PROCESS FOR PRODUCING PHOSGENE BY REACTION OF POLYCHLORINE ANIONS AND CARBON MONOXIDE

Abstract

A process comprising at least the steps a) providing a reaction space containing a component including at least one polychlorine anion-containing compound, preferably at least one polychlorine anion-containing compound in the form of an ionic liquid, b) contacting carbon monoxide with said component in the reaction space and there reacting the carbon monoxide to form phosgene-containing product, c) optionally collecting the phosgene from the phosgene-containing product of step b), d) optionally reacting the phosgene from the phosgene-containing product of step b) or the collected phosgene from step c) with a phosgene-reactive component, makes it possible to prepare, in step b), a phosgene-containing product which contains less than 5.0% by weight of Cl.sub.2 base on its total weight.

Claims

1. A process for producing phosgene, comprising: a) providing a reaction chamber comprising a component having at least one polychlorine anion-containing compound, b) bringing carbon monoxide into contact with said component in the reaction chamber and converting the carbon monoxide therein to form a phosgene-containing product, c) optionally collecting the phosgene from the phosgene-containing product of step b), d) optionally reacting the phosgene from the phosgene-containing product of step b) or the phosgene collected from step c) with a phosgene-reactive component, with the proviso that the phosgene-containing product formed in step b) comprises less than 5.0% by weight Cl.sub.2, based on the total weight of the phosgene-containing product formed in step b).

2. The process as claimed in claim 1, wherein said component from step a) comprises at least one polychlorine anion-containing compound, wherein the cation of which is selected from the group of one or more each differently alkyl- and/or aryl-substituted cations selected from ammonium, phosphonium, sulfonium, imidazolium, pyridinium or guanidinium cations or mixtures thereof and the polychlorine anion present is Cl.sub.(r+2).sup., in which r is an odd integer from 1 to 7.

3. The process as claimed in claim 1, wherein the component from step a) comprises at least one polychlorine anion-containing compound of the formula (III) or the formula (IV) or a mixture thereof,
NR.sup.1.sub.mR.sup.2.sub.nR.sup.3.sub.o.sup.+Cl.sub.(r+2).sup.(III)
PR.sup.4.sub.pR.sup.5.sub.q.sup.+Cl.sub.(s+2).sup.(IV) in which the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are each independently identical or different alkyl radicals selected from the group of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and 2-methylpropyl, with the proviso that at least one radical of R.sup.1, R.sup.2 or R.sup.3 is different from the other respective radicals R.sup.1, R.sup.2 and R.sup.3 and the radicals R.sup.4 and R.sup.5 are different from each other, m, n, o, p, and q are each independently an integer in the series from 0 to 3 and where the sum of m+n+o and the sum of p+q equals 4, and where r and s are each independently an odd integer from 1 to 7.

4. The process as claimed in claim 3, wherein the compound of the formula (III) or (IV) is selected from at least one compound of the series: NEtMe.sub.3Cl.sub.(r+2), NEt.sub.2Me.sub.2Cl.sub.(r+2), NEt.sub.3MeCl.sub.(r+2), NBuEt.sub.2MeCl.sub.(r+2), NMePr.sub.3Cl.sub.(r+2), NBu.sub.2Me.sub.2Cl.sub.(r+2), and PEt.sub.3MeCl.sub.(r+2), where Me is methyl, Et is ethyl, Pr is n-propyl, and Bu is n-butyl.

5. The process as claimed in claim 1, wherein said component of step a), based on the total weight thereof, comprises at least 50% by weight of compounds having polychlorine anions.

6. The process as claimed in claim 1, wherein the molar ratio of the total amount of carbon monoxide provided for the reaction in step b) to the polychlorine anion-containing compound provided in step a) is at least 1.

7. The process as claimed in claim 1, wherein the molar ratio of the total amount of carbon monoxide provided for the reaction in step b) to the polychlorine anion-containing compound provided in step a) is at most 100.

8. The process as claimed claim 1, wherein step b) is carried out at a temperature of <500 C.

9. The process as claimed in claim 1, wherein the liquid component of step a) additionally comprises at least one liquid organic solvent as a liquid composition, in which said polychlorine anion-containing compound is incorporated, to obtain a solution or dispersion.

10. The process as claimed in claim 1, wherein the carbon monoxide is introduced into the reaction chamber in step b) so that the internal pressure of the reaction chamber is higher than atmospheric pressure, and the carbon monoxide is brought into contact with said component.

11. The process as claimed in claim 1, wherein step d) is carried out and the phosgene of the phosgene-containing product formed in step b) is reacted with at least one phosgene-reactive component in said reaction chamber.

12. The process as claimed in claim 1, wherein the phosgene-containing product formed in step b) passes into the gas phase and remains on said component in the reaction chamber during the conversion of the carbon monoxide.

13. The process as claimed in claim 1, wherein the phosgene-containing product formed in step b) is removed from the reaction chamber and the phosgene present therein formed in step b) is collected outside the reaction chamber in step c).

14. The process as claimed in claim 1, wherein the phosgene of the phosgene-containing product formed in step b) is dissolved in a liquid composition containing organic solvent in step c) and thereby collected, wherein said liquid composition is in the reaction chamber.

15. The process as claimed in claim 1, wherein a liquid composition in the form of a liquid phase containing organic solvent is present in the reaction chamber in addition to said component, wherein said liquid phase is in contact with said component.

16. The process as claimed in claim 9, wherein said liquid composition, based on the total weight thereof, comprises a total amount of at least 50% by weight organic solvent.

17. The process as claimed in claim 9, wherein at least one organic solvent is present in the liquid composition, in which phosgene dissolves at 20 C. and 1013 mbar to an extent of at least 1 g/L.

18. A composition having at least two phases, comprising gaseous carbon monoxide as the first phase, and at least one polychlorine anion-containing component as a phase different therefrom, characterized in that the composition additionally comprises at least one organic solvent.

19. A composition having at least one phase containing phosgene, at least one ionic, organic monochlorine anion-containing compound and at least one organic solvent.

Description

EXAMPLES

[0111] Synthesis of Phosgene from [NEt.sub.3Me][Cl.sub.3-7] and Organic Solvent Containing CO

[0112] o-Dichlorobenzene (oDCB, 20 mL) and [NEt.sub.3Me][Cl.sub.x] (x=3-7, x(averaged)=3.95, 3.90 g, 15.3 mmol) were initially charged in a reactor equipped with a diffuser and a drain cock. The reactor was connected to a peristaltic pump and an IR and UV/Vis spectrometer to form a circuit. The system was flushed with excess CO (32 mmol). The gas phase was pumped through the system of oDCB and [NEt.sub.3Me][Cl.sub.x] for up to 7 hours and the gas phase is characterized every 5 minutes by IR and UV/Vis spectroscopy. In the IR spectra, the formation of phosgene was observed, evident from the steady decrease in the characteristic absorption band of CO at 2171 cm.sup.1 and the increase in the absorption band characteristic of phosgene at 1682 cm.sup.1. This is consistent with the steady decrease in the characteristic absorption band for Cl.sub.2 observed in the UV/Vis spectrum at 330 nm and the increase in the absorption band of phosgene at 231 nm. An oDCB phase was then transferred to a reaction vessel via the drain cock. The presence of the phosgene formed in the gas phase of the reaction vessel containing oDCB was confirmed by IR spectroscopy. In the IR spectrum, only the bands characteristic of phosgene were observed at v=3632 (vw) cm.sup.1, 1826 (s) cm.sup.1, 1626 (w) cm.sup.1, 1409 (vw) cm.sup.1, 1107 (w) cm.sup.1, 851 (vs) cm.sup.1 and 571 (w) cm.sup.1. The phosgene-containing oDCB solution can now be used directly for phosgenation reactionsin particular for the phosgenation of amines and alcohols to form isocyanates and carbonates.

Synthesis of Phosgene from [NEt.sub.3Me][CLv7] and CO

[0113] [NEt.sub.3Me][Cl.sub.x] (x=3-7, x(averaged)=3.9, 3.8 g, 15.0 mmol) was filled into a reactor and the gas phase thereof with CO (0.171 mg, 6.0 mmol). The reaction was then stirred at 35 C. for 4 days to react the CO with [NEt.sub.3Me][Cl.sub.x] to give phosgene. The formation of phosgene was clearly demonstrated by IR spectroscopy after completion of the reaction (v=3632 (vw) cm.sup.1, 1826 (s) cm.sup.1, 1626 (w) cm.sup.1, 1409 (vw) cm.sup.1, 1107 (w) cm.sup.1, 851 (vs) cm.sup.1 and 571 (w) cm.sup.1; conversion96% based on the amount of CO used). The phosgene can now be used directly for phosgenation reactionsin particular for the phosgenation of amines and alcohols to form isocyanates and carbonates.

Synthesis of Phenyl Isocyanate from [NEt.sub.3Me][Cl.sub.3-7], CO and Phenylamine

[0114] An excess of CO was introduced into a mixture of o-dichlorobenzene (20 mL) and [NEt.sub.3Me][Cl.sub.x] (x=3-7, x(averaged)=3.2, 0.57 g, 2.42 mmol). The reaction mixture was stirred at room temperature until the [NEt.sub.3Me][Cl.sub.x] was fully converted. The resulting suspension was cooled to 15 C., to which aniline (0.51 g, 5.48 mmol) in o-dichlorobenzene (5 mL) was added dropwise, and stirred at 100 C. for 8 hours. The reaction product was examined by means of IR spectroscopy and showed the band characteristic of phenyl isocyanate at v=2273 cm.sup.1.