CA2072034A1 - Process for the preparation of bis-(ethoxycarbonylamino) toluenes and for the preparation of diisocyanatotoluenes therefrom - Google Patents
Process for the preparation of bis-(ethoxycarbonylamino) toluenes and for the preparation of diisocyanatotoluenes therefromInfo
- Publication number
- CA2072034A1 CA2072034A1 CA 2072034 CA2072034A CA2072034A1 CA 2072034 A1 CA2072034 A1 CA 2072034A1 CA 2072034 CA2072034 CA 2072034 CA 2072034 A CA2072034 A CA 2072034A CA 2072034 A1 CA2072034 A1 CA 2072034A1
- Authority
- CA
- Canada
- Prior art keywords
- diaminotoluene
- bis
- ethoxycarbonylamino
- toluene
- preparation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 39
- RQHLPJYRTSWDRG-UHFFFAOYSA-N ethyl n-[(ethoxycarbonylamino)-phenylmethyl]carbamate Chemical class CCOC(=O)NC(NC(=O)OCC)C1=CC=CC=C1 RQHLPJYRTSWDRG-UHFFFAOYSA-N 0.000 title claims abstract description 15
- 238000002360 preparation method Methods 0.000 title abstract description 12
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000003054 catalyst Substances 0.000 claims abstract description 16
- DYFXGORUJGZJCA-UHFFFAOYSA-N phenylmethanediamine Chemical compound NC(N)C1=CC=CC=C1 DYFXGORUJGZJCA-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000001816 cooling Methods 0.000 claims abstract description 9
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 6
- 125000003277 amino group Chemical group 0.000 claims abstract description 6
- 239000013078 crystal Substances 0.000 claims abstract description 4
- 239000000203 mixture Substances 0.000 claims description 14
- VOZKAJLKRJDJLL-UHFFFAOYSA-N 2,4-diaminotoluene Chemical group CC1=CC=C(N)C=C1N VOZKAJLKRJDJLL-UHFFFAOYSA-N 0.000 claims description 6
- 150000001875 compounds Chemical class 0.000 claims description 6
- 238000004821 distillation Methods 0.000 claims description 6
- RLYCRLGLCUXUPO-UHFFFAOYSA-N 2,6-diaminotoluene Chemical compound CC1=C(N)C=CC=C1N RLYCRLGLCUXUPO-UHFFFAOYSA-N 0.000 claims description 5
- 230000000737 periodic effect Effects 0.000 claims description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000011701 zinc Substances 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- JXCHMDATRWUOAP-UHFFFAOYSA-N diisocyanatomethylbenzene Chemical compound O=C=NC(N=C=O)C1=CC=CC=C1 JXCHMDATRWUOAP-UHFFFAOYSA-N 0.000 claims description 2
- 229910052751 metal Inorganic materials 0.000 claims 3
- 239000002184 metal Substances 0.000 claims 3
- 150000002739 metals Chemical class 0.000 claims 1
- 239000011541 reaction mixture Substances 0.000 abstract description 10
- 150000003613 toluenes Chemical class 0.000 abstract description 2
- 239000007858 starting material Substances 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 20
- 239000000047 product Substances 0.000 description 11
- 239000006227 byproduct Substances 0.000 description 7
- 239000000706 filtrate Substances 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 238000001704 evaporation Methods 0.000 description 6
- 150000003673 urethanes Chemical class 0.000 description 6
- 230000008020 evaporation Effects 0.000 description 5
- 229920002396 Polyurea Polymers 0.000 description 4
- 150000004985 diamines Chemical class 0.000 description 4
- PHYURWGMBQTCSY-UHFFFAOYSA-N ethyl n-[3-(ethoxycarbonylamino)-4-methylphenyl]carbamate Chemical compound CCOC(=O)NC1=CC=C(C)C(NC(=O)OCC)=C1 PHYURWGMBQTCSY-UHFFFAOYSA-N 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000012948 isocyanate Substances 0.000 description 3
- 150000002513 isocyanates Chemical class 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 150000001412 amines Chemical class 0.000 description 2
- 150000001448 anilines Chemical class 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 description 2
- 150000007942 carboxylates Chemical class 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 150000002736 metal compounds Chemical class 0.000 description 2
- WTEVQBCEXWBHNA-YFHOEESVSA-N neral Chemical compound CC(C)=CCC\C(C)=C/C=O WTEVQBCEXWBHNA-YFHOEESVSA-N 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000005979 thermal decomposition reaction Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- OBETXYAYXDNJHR-SSDOTTSWSA-M (2r)-2-ethylhexanoate Chemical class CCCC[C@@H](CC)C([O-])=O OBETXYAYXDNJHR-SSDOTTSWSA-M 0.000 description 1
- GWEHVDNNLFDJLR-UHFFFAOYSA-N 1,3-diphenylurea Chemical compound C=1C=CC=CC=1NC(=O)NC1=CC=CC=C1 GWEHVDNNLFDJLR-UHFFFAOYSA-N 0.000 description 1
- XZOYHFBNQHPJRQ-UHFFFAOYSA-N 7-methyloctanoic acid Chemical class CC(C)CCCCCC(O)=O XZOYHFBNQHPJRQ-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- WTEVQBCEXWBHNA-UHFFFAOYSA-N Citral Natural products CC(C)=CCCC(C)=CC=O WTEVQBCEXWBHNA-UHFFFAOYSA-N 0.000 description 1
- 206010011416 Croup infectious Diseases 0.000 description 1
- 241001527806 Iti Species 0.000 description 1
- 239000002841 Lewis acid Substances 0.000 description 1
- 101100514056 Rhodobacter capsulatus modD gene Proteins 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- UKLDJPRMSDWDSL-UHFFFAOYSA-L [dibutyl(dodecanoyloxy)stannyl] dodecanoate Chemical compound CCCCCCCCCCCC(=O)O[Sn](CCCC)(CCCC)OC(=O)CCCCCCCCCCC UKLDJPRMSDWDSL-UHFFFAOYSA-L 0.000 description 1
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 150000007514 bases Chemical class 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- WTEVQBCEXWBHNA-JXMROGBWSA-N citral A Natural products CC(C)=CCC\C(C)=C\C=O WTEVQBCEXWBHNA-JXMROGBWSA-N 0.000 description 1
- 235000019628 coolness Nutrition 0.000 description 1
- 201000010549 croup Diseases 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- JGFBRKRYDCGYKD-UHFFFAOYSA-N dibutyl(oxo)tin Chemical compound CCCC[Sn](=O)CCCC JGFBRKRYDCGYKD-UHFFFAOYSA-N 0.000 description 1
- 239000012975 dibutyltin dilaurate Substances 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- -1 e.g. Chemical compound 0.000 description 1
- QNJPOHYCQROUCT-UHFFFAOYSA-N ethyl n-[3-(ethoxycarbonylamino)-2-methylphenyl]carbamate Chemical compound CCOC(=O)NC1=CC=CC(NC(=O)OCC)=C1C QNJPOHYCQROUCT-UHFFFAOYSA-N 0.000 description 1
- VYSYZMNJHYOXGN-UHFFFAOYSA-N ethyl n-aminocarbamate Chemical class CCOC(=O)NN VYSYZMNJHYOXGN-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011133 lead Substances 0.000 description 1
- 150000007517 lewis acids Chemical class 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- IAGUPODHENSJEZ-UHFFFAOYSA-N methyl n-phenylcarbamate Chemical compound COC(=O)NC1=CC=CC=C1 IAGUPODHENSJEZ-UHFFFAOYSA-N 0.000 description 1
- SYSQUGFVNFXIIT-UHFFFAOYSA-N n-[4-(1,3-benzoxazol-2-yl)phenyl]-4-nitrobenzenesulfonamide Chemical class C1=CC([N+](=O)[O-])=CC=C1S(=O)(=O)NC1=CC=C(C=2OC3=CC=CC=C3N=2)C=C1 SYSQUGFVNFXIIT-UHFFFAOYSA-N 0.000 description 1
- 150000005677 organic carbonates Chemical class 0.000 description 1
- XPGAWFIWCWKDDL-UHFFFAOYSA-N propan-1-olate;zirconium(4+) Chemical compound [Zr+4].CCC[O-].CCC[O-].CCC[O-].CCC[O-] XPGAWFIWCWKDDL-UHFFFAOYSA-N 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 235000015096 spirit Nutrition 0.000 description 1
- 150000003606 tin compounds Chemical class 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- DJWUNCQRNNEAKC-UHFFFAOYSA-L zinc acetate Chemical compound [Zn+2].CC([O-])=O.CC([O-])=O DJWUNCQRNNEAKC-UHFFFAOYSA-L 0.000 description 1
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C269/00—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
- C07C269/04—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups from amines with formation of carbamate groups
Abstract
Mo3746 A PROCESS FOR THE PREPARATION OF
BIS-(ETHOXYCARBONYLAMINO)TOLUENES
AND FOR THE PREPARATION OF
DIISOCYANATOTOLUENES THEREFROM
ABSTRACT OF THE DISCLOSURE
A process for the preparation of bis-(ethoxycarbonyl-amino)-toluenes in which a diaminotoluene is reacted with diethylcarbonate in the presence of a catalyst at 100 to 300°C
with simultaneous or subsequent removal of the alcohol formed.
The diethylcarbonate being used in an at least 5-times molar excess based on the amino groups of the diaminotoluene. The bis-(ethoxycarbonylamino) toluenes formed are isolated in the form of crystals of great purity obtained after cooling of the reaction mixture. The resulting bis-(ethoxycarbonylamino)-toluenes may then be used as starting materials for the preparation of diisocyanatotoluenes.
Le A 28 489
BIS-(ETHOXYCARBONYLAMINO)TOLUENES
AND FOR THE PREPARATION OF
DIISOCYANATOTOLUENES THEREFROM
ABSTRACT OF THE DISCLOSURE
A process for the preparation of bis-(ethoxycarbonyl-amino)-toluenes in which a diaminotoluene is reacted with diethylcarbonate in the presence of a catalyst at 100 to 300°C
with simultaneous or subsequent removal of the alcohol formed.
The diethylcarbonate being used in an at least 5-times molar excess based on the amino groups of the diaminotoluene. The bis-(ethoxycarbonylamino) toluenes formed are isolated in the form of crystals of great purity obtained after cooling of the reaction mixture. The resulting bis-(ethoxycarbonylamino)-toluenes may then be used as starting materials for the preparation of diisocyanatotoluenes.
Le A 28 489
Description
2~37~3~
Mo3746 A PROCESS FOR THE PREPA~ATION OF
BIS-(ETHOXYCARBONYLAMINO)TOLUENES
AND FOR THE PREPARATION OF
DIISOCYANATOTOLUENES THEREFROM
BACKGROUND OF THE INVENTION
This invention relates to a process for the preparation of bis-(ethoxycarbonylamino)-toluenes (also known as tolylene-bis-(O-ethylurethanes)) and to a process for the preparation of diisocyanatotoluenes therefrom.
The preparation of urethanes by the reaction of amines with organic carbonates is known. Various procedures have been described in the literature for working up the reaction mixtures and isolating the pure products.
Monourethanes, for example, may be purified and isolated by distillation (DE-OS 3,035,354, EP-A-0,323,514 and EP-A-0,391,473). This method, however, cannot be used for tolylene-bis-(O-alkylurethanes) because these urethanes cannot be distilled without decomposition.
Another method of purifying the urethanes formed from the reaction of amines with carbonates is recrystallization.
According to DE-OS 2,160,111,~for example, diphenylurea formed as by-product from the reaction of aniline with dimethylcarbonate is filtered off, the filtrate is concentrated by evaporation and the residue is recrystallized from hexane to obtain N-phenyl-O-methyl urethane. The product of the process, however, still contains about 20% of N-alkylated anilines as impurity af$er recrystallization, these anilines having been formed as by-products of the reaction.
According to Example 8 of DE-OS 3,035,354, 2,4-bis-(ethoxycarbonylamino)toluene can be isolated after the titanium tetrabutylate catalyzed reaction of 2,4-diamino-toluene with excess diethylcarbonate by filtering off the polyurea form~d as the main product, concentrating the filtrate by evaporation and recrystallizing the residue from toluene. Disadvantages of this Le A 28 489-FC
,`
:
2~72~3~
process are the low yield of diurethane (26% of theoretical) and the formation of large quantities of polyurea which ~ust be converted into the diurethane in an additional process step.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for the preparation of tolylene-bls-(O-alkylurethanes) by which the products can be prepared and isolated in a very pure form by a simple and efficient method of working up without the above-described disadvantages of known processes.
It was surprisingly found that this problem could be solved in the specific example of bis ~thoxycarbonylamino)-toluenes (tolylene-bis-(O-ethylurethanes)) by reacting a diaminotoluene with a large excess of the diethylcarbonate in the presence of a suitable catalyst. The use of such excess 1~ amounts of the diethylcarbonate prevents the formation of large amounts of by-products, in particular of prematurely crystallizing polyureas. Consequently, the desired product can easily be isolated in a very pure form in high y;elds.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS OF THE INVENTION
This invention relates to a process for the preparation of a bis-(ethoxycarbonylamino)toluene by the reaction of a diaminotoluene with diethylcarbonate in the presence of a --catalyst at 100 to 300DC with simultaneous or subsequent removal of the alcohol formed by distillation. The diethylcarbonate is used in an at least 5-times molar excess, based on the amino groups of the diaminotoluene. The bis-(ethoxycarbonylamino)-toluenes formed are isolated in the form of very pure crystals after cooling and optionally partial concentration by evaporation of the reaction mixture without previous removal of by-products. The present invention also relates to a process for the production of a diisocyanato-toluene by thermal decomposition of the bis-(ethoxycarbonyl-amino)toluene thus produced.
Le A 28 489 . :
.
2V72~
Any diaminotoluenes may be used in the process of the invention but 2,4-diaminotoluene and its commercial mixtures in which up to 40% by weight, preferably up to 35% by weight of 2,6-diaminotoluene, based on the quant~ty of diamine mixture, is present are preferred.
Metal compounds of the 1st to 5th Main Group and the 1st to 8th sub-Croup of the Periodic System of Elements may be used as the catalyst. The catalysts used are preferably metal compounds of the 4th Main Group and the 2nd sub-Group of the Periodic System. Compounds of tin, zinc and lead are particularly preferred.
Examples of suitable catalysts include: Lewis acids such as salts or compounds of zinc, lead, titanium or zirconium, e.g., zinc ( I I ) chloride, zinc ( I I ) acetate and other zinc(II)carboxylates, lead ~II) acetate and other lead (II) carboxylates, titanium tetrabutylate and zirconium tetrapropylate; organic tin compounds, e.g. dibutyl tin oxide or dibutyl tin dilaurate; and basic compounds such as alkali metal or alkaline earth metal hydroxides or alkoxides.
It is preferred to use catalysts which, if they remain in the product, do not deleteriously affect subsequent decomposition of the urethanes formed by the process of the present invention into the corresponding isocyanates and alcohols. Oatalysts which have this characteristic include those identified above as being particularly preferred catalysts.
The catalyst is used in a quantity of from about O.Cl to about 20 mol%, preferably from about 0.05 to about 15 molX, most preferably from about 0.1 to about 10 mol%, based on the amount of diamine used ;n the prucess.
The reaction temperature is generally in the range of from about 100 to about 300~C, preferably from about 120 to about 250C.
The process may be carried out at normal pressure or elevated pressure. Elevated pressure is necessary if the Le A 28 489 ,. . .
.:
, . .
, 2~7~
.
reaction temperature is above the boiling point of the reaction mixture at normal pressure.
It is essential that the diethylcarbonate should be used in large excess, based on the diamine. It is generally used in an at least 5-times molar excess, preferably an at least 10-times and most preferably 10- to 30-times molar excess, based on the amino groups of the diamine.
The diethylcarbonate present in excess has the important function of a solvent which appears to maximize the yield and enable the product bis-(ethoxycarbonylam~no)-toluene to be obtained in a pure form by simple crystallization. The alcohol formed du~ing the reaction in accordance with the following reaction equation R-(NH2)n + n (R'0~2CO~ R-(NHCOOR')n + n R'OH
in which the groups R and R' represent the inert groups of the reactants in this equation (shown here only to illustrate the principle of the reaction) 2Q ;s removed by distillation either continuously during the reaction or at a suitable stage after the reaction has been completed.
Surprisingly, the product of the process of the present invention (in contrast to the process of DE-OS 3,035,354), has no significant quanti~ies of by-products, which crystal-lize on cooling of the reaction mixture tin particular polyureas). The bis-10-ethylurethanes) formed an ~here-fore be obtained in a very pure crystalline form (d~gree of purity at least 95% by weight, preferably at least 97% by weigh~) wi~hout further puri f i ca~ion after cool-ing of the reac~ion mixture to below 80C (preferablY
below 50C), and op~ionally conc@ntration of th~ re-action mixture. The high purity produc~ can be isolated by simple filtration, optionally af~er b~ing washed with diethylcarbonate. ~he distribution of isomers in ~he products of the process ~hus obtained Le A 28 489 ., . - . -. ;. ,.
' ~
~72~3~
corresponds substantially to that of the diaminotoluenes used as the start;ng material. The products of the process are therefore substantially 2,4-bis-(ethoxycarbonylamino)-toluene or mixtures thereof with up to 40% by weight, preferably up to 35% by weight, based on the mixture, of 2,6-bis-(ethoxy-carbonylamino)toluene and have a degree of purity of at least 95% by weight, preferably not less than 97% by we~ght.
The filtrate remaining after separation of the bis-(ethoxycarbonylamino)-toluene produced by the process of ~he presen~ invention contains mainly diurethanes.
Aminourethanes and other by-products and intermediate produ~s which can be con~er~ed into diurethane~ by re-newed reaction wi~h dialkylcarbonates are also present.
The filtrate may also contain small suan~ities of N-alkylated compounds. The filtrate may be returned to the process according to ~he in~ention~ optionally after separation of the alroh~l formed in ~he reaction and optionally af~er separa~ion of part of the N-alkylated by-product. Any distillation obtained during ~he optional concen~ration of ~he reaction mix~ure by evaporating may also be returned to the process afte~
separation of the alcohol formed in the reaction.
The process of the present invention may be carried out continuously or discontinuously.
The urethanes prepared by the process of the present invention may be used to produce the corresponding isocyanates without further working up. The urethanes may be converted into the corresponding isocyanates and alcohols by thermal decomposition and the resulting products of decomposition subsequently separated.
The process of the present invention is illustrated in more detail with the aid of the following Examples. All percentages are based on weight.
~5 Le A 28 489 . . .
-" ''. : ' :
~, :
20~2~3~
EXAMPLES
Example 1 A mixture of 48.8 9 (0.4 mol) of 2,4-diaminotoluene, 1890 9 (16 mol) of diethylcarbonate (corresponding to a molar ratio of amino groups to carbonate of 1:20) and 3.6 9 of a catalyst solution made up of a mixture of lead salts of 2-ethylhexanoic and isononanoic acid dissolved in m;neral spirits (lead content of the solution 24%) was heated to 200C in a 3 liter autoclave. The reaction was stopped after 2 hours by cooling the reaction mixture to 254C. The reaction mixture was concentrated by evaporation in a water jet vacuum. The solid which precipitated was filtered off, washed with 50 ml of diethylcarbonate and dried. 75.7 9 of 2,4-bis-(ethoxycarbonyl-amino)-toluene (purity 98%, melting point 133C) were obtained.
This corresponds to a yield of 71% of the theoretical yield.
The yield of isolated 2,4-bis-(ethoxycarbonylamino)-toluene may be increased to about 95% of the theoretical by returning the filtrates to the reaction vessel for further reaction.
Example 2 A mixture of 48.8 g (0.4 mol) of diaminotoluene (commercial mixture of 2,4- and 2,6-isomers in a ratio by weight of 65:35), 1890 9 (16 mol) of diethylcarbonate and 3.6 9 of the catalyst solution described in Example 1 was heated to 200C in a 3-liter autoclave. The reaction was stopped after 4 hours by cooling the reaction mixture to 25~C. The reaction mixture was concentrated by evaporation in a water jet vacuum.
The precipitated solid was filtered off, washed with gO ml of diethylcarbonate and dried. 63.2 9 of 2,4-/2,6-bis-(ethoxy-carbonylamino)-toluene were obtained (2,6-isomer content 32X).
This corresponds to a yield of 59% of the theoretical yield.
The yield of isolated 2,4-12,6-bis-(ethoxycarbonylamino~-toluene may be increased to more than 90% of the theoretical yield by returning the filtrates to the reaction vessel for further react;on.
Le A 28 489 , 207~
. . , Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such deta;l is solely for that purpose and tha$
variations can be made therein by those skilled in the art without departing from $he spirit and scope of the invention except as it may be limited by the claims.
L.8 A 28 48~
~':
: '
Mo3746 A PROCESS FOR THE PREPA~ATION OF
BIS-(ETHOXYCARBONYLAMINO)TOLUENES
AND FOR THE PREPARATION OF
DIISOCYANATOTOLUENES THEREFROM
BACKGROUND OF THE INVENTION
This invention relates to a process for the preparation of bis-(ethoxycarbonylamino)-toluenes (also known as tolylene-bis-(O-ethylurethanes)) and to a process for the preparation of diisocyanatotoluenes therefrom.
The preparation of urethanes by the reaction of amines with organic carbonates is known. Various procedures have been described in the literature for working up the reaction mixtures and isolating the pure products.
Monourethanes, for example, may be purified and isolated by distillation (DE-OS 3,035,354, EP-A-0,323,514 and EP-A-0,391,473). This method, however, cannot be used for tolylene-bis-(O-alkylurethanes) because these urethanes cannot be distilled without decomposition.
Another method of purifying the urethanes formed from the reaction of amines with carbonates is recrystallization.
According to DE-OS 2,160,111,~for example, diphenylurea formed as by-product from the reaction of aniline with dimethylcarbonate is filtered off, the filtrate is concentrated by evaporation and the residue is recrystallized from hexane to obtain N-phenyl-O-methyl urethane. The product of the process, however, still contains about 20% of N-alkylated anilines as impurity af$er recrystallization, these anilines having been formed as by-products of the reaction.
According to Example 8 of DE-OS 3,035,354, 2,4-bis-(ethoxycarbonylamino)toluene can be isolated after the titanium tetrabutylate catalyzed reaction of 2,4-diamino-toluene with excess diethylcarbonate by filtering off the polyurea form~d as the main product, concentrating the filtrate by evaporation and recrystallizing the residue from toluene. Disadvantages of this Le A 28 489-FC
,`
:
2~72~3~
process are the low yield of diurethane (26% of theoretical) and the formation of large quantities of polyurea which ~ust be converted into the diurethane in an additional process step.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for the preparation of tolylene-bls-(O-alkylurethanes) by which the products can be prepared and isolated in a very pure form by a simple and efficient method of working up without the above-described disadvantages of known processes.
It was surprisingly found that this problem could be solved in the specific example of bis ~thoxycarbonylamino)-toluenes (tolylene-bis-(O-ethylurethanes)) by reacting a diaminotoluene with a large excess of the diethylcarbonate in the presence of a suitable catalyst. The use of such excess 1~ amounts of the diethylcarbonate prevents the formation of large amounts of by-products, in particular of prematurely crystallizing polyureas. Consequently, the desired product can easily be isolated in a very pure form in high y;elds.
DETAILED DESCRIPTION OF THE PREFERRED
EMBODIMENTS OF THE INVENTION
This invention relates to a process for the preparation of a bis-(ethoxycarbonylamino)toluene by the reaction of a diaminotoluene with diethylcarbonate in the presence of a --catalyst at 100 to 300DC with simultaneous or subsequent removal of the alcohol formed by distillation. The diethylcarbonate is used in an at least 5-times molar excess, based on the amino groups of the diaminotoluene. The bis-(ethoxycarbonylamino)-toluenes formed are isolated in the form of very pure crystals after cooling and optionally partial concentration by evaporation of the reaction mixture without previous removal of by-products. The present invention also relates to a process for the production of a diisocyanato-toluene by thermal decomposition of the bis-(ethoxycarbonyl-amino)toluene thus produced.
Le A 28 489 . :
.
2V72~
Any diaminotoluenes may be used in the process of the invention but 2,4-diaminotoluene and its commercial mixtures in which up to 40% by weight, preferably up to 35% by weight of 2,6-diaminotoluene, based on the quant~ty of diamine mixture, is present are preferred.
Metal compounds of the 1st to 5th Main Group and the 1st to 8th sub-Croup of the Periodic System of Elements may be used as the catalyst. The catalysts used are preferably metal compounds of the 4th Main Group and the 2nd sub-Group of the Periodic System. Compounds of tin, zinc and lead are particularly preferred.
Examples of suitable catalysts include: Lewis acids such as salts or compounds of zinc, lead, titanium or zirconium, e.g., zinc ( I I ) chloride, zinc ( I I ) acetate and other zinc(II)carboxylates, lead ~II) acetate and other lead (II) carboxylates, titanium tetrabutylate and zirconium tetrapropylate; organic tin compounds, e.g. dibutyl tin oxide or dibutyl tin dilaurate; and basic compounds such as alkali metal or alkaline earth metal hydroxides or alkoxides.
It is preferred to use catalysts which, if they remain in the product, do not deleteriously affect subsequent decomposition of the urethanes formed by the process of the present invention into the corresponding isocyanates and alcohols. Oatalysts which have this characteristic include those identified above as being particularly preferred catalysts.
The catalyst is used in a quantity of from about O.Cl to about 20 mol%, preferably from about 0.05 to about 15 molX, most preferably from about 0.1 to about 10 mol%, based on the amount of diamine used ;n the prucess.
The reaction temperature is generally in the range of from about 100 to about 300~C, preferably from about 120 to about 250C.
The process may be carried out at normal pressure or elevated pressure. Elevated pressure is necessary if the Le A 28 489 ,. . .
.:
, . .
, 2~7~
.
reaction temperature is above the boiling point of the reaction mixture at normal pressure.
It is essential that the diethylcarbonate should be used in large excess, based on the diamine. It is generally used in an at least 5-times molar excess, preferably an at least 10-times and most preferably 10- to 30-times molar excess, based on the amino groups of the diamine.
The diethylcarbonate present in excess has the important function of a solvent which appears to maximize the yield and enable the product bis-(ethoxycarbonylam~no)-toluene to be obtained in a pure form by simple crystallization. The alcohol formed du~ing the reaction in accordance with the following reaction equation R-(NH2)n + n (R'0~2CO~ R-(NHCOOR')n + n R'OH
in which the groups R and R' represent the inert groups of the reactants in this equation (shown here only to illustrate the principle of the reaction) 2Q ;s removed by distillation either continuously during the reaction or at a suitable stage after the reaction has been completed.
Surprisingly, the product of the process of the present invention (in contrast to the process of DE-OS 3,035,354), has no significant quanti~ies of by-products, which crystal-lize on cooling of the reaction mixture tin particular polyureas). The bis-10-ethylurethanes) formed an ~here-fore be obtained in a very pure crystalline form (d~gree of purity at least 95% by weight, preferably at least 97% by weigh~) wi~hout further puri f i ca~ion after cool-ing of the reac~ion mixture to below 80C (preferablY
below 50C), and op~ionally conc@ntration of th~ re-action mixture. The high purity produc~ can be isolated by simple filtration, optionally af~er b~ing washed with diethylcarbonate. ~he distribution of isomers in ~he products of the process ~hus obtained Le A 28 489 ., . - . -. ;. ,.
' ~
~72~3~
corresponds substantially to that of the diaminotoluenes used as the start;ng material. The products of the process are therefore substantially 2,4-bis-(ethoxycarbonylamino)-toluene or mixtures thereof with up to 40% by weight, preferably up to 35% by weight, based on the mixture, of 2,6-bis-(ethoxy-carbonylamino)toluene and have a degree of purity of at least 95% by weight, preferably not less than 97% by we~ght.
The filtrate remaining after separation of the bis-(ethoxycarbonylamino)-toluene produced by the process of ~he presen~ invention contains mainly diurethanes.
Aminourethanes and other by-products and intermediate produ~s which can be con~er~ed into diurethane~ by re-newed reaction wi~h dialkylcarbonates are also present.
The filtrate may also contain small suan~ities of N-alkylated compounds. The filtrate may be returned to the process according to ~he in~ention~ optionally after separation of the alroh~l formed in ~he reaction and optionally af~er separa~ion of part of the N-alkylated by-product. Any distillation obtained during ~he optional concen~ration of ~he reaction mix~ure by evaporating may also be returned to the process afte~
separation of the alcohol formed in the reaction.
The process of the present invention may be carried out continuously or discontinuously.
The urethanes prepared by the process of the present invention may be used to produce the corresponding isocyanates without further working up. The urethanes may be converted into the corresponding isocyanates and alcohols by thermal decomposition and the resulting products of decomposition subsequently separated.
The process of the present invention is illustrated in more detail with the aid of the following Examples. All percentages are based on weight.
~5 Le A 28 489 . . .
-" ''. : ' :
~, :
20~2~3~
EXAMPLES
Example 1 A mixture of 48.8 9 (0.4 mol) of 2,4-diaminotoluene, 1890 9 (16 mol) of diethylcarbonate (corresponding to a molar ratio of amino groups to carbonate of 1:20) and 3.6 9 of a catalyst solution made up of a mixture of lead salts of 2-ethylhexanoic and isononanoic acid dissolved in m;neral spirits (lead content of the solution 24%) was heated to 200C in a 3 liter autoclave. The reaction was stopped after 2 hours by cooling the reaction mixture to 254C. The reaction mixture was concentrated by evaporation in a water jet vacuum. The solid which precipitated was filtered off, washed with 50 ml of diethylcarbonate and dried. 75.7 9 of 2,4-bis-(ethoxycarbonyl-amino)-toluene (purity 98%, melting point 133C) were obtained.
This corresponds to a yield of 71% of the theoretical yield.
The yield of isolated 2,4-bis-(ethoxycarbonylamino)-toluene may be increased to about 95% of the theoretical by returning the filtrates to the reaction vessel for further reaction.
Example 2 A mixture of 48.8 g (0.4 mol) of diaminotoluene (commercial mixture of 2,4- and 2,6-isomers in a ratio by weight of 65:35), 1890 9 (16 mol) of diethylcarbonate and 3.6 9 of the catalyst solution described in Example 1 was heated to 200C in a 3-liter autoclave. The reaction was stopped after 4 hours by cooling the reaction mixture to 25~C. The reaction mixture was concentrated by evaporation in a water jet vacuum.
The precipitated solid was filtered off, washed with gO ml of diethylcarbonate and dried. 63.2 9 of 2,4-/2,6-bis-(ethoxy-carbonylamino)-toluene were obtained (2,6-isomer content 32X).
This corresponds to a yield of 59% of the theoretical yield.
The yield of isolated 2,4-12,6-bis-(ethoxycarbonylamino~-toluene may be increased to more than 90% of the theoretical yield by returning the filtrates to the reaction vessel for further react;on.
Le A 28 489 , 207~
. . , Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such deta;l is solely for that purpose and tha$
variations can be made therein by those skilled in the art without departing from $he spirit and scope of the invention except as it may be limited by the claims.
L.8 A 28 48~
~':
: '
Claims (9)
1. A process for the production of a bis-(ethoxy-carbonylamino)-toluene comprising a) reacting a diaminotoluene with a molar excess which is at least five times the stoichiometric amount, based on the amino groups of the diaminotoluene of diethylcarbonate in the presence of a catalyst at 100 to 300°C, b) removing the alcohol formed in a) by distillation, c) cooling the product of b) until crystals of bis-(ethoxycarbonylamino)-toluene are formed and d) recovering the crystalline bis-(ethoxycarbonyl-amino)-toluene formed in c).
2. The process of Claim 1 in which the product of b) is concentrated prior to cooling in accordance with c).
3. The process of Claim 1 in which the diaminotoluene is 2,4-diaminotoluene.
4. The process of Claim 1 in which the diaminotoluene is a mixture of 2,4-diaminotoluene and 2,6-diaminotoluene in which up to 40% by weight of the total mixture is 2,6-diaminotoluene.
5. The process of Claim 1 in which the catalyst is a compound of a metal selected from the metals of First to Fifth Main Groups and First to Eighth Subgroups of the Periodic System of Elements.
6. The process of Claim 1 in which the catalyst is a compound of a metal of the Fourth Main Group or Second Subgroup of the Periodic System of Elements.
7. The process of Claim 1 in which the catalyst is a compound of tin, zinc or lead.
8. The process of Claim 7 in which the diaminotoluene is a mixture of 2,4-diaminotoluene and 2,6-diaminotoluene in which up to 40% by weight of the total mixture is 2,6-diaminotoluene.
9. A process for the production of a diisocyanato-toluene comprising Le A 28 489 a) reacting a diaminotoluene with a molar excess which is at least five times the stoichiometric amount, based on amino groups of the diaminotoluene of a diethylcarbonate in the presence of a catalyst at a temperature of from about 100 to about 300°C, b) removing the alcohol formed in a) by distillation, c) cooling the product of b) until crystals of bis-(ethoxycarbonylamino)-toluene form, d) recovering crystalline bis-(ethoxycarbonylamino)-toluene from the product of c), and e) thermally decomposing the bis-(ethoxycarbonylamino)-toluene of d).
Le A 28 489
Le A 28 489
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19914121211 DE4121211A1 (en) | 1991-06-27 | 1991-06-27 | METHOD FOR PRODUCING BIS (ETHOXYCARBONYLAMINO) TOLUOLS AND THE USE THEREOF FOR PRODUCING DIISOCYANATOTOLUOLS |
| DEP4121211.8 | 1991-06-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2072034A1 true CA2072034A1 (en) | 1992-12-28 |
Family
ID=6434852
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2072034 Abandoned CA2072034A1 (en) | 1991-06-27 | 1992-06-23 | Process for the preparation of bis-(ethoxycarbonylamino) toluenes and for the preparation of diisocyanatotoluenes therefrom |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0520273A3 (en) |
| JP (1) | JPH05201953A (en) |
| CA (1) | CA2072034A1 (en) |
| DE (1) | DE4121211A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8513453B2 (en) | 2009-03-16 | 2013-08-20 | Bayer Materialscience Ag | Process for preparing aromatic carbamates |
| US9988344B2 (en) | 2013-05-22 | 2018-06-05 | Covestro Deutschland Ag | Zinc cluster compounds and their use as catalysts in the reaction of amines with dialkyl carbonates |
| US10807084B2 (en) | 2017-05-15 | 2020-10-20 | Covestro Deutschland Ag | Silica-based zinc catalysts, their preparation and use in the alkoxycarbonylation of amines |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU7766098A (en) * | 1997-06-05 | 1998-12-21 | Huntsman Ici Chemicals Llc | Method for the preparation of carbamates |
| WO1998056758A1 (en) * | 1997-06-09 | 1998-12-17 | Huntsman Ici Chemicals Llc | Process for the production of organic isocyanates |
| EP1093452A1 (en) * | 1998-03-17 | 2001-04-25 | Huntsman International Llc | Method for the preparation of organic carbamates |
| BRPI0616023A2 (en) * | 2005-07-20 | 2011-06-07 | Dow Global Technologies Inc | process for the preparation of aromatic carbamates and process for the formation of an isocyanate |
| EP2036884A1 (en) | 2007-09-14 | 2009-03-18 | Repsol Ypf S.A. | Process for producing fluorinated isocyanates and carbamates |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3763217A (en) * | 1970-12-03 | 1973-10-02 | Halcon International Inc | Preparation of carbamates |
| DE3035354A1 (en) * | 1980-09-19 | 1982-04-29 | Bayer Ag, 5090 Leverkusen | METHOD FOR THE PRODUCTION OF N, O-DISUBSTITUTED URETHANES AND THE USE THEREOF AS THE STARTING MATERIAL FOR THE PRODUCTION OF ORGANIC ISOCYANATES |
| EP0065026A1 (en) * | 1981-05-18 | 1982-11-24 | The Dow Chemical Company | Preparation of carbamates from aromatic amines and organic carbonates |
-
1991
- 1991-06-27 DE DE19914121211 patent/DE4121211A1/en not_active Withdrawn
-
1992
- 1992-06-15 EP EP19920110039 patent/EP0520273A3/en not_active Withdrawn
- 1992-06-23 CA CA 2072034 patent/CA2072034A1/en not_active Abandoned
- 1992-06-25 JP JP19028192A patent/JPH05201953A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8513453B2 (en) | 2009-03-16 | 2013-08-20 | Bayer Materialscience Ag | Process for preparing aromatic carbamates |
| US9988344B2 (en) | 2013-05-22 | 2018-06-05 | Covestro Deutschland Ag | Zinc cluster compounds and their use as catalysts in the reaction of amines with dialkyl carbonates |
| US10807084B2 (en) | 2017-05-15 | 2020-10-20 | Covestro Deutschland Ag | Silica-based zinc catalysts, their preparation and use in the alkoxycarbonylation of amines |
Also Published As
| Publication number | Publication date |
|---|---|
| DE4121211A1 (en) | 1993-01-14 |
| JPH05201953A (en) | 1993-08-10 |
| EP0520273A2 (en) | 1992-12-30 |
| EP0520273A3 (en) | 1993-07-07 |
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