DD268936A1 - PROCESS FOR THE PREPARATION OF N-ARYLCARBAMATES - Google Patents

Abstract

The aim of the invention is an improved process for the economical production of N-aryl carbamates which operates without phosgene and which extracts N-aryl carbamates from the nitroaromatics in a one-step process in the presence of simple, commercial and inexpensive sulfur-based catalysts. Wherein the N-aryl carbamates are formed in good selectivity, when the total amount of sulfur and / or sulfur compound accounts for only a maximum of 10 mol% per nitro group of the nitroaromatic used. For this purpose, nitroaromatics with alcohols and carbon monoxide under substantially anhydrous conditions in the presence of sulfur and / or sulfur compounds and Alkalimetallvanadaten the general formula MkVlOm (H2O) numbered. In the formula, M is Li, Na, K, Rb, Cs, k, l, m, n are integer indices with K, l1, m3, n0.

Description

enhalten.

2. The method according to claim 1, characterized in that are used as Alkalimetallvanadate the Alkalimetallavanadate sodium metavanadate (NaVO ₃ ), potassium metavanadate (KVO ₃ ) and / or cesium metavanadate (CsVO ₃ ).

3. The method according to claim 1, characterized in that are used as Alkalimetallvanadate the Alkalimetallorthovanadate sodium orthovanadate (Na ₃ VO ₄ ), potassium orthovanadate (K ₃ VO ₄ ) and / or cesium orthovanadate Cs ₃ VO ₄ .

4. The method according to claim 1 to 3, characterized in that suitable starting materials for forming the alkali metal vanadates are used in situ under the conditions of the reaction.

5. The method according to item 1 to 4, characterized in that are used as the nitroaromatic nitrobenzene, nitrotoluene, Ni; rochlorbenzene, nitrooxylenes, itrodichlorbenzene, Nitrochlortoluene, Nitrocumene or nitromesitylene.

6. The method according to claim 1 to 4, characterized in that are used as the nitroaromatic 2,4-Dinitrotoluen and / or 2,6-Dinitrotoiuen.

7. The method according to claim 1 to 6, characterized in that are used as alcohols methanol, ethanol, n-propanol or iso-propanol.

Field of application of the invention The invention relates to an improved process for the preparation of N-aryl carbamates by reaction of nitroaromatics

with alcohols and carbon monoxide in the presence of a new, inexpensive catalyst system.

N-Arylcarbamate are active ingredients in plant protection products and starting materials for pesticides and Polyurethane production. Characteristic of the bekannton technical solutions

N-aryl carbamates are produced industrially by reacting alcohols with aryl isocyanates, which are obtained by phosgenation of arylamines. Arylamines are accessible by reduction of the corresponding nitroaromatics. The use of toxic phosgene and thus of chlorine, which does not appear in the final product, taxed this three-stage process and brings with it special corrosion and environmental problems. Therefore, it has long been attempted to prepare N-aryl carbamates directly from nitroaromatics, alcohols and carbon monoxide in order to avoid the problems mentioned with this more economical one-step process.

Vide methods such as DE-OS 2,342,458, DE-OS 2,555,557, DE-OS 2,603,574 use noble metal-containing catalyst systems that are technically not applicable because significant losses of expensive catalysts occur and relatively expensive, largely hydrogen-free carbon monoxide is needed to this Process selectively. The process according to DE-OS 2,343,826 uses selenium and / or sulfur or compounds of these elements in combination with bases such as amines and alkali metal carboxylates as catalyst system. However, N-aryl carbamates are selectively formed only with selenium-containing catalysts. By-products are always arylamines and N, N'-diarylureas. Arylamines become the major product when using hydrous alcohol or sulfur-based catalysts. The following variants of this method (DE-OS 2,614,101, DE-OS 2,623,694, DE-OS 2,808,980 and DE-OS 2,808,990) work with special bases and other additives. As catalyst components, i.a. Bicyclic amidines, phonene, Carbonsäuran, alkali metal iodides, cyanides, rhodanides, oxidizing agents and even the already resulting N-aryl amines and Ν, Ν'-diaryl ureas described. All of these methods have the disadvantage that N-aryl carbamates are formed with sufficient selectivity only with sol-containing catalysts. These catalysts are also expensive and considerable selenium losses can only be avoided with extreme technological effort. The use of selenium is toxicologically questionable even in small amounts, since various Organoselenverbindungen arise that adhere to the N-aryl carbamates, give them an unpleasant odor and prohibit its use as a pesticide.

For this reason, DE-OS 2,838,754 has described an improved process which achieves good N-aryl carbamate selectivities only with sulfur-containing multicontroller catalyst systems. The main disadvantage of this method is the necessary amount of elemental sulfur and / or sulfur compound. The total amount of sulfur and / or sulfur compound indicated in the exemplary embodiments of OE-OS 2,838,754 is 14.6 to 52 mol% of the nitrobenzene used, but usually 37 mol% l The total amount of all catalyst components is often unfavorable, often more is 50% by weight of the nitrobenzene used. This and the diversity of the heterogeneous and homogeneous catalyst components complicates the separation and purification processes. The catalyst system consists, for example, of sulfur and / or a sulfur compound, aniline, a potassium salt, an iron oxide-vanadium oxide mixture and a secondary aliphatic amine.

Object of the invention

The aim of the invention is an improved process for the economical production of N aryl carbamates, which works without phosgene and which extracts N-aryl carbamates from the Nitraromatics in a one-step process.

Explanation of the essence of invention

The invention has for its object to develop a process for the preparation of N-aryl carbamates of nitroaromatics, alcohols and carbon monoxide, which works with simple, commercial, biligen sulfur-based catalysts and N-Arylcarbamate provides in good selectivity, even if the total amount of Sulfur and / or sulfur compound is only a maximum of 10 mol% per nitro group of the nitroaromatic used.

According to the invention the object is achieved in that nitroaromatics have been reacted with alcohols and carbon monoxide under substantially anhydrous conditions in the presence of sulfur and / or sulfur compounds, characterized in that one uses catalyst systems, dio as component Alkalimetallvanadate the general formula

M _k V, 0 _m · (H ₂ O) _n

M = Li, Na, K, Rb, Cs

k, I, m, η = integer indices with

k, l g1, MAE3, NS0

contain.

Examples of such alkali metal vanadates are the alkali metal metavanadates LiVO ₃ , NaVO ₃ , KVO ₃ , RbVO ₃ , CsVO ₃ , the alkali metal orthovanadates Li ₃ VO ₄ , Na ₃ VO ₄ , K ₃ VO ₄ , Rb ₃ VO ₄ , Cs ₃ VO ₄ and their hydrates as well as all intermediate forms, which correspond to the general formula. Preference is given to using the alkali metal vanadates, which are sufficiently soluble in the respective reaction mixture and free of water of hydration.

Preferably, the alkali metal vanadates are used directly as Katalysatorkcmponente, but also their in situ formation of suitable starting materials is possible.

Suitable starting materials are all compounds which form Alkalimetollvanadate under the conditions of the reaction of nitroaromatics with alcohols and carbon monoxide, such as alkali metal hydroxides, alkali metal oxides, alkali metal oxides and alkali metal carbonates in combination with Vanadinoxiden, Vanadinoxihalogeniden, Vanadinhalogeniden and Ammoniumvanadaten whose ammonium ion NH ₄ ⁺ but also a cationic organic Nitrogen compound can be. Sulfur and / or sulfur compounds are necessary components of the catalyst system. Sulfur suitable for the erfindungsgemäßo method, for example, in any elemental form, carbon oxysulphide (COS), and organic and inorganic sulfur compounds, the method of the invention under the reaction conditions and with the reactants or other catalyst components de _a insitu carbonyl sulfide (COS) form such. Alkali metal sulfides, alkali metal iodides, alkali metal sulfides and their analogous ammonium sulfide compounds whose ammonium ion NH ₄ ⁺ may also be a cationic organic nitrogen compound, hydrogen sulfide, dialkyl, diarylkylsulfides, disulfides, organic thiocarbonates and thioureas and thioureas ,

Preferably, from an economic point of view, elemental sulfur, finely ground or in other finely divided form may also be used on suitable support materials

 Starting compounds for the process according to the invention are:

1. Nitroaromatics, such as all substituted and unsubstituted aromatic mono-, di- and Polynitroverbindungen having preferably 6 to 20 carbon atoms per molecule. Examples of such nitroaromatics are nitrobenzene, nitronaphthalenes, nitrotoluenes, nitrochlorobenzenes, nitroxylenes, nitrodichlorobenzenes, nitrochloro-lenzenes, nitrocenes, nitromesitylene, dinitrotoluenes, dinitrochlorobenzenes, dinitroxylenes, dinitromesitylene, dinitrodipho-yl, dinitrophenyl ethers, dinitrodiphenylmethanes, trinitrodiphenylmethanes and tetranitrodiphenylmethanes. Aromatic di- or polynitro compounds whose nitro groups have already been partly converted into carbamate groups can also be used as starting compounds, such as, for example, ethyl N- (3-nitro-4-methylphenyl) carbamate and ethyl N- (5-nitro-2-) methylphenyl) carbamate, which may occur as products of incomplete reaction of 2,4-dinitrotoluene with ethanol and carbon monoxide. Such nitroaromatics were used as starting compounds, especially when the process according to the invention is carried out continuously in the circulation or batchwise, batchwise and incompletely reacted aromatic di- or polynitro compounds are recycled back into the process.

-3- 2'38 936

2. Alcohols, such as all aliphatic, cycloaliphatic and araliphatic alcohols preferably having 1 to

20 carbon atoms per molecule which have a hydroxyl group on a primary, secondary or tertiary carbon atom and whose other molecular residue is inert under the reaction conditions. Examples of such alcohols are methanol, ethanol, n-propanol, all isomeric butanols, pentanols, hexanols, heptanols, Oc. Diols, etc .. Cyclohexanol, benzyl alcohol u. a. Preferably, methanol, ethanol, η- and iso-propanol are used in the process according to the invention.

3. Gaseous carbon monoxide. It is essential for the efficiency of the process according to the invention that no special requirements have to be made of the purity of the carbon monoxide. The carbon monoxide should be anhydrous but may contain some CO ₂ , O ₂ , inert gases and also hydrogen. Even 10 vol .-% H ₂ in carbon monoxide have no negative influence on the reaction.

The mixture of the three starting materials and the catalyst system forms the reaction mixture of the process according to the invention in the simple embodiment of the alcohol reactants and solvents idt.

In this FaIII the alcohol is used in such amounts that for each nitro group of the nitro aromatic used 8 to 50 hydroxyl groups of the alcohol used are present. In another embodiment of the method according to the invention Nitroaiomat and alcohol are dissolved in an inert solvent in which the catalyst is dissolved or suspended. In this case, the alcohol is used in amounts such that there are 1.2 to 15 hydroxyl groups of the alcohol used for each nitro group of the nitroaromatic used. To convert a nitro group, 3 moles of carbon monoxide are needed. Practically, however, one always works with an excess of carbon monoxide. In addition to the starting materials and the components of the catalyst system, the reaction mixture of the process according to the invention may contain further substances, for example the by-products which are always formed during the reaction, such as arylamines, N-arylformamides, Ν, Ν'-diarylureas, azo compounds and azooxo compounds. Their presence in the reaction mixture is given especially when the invention is carried out continuously in the circulation or batchwise, batchwise with partial recycling of the reaction solution. The presence of such by-products is not the subject of the invention, since it has been found that the results of the implementation of the method according to the invention thereof are not or only insignificantly influenced.

For the process according to the invention, the sulfur and / or the sulfur compounds are used in amounts such that the total amount of sulfur is 5 to 10 mol% per nitro group of the nitroaromatic used.

The alkali metal vanadato be used in amounts such that the amount of vanadium in the reaction mixture is 5 to 20 mol% per nitro group of the nitroaromatic used.

In the embodiment of the process according to the invention which uses an inert solvent, preference is given to using polar aprotic solvents having sufficient dissolving power for the alkali metal vanadates, such as acetonitrile, tetramethylurea and dialkylsulphoxides. Sulfones, dimethylformamide, N-methyloxazo.one, esters and ketones.

All components of the reaction mixture of the method according to the invention can be added to the reaction vessel in an optional order. The order of composition depends on the particular embodiment and the apparatus used. A suitable discontinuous embodiment of the process according to the invention consists for example in that nitroaromatic, alcohol and optionally a solvent are placed together with the catalyst components in an autoclave, the material must be inert to all components of the reaction mixture under the reaction conditions or contains the corresponding linings or inserts ,

Then carbon monoxide is introduced under pressure and stirred or shaken while warming. Carbon monoxide can be continuously replenished during the reaction.

A suitable continuous embodiment of the process according to the invention consists, for example, in reacting the reactants and the catalyst component with each other during the passage through a pressure reaction tube or a reaction vessel cascade. The reaction temperature is generally maintained in the range of 120 ° C to 220 ° C.

The reaction pressure is generally between 10 and 35 MPa. The reaction time is dependent on the particular nitroaromatic, the alcohol, the reaction temperature, the reaction pressure, the catalyst system and the amount of the catalyst components and is about 15 minutes to 4 hours. After the reaction, the reaction mixture is cooled to room temperature and the reaction mixture is relaxed. To obtain the N-aryl carbamates, the liquid reaction mixture is subjected to suitable separation operations such as filtration, extraction, distillation or crystallization.

Recoverable, usable reaction parts (catalyst components, alcohol, etc.) are used again.

The inventive method has the advantage that a sufficiently selective formation of N-Ary! Rarbamsten in a one-step process of nitroaromatics, alcohols and carbon monoxide in the presence of a simple, commercial and cheap sulfur-based catalyst is possible if the total amount of sulfur only a maximum of 10 mol% per nitro group of the nitroaromatic used.

The invention will be explained below with reference to 11 exemplary embodiments and 4 comparative examples.

Embodiment 1

0.45 mmol of finely ground sulfur (14.4 mg) and 0.45 mmol of potassium metavanadate (KVO ₃ , t-2 mg) were placed in a 25 cm ^J stainless steel autoclave together with ³ cm ^{3 of} 1.5 M nitrobenzene in absolute ethanol in a special glass apparatus. The sealed autoclave was then introduced 3 times with about 5 MPa of ultrapure carbon monoxide to the starting pressure of 24.5 MPa. The

AUTC klav was placed in a container heated to 18O ⁰ C heating block and moved by a shaker. The pressure increased during the reaction up to 27MPa. After 2 hours, the autoclave was removed from the heating block and cooled. After relaxing and opening, the contents of the glass insert were analyzed by high pressure liquid chromatography. The analysis showed:

Residual concentration of nitrobenzene c _NB = Ο, Οϋ Μ,

Ethyl N-phenylcarbamate concentration c _EPC = 1.30 M,

Aniline concentration c _A = 0.21 M,

Ν, Ν'-diphenylurea concentration c _O ph = 0.02 M,

Formanilide concentration c _fA - = 0.01 M.

Comparative Example 1

Example 1 was repeated by using ³ cm ^{3 of} an ethanolic solution of nitrobenzene (1.5 M) and aniline (0.5 M) instead of the nitrobenzene solution used. The initial pressure was 24.5 MPa, the reaction pressure 28.4 MPa. The HPLC analysis showed:

c _NB = 0.02M, c _E pc = 1.34 M, c _A = 0.64 M, c _DP "= 0.08 M, c _FA = 0.01 M.

It can be seen that Anilinzusätze have no positive influence on the implementation of the method according to the invention, but significantly increase the yield of undesirable N, N'-diphenylurea.

Exemplary embodiment 2

Embodiment 1 was repeated but using only 0.225 mmol KVO ₃ (31 mg). The heating block temperature was 190 ° C, the outlet pressure 27.45 MPa and the reaction pressure 29.42 MPa. The HPLC analysis showed:

Cnb = 0.01M, c _E pc = 1.3OM, c _a = 0.09M, Coph = 0.02M, c _F a = 0.01M.

Embodiment 3

Embodiment 1 was repeated by using a carbon monoxide with 10% by volume of H ₂ instead of high-purity carbon monoxide.

The starting pressure was 27.45 MPa, the reaction pressure 29.0 M / Pa. The HPLC analysis showed:

c _NB = 0.02M, c _E p _C = 1.22M, c _A = 0.19M, c _Ol > _H = 0.02M, c _FA = 0.01M.

Embodiment 4

Embodiment 1 was repeated by using 0.45 μmol of CsVO ₃ (104 mg) instead of KVO ₃ . The initial pressure was 24.5 MPa, the reaction pressure 29.42 MPa. The HPLC analysis showed:

Cnb = 0.03M, c _E pc = 1.22M, c _A = 0.2OM, Coph = 0.01M, c _fA = 0.01M.

Embodiment 5

Embodiment 4 was repeated with only 0.225 mmol of CsVO ₃ (52 mg). The starting pressure was 24.5 MPa, the reaction pressure 30.4 MPa. The HPLC analysis showed:

Cnb = 0.05M, c _E p _C = 1.10M, c _A = 0..36M, fw. = 0.01M.

Embodiment β

Example 1 was repeated by using 0.45 μmol of NaVO ₃ (55 mg) instead of KVO ₃ . The heating block temperature was 190 ° C, the outlet pressure 26.5 MPa, the reaction pressure 29.9 MPa, the reaction time 3 hours and 10 minutes. The HPLC analysis showed:

c _NB = 0.3OM, c _EPC = 0.8OM, c _A = 0.34M, c _0P n = 0.03M, c _FA = 0.01M.

Embodiment 7

Embodiment 1 was repeated by using suitable starting materials instead of KVO ₃ to form potassium metavanadate in situ. 0.45 mmol KOH (26 mg powdered) and 0.225 mmol V ₂ O ₅ (41 mg) were used as starting materials.

The initial pressure was 24.5 MPa, the reaction pressure 30.8 MPa. The HPLC analysis showed:

c _ND = 0,1OM, c _E pc = 0.96M, c _A = 0.41 M, c _O ph = 0.07M.

Embodiment 8

Embodiment 7 was repeated using 0.225 mmol K ₂ CO ₃ (31 mg) instead of KOH.

The reaction pressure was 28.3 MPa. The HPLC analysis showed:

cnb = 0.04M, c _epc = 1.10M, c _A = 0.3OM, c _DPH = 0.05M, c _fA = 0.01M.

The following Comparative Examples 2 to 4 were conducted with catalysts representing the prior art to illustrate the improvements achieved by the process of the present invention.

Comparative Example 2

Example 1 was repeated by using as catalyst system 0.45 mmol of finely ground sulfur (14.4 mg), 17 mg of KOOCCH ₃ , 22 mg of mixed oxide Fe ₂ O ₃ .V ₂ O ₆ (11: 1), 19 mg of dibutylamine and 86 mg of aniline ( cA 0.3 M) were used. The

Starting pressure was 14.7 MPa, the reaction pressure 17.65 MPe, the reaction time 2 hours and 50 minutes. The HPLC analysis showed:

c _NB = 1.41 M, c _E pc = 0.17M, c _A = 0.19M, c _DP h = 0.02M, c _FA = 0.01M.

Comparative Example 3

Comparative Example 2 was repeated with an increased amount of the following catalyst components:

63mg KOOCCH ₃ , 80mg mixed oxide Fe ₂ O ₃ · ν ₂ θ _& (11: 1), 70mg dibuylamine. The reaction time was 2 hours. The HPLC analysis showed:

c _NB = 1.05M, c _E pc = 0.39M, c _A = 0.25M, c _0PH = 0.06M.

Comparative Example 4

Comparative Example 3 was repeated with significantly increased amount of sulfur (1.67 mmol = 53.4 mg). The HPLC analysis showed:

c _NB = 0.14M, c _EPC = 1.28M, c _A = 0.34M, c _0PH = 0.12M, c _fA = 0.01M.

Compared with the process according to the invention, the process of the prior art must use 3.7 times the amount of sulfur in order to achieve comparable conversions and EPC bulges, but considerable amounts of undesired Ν, Ν'-diphenylurea are formed.

Embodiment 9

Embodiment 9 was carried out to prepare methyl N-phenylcarbamate (MPC) by repeating Example 4 with ³ cc of 1.5 M nitrobenzene in absolute methanol instead of the etharian solution.

The initial pressure was 25.5 MPa, the reaction pressure 30.4 MPa. The HPLC analysis showed:

c _ND = 0.02M, c _M pc = 1.28M, 0.24m c _A = c _O ph = 0.04M, c _fA 30,03M.

embodiment

Embodiment 9 was repeated with 0.45 mM NaVO ₃ (55 mg) instead of CsVO ₃ . The initial pressure was 24.5 MPa, the reaction pressure 28.0 MPa. The HPLC analysis showed:

c _NB = 0.69 M, c _M pc = 0.63 M, c _A = 0.23 M, c = _0PH = 0.02 M, c _fA = 0.01 M.

Embodiment The embodiment 11 was conducted for the preparation of isopropyl-N-phenyl carbamate (IPC) by the embodiment 1 with 3 cm ³ of a solution of nitrobenzene (1.5 M) and iso-propanol (2.0M) in dimethyl sulfoxide instead of ethanolic solution was repeated. The initial pressure was 24.5 MPa, the reaction pressure 27.3 MPa, the reaction time 2 hours and 10 minutes.

The HPLC analysis showed:

c _NB = 0.24M, Cipc = 1.12M, c _A = 0.10M, C ₀ PH = 0.12M.

Claims (1)

1. A process for the preparation of N-acrylcarbamates by reacting nitroaromatics with alcohols and carbon monoxide under substantially anhydrous conditions in the presence of sulfur and / or sulfur compounds, characterized in that one uses Katalysatorysterne containing as component Alkalimetallvanadate the general formula M _k V, O _m · (H ₂ O) _n M = Li, Na, K, Rb, Cs k, I, m, η = integer indices with k, l§1, m§3, n ^ 0