DE2025497A1 - Improved process for aromatic isocyanate(s) - from nitro compounds - Google Patents

Abstract

Aromatic isocyanates are prepared by reacting an aromatic nitro cpd. (with up to 20C) with CO at elevated temp. and pressure in the presence of a catalyst mixt. of (A) a noble metal-based catalyst of (1) Ru, Rh, Pd, Os, Ir or Pt or (2) a cpd. of (A)(1) metal which is an oxide, sulphide, halide, nitrate, sulphate, carbonate or oxylate and (B) (a) a non-noble metal-based catalyst of (a) Cr, Si, Ge, Co, Ni, V, Mo, W or Mn or (b) an iodide, chloride, nitrate, sulphate or sulphide of (B), using 0.01-50 wt.% catalyst based on the nitro cpd.. CO:NO2 gps. ratio is 0.1-50:1 molar; pressure is, e.g., 100-5000 psig; temp. is pref. 25 deg.C up to isocyanate decomposition temp., pref. 150-215 deg.C. Wt. ratio of (A):(B) is pref. 0.1-100:1; SO2 may be added to the reaction mixt. in the proportion of SO2:nitro gp. 0.05-25:1.

Description

1? Process for the production of organic isocyanates "Organic Isocyanates, from which both urethane foams and Uborzüge and z. B. Insecticides and pesticides can be produced are in increasing demand.

In the conventional technical processes for the production of organic Isocyana-te need organic nitro compounds in the presence of catalysts too the corresponding amines are hydrogenated, after which the amine with phosgene to the corresponding Isocyanate converts.

It is a process for making isocyanates from the appropriate Nitro compounds known, according to which an organic nitro compound in the presence brought a catalyst based on noble metal with carbon monoxide to implement will.

In the practical application of this method to implement organic Nitro compounds with carbon monoxide using a noble metal catalyst, such as rhodium trichloride, palladium chloride, iridium trichloride or osmium trichloride, However, only trace amounts of the organic isocyanates are retained.

Because of the cost of the conventional methods of manufacture organic isocyanates' there is great interest in a simple, economical one Process for the preparation of these isocyanates from the corresponding organic nitro compounds.

The object of the invention was to provide a new, catalytic process for Production of organic isocyanates, especially phenyl isocyanate, tolylene diisocyanates and bis (isocyanatophenyl) methanes, according to which organic Nitro compounds converted directly into the corresponding organic isocyanates can be. This object is achieved by the invention.

The invention thus relates to a process for initialization of organic isocyanates by converting up to 20 carbon atoms organic nitro compounds with carbon monoxide at increased demelleatures and pressures in present a catalytic converter, which is characterized by: that the catalyst used is from about 0.01 to about 50% by weight, based on the organic Nitro compounds, a mixture of A) a noble metal catalyst component of 1) ruthenium, rhodium, palladium, osmium, iridium or platinum and / or 2) one Oxide, sulfide, halide, nitrate, sulfate, carbonate or oxalate one of the under A1) metals mentioned and B) a non-noble metal catalyst component made of 1) chromium, Silicon, germanium, cobalt, nickel, vanadium, molybdenum, tungsten or manganese and / or 2) a chloride, bromide, iodide, nitrate, sulfide or sulfate one of the under Bi) metals mentioned and / or 3) an alloy of the metals mentioned under B1) are used.

Any organic nitro compound can be converted into an organic Isocyanate is convertible, use in the process of the invention as a starting compound. Aliphatic, cycloaliphatic and aromatic mono- or polynitro compounds can generally by the method of the invention to the corresponding mono- or polyisocyanates are reacted.

Examples of organic nitro compounds produced according to the method of the invention can be converted to isocyanates are aromatic nitro compounds, such as nitrobenzene, nitro-naphthalene, ititroanthracene, slitrodiphenyl, bis (nitrophenyl) methane, Bis (nitrophenyl) ether, bis (nitrophenyl) thioether, Bis (nitrophenyl) sulfones, Nitrodiphenoxyalkanes or nitrophenothiazines, nitrocycloalkanes, such as nitrocyclobutane, Witrocyclopentane, nitrocyclohexane, dinitrocyclohexane or bis (nitrocyclohexyl) methane, and nitroalkanes, such as nitromethane, nitroethane, nitropropane, nitrobutane, nitrohexane, Nitrooctane, Nitrooctadekane, Dinitroäthan, Dinitropropane, Dinitrobutane, Dinitrohexane, Dinitrodecanes, phenylnitromethane, bromophenylnitromethane, nitrophenylnitromethane, Methoxyphenylnitromethane, bis- (nitromethyl) -cyclohexane or bis- (nitromethyl) benzenes.

The aforementioned compounds can each have at least one further Substituents such as halogen atoms, nitro, cyano or isocyanato groups or alkyl, Alkoxy, alkylthio, carboxyalkyl, nitroalkyl, alkenyl, aryloxy or arylthio radicals, exhibit. Specific examples of substituted nitro compounds which can be used according to the invention are o-nitrotoluene, m-nitrotoluene, p-nitrotoluene, o-nitro-p-xylene, 2-methyl-1-nitrnaphthalene, m-dinitrobenzene, p-dinitrobenzene, 2,4-dinitrotoluene, 2,6-dinitrotoluene, dinitromesitylene, 4,48-dinitrodiphenyl, 2,4-dinitrodiphenyl, 4,4'-dinitrodibenzyl, bis (pnitrophenyl) methane, Bis (2,4-dinitrophenyl) methane, bis (pnitrophenyl) ether, bis (2,4-dinitrophenyl) ether, Bis (pnitrophenyl) thioether, bis (p-nitrophenyl) sulfone, bis (pnitrophenoxy) ethane, 'α', 'α' '- dinitro-p-xylene, 2,4,6-trinitrotoluene, 1,3,5-trinitrobenzene, 1-chloro-2-nitrobenzene, 1-chloro-4-nitrobenzene, 1-chloro-3-nitrobenzene, 2-chloro-6-nitrotoluene, 4-chloro-3-nitrotoluene, 1-chloro-2,4-dinitrobenzene, 1,4-dichloro 2-nitrobenzene, 'α'-chloro-p-nitrotoluene, 1,3,5-trichloro-2-nitrobenzene, 1,3,5-trichloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, 'α'-chloro-m-nitrotoluene, 1,2,4-trichloro-5-nitrobenzene, 1-bromo-4-nitrobenzene, 1-bromo-2-nitrobenzene, 1-bromo-3-nitrobenzene, 1-bromo-2,4-dinitrobenzene, 'α', 'α'-dibromo-p-nitrotoluene, R-bromo-p-nitrotoluene, 1-fluoro-4-nitrobenzene, 1-Bluor-2,4-dinitrobenzene, 1-fluoro-2-nitrobenzene, o-nitrophenyl isocyanate, m-nitrophenyl isocyanate, p-nitrophenyl isocyanate, o-nitroanisole, p-nitroanisole, p-nitrophenetol, o-nitrophenetol, 2,4-dinitrophenetol, 2,4-dinitroanisole, 1-chloro-2,4-dimethoxy-5-nitrobenzene, 1 , 4-dimethoxy-2-nitrobenzene, m-nitrobenzaldehyde, p-nitrobenzaldehyde, p-nitrobenzoyl chloride, m-nitrobenzoyl chloride, 3,5-dinitrobenzoyl chloride, ethyl p-nitrobenzoate, methyl o-nitrobenzoate, m-nitrobenzenesulfonyl chloride, p-nitrobenzenesulfonyl chloride, o-nitrobenzenesulfonyl chloride, 4-chloro-3-nitrobenzenesulfonyl chloride, 2,4-dinitrobenzenesulfonyl chloride, 3-nirtophthalic anhydride, p-nitrobenzonitrile, m-nitrobenzonitrile, 1,4-dinitrocyclohexane, bis- (p-nitrocyclohexyl) methane, 1-nitro-n-hexane, 2,2-dimethyl-1-nitrobutane, 1,6-dinitro-nhexane and 1,4-bis (nitromethyl) cyclohexane.

One can also use isomers and mixtures of the in the process of the invention the aforementioned organic nitro compounds and substituted organic nitro compounds use, as well as homologues and other derivatives of these compounds. The in Process of the invention used, optionally substituted organic Nitro compounds generally contain 1 to about 20, preferably 1 to about 14, carbon atoms.

The catalyst used in the process of the invention consists of how mentioned, of a noble metal catalyst component (A) and a non-noble metal catalyst component (B), hereinafter also referred to as "co-catalyst component".

The precious metal catalyst components used are rhodium trichloride, rhodium dioxide, Palladium dichloride, palladium dioxide and platinum dichloride are preferably used.

Nickel alloys are among the two- and multi-component alloys preferably used as co-catalyst component according to the invention. Specific examples that's why swex im. ffandel available nickel alloys, one of which ("Nickel Alloy B ") made of 64% nickel, 28% molybdenum, 5% iron, 1% silicon, 1% chromium and 1% manganese and the other ("nickel alloy c") 56 % from nickel, to 16, b from chroia, to 16% from molybdenum, to 5% from iron, to 4 % of tungsten, 1 9'o of cobalt, 0.5% of silicon, 0.5% of manganese, 0.5% from vanadium and the remainder from trace amounts of carbon, phosphorus and there is sulfur.

Specific examples of catalyst systems which can preferably be used according to the invention are combinations of rhodium trichloride with chromium, chromium trichloride, silicon, vanadium, Germanium, cobalt, cobalt chloride or cobalt iodide, of palladium chloride with cobalt chloride, Cobalt iodide, chromium trichloride or silicon and of platinum dichloride with chromium, chromium trichloride, Silicon, Vanadium, cobalt, cobalt chloride or cobalt iodide.

The catalysts can be used in the process of the invention with or without Carriers are used. Specific examples of these for dispersing the metals and thus increasing the active surface serving carriers are aluminum oxide, silicon dioxide, Carbon, barium sulfate, calcium carbonate, asbestos, bentonite, diatomite and fuller's earth (Puller earth).

To achieve a catalytic effectiveness, the catalysts in the process of the invention generally in proportions from about 0.01 to about 50.0 % By weight, preferably about 0.1 and about 4.0% by weight, based on the organic nitro compound, used.

The weight ratio used in the process of the invention non- Noble metal of / noble metal catalyst component to / catalyst component is generally about 0.1: 1 to about 100: 1, preferably about 1: 1 to about 10 : 1.

The process of the invention is performed in the absence of solvents carry out. However, it is appropriate to chemically oppose the reaction system USE inert solvent. It is preferably used in the process of the invention Sulfur dioxide. Although the mode of action of sulfur dioxide has not been fully elucidated is, it is assumed that the # promotes ionization of the nitro groups, thereby the Ali # the oxygen a # relieves and the oxygen atoms on the carbon oxide I molecules transmits, whereby the carbon monoxide is converted to carbon dioxide.

When sulfur dioxide is used as the solvent in the process of the invention is generally used per mole of the organic nitro compound about 0.05 to about 25, preferably about 0.1 to about 10 moles of SO2.

The order of mixing the reactants is not important and may be imposed within the scope of the particular device used Restrictions can be varied. According to one embodiment of the method of the invention one charged a suitable pressure reactor, such as an autoclave, in the previously a nitrogen atmosphere was generated and preferably with a device to keep the reaction mixture moving, such as a stirrer or a gun attached / televice equipped with the organic nitro compound and the catalyst and optionally with sulfur dioxide. Then you act the autoclave to a pressure of about 2.8 to 700 kg / cm2, preferably about 7 to 350 kg / cm2, with carbon monoxide. However, you can also work at pressures which are above or below the aforementioned ranges.

The amount of carbon monoxide in the free space of the reactor is sufficient generally both to maintain the required pressure and as CO-2 to be converted in the process, part sv.s If necessary, the reactor is charged at the Progress of implementation either in the form of subsets or continuously with additional carbon monoxide. The whole during the implementation added carbon monoxide content depends on the volume of free space in the reactor and from the required pressure, but generally corresponds to a molar.

ratio of carbon monoxide to the nitro groups of the organic nitro compound from about 0.1: 1 to about 50: 1, preferably about 0.3: 1 to about 20: 1.

The reactor can be installed by means of internal or external devices be heated, with temperatures of about 250C to the decomposition temperature of the Isocyanate, preferably from about 150 to about 215po.

The reaction time is not critical and is generally about 36 seconds to about 48 hours, preferably about 30 minutes to about 4 hours.

After the reaction has ended, the crude reaction mixture can be added Cool down to room temperature, vent the gases from the pressure reactor and the reaction products withdraw from the reactor. The catalyst can then be filtered off from the reaction product or by another suitable method for the separation of solid constituents separate from liquids.

Preference is given to isolating the organic isocyanate a fractional distillation of the reaction product. However, it can also, for. B. an extraction or sublimation process for removing the organic isocyanate from the unreacted organic nitro compound and given if by-products are used.

The examples illustrate the invention.

Example 1 A shaker equipped with a 300 ml autoclave with 40 g (0.33 hol) itrobenzene, 0.5 g anhydrous rhodium trichloride and 0.9 g of the above-described nickel alloy B in the form of shavings. The reactor is then closed, it is flushed with nitrogen and then flushed with it Carbon monoxide and finally pressurizes it up to a pressure of about 101 kg / cm² with sole monoxide (corresponding to about 1.1 mol of CO). The reaction mixture is then heated to 2000C and maintains this temperature for 3 hours. There is a maximum pressure of about 161 kg / cm2. then the reactor is cooled to room temperature, with the pressure reaches a value of about 80.5 kg / cm² and leaves that of carbon monoxide and carbon dioxide from existing gas mixture. The conversion product becomes a quantitative one Subjected to IR and programmed gas chromatographic analysis.

It consists of 18% phenyl isocyanate and 81% ITitrobenzene.

Through the fractional distillation of the crude product, the analysis results are confirmed.

For comparison purposes, 40 g (0.33 mol) of nitrobenzene are brought into the presence of 0.5 g of anhydrous rhodium chloride among the aforementioned conditions for implementation. It is therefore based on the nickel alloy serving as a co-catalyst component B waived. In this reaction, not even trace amounts of phenyl isocyanate are obtained and rather it recovers the nitrobenzene quantitatively.

Example 2 A 1 liter equipped with a stirrer is charged capacity autoclave with 100 g (0.83 mol) of nitrobenzene, 1.0 g of anhydrous rhodium chloride and 10.0 g of nickel alloy B, seal it and purge it with nitrogen and then with carbon monoxide. Finally, the reactor 2 is acted upon.

up to a pressure of about 7 kg / cm2 with carbon monoxide (eespeaking about 0.26 moles of CO). The reaction mixture is then heated for 3 hours with stirring at a maximum pressure of about 10.5 kg / cm² to 18500. The reaction product is obtained 1.2 g of phenyl isocyanate, which corresponds to an uncorrected yield of 10 ° ó of theory In contrast to the tests described using the other examples The yield here is based on the amount of carbon monoxide used.

Example 3 brings 40 g (0.33 mol) of nitrobenzene for 3 hours at 2060C in the presence of 0.5 anhydrous rhodium trichloride and 10.0 g of powdered chromium metal with 1.0 mol of carbon monoxide (equivalent to a pressure of 91 kg / cm²) for reaction. That received The reaction mixture consists of 6% phenyl isocyanate and 94% unreacted nitrobenzene. The degree of conversion of the nitrobenzene is thus 6%, the corrected yield of phenyl isocyanate 100% of theory.

Example 4 40 g (0.33 mol) of nitrobenzene are brought at 2040 ° C. for 3 hours in the presence of 0.5 g of anhydrous rhodium trichloride and 10 g of powdered molybdenum metal with 1.0 mol of carbon monoxide. (- corresponding to a pressure of about 94 kg / cm2) for implementation. The product obtained consists of 91.5% nitrobenzene and 4.7% phenyl isocyanate.

EXAMPLE 5 15 g (0.12 mol) of nitrobenzene are brought at 2000 ° C. for 3 hours in the presence of 0.2 g of anhydrous rhodium trichloride and 2.5 g of molten silicon with 0.43 mol of carbon monoxide (corresponding to a pressure of about 107 kg / cm²) for reaction. The mixture obtained consists of 7.6% phenyl isocyanate and 92.4% unreacted Nitrobenzene Example 6 40 g (0.33 mol) of nitrobenzene are added in the presence of 0.5 g of anhydrous rhodium trichloride and 10 g of powdered vanadium metal at 1.0 Moles of carbon monoxide (corresponding to one pressure of 90 kg / cm2) to Implementation. The mixture obtained contains 13 ° b phenyl isocyanate and 61% nitrobenzene.

EXAMPLE 7 40 g (0.33 mol) of nitrobenzene are brought at 2000 ° C. for 3 hours in the presence of 0.5 g of anhydrous rhodium trichloride and 10 g of powdered germanium with 0.79 mol of carbon monoxide (corresponding to a pressure of about 72 kg / cm2) for implementation. The nitrobenzene is converted to phenyl isocyanate.

EXAMPLE 8 40 g (0.33 mol) of nitrobenzene are brought at 2000 ° C. for 3 hours in the presence of 0.5 g of anhydrous rhodium trichloride and 1.0 g of cobalt iodide with 1.0 mol of carbon monoxide (corresponding to a pressure of about 90 kg / cm²) for reaction. The product obtained consists of 6% phenyl isocyanate and 94% unreacted Nitrobenzene.

Example 9 The experiment from Example 8 is repeated, however ten times the amount of rhodium trichloride and ten times the amount of cobalt iodide used. The reaction mixture obtained in this experiment consists of 21% phenyl isocyanate and 79% nitrobenzene.

Example 10 Bring 15 g (0.12 mol) of nitrobenzene in the presence of 0.2 g palladium dichloride and 5.0 g powdered chromium metal with 0.42 mol carbon monoxide (corresponding to a pressure of about 110 kg / cm²) to react. The product obtained consists of 1.8% phenyl isocyanate and 98.2% nitrobenzene.

Example 11 The experiment of Example 10 is repeated instead of palladium dichloride and chromium metal, however, iridium trichloride and Nickel alloy Bo The nitrobenzene is converted to phenyl isocyanate.

Example 12 The experiment of Example 10 is repeated instead of palladium dichloride and chromium metal, however, osmium trichloride and Nickel alloy B. The nitrobenzene is essentially converted into phenyl isocyanate converted.

Example 13 A 300 ml autoclave is sent with t, - 40 g (0.33 mole) nitrobenzene, 0.5 g anhydrous rhodium trichloride and 0.9 g nickel alloy B in the form of filings, closes it, displaces the air with nitrogen ' and cools the reactor to 500C- from Then you use a Pressure cylinder to 5.6 g (0.09 mol) of sulfur dioxide. Then you apply the autoclave up to a pressure of about 98 kg / cm2 with carbon monoxide (corresponding to about 1.1 ol CO), heats it to 2140C (the pressure at this temperature is about 133 kg / cm2) and keeps it for 3 hours at 2140C. After cooling to room temperature the gases are released and the liquid contents of the reactor are distilled. The implementation results in 6.6 g of phenyl isocyanate (corresponding to a corrected yield of 100% of theory) and 33.0 g of nitrobenzene (corresponding to a degree of conversion of 16.5 %).

Example 14 A 1180 ml autoclave is charged with 100 ml g (0.81 moles) nitrobenzene, 118.5 g (1.85 moles) sulfur dioxide, 1.0 g anhydrous Rhodium trichloride, 1.0 g anhydrous cobalt chloride and 2.0 g nickel alloy B. in the form of filings and applies it up to a pressure of about 70kg / cm² with carbon monoxide (corresponding to about 2.9 moles of CO). Then the reactor is underheated Shake for 3 hours at 2000C. The reaction results in 10.5 g of phenyl isocyanate (corresponding to a corrected yield of 100% of theory) and 89 g of nitrobenzene (corresponding to a degree of conversion of 10.5 96).

After working iron the methods described in Examples 1 to 14 ######, dinitrotoluene can also be converted into toluylene diisocyanate 4,4'-dinitrodiphenylethene to 4,4'-diisocyanatodiphenylmethane are converted claims:

Claims (9)

P a t e n t a n s p r ü c h e 1. Process for the production of organic Isocyanates by reacting organic nitro compounds containing up to 20 carbon atoms with carbon monoxide at elevated temperatures and pressures in the presence of a catalyst, d a d u r c h e k e n n n z e i c h n e t that the catalyst used is about 0.01 to about 50% by weight, based on the organic nitro compounds, of a mixture from A) a noble metal catalyst component from 1) ruthenium, rhodium, palladium, Osmium, iridium or platinum and / or 2) an oxide, sulfide, halide, nitrate, sulfate, Carbonate or oxalate of one of the metals mentioned under A1) and B) a non-noble metal catalyst component from 1) Chromium, silicon, germanium, cobalt, nickel, vanadium, molybdenum, tungsten or Manganese and / or 2) a chloride, bromide, iodide, nitrate, sulfide or sulfate one the metals mentioned under B1) and / or 3) an alloy of those mentioned under B1) Metals used. 2. The method according to claim 1, d a d u r c h g e k e n n -z e i c n e t that one has a molar ratio of the carbon monoxide to that in the organic Nitro compound containing nitro groups from about 0.1: 1 to about 50: 1, preferably about 0.3: 1 to about 20: 1, applies. 1 or 2, 5. The method according to claim, d a d u r c h g e k e n n -z E i c h n e t that one takes place at temperatures from about 250C up to the decomposition temperature of the organic isocyanate and pressures of about 7 to about 350 kg / cm². 4. The method according to claim 3, d a d u r c h g e k e n n -z e i c h n e t that one works at temperatures of about 150 to about 215 ° C. 5. The method according to claim 1 to 4, d a d ur c h g e -k e n n z e i c h n e t that the reaction is carried out in the presence of about 0.05 to about 25 mol, preferably about 0.1 to about 10 MGl sulfur dioxide pI0 mol of the organic nitro compound performs. 6. The method according to claim 1 to 5, d a d u r c h g e -k e n n z e i c h e t that one has a weight ratio of the base / noble metal catalyst component (B) for the noble metal catalyst component (A) from about 0.1 0 1 to about 100: 1, preferably about 1: 1 to about 10: 1 applies. 7. The method according to claim 1 to 6, d a du r c h g e -k e n n z e i c h n e t that the catalyst used is a mixture of rhodium trichloride with vanadium, Nickel, chromium trichloride or cobalt iodide or a mixture of palladium dichloride used with chromium or chromium trichloride. 8. The method according to claim 1 to 7, d a d u r c h g e -k e It is noted that the catalyst can be used in a proportion of from about 0.1 to about 4.0% by weight, based on the organic nitro compound, is used. 9. The method according to claim 1 to 8, d a d u r c h g e -k e n n z e i c h n e t that the organic nitro compound (s) / aromatic nitro compound (s), preferably nitrobenzene and / or dinitrotoluene and / or bis (nitrophenyl) methane, begins.