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Isothermal continuous method for preparing methyl mononitrobenzene in the presence of phosphoric acid

A mononitrotoluene and nitrotoluene technology, applied in the temperature continuous field, can solve problems such as unusable nitric acid, weakened space-time gain, and accidental decomposition of nitrotoluene

Inactive Publication Date: 2005-09-21
LANXESS DEUTDCHLAND GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, enrichment of nitrosylsulfuric acid may also occur
The decomposition of these by-products and the heat of decomposition released during the decomposition process may lead to unintended decomposition of the reaction product nitrotoluene
[0013] Moreover, the space-time gain is weakened, since the organic by-products react with the nitric acid used in the oxidative degradation reaction, so that a part of the nitric acid is not usable in the actual nitrification process

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] In a small test facility, 75% H 2 SO 4 , 13%H 3 PO 4 and 12%H 2 The mixed acid 1.03Kg of O, the nitric acid 0.33Kg of 68% intensity and toluene 0.33Kg join in a cascaded stirring tank. The temperature in the stirred tank was about 45°C. After the reaction is complete, the crude nitrotoluene is separated from the spent acid by a static separator. The spent acid is fed into an evaporator through a preheater and concentrated to 75% H at 100mbar and 170°C 2 SO 4 , 13%H 3 PO 4 and 12%H 2 O, while organic compounds are distilled off or destroyed. The concentrated spent acid is sent back to the nitration reaction.

[0060] The resulting crude nitrotoluene had the following composition: 2.23% toluene, 55.88% o-nitrotoluene, 4.39% m-nitrotoluene, 37.16% p-nitrotoluene, 0.31% dinitrotoluene and 0.26% dinitrocresol.

[0061] o-nitrotoluene / p-nitrotoluene=1.50

Embodiment 2

[0063] In a small test facility, 54% H 2 SO 4 , 38%H 3 PO 4 and 8%H 2 The mixed acid 1.03Kg of O, the nitric acid 0.33Kg of 68% intensity and toluene 0.33Kg join in a cascaded stirring tank. The temperature in the stirred tank was about 45°C. After the reaction is complete, the crude nitrotoluene is separated from the spent acid by a static separator. The spent acid was fed into an evaporator via a preheater and concentrated to 54% H at 100mbar and 170°C 2 SO 4 , 38%H 3 PO 4 and 8%H 2 O, while organic compounds are distilled off or destroyed. The concentrated spent acid is sent back to the nitration reaction.

[0064] The resulting crude nitrotoluene had the following composition: 2.44% toluene, 54.99% o-nitrotoluene, 4.42% m-nitrotoluene, 37.67% p-nitrotoluene, 0.19% dinitrotoluene and 0.29% dinitrocresol.

[0065] o-nitrotoluene / p-nitrotoluene=1.46

Embodiment 3

[0067] In a small test facility, 67% H 2 SO 4 , 22%H 3 PO 4 and 11% H 2 The mixed acid 1.03Kg of O, the nitric acid 0.33Kg of 68% intensity and toluene 0.33Kg join in a cascaded stirring tank. The temperature in the stirred tank was about 45°C. After the reaction is complete, the crude nitrotoluene is separated from the spent acid by a static separator. The spent acid was fed into an evaporator via a preheater and concentrated to 67% H at 100mbar and 168°C 2 SO 4 , 22%H 3 PO 4 and 11%H 2 O, while organic compounds are distilled off or destroyed. The concentrated spent acid is sent back to the nitration reaction.

[0068] The resulting crude nitrotoluene had the following composition: 2.25% toluene, 55.66% o-nitrotoluene, 4.36% m-nitrotoluene, 37.24% p-nitrotoluene, 0.23% dinitrotoluene and 0.26% dinitrocresol.

[0069] o-nitrotoluene / p-nitrotoluene=1.49

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Abstract

Continuous, isothermal production of mononitrotoluene by reaction of toluene with HNO3, H2SO4 and H3PO4 is such that the latter two acids are introduced as a mixture of H2SO4 (45-80 wt.%), H3PO4 (9-45 wt.%) and water (5-15 wt.%), i.e. as a single component.

Description

technical field [0001] The present invention relates to an isothermal continuous process for the preparation of mononitrotoluene using a mixture of sulfuric and phosphoric acids. The spent acid obtained from the synthesis reaction is subjected to a concentration process integrated in the method, and the concentrated spent acid is then recycled for use in the method. Background technique [0002] Mononitrotoluene is an important intermediate in the preparation of optical brighteners, crop protection agents and pharmaceutical products. They can be prepared on an industrial scale, for example by isothermal nitration of toluene. In this case, toluene was reacted with a mixture of sulfuric and nitric acids (mixed acid, nitrating acid) (Kirk-Othmer, Encyclopedia of Chemical Technology, Volume 17, 4th edition, 1996, "Nitration" and "Nitrobenzene and Nitrotoluene"). [0003] When the nitration reaction is carried out in pure sulfuric acid, a ratio of about 1...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C201/08C07B61/00C07C201/06C07C205/06
CPCC07C205/06C07C201/08C07C201/06
Inventor M·戈塔R·德穆斯E·茨恩吉布尔H·-M·韦伯G·龙格
Owner LANXESS DEUTDCHLAND GMBH
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