EP0000602B1 - Process for the preparation of isocyanates from formamides - Google Patents

Process for the preparation of isocyanates from formamides Download PDF

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Publication number
EP0000602B1
EP0000602B1 EP78200097A EP78200097A EP0000602B1 EP 0000602 B1 EP0000602 B1 EP 0000602B1 EP 78200097 A EP78200097 A EP 78200097A EP 78200097 A EP78200097 A EP 78200097A EP 0000602 B1 EP0000602 B1 EP 0000602B1
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Prior art keywords
process according
isocyanate
reaction
water
reaction mixture
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German (de)
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French (fr)
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EP0000602A1 (en
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Nico Heyboer
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Akzo NV
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Akzo NV
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/72—Copper
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C263/00—Preparation of derivatives of isocyanic acid
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C263/00—Preparation of derivatives of isocyanic acid
    • C07C263/18—Separation; Purification; Stabilisation; Use of additives
    • C07C263/20—Separation; Purification
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00—Systems containing only non-condensed rings
    • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
    • C07C2601/14—The ring being saturated

Definitions

  • the invention relates to a process for the preparation of isocyanates from formamides by contacting a formamide with a metal catalyst under the action of heat.
  • a process of the type indicated above is known from, for instance, United States Patent Specification 3 960 914.
  • a formamide having the formula R-NHCHO, where R represents an organic group is heated to a temperature in the range of 50° to 300°C in the presence of a dehydrogenation catalyst.
  • the present invention provides a process which no longer shows these drawbacks.
  • the invention consists in that in a process of the known type indicated above N-monosubstituted formamides having the general formula where R represents a substituted or unsubstituted hydrocarbon radical and n is 1 or 2, are oxidized in gas phase with a molecular oxygen-containing gas fed into the reaction zone which is maintained at a temperature in the range of 300° to 600°C and in the presence, for a contacting time of 0.01 to 6 seconds, of a catalytic amount of copper and/or one or more metals of the groups IB and VIII of the 5th and 6th period of the Periodic System of Elements to yield the corresponding isocyanates having the general formula R(NCO),, where R and n have the above-mentioned meaning, and the resulting reaction mixture in gas phase is subjected to a separation treatment known per se, care being taken that any condensed isocyanate is immediately separated from the reaction mixture or dissolved into a water-immiscible, or practically water-immiscible, solvent.
  • N-monosubstituted formamide compounds which may be gasified under said reaction conditions and of which the substituents, if any, other than the N-monosubstituted formamide groups do not undergo any undesirable decomposition under the prevailing reaction conditions nor unduly poison the catalyst used.
  • R may represent a substituted or unsubstituted alkyl group, cycloalkyl group, aryl group, aralkyl group, or alkaryl group.
  • Group R will generally contain not more than 24 and preferably not more than 18 carbon atoms.
  • substituents may be mentioned chlorine, fluorine, cyano and alkyl carbonyl or alkoxy carbonyl preferably containing not more than 10 carbon atoms in the alkyl group or in the alkoxy group.
  • the contacting time used will be very much dependent on other conditions, such as the type of catalyst, the reactivity of the formamide and the temperature.
  • the selectivity of this catalyst may, if desired, be further increased in the presence of a chloride, iodide or cyanide of Cu, Ru, Pd, Os, Ir or Pt in an amount which is 0.1 to 40 per cent by weight of the silver.
  • catalytically active metals may, if desired, form part of an alloy that may still contain other elements which may or may not be catalytically active in themselves.
  • the physical form of the catalyst may be of beneficial influence on the course of the reaction.
  • the temperature at which the reaction can be satisfactorily carried out is in the range of 300° to 600°C.
  • the proportion of formamide in the reaction mixture at the start of the reaction will generally be chosen between 0.1 and 10 per cent by volume.
  • the volume percentage of oxygen in the reaction mixture at the start of the reaction will generally be in the range of 0.05 to 10 per cent by volume. A higher percentage may not only have a detrimental effect on the yield, but it also carries with it the risk of flammability of the reaction mixture.
  • the percentage by volume of oxygen in the reaction mixture at the start of the reaction is chosen between 0.5 and 5 per cent by volume.
  • the reaction will generally be carried out in the presence of a high excess of inert gas. Consequently, the partial pressure of the gases taking part in the reaction will only be a fraction of the absolute pressure of the gas mixture.
  • the latter pressure may vary from ⁇ 100 kPa to 1000 kPa or higher.
  • the reaction mixture may contain inert solvent in addition to inert gas.
  • hydrocarbons such as benzene, toluene, ethyl benzene, xylene, biphenyl, n-pentane, n-hexane, n-heptane, cyclopentane, cyclohexane, methylcyclopentane, nitriles such as benzonitrile, tolunitrile and adipodinitrile; esters such as the octyl esters of acetic acid and butyric acid; 1-methyl-naphthalene and tetrahydronaphthalene.
  • hydrocarbons such as benzene, toluene, ethyl benzene, xylene, biphenyl, n-pentane, n-hexane, n-heptane, cyclopentane, cyclohexane, methylcyclopentane, nitriles such as benzonitrile, tolunit
  • the selectivity of the reaction may still be considerably improved if it is carried out in the presence of a chlorinated organic compound.
  • a chlorinated organic compound examples thereof may be mentioned methyl chloride, ethyl chloride, dichloroethane, chlorinated polyphenyl compounds, chlorinated biphenyl, o-dichlorobenzene or mixtures of these compounds.
  • the selectivity of the reaction can also be improved in the presence of sulphur, hydrogen sulphide and/or an organic sulphur compound the sulphur of which is in divalent form.
  • an organic compound also carbon disulphide can be mentioned.
  • thioalcohols such as methane thiol, butane thiol, thio-ethers, thioacetals, thiol esters, thiophene and homologous compounds.
  • the amounts to be used thereof in the reaction mixture may vary from a few p.p.m. by volume up to as much as more than the equivalent amount by weight of the N-monosubstituted formamide compounds.
  • the amount of the chlorinated organic compound and/or the amount of S, H 2 S and/or organic sulphur compound in the reaction mixture is chosen between 1 and 100 p.p.m. by volume.
  • This problem may be solved in various ways.
  • One solution consists in that upon termination of the reaction the reaction mixture is rapidly cooled, after which the H 2 0-containing phase and the isocyanate-containing phase are separated from each other as fast as possible by a separation method known in itself, for instance a physical separation method such as filtration and/or extraction.
  • a separation method known in itself, for instance a physical separation method such as filtration and/or extraction.
  • Another solution provided by the invention consists in that upon termination of the reaction, but prior to condensation of the isocyanate, the reaction mixture is passed over a water-absorbing agent.
  • water-absorbing agents may be mentioned magnesium sulphate, sodium sulphate and/or calcium chloride.
  • Suitable solvents may be mentioned benzene, toluene, xylene, chlorinated hydrocarbons such as carbon tetrachloride, trichloroethylene, ethylene dichloride and various isomers of chlorobenzene, such as 1,3-dichlorobenzene.
  • chlorinated hydrocarbons such as carbon tetrachloride, trichloroethylene, ethylene dichloride and various isomers of chlorobenzene, such as 1,3-dichlorobenzene.
  • the water formed in the reaction will condense or not. If use is made of sufficient solvent and a not unduly long contacting time, the percentage isocyanate which will decompose as a result of its reacting with water of condensation, if any, is practically negligible. If these two requirements are difficult to satisfy, if at all, then the invention provides a process which is so carried out that a water-absorbing agent is present during or after condensation of the isocyanate.
  • An alternative process in which rapid cooling or drying of the reaction mixture prior to condensation of the isocyanate is no longer required consists in that the reaction mixture emerging from the reaction zone, after having been cooled to some degree or not, is passed into a water-immiscible or practically water-immiscible solvent for the isocyanate. Upon condensation, if any, of the water formed during the reaction, it may be separated in the form of an immiscible phase.
  • a finely divided water-absorbing agent may be suspended in the solvent. Both for the solvent and the water-absorbing agent the same substances may be used as indicated above.
  • the solvent present during condensation of the isocyanate may be incorporated into the reaction mixture during, before or after the reaction. It may be added in the liquid or in the gaseous state.
  • the amount of solvent should be so chosen that it is capable of absorbing as much as possible of the isocyanate formed.
  • An attractive method of adding the solvent consists in the solvent being sprayed into the reaction mixture emerging from reaction zone.
  • the temperature at which the solvent-isocyanate mixture is caused to condense or the temperature of the solvent through which the reaction mixture is passed should be so chosen that it is just above the dew point of the water contained in the reaction mixture after both the solvent and the isocyanate have been separated therefrom.
  • a solvent for the isocyanate should be chosen that its boiling point is not lower than 150°C. It is preferred that use be made of a solvent having a boiling point in the range of about 200° to about 300°C.
  • aromatic hydrocarbons such as cumene, pseudo cumene, biphenyl, a-methyl naphthalene
  • aliphatic and cycloaliphatic hydrocarbons such as decane, hexahydrocumene, aromatic halohydrocarbons such as ortho- dichlorobenzene, bromobenzene, a-chloronaphthalene, esters such as the octyl esters of acetic acid and butyric acid
  • nitriles such as adipodinitrile, benzonitrile, and ketones such as benzophenone.
  • the oxidation reaction in the gas phase of the N-monosubstituted formamides to isocyanates can be conducted in a continuous or batch operation.
  • reaction should be carried out continuously. Separation of the resulting reaction mixture may again be carried out continuously or batchwise. Here too, preference is given generally to a continuous process.
  • organic isocyanates that may be prepared by the process according to the invention may be mentioned hexyl isocyanate, octyl isocyanate, dodecyl isocyanate, octadecyl isocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, undecamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexyl isocyanate, ⁇ - naphthyl isocyanate, xylene diisocyanate, diphenyl methane-4,4'-diisocyanate, benzyl isocyanate, phenylethyl isocyanate, phenyl isocyanate, methyl isocyanate, ethyl isocyanate, propyl isocyanate, eicosyl isocyanate, tetracosy
  • FIG. 1 a reactor which is schematically illustrated in Figure 1.
  • the numeral 1 refers to a stainless steel tubular reactor 70 cm long and 2.5 cm in diameter.
  • the tubular reactor is provided with a heating jacket 2 accommodating electric heating elements.
  • the temperature of the reactor is kept at a pre-set value by means of two thermocouples.
  • the tube 3 running along the centre line of the tubular reactor contains thermocouples 4, 5, 6, 7, 8 and 9, which are connected to a recorder 10.
  • the hatched part of the reactor is filled with carborundum and the cross-hatched part contains the catalyst.
  • Near the thermocouple 8 ends a stainless steel tube 11 through which a high-boiling solvent 13 was passed which, upon evaporation, immediately mixed with the reaction mixture emerging from the catalyst bed.
  • the mixture 14 consisting of the solvent 13 and the components of the reaction mixture was passed to a cooler.
  • the feed stock of the reactor was formed by a gaseous mixture 12, which had been obtained by dropwise charging a liquid mixture of formamide and a liquid which is chemically inert to the reactants, to a carborundum-filled vertically positioned glass evaporator through which there was passed a nitrogen stream into which a particular amount of air or oxygen had been taken up.
  • the evaporator was heated in an oil bath to a temperature in the range of about 160° to 200°C.
  • the condensor consisted of a glass tube provided with a water jacket and was filled with small glass rings. The condensor was set to the mixture 14 being cooled down to 25°C. Under these conditions there was no or hardly any condensation of water. The composition of the condensed mixture was analysed gaschromatographically with a 1 m glass OV 225 column at a temperature of 100° to 250°C.
  • Example X The procedure in this example was entirely in accordance with that used in Example X, except that the starting mixture was evaporated at a rate of 30 ml/hour in a gas stream of nitrogen (117 litres/hour) and air (7.2 litres/hour). As high-boiling solvent 1-bromonaphthalene was supplied at a rate of 100 ml/hour. The mean residence time was 0.35 seconds. The yield of n-hexyl isocyanate was 85% and the selectivity 91%.
  • n-hexyl formamide was evaporated at a rate of 10.5 g/hour in a gas stream of nitrogen (120 litres/hour) and air (5.5 litres/hour).
  • 1-methyl naphthalene was used as high boiling solvent 1-methyl naphthalene.
  • the n-hexyl isocyanate yield was determined both gaschromatographically (68%) and by titration with dibutylamine in accordance with the method of David and Staley in High Polymers Vol. Xvl'Analytical Chem. of Polyurethanes Part III (1969) 87 (Wiley Interscience). This method gave a yield of 70%. The selectivity was 82%.
  • Example X This example was carried out entirely in accordance with Example X, except that the feed stock was evaporated at a rate of 6 ml/hour. Nitrogen was fed at a rate of 100 litres/hour and air at a rate of 1.7 litres/hour. To the gas stream there was moreover fed 0.25% of 1,2-dichloroethane, calculated on the amount by weight of hexyl formamide. The mean residence time weas 0.45 seconds. As high-boiling solvent 1-chloronaphthalene was charged to the reactor at a rate of 30 ml/hour. The use of a reaction temperature of 420°C and a catalyst bed of 20 ml (20g) of silver wool gave n-hexyl isocyanate in 67% yield at a selectivity of 97%.
  • Example X Use being made of the procedure of Example X a feed mixture of equal amounts by weight of n-hexyl formamide and benzonitrile was evaporated at a rate of 9 ml/hour in a gas stream of nitrogen (48 litres/hour) and air (2 litres/hour). This gas mixture was passed over an 8 cm-long catalyst bed of 15 grammes of silver wool at a temperature of 425°C. The residence time was 0.44 seconds. The feed rate of 1-chloronaphthalene was 50 ml/hour. The condensor was set to the reaction mixture being . cooled down to a temperature of about 0°C, which resulted in the separation in the condensor of two immiscible liquid phases.
  • the upper phase consisted of water, the other of 1-chloronaphthalene in which n-hexyl isocyanate and non-converted n-hexyl formamide were dissolved. After separation of the two phases the amount of n-hexyl isocyanate was determined. The yield calculated from it was 76% at a selectivity of 94%.
  • Example XIV This example was carried out entirely in accordance with the procedure described in Example XIV, except that the water was not separated but bound with the aid of drying agents.
  • Example XIV This example was carried out entirely in accordance with the procedure given in Example XIV, except that the small glass rings in the condenser had been replaced with molecular sieve A3. It was found that both the yield and the selectivity were the same as obtained in Example XIV.
  • Example XVII The experiment of Example XVII was repeated in such a way that a catalyst bed of only 2 ml was used.
  • the N 2 was fed at a rate of 106 litres per hour along with air at a rate of 2.2 litres per hour.
  • the residence time was 0.025 seconds at 495°C.
  • the yield of isocyanate was 32% at a selectivity of 57%.
  • Example XIX The experiment was carried out entirely in accordance with the procedure given in Example XIX, except that a mixture of equal amounts by weight of n-hexyl formamide, benzonitrile and o-dichlorobenzene was evaporated at a rate of 9 ml/hour in a gas stream consisting of nitrogen (90 litres/hour) and air (9 mi/hour).
  • the gas mixture was passed over 20 ml of silver wool at a temperature of 410°C, which corresponded to a mean residence time of 0.5 seconds.
  • high-boiling solvent 1-chloronaphthalene was charged to the reactor at a rate of 30 ml/hour.
  • the yield of n-hexyl isocyanate was 41% at a selectivity of 72%.
  • the o-dichlorobenzene could be recovered quantitatively.
  • Example XIX This example is entirely in accordance with Example XIX, except that use was made of a mixture of equal amounts by weight of benzyl formamide and 1-methyl naphthalene which was evaporated at a rate of 5.7 grammes per hour in a gas stream of nitrogen (118 litres/hour) and air (1.4 litres/hour).
  • the temperature of the catalyst bed was 415°C, the mean residence time 0.4 seconds.
  • high-boiling solvent 1-chloronaphthalene was charged to the reactor at a rate of 30 ml/hour.
  • the yield of benzyl isocyanate was 57% at a selectivity of 80%.
  • Example X The experiment of Example X was repeated in such a way that a mixture of phenyl formamide and benzonitrile was evaporated at a rate of 5 ml/hour in a gas stream of 110 litres of nitrogen and 3 litres of air/hour.
  • the gas mixture also comprised carbon disulphide, which was fed at a rate of 0.67% per hour, calculated on the added amount by weight of n-hexyl formamide.
  • Use of the same catalyst bed as in Example XIX at a temperature of 375°C resulted in a yield of phenyl isocyanate of 41% at a selectivity of 74%.
  • Example XIX The experiment of Example XIX was repeated in such a way that a mixture of equal parts by weight of m-tolyl formamide and benzonitrile was evaporated at a rate of 5 ml/hour in a gas stream of nitrogen and air fed at rates of 118 litres and 2.8 litres, per hour, respectively.
  • 1-chloronaphthalene was charged to the reactor at a rate of 30 ml/hour.
  • the yield of m-tolyl isocyanate was 70% and the conversion of the formamide was practically quantitative.
  • the apparatus is schematically illustrated in Figure 2.
  • the numeral 1 refers to a stainless steel tubular reactor 70 cm long and 2 cm in diameter.
  • the vertically positioned tubular reactor was provided with a stainless steel jacket 2 accommodating electric heating elements.
  • Above the jacket 2 the tubular reactor ends in a space 3 to which there is connected a line 4 for the supply of the gas stream.
  • a stainless steel tube 5 which ends in a capillary tube 6.
  • the feed stock of mono- and/or diformamide along with, if desired, some solvent is charged to the reactor through the stainless steel tube 5.
  • the distance from the lower end of the capillary tube to the upper end of the hatched part 7 inthe tubular reactor is about 20 cm.
  • the hatched part 7 comprises a carborundum bed 15 cm long.
  • Catalyst bed 8, which in the experiments described hereinafter exclusively consisted of silver wool, is the cross hatched part below the carborundum bed 7, and the hatched part 9 below the bed 8 is a carborundum bed 9-13 cm long.
  • a glass condensor 11 Under the reactor 1 is a glass condensor 11 which is filled with glass beads.
  • the low-volatile components are collected in a sampling bottle 12 and subsequently analysed gaschromatographically with a 1 m glass OV 225 column.
  • the mixture fed through the tube 5 had already been heated to a temperature of about 100°C.
  • the temperature had further been so set that at the end of the capillary tube 6 it was about 150°C.
  • the temperature was about 300°C and gradually increased to the temperature of the catalyst bed 8 (about 410° to 470°C).
  • the temperature of the condenser was so set that the reaction mixture left the condenser at a temperature of approximately 25°C.
  • the procedure in this example was entirely in accordance with that of the preceding example, except that the starting material consisted of a mixture of equal amounts by weight of m-methoxy carbonylphenyl formamide and m-tolunitrile fed to the reactor at a rate of 4.5 ml/hour. This mixture was evaporated in a gas stream of nitrogen (136 litres/hour) and air (0.9 litres/hour). The temperature of the catalyst bed (15 ml) was 410°C. The residence time was 0.17 seconds. As high-boiling solvent for the isocyanate tetralin was added at a rate of 30 ml/hour.
  • Example XXV The experiment of Example XXV was repeated in such a way that a mixture of m-cyanophenyl formamide, m-tolunitrile and benzonitrile in a weight ratio of 1:1:5'was fed to the reactor at a rate of 12 ml/hour. The mixture was evaporated in a gas stream of nitrogen (108 litres/hour) and air (1.8 litres/hour).
  • Example XXV a mixture of hexamethylene diformamide, adiponitrile (internal reference for the gaschromatographical determination) and biophenyl in a weight ratio of 1:1:5 was fed at a rate of 12 ml/hour.
  • the gas stream consisted of nitrogen (110 litres/hour) and air (10 litres/hour).
  • the residence time in the catalyst bed (20 ml, or about 20 grammes of silver wool, the filaments of which had a diameter of 0.03 mm) was 0.25 seconds at a temperature of 430°C.
  • As high-boiling solvent 1-chloronaphthalene was added at a rate of 30 ml/hour. The conversion was found to be quantitative.
  • the yield of hexamethylene diisocyanate was 30%.
  • Example XXVII The experiment of Example XXVII was repeated in such a way that use was made of 12 mi/hour of a mixture of decamethylene diformamide adiponitrile (internal reference) and biphenyl in a weight ratio of 1:1:5. The conversion was again quantitative, with decamethylene diisocyanate being obtained in 31% yield.
  • Example XXVII 12 ml/hour of a mixture of 2,4-toluene diformamide, benzonitrile (internal reference) and gamma-butyrolactone in a weight ratio of 1:1:5 were evaporated in a gas stream of 120 I/hour N 2 and 8.5 I/hour air.
  • the residence time in the catalyst bed was 0.2 seconds at a temperature of 430°C.
  • the conversion was quantitative and the yield of 2,4-toluene diisocyanate 27%.
  • Example XXVII 12 ml/hour of a mixture of m-xylylene diformamide, 1-methyl-naphthalene (internal reference) and gamma-butyrolactone in a weight ratio of 1:1:5 were evaporated in a gas stream of 112 1/hour N 2 and 6.0 1/hour air.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
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EP78200097A 1977-08-02 1978-07-14 Process for the preparation of isocyanates from formamides Expired EP0000602B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL7708510 1977-08-02
NL7708510 1977-08-02

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EP0000602A1 EP0000602A1 (en) 1979-02-07
EP0000602B1 true EP0000602B1 (en) 1981-07-22

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EP78200097A Expired EP0000602B1 (en) 1977-08-02 1978-07-14 Process for the preparation of isocyanates from formamides

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US (1) US4207251A (it)
EP (1) EP0000602B1 (it)
JP (1) JPS5439018A (it)
CA (1) CA1117962A (it)
DE (1) DE2860856D1 (it)
IT (1) IT1097592B (it)

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US4430262A (en) * 1981-06-05 1984-02-07 Shell Oil Company Preparation of isocyanates and/or derivatives thereof
DE3229323A1 (de) * 1982-08-06 1984-02-09 Basf Ag, 6700 Ludwigshafen Verfahren zur herstellung aliphatischer isocyanate durch oxidative dehydrierung von formamiden
US4469640A (en) * 1983-03-14 1984-09-04 E. I. Du Pont De Nemours And Company Catalytic conversion of formamides to isocyanates
US4694101A (en) * 1984-08-09 1987-09-15 E. I. Du Pont De Nemours And Company Process for separating methyl isocyanate
US4824991A (en) * 1984-08-09 1989-04-25 E. I. Du Pont De Nemours And Company Process for separating methyl isocyanate
US4537726A (en) * 1984-11-09 1985-08-27 E. I. Du Pont De Nemours And Company Multi-stage process with adiabatic reactors for the preparation of isocyanates
US4698438A (en) * 1985-04-26 1987-10-06 E. I. Du Pont De Nemours And Company Process for the preparation of methyl carbamates and thioimidates
US4603016A (en) * 1985-11-14 1986-07-29 E. I. Du Pont De Nemours And Company Cryogenic brine separation of water and isocyanates
EP0227863B1 (en) * 1985-12-12 1989-09-20 E.I. Du Pont De Nemours And Company Process for separating methyl isocyanate
US4683329A (en) * 1986-04-16 1987-07-28 E. I. Dupont De Nemours And Company Beneficial use of water in catalytic conversion of formamides to isocyanates
US4795830A (en) * 1986-09-02 1989-01-03 E. I. Du Pont De Nemours And Company Use of water to inhibit decomposition of monoalkylformamides
US5126480A (en) * 1990-06-01 1992-06-30 Arco Chemical Technology, L.P. Isocyanate preparation
US5155267A (en) * 1991-10-24 1992-10-13 Arco Chemical Technology, L.P. Synthesis of isocyanate precursors from primary formamides
BRPI0921194A2 (pt) * 2008-11-24 2015-08-25 Reliance Life Sciences Pvt Ltd Processo para preparação de derivados de tetrazina
WO2011067242A1 (de) * 2009-12-01 2011-06-09 Basf Se Verfahren zur herstellung von isocyanaten durch thermische spaltung von carbamaten
ES2530272T3 (es) 2009-12-04 2015-02-27 Basf Se Procedimiento para la preparación de isocianatos
DK2701841T3 (en) * 2011-04-26 2015-09-21 Basf Se METHOD FOR oxidative DEHYDRATION OF METHANOL TO FORMALDEHYDE ON argentiferous KNIT
CN107473989B (zh) * 2016-06-08 2020-04-28 中国科学院大连化学物理研究所 一种催化甲醇转化制氨基甲酸甲酯的方法
EP4363399A1 (en) 2021-06-28 2024-05-08 Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. Catalytic synthesis of free isocyanates

Family Cites Families (6)

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US3099673A (en) * 1959-08-19 1963-07-30 Bayer Ag Process for the production of organic isocyanates
US3277140A (en) * 1963-07-16 1966-10-04 Air Prod & Chem Preparation of aliphatic isocyanates
DE1277851B (de) 1966-04-20 1968-09-19 Bayer Ag Verfahren zur Herstellung von 2-Chlorcarbonylphenylisocyanaten
US3929859A (en) * 1974-11-18 1975-12-30 Standard Oil Co Ohio Manufacture of dinitriles from thiodinitriles
US3960914A (en) * 1975-05-06 1976-06-01 Sun Ventures, Inc. Conversion of formamides to isocyanates
DE2520219C3 (de) 1975-05-07 1983-02-24 Basf Ag, 6700 Ludwigshafen Verfahren zur Herstellung von Formaldehyd

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JPH0118067B2 (it) 1989-04-03
JPS5439018A (en) 1979-03-24
IT1097592B (it) 1985-08-31
US4207251A (en) 1980-06-10
IT7826324A0 (it) 1978-07-31
DE2860856D1 (en) 1981-10-29
EP0000602A1 (en) 1979-02-07
CA1117962A (en) 1982-02-09

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