Claims
- 1. In a process for the preparation of 4-nitrotoluene-2-sulphonic acid by reacting 4-nitrotoluene with gaseous sulphur trioxide at an elevated temperature, the improvement wherein molten 4-nitrotoluene is reacted with undiluted gaseous sulphur trioxide or gaseous technical grade SO.sub.3 and diluted up to 50% by volume at a temperature in the range from 60.degree. to 150.degree. C. under a pressure above the vapor pressure of 4-nitrotoluene, in a molar ratio of sulphur trioxide to 4-nitrotoluene of 0.1:1 to 1.5:1, said sulphur trioxide being introduced into said molten 4-nitrotoluene and, after a conversion of at least 70 percent of the reaction component not employed in excess is achieved, the sulphonation mixture is treated with water.
- 2. Process according to claim 1 wherein the sulphonation mixture treated with water is subjected to a purification process.
- 3. Process according to claim 2 wherein the reaction mixture is purified by extraction with an organic solvent which is not miscible with water in all proportions.
- 4. Process according to claim 3 wherein a chlorinated aliphatic hydrocarbon with 1 to 5 carbon atoms is used as the organic solvent.
- 5. Process according to claim 3 wherein an aromatic hydrocarbon with 6 to 18 carbon atoms is used as the organic solvent.
- 6. Process according to claim 3 wherein methylene chloride and/or toluene is used as the organic solvent.
- 7. Process according to claim 1 wherein unreacted 4-nitrotoluene is recycled into the sulphonation stage.
- 8. Process according to claim 1 wherein SO.sub.3 is employed in an excess of up to 20 percent, relative to 4-nitrotoluene employed.
- 9. Process according to claim 1 wherein the process is carried out continuously.
- 10. A process according to claim 1, wherein the gaseous SO.sub.3 is undiluted or diluted up to 50%.
- 11. A process according to claim 1, wherein said gaseous sulphur trioxide is technical grade SO.sub.3.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2916912 |
Apr 1979 |
DEX |
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Parent Case Info
This is a continuation, of application Ser. No. 139,496, filed Apr. 11, 1980 now abandoned.
Foreign Referenced Citations (1)
Number |
Date |
Country |
2419455 |
Nov 1974 |
DEX |
Non-Patent Literature Citations (1)
Entry |
Gilbert, "Sulfonation & Related Reactions" (1965) pp. 71, 82. |
Continuations (1)
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Number |
Date |
Country |
Parent |
139496 |
Apr 1980 |
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