between the decomposition reactors of two stages. According to the process, TDC is synthesized through catalyzing toluenediamine and dimethyl carbonate by zinc acetate, and the deactivation catalyst, namely ZnO, of TDC synthesis is selected as an efficient catalyst for TDC decomposition reaction, so that the catalysis effect is good, and the yield of TDI is high; and the temperature of the TDC decomposition reaction is low, so that the total production cost can be greatly reduced.
Description
Technical field
The present invention be with tolylene diamine and methylcarbonate for raw material, first synthesize tolylene dicarbamate, and then prepare the technology of tolylene diisocyanate through catalytic decomposition.
Background technology
Tolylene diisocyanate (TDI) is important organic chemical industry's intermediate, is one of important source material of polyurethane industrial.Current industrial TDI produces and adopts phosgenation, but its raw material phosgene severe toxicity and by product HCl easily cause equipment corrosion, therefore enjoy domestic and international attention to the research of non-phosgene synthesis TDI always.Wherein have much industrialization potential through decomposing the technique obtaining TDI with tolylene diamine (TDA) again with methylcarbonate (DMC) Reactive Synthesis tolylene dicarbamate (TDC), TDC.
Existing many about amine and organic carbonate synthesis of carbamates, carbamate again through decomposing the bibliographical information preparing isocyanic ester.
Amine and organic carbonate Reactive Synthesis carbamate aspect: patent US4268683, US4268684 and WO99/47493 etc. all use catalyzer to carry out organic carbonate and amine Reactive Synthesis carbamate, but do not relate to the recycling of catalyzer.Patent ZL03156418.6 prepares tolylene dicarbamate with zinc acetate catalysis tolylene diamine and dimethyl carbonate, provides the renovation process of catalyzer.Patent ZL200710056664.X catalyzes and synthesizes tolylene dicarbamate with zinc acetate, is inorganic materials nano zine oxide by the catalyst development of inactivation simultaneously.
Carbamate decomposes and prepares isocyanic ester aspect: patent EP0672653A1 decomposes about carbamate to prepare isocyanic ester, and the catalyzer of employing is an alkali metal salt of organic sulfonic acid or organic sulfonic acid, and decomposition temperature is 150 ~ 350 DEG C.When Zhao Qian [Master's thesis: Hebei University of Technology, 2002.3] take zinc oxide as catalyzer, decompose tolylene dicarbamate at 260 DEG C and prepare tolylene diisocyanate, adopt chemistry titration quantitative analysis, the total recovery obtaining isocyanic ester is 80.61%.
In addition, patent EP0323514A1 to describe with diamines and methylcarbonate as the complete procedure of vulcabond prepared by raw material: first under basic catalyst effect, diamines and dimethyl carbonate prepare carbamate, and product obtains carbamate after phosphoric acid neutralization, benzene and/or washing, distillation; Then, under the katalysis of the metals such as Mn, Mo, W, Zn or Be or its compound, carbamate decomposes and obtains product isocyanic ester, decomposition temperature 150-300 DEG C.
Patent US20030162995A1 to provide with aromatic amine and organic carbonate as the integrated approach of aromatic isocyanates prepared by raw material: first in the presence of a catalyst, aromatic amine and organic carbonate Reactive Synthesis carbamate, then remove used catalyst, then make carbamate thermolysis be isocyanic ester.The temperature range of first step decomposition reactor is 230-380 DEG C, and the temperature of second stage decomposition reactor is 300-600 DEG C.
As fully visible:
(1) for amine and organic carbonate Reactive Synthesis carbamate process: need carbamate and catalyst separating after having reacted in document, then just can carry out next step decomposition reaction.Namely must there is catalyst separating step, and not consider that the comprehensive reasonable of catalyzer in synthesizing isocyanate process utilizes.
(2) prepare isocyanic ester process for carbamate decomposition: most literature is carried out under catalyst action, and the catalyzer adopted all has nothing to do with carboxylamine catalyst for ester synthesis, decomposition temperature is high; Although there is decomposition reaction in document not adopt catalyzer, but need to carry out at very high temperatures, the temperature of first step reactor reaches 230-380 DEG C, the decomposition temperature of second stage reactor reaches 300-600 DEG C, easily there is side reaction in so high temperature of reaction, cause product yield low, and can greatly increase equipment cost and production cost.
Instant invention overcomes the deficiency of previous method, optimize TDI synthetic technology.The decaying catalyst zinc oxide of synthesis TDC process is directly used in catalysis TDC and decomposes preparation TDI process by the present invention, inactivation zinc oxide is efficiently recycled, again for TDC decomposition reaction provides effective catalyst; The TDC of synthesis and the separating step of decaying catalyst zinc oxide can be saved simultaneously, whole TDI synthetic operation be simplified, is conducive to suitability for industrialized production; TDC decomposes preparation TDI process and adopts two-stage decomposition reactor serial operation, is provided with partial condenser, has both reduced decomposition reaction temperature, avoid again side reaction to occur, effectively improve product yield between two-stage decomposition reactor.
Have not yet to see and decompose the research preparing isocyanate reaction report about the decaying catalyst of amine and organic carbonate Reactive Synthesis carbamate being directly used in catalytic amino manthanoate, also not about carbamate decompose prepare the operation of isocyanic ester process two-stage series connection decomposition reactor between be provided with the process introduction of partial condenser.
Summary of the invention
Technical problem to be solved by this invention is: provide that a kind of technique is simple, catalyzer efficiently recycles, reaction conditions is gentle, avoid high-temperature operation, the new technology of TDI yield is high, cost is low preparation TDI.Its core is: decaying catalyst zinc oxide zinc acetate catalysis tolylene diamine and dimethyl carbonate synthesis TDC reacted is used as TDC and decomposes the catalyzer prepared TDI and react, the decaying catalyst ZnO of this reaction does not need to be separated with product TDC, but be directly used in catalysis TDC decomposition preparation TDI reaction, TDC decomposes preparation TDI process and adopts two-stage decomposition reactor serial operation, and is provided with partial condenser between two-stage decomposition reactor.
The present invention solves this technical problem adopted technical scheme:
Utilize tolylene diamine and methylcarbonate to prepare a technique for tolylene diisocyanate, comprise the following steps:
1) tolylene diamine and methylcarbonate are raw material, zinc acetate is that catalyzer synthesizes TDC
First in a kettle. tolylene diamine, zinc acetate and methylcarbonate is added successively, its mol ratio is tolylene diamine: zinc acetate: methylcarbonate=1: 0.05 ~ 0.4: 18 ~ 30, then sealed reactor, under agitation, being heated to temperature is 120 ~ 180 DEG C, reacts 3 ~ 8 hours; After reaction terminates, cooling, discharging, feed liquid goes still kettle, 30 ~ 60 DEG C, 5 ~ 30kPa underpressure distillation, namely obtains the mixture of solid product TDC and decaying catalyst ZnO;
Gas phase to the first condenser that underpressure distillation goes out, obtains the liquid mixture of methylcarbonate, methyl alcohol and methyl acetate after condensation;
2) TDC catalytic decomposition prepares TDI
First thermal barrier is added respectively in first step decomposition reactor and second stage decomposition reactor; The mixture of TDC and the ZnO upper step obtained, in dissolving tank dissolution with solvents, then adds first step decomposition reactor, then gets the mixture of TDC and the ZnO that step obtains, and obtains ZnO, added second stage decomposition reactor after being separated; In first step decomposition reactor, 170 ~ 260 DEG C, react under system pressure 5 ~ 25kPa condition, the gas-phase product of first step decomposition reactor is through the first fractional column, enter the first partial condenser, at 15 ~ 35 DEG C, obtain intermediate product toluene monoisocyanates (TMI) liquid, TMI is added to the further decomposition reaction of second stage decomposition reactor, and uncooled gas phase TDI, methyl alcohol remove the second partial condenser; Decomposition reaction actuator temperature in the second stage is 180 ~ 260 DEG C, under system pressure 5 ~ 25kPa condition, carry out decomposition reaction; The gas-phase product of second stage decomposition reactor, after after-fractionating post, enters the second partial condenser equally; The condensation at 15 ~ 35 DEG C of second partial condenser, obtains object product TDI; By-product carbinol obtains methyl alcohol through the condensation at-5 ~ 15 DEG C of the second condenser;
The same solvent of material that described thermal barrier adopts; Wherein, in two-stage decomposition reactor, ZnO concentration range is equal to or is greater than 8.0 × 10
-4g/mL thermal barrier.
Described thermal barrier is alkane, aromatic hydrocarbon, naphthenic hydrocarbon, ether, ester, amine or sulfone.
Described thermal barrier is preferably dimethyl phthalate, dioctyl phthalate (DOP), dibutyl phthalate, whiteruss, dioctyl sebacate, butyl (tetra) titanate, tetramethylene sulfone or naphthenic oil.
In described step (2), in first step decomposition reactor, the feed way of TDC and ZnO is that continuous charging or interval are reinforced.
When in described step (2), in first step decomposition reactor, the feed way of TDC and ZnO is for feeding in raw material for interval, the first step decomposition reactor reaction times is 0.8-2.0 hour, the reaction times of second stage decomposition reactor starts timing with material when the first partial condenser flows into this reactor, and the reaction times is 0.8-2.0 hour.
In described step (1), the tolylene diamine added is 2,4-tolylene diamine, 2,6-tolylene diamines or their blend.
In described step (1), the tolylene diamine added is the blend of 2,4-tolylene diamine, 2,6-tolylene diamines, and the mass ratio of its component is 2,4-tolylene diamine: 2,6-tolylene diamine=65 ~ 80: 20 ~ 35.
In two-stage reactor, ZnO concentration range is preferably all 8.0 × 10
-4~ 4.0 × 10
-2between g/mL thermal barrier.
Described step 1) tolylene diamine and methylcarbonate are raw material, zinc acetate is that catalyzer synthesizes in TDC, when reacting at 120 ~ 180 DEG C, react for isothermal reaction or two sections of temperature reactions; When for two sections of temperature reactions, react 1 ~ 3 hour at 120 ~ 140 DEG C, at being then warming up to 140 ~ 180 DEG C, react 2 ~ 5 hours again.
The invention has the beneficial effects as follows: the preparation method of TDI of the present invention is that technique is simple, reaction conditions is gentle, catalyzer efficiency utilization, avoid high-temperature operation, TDI yield is high, production cost is low methylcarbonate legal system is for the new technology of TDI.More outstanding substantive distinguishing features is, decaying catalyst ZnO that TDC reacts prepared by zinc acetate catalysis tolylene diamine and methylcarbonate and is used for catalysis TDC and decomposes and prepare TDI process; Save the separating step of decaying catalyst and product TDC; TDC decomposes preparation TDI process and adopts two-stage decomposition reactor serial operation, and is provided with partial condenser between two-stage decomposition reactor, can under the TDC decomposition temperature of gentleness, obtain the TDI of high yield.
Above-mentioned beneficial effect is embodied in:
(1) effective catalyst of decaying catalyst ZnO as TDC decomposition reaction of TDC is synthesized: excellent catalytic effect, TDI yield is high.Products therefrom yield than in background technology with outsourcing zinc oxide for the yield that obtains during catalyzer is high a lot.Save the expense of TDC decomposition course for catalyzer, reduce the production cost of TDI.
(2) the efficient recycling of decaying catalyst ZnO: decaying catalyst ZnO that TDC reacts prepared by tolylene diamine and methylcarbonate and be used as TDC and decompose the catalyzer preparing TDI, decaying catalyst ZnO is efficiently recycled, avoids decaying catalyst and discard the waste caused and the detrimentally affect that environment is caused.
(3) operation steps is saved: the decaying catalyst ZnO of synthesis TDC reaction is used for catalysis TDC and decomposes preparation TDI reaction, the sepn process of TDC and decaying catalyst ZnO can be saved, save operation steps, reduce with tolylene diamine and methylcarbonate as the production cost of TDI prepared by raw material.
(4) reduce decomposition reaction temperature, improve TDI yield: TDC decomposes preparation TDI process and adopts two-stage decomposition reactor serial operation, and is provided with partial condenser between two-stage decomposition reactor.Avoid only adopt A reactor time, if at low-temp reaction, can because of intermediate product completely decompose cause TDI yield low; And according to pyroreaction, can cause because of high temperature polymerization side reaction the shortcoming that TDI yield is low again; It also avoid the shortcoming of not establish partial condenser that TDI can be caused to repeat to enter reactor between two decomposition reactors to cause polymerization side reactions.The present invention under the decomposition temperature of gentleness, can obtain the TDI of high yield.
(5) reduce equipment cost and running cost: TDC decomposition reaction temperature of the present invention is low, equipment cost can be reduced, also can save the cold medium consumption of reaction later stage condenser, reduce the cost recovery of by-product carbinol, total cost of production is reduced.
Accompanying drawing explanation
Accompanying drawing 1 is that tolylene diamine (TDA) synthesizes tolylene diisocyanate (TDI) process schematic with methylcarbonate (DMC), wherein, and 1-reactor, 2-underpressure distillation still, 3-first condenser, 4-dissolving tank, 5-first step decomposition reactor, 6-second stage decomposition reactor, 7-first fractional column, 8-after-fractionating post, 9-first partial condenser, 10-second partial condenser, 11-second condenser
Embodiment:
By the following example, the present invention is described, but the invention is not restricted to the following example.
Tolylene diisocyanate synthesizer of the present invention as shown in Figure 1.
Tolylene dicarbamate synthesizes: first tolylene diamine, methylcarbonate and catalyst acetic acid zinc are added reactor 1, its mol ratio is tolylene diamine: zinc acetate: methylcarbonate=1: 0.05 ~ 0.4: 18 ~ 30, then sealed reactor, under agitation, being heated to temperature is 120 ~ 180 DEG C, reacts 3 ~ 8 hours.This building-up reactions can be carried out by constant temperature, also can carry out by alternating temperature.The pressure of reactor is system autogenous pressure, does not need other adjustment.After having reacted, material cooling, discharging, feed liquid is to underpressure distillation still 2,30 ~ 60 DEG C, 5 ~ 30kPa underpressure distillation, obtain the mixture of solid product tolylene dicarbamate and decaying catalyst zinc oxide, gas phase, to condenser 3, obtains the liquid mixture of methylcarbonate, methyl alcohol and methyl acetate after condensation.
Tolylene dicarbamate decomposes: first thermal barrier is added respectively first step decomposition reactor 5 and second stage decomposition reactor 6, the mixture of TDC and the ZnO upper step obtained adds first step decomposition reactor 5 after dissolving tank 4 dissolves, get the mixture of TDC and the ZnO that step obtains again, after being separated, obtaining ZnO, being added second stage decomposition reactor 6; In first step decomposition reactor 5,170 ~ 260 DEG C, react under system pressure 5 ~ 25kPa condition, the gas-phase product of first step decomposition reactor 5 is through fractional column 7, enter partial condenser 9, at 15 ~ 35 DEG C, obtain intermediate product toluene monoisocyanates (TMI), TMI is added to second stage decomposition reactor 6 decomposition reaction further, and uncooled gas phase TDI, methyl alcohol remove partial condenser 10; Second stage decomposition reactor 6 temperature is 180 ~ 260 DEG C, under system pressure 5 ~ 25kPa condition, carry out decomposition reaction; The gas-phase product of second stage decomposition reactor 6, after fractional column 8, enters partial condenser 10 equally; Partial condenser 10 condensation at 15 ~ 35 DEG C, obtains object product TDI; By-product carbinol obtains methyl alcohol through condenser 11 condensation at-5 ~ 15 DEG C.
In two-stage decomposition reactor, ZnO concentration range is equal to or is greater than 8.0 × 10
-4g/mL thermal barrier; In two-stage decomposition reactor, ZnO concentration range is preferably all 8.0 × 10
-4~ 4.0 × 10
-2between g/mL thermal barrier.
Embodiment 1:
(1) 5g2 is added successively in reactor 1,4-tolylene diamine, 97mL methylcarbonate, 0.82g zinc acetate, then sealed reactor.Under agitation, being heated to temperature is 140 DEG C, reacts 3 hours; Be warming up to 170 DEG C again, and count from intensification, maintain reaction 3 hours, reaction terminates.Feed liquid cooling, discharging are reacted, to underpressure distillation still 2 at 30 DEG C, 5kP
aunderpressure distillation under condition, obtains the mixture 10.1g of solid product tolylene dicarbamate and zinc oxide, and adopt high performance liquid chromatography to analyze product, tolylene dicarbamate yield is 99.2%.
The gas phase that underpressure distillation goes out, to condenser 3, obtains the liquid mixture of methylcarbonate, methyl alcohol and methyl acetate, traditionally isolates methylcarbonate after condensation, methylcarbonate loops back TDC building-up process (following examples are same);
(2) add 50mL dioctyl phthalate (DOP) respectively in two-stage decomposition reactor 5 and 6, simultaneously logical nitrogen, in second stage decomposition reactor 6, add 0.4g zinc oxide (above walk the mixture of TDC and the ZnO obtained, obtain ZnO after being separated).Reacting system pressure is adjusted to 8kPa, the cold medium temperature regulating partial condenser 9 is 15 DEG C, the cold medium temperature regulating partial condenser 10 is 20 DEG C, the cold medium temperature of condenser 11 is-5 DEG C, and first step decomposition reactor 5 temperature is 260 DEG C, and second stage reactor 6 temperature is 180 DEG C.The mixture of the TDC obtained in 1.4g above-mentioned steps (1) and zinc oxide is dissolved in dioctyl phthalate (DOP), and it is at the uniform velocity added first step decomposition reactor 5, charging reaction time remaining 1.5h, after reaction terminates, the TDI amount that the decomposition reaction of metering two-stage is collected, adopts ethanol derivatization method to carry out efficient liquid phase chromatographic analysis to product, to join the TDC of decomposition reactor 5, TDI yield is 90.6%, TDI and TMI total recovery is 99.8%.
The cooling medium that in the present embodiment, condenser uses is industrial spirit (following examples are same).
Embodiment 2
Step (1) is with embodiment 1.
(2) add 50mL dibutyl phthalate respectively in two-stage decomposition reactor 5 and 6, simultaneously logical nitrogen, in second stage decomposition reactor 6, add 0.2g zinc oxide (above walk the mixture of TDC and the ZnO obtained, obtain ZnO after being separated).Reacting system pressure is adjusted to 10kPa, the cold medium temperature regulating partial condenser 9 is 15 DEG C, and the cold medium temperature regulating partial condenser 10 is 20 DEG C, and the cold medium temperature of condenser 11 is 0 DEG C, first step decomposition reaction actuator temperature is 220 DEG C, and decomposition reaction actuator temperature in the second stage is 240 DEG C.The mixture of the TDC obtained in 1.4g step (1) and zinc oxide is dissolved in appropriate dibutyl phthalate, and it is at the uniform velocity added first step decomposition reactor, charging reaction time remaining 1.8h, after reaction terminates, the TDI amount that the decomposition reaction of metering two-stage is collected, adopts ethanol derivatization method to carry out efficient liquid phase chromatographic analysis to product, to join the TDC of decomposition reactor 5, TDI yield is 95.1%, TDI and TMI total recovery is 99.9%.
Embodiment 3:
(1) 5g2 is added successively in reactor 1,6-tolylene diamine, 104mL methylcarbonate, 0.38g zinc acetate, then sealed reactor.Under agitation, being heated to temperature is 120 DEG C, reacts 1 hour; Be warming up to 180 DEG C again, and count from intensification, maintain reaction 2 hours, reaction terminates.Cooling, discharging, feed liquid, 40 DEG C, underpressure distillation under 15kPa condition, obtains solid product Toluene-2,4-diisocyanate, the mixture 9.71g of 4-diamino-methyl formate and zinc oxide, adopt high performance liquid chromatography to analyze product, tolylene dicarbamate yield is 95.0%.
(2) add 50mL naphthenic oil respectively in two-stage decomposition reactor 5 and 6, simultaneously logical nitrogen, in the decomposition reactor of the second stage, add 2g zinc oxide (above walk the mixture of TDC and the ZnO obtained, obtain ZnO after being separated).Reacting system pressure is adjusted to 15kPa, the cold medium temperature regulating partial condenser 9 is 20 DEG C, and the cold medium temperature regulating partial condenser 10 is 25 DEG C, and the cold medium temperature of condenser 11 is 10 DEG C, first step decomposition reaction actuator temperature is 200 DEG C, and decomposition reaction actuator temperature in the second stage is 230 DEG C.The mixture of the TDC obtained in 2.8g above-mentioned steps (1) and zinc oxide is dissolved in appropriate naphthenic oil, and it is at the uniform velocity added first step decomposition reactor, charging reaction time remaining 1.4h, after reaction terminates, the TDI amount that the decomposition reaction of metering two-stage is collected, adopts ethanol derivatization method to carry out efficient liquid phase chromatographic analysis to product, to join the TDC of decomposition reactor, TDI yield is 85.8%, TDI and TMI total recovery is 99.8%.
Embodiment 4:
(1) adding 5g mass ratio in reactor 1 is successively 2,4-tolylene diamine: 2,6-tolylene diamine=80: the mixture of 20,62mL methylcarbonate, 1.05g zinc acetate, then sealed reactor.Under agitation, being heated to temperature is 130 DEG C, reacts 2 hours; Be warming up to 160 DEG C again, and count from intensification, maintain reaction 5 hours, reaction terminates.Cooling, discharging, feed liquid, 50 DEG C, underpressure distillation under 20kPa condition, obtains the mixture 9.9g of solid product tolylene dicarbamate and zinc oxide, and employing high performance liquid chromatography is analyzed product, and tolylene dicarbamate yield is 94.2%.
(2) add 50mL butyl (tetra) titanate respectively in two-stage decomposition reactor 5 and 6, simultaneously logical nitrogen, in the decomposition reactor of the second stage, add 0.3g zinc oxide (above walk the mixture of TDC and the ZnO obtained, obtain ZnO after being separated).Reacting system pressure is adjusted to 5kPa, regulates the cold medium temperature of partial condenser 9 and 10 to be 15 DEG C, regulate the cold medium temperature of condenser 11 to be-5 DEG C, first step decomposition reaction actuator temperature is 170 DEG C, and decomposition reaction actuator temperature in the second stage is 260 DEG C.The mixture of the TDC obtained in 1.4g above-mentioned steps (1) and zinc oxide is dissolved in appropriate butyl (tetra) titanate, and it is at the uniform velocity added first step decomposition reactor, charging reaction time remaining 1.2h, after reaction terminates, the TDI amount that the decomposition reaction of metering two-stage is collected, adopts ethanol derivatization method to carry out efficient liquid phase chromatographic analysis to product, to join the TDC of decomposition reactor, TDI yield is 85.4%, TDI and TMI total recovery is 99.7%.
Embodiment 5:
(1) 5g2 is added successively in reactor 1,4-tolylene diamine benzene, 97mL methylcarbonate, 3.01g zinc acetate, then sealed reactor.Under agitation, being heated to temperature is 160 DEG C, reacts 8 hours, and reaction terminates.Cooling, discharging, feed liquid, 60 DEG C, underpressure distillation under 30kPa condition, obtains the mixture 11.1g of solid product tolylene dicarbamate and zinc oxide, and employing high performance liquid chromatography is analyzed product, and tolylene dicarbamate yield is 97.3%.
(2) add 50mL dimethyl phthalate respectively in two-stage decomposition reactor, simultaneously logical nitrogen, in the decomposition reactor of the second stage, add 0.04g zinc oxide (above walk the mixture of TDC and the ZnO obtained, obtain ZnO after being separated).Reacting system pressure is adjusted to 25kPa, and regulate the cold medium temperature of partial condenser 9 and 10 to be 35 DEG C, the cold medium temperature regulating condenser 11 is 15 DEG C, and first step decomposition reaction actuator temperature is 230 DEG C, and decomposition reaction actuator temperature in the second stage is 250 DEG C.The TDC obtain reaction in 1.4g above-mentioned steps (1) and the mixture of zinc oxide are dissolved in appropriate dimethyl phthalate, and it is at the uniform velocity added first step decomposition reactor, charging reaction time remaining 2h, after reaction terminates, the TDI amount that the decomposition reaction of metering two-stage is collected, adopts ethanol derivatization method to carry out efficient liquid phase chromatographic analysis to product, to join the TDC of decomposition reactor, TDI yield is 82.3%, TDI and TMI total recovery is 95.5%.
Embodiment 6:
Step (1) is with embodiment 5.
(2) thermal barrier using the rear thermal barrier dioctyl phthalate (DOP) reclaimed as the present embodiment two-stage decomposition reactor is adopted in embodiment 1 step (2); Second stage decomposition reactor 6 in embodiment 1 step (2) is adopted to use the zinc oxide of rear recovery as the catalyzer of the present embodiment second stage decomposition reactor 6.
Add 50mL dioctyl phthalate (DOP) respectively in two-stage decomposition reactor, logical nitrogen, adds 0.3g zinc oxide in the decomposition reactor of the second stage simultaneously.Reacting system pressure is adjusted to 10kPa, the cold medium temperature regulating partial condenser 9 is 25 DEG C, and the cold medium temperature regulating partial condenser 10 is 30 DEG C, and the cold medium temperature of condenser 11 is 15 DEG C, first step decomposition reaction actuator temperature is 190 DEG C, and decomposition reaction actuator temperature in the second stage is 260 DEG C.The TDC obtain reaction in 1.4g step (1) and the mixture of zinc oxide are dissolved in appropriate dioctyl phthalate (DOP), and divided equally three times and add first step decomposition reactor, reaction times 0.8h, after reaction terminates, the TDI amount that the decomposition reaction of metering two-stage is collected, adopts ethanol derivatization method to carry out efficient liquid phase chromatographic analysis to product, to join the TDC of decomposition reactor, TDI yield is 81.2%, TDI and TMI total recovery is 92.6%.
Claims (8)
1. utilize tolylene diamine and methylcarbonate to prepare a technique for tolylene diisocyanate, it is characterized by and comprise the following steps:
1) tolylene diamine and methylcarbonate are raw material, zinc acetate is that catalyzer synthesizes tolylene dicarbamate (TDC)
First in a kettle. tolylene diamine, zinc acetate and methylcarbonate is added successively, its mol ratio is tolylene diamine: zinc acetate: methylcarbonate=1: 0.05 ~ 0.4: 18 ~ 30, then sealed reactor, under agitation, being heated to temperature is 120 ~ 180 DEG C, reacts 3 ~ 8 hours; After reaction terminates, cooling, discharging, feed liquid goes still kettle, 30 ~ 60 DEG C, 5 ~ 30kPa underpressure distillation, namely obtains the mixture of solid product TDC and decaying catalyst ZnO;
Gas phase to the first condenser that underpressure distillation goes out, obtains the liquid mixture of methylcarbonate, methyl alcohol and methyl acetate after condensation;
2) TDC catalytic decomposition prepares tolylene diisocyanate (TDI)
First thermal barrier is added respectively in first step decomposition reactor and second stage decomposition reactor; The mixture of TDC and the ZnO upper step obtained, in dissolving tank dissolution with solvents, then adds first step decomposition reactor, then gets the mixture of TDC and the ZnO that step obtains, and obtains ZnO, added second stage decomposition reactor after being separated; In first step decomposition reactor, 170 ~ 260 DEG C, react under system pressure 5 ~ 25kPa condition, the gas-phase product of first step decomposition reactor is through the first fractional column, enter the first partial condenser, at 15 ~ 35 DEG C, obtain intermediate product toluene monoisocyanates (TMI), TMI is added to the further decomposition reaction of second stage decomposition reactor, and uncooled gas phase TDI, methyl alcohol remove the second partial condenser; Decomposition reaction actuator temperature in the second stage is 180 ~ 260 DEG C, under system pressure 5 ~ 25kPa condition, carry out decomposition reaction; The gas-phase product of second stage decomposition reactor, after after-fractionating post, enters the second partial condenser equally; The condensation at 15 ~ 35 DEG C of second partial condenser, obtains object product TDI; By-product carbinol obtains methyl alcohol through the condensation at-5 ~ 15 DEG C of the second condenser;
The same solvent of material that described thermal barrier adopts; Wherein, in two-stage decomposition reactor, ZnO concentration range is equal to or is greater than 8.0 × 10
-4g/mL thermal barrier;
Described thermal barrier is alkane, aromatic hydrocarbon, naphthenic hydrocarbon, ether, ester, amine or sulfone.
2. utilize tolylene diamine and methylcarbonate to prepare the technique of tolylene diisocyanate as claimed in claim 1, it is characterized by described thermal barrier and be preferably dimethyl phthalate, dioctyl phthalate (DOP), dibutyl phthalate, dioctyl sebacate, butyl (tetra) titanate or tetramethylene sulfone.
3. utilize tolylene diamine and methylcarbonate to prepare the technique of tolylene diisocyanate as claimed in claim 1, the feed way that it is characterized by TDC and ZnO in first step decomposition reactor in described step (2) is that continuous charging or interval are reinforced.
4. utilize tolylene diamine and methylcarbonate to prepare the technique of tolylene diisocyanate as claimed in claim 3, the feed way that it is characterized by TDC and ZnO in first step decomposition reactor in described step (2) for interval feed in raw material time, the first step decomposition reactor reaction times is 0.8-2.0 hour, the reaction times of second stage decomposition reactor starts timing with material when the first partial condenser flows into this reactor, and the reaction times is 0.8-2.0 hour.
5. utilize tolylene diamine and methylcarbonate to prepare the technique of tolylene diisocyanate as claimed in claim 1, it is characterized by described step (1), the tolylene diamine added is 2,4-tolylene diamine, 2,6-tolylene diamines or their blend.
6. utilize tolylene diamine and methylcarbonate to prepare the technique of tolylene diisocyanate as claimed in claim 5, it is characterized by described step (1), the tolylene diamine added is 2,4-tolylene diamine, 2, the blend of 6-tolylene diamine, the mass ratio of its component is 2,4-tolylene diamine: 2,6-tolylene diamine=65 ~ 80: 20 ~ 35.
7. utilize tolylene diamine and methylcarbonate to prepare the technique of tolylene diisocyanate as claimed in claim 1, it is characterized by ZnO concentration range in two-stage reactor and be preferably all 8.0 × 10
-4~ 4.0 × 10
-2between g/mL thermal barrier.
8. utilize tolylene diamine and methylcarbonate to prepare the technique of tolylene diisocyanate as claimed in claim 1, it is characterized by described step 1) tolylene diamine and methylcarbonate are raw material, zinc acetate is that catalyzer synthesizes in TDC, when reacting at 120 ~ 180 DEG C, react for isothermal reaction or two sections of temperature reactions; When for two sections of temperature reactions, react 1 ~ 3 hour at 120 ~ 140 DEG C, at being then warming up to 140 ~ 180 DEG C, react 2 ~ 5 hours again.
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