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US 2010/0160675 A1Published application
Integrated process for the preparation of polybenzimidazole precursors
AssigneeE.I. du Pont de Nemours and Company
InventorsRajiv DHAWAN, Joachim C. Ritter
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Abstract
An integrated process is provided for preparing complexes of 2,3,5,6-tetraminotoluene with an aromatic diacid starting with nitration of 2,6-dihalotoluene. The process design eliminates costly intermediate drying and recrystallization steps. Handling of solid materials with possible skin sensitizing properties and toxicity is avoided, thereby eliminating human and environmental exposure.
Claims13
An integrated process for preparing a complex of 2,3,5,6-tetraminotoluene and the aromatic diacid XYTA, wherein the complex is generally described by Formula I
- wherein X and Y are each independently selected from the group consisting of H, OH, SH, methyl, ethyl, F, Cl, and Br;
- comprising the sequential steps under exclusion of oxygen:
- a) nitrating 2,6-dihalotoluene (II)
- wherein each Z is independently Cl or Br, in a reaction mixture comprising oleum or SO3, nitric acid, and H2SO4
- wherein
- (i) the concentration of nitric acid is about 2.0 to about 2.3 moles per mole of 2,6-dihalotoluene;
- (ii) the concentration of SO3 is about 1 to about 3 moles per mole of 2,6-dihalotoluene and
- (iii) the concentration of 2,6-dihalotoluene in the reaction mixture is between about 12 and about 24 weight percent;
- and
- wherein the temperature of the reaction mixture does not exceed 120° C.;
- thereby producing 2,6-dihalo-3,5-dinitrotoluene;
- b) directly separating the 2,6-dihalo-3,5-dinitrotoluene from the reaction mixture by filtration, while recycling the sulfuric acid mother liquor;
- c) washing the 2,6-dihalo-3,5-dinitrotoluene with water or acid then water, then with NH4OH, and then mixing it with glycol as a suspension;
- d) aminating the 2,6-dihalo-3,5-dinitrotoluene by heating the suspension formed in step (c) to a temperature in the range of about 100° C. to about 160° C. and contacting it with NH3(g), thereby converting the 2,6-dihalo-3,5-dinitrotoluene to 2,6-diamino-3,5-dinitrotoluene;
- e) directly separating the 2,6-diamino-3,5-dinitrotoluene from the reaction mixture by filtration, washing with glycol, then washing with water;
- f) forming a slurry of the 2,6-diamino-3,5-dinitrotoluene with water and transferring the slurry to a hydrogenation reactor containing a hydrogenation catalyst to form a reaction mixture;
- g) hydrogenating the 2,6-diamino-3,5-dinitrotoluene by contacting the reaction mixture formed in step (f) with hydrogen at a pressure in the range of about 0.31 to about 3.45 MPa and a temperature in the range of about 20° C. to about 100° C. to hydrogenate the 2,6-diamino-3,5-dinitrotoluene, thereby producing 2,3,5,6-tetraminotoluene;
- h) contacting the 2,3,5,6-tetraminotoluene produced in (a) with an aqueous solution comprising 1 to 6 equivalents of acid per mol of 2,3,5,6-tetraminotoluene, optionally heating the solution, thereby dissolving the 2,3,5,6-tetraminotoluene;
- i) filtering the reaction mixture, thereby removing the spent hydrogenation catalyst;
- j) combining the filtered reaction mixture with
- i) 0 to 5 equivalents of an acid selected from the group consisting of HCl, acetic acid, H2SO4, and H3PO4;
- ii) 0 to 5 equivalents of an organic base or an inorganic base;
- iii) optionally, a buffer solution;
- and
- iv) an XYTA source selected from XYTA and M2XYTA (Formula III)
- wherein M is K or Na, and wherein the molar ratio of XYTA to the 2,3,5,6-tetraminotoluene salt is from 1:1 to 1:1.1;
- thereby adjusting the pH of the mixture to between about 3 and about 10 and thereby producing and precipitating the complex generally described by Formula (I);
- and
- k) cooling, filtering, and washing the precipitated complex.
26 more elements
An integrated process for preparing a complex of 2,3,5,6-tetraminotoluene and the aromatic diacid XYTA, wherein the complex is generally described by Formula I
- wherein X and Y are each independently selected from the group consisting of H, OH, SH, methyl, ethyl, F, Cl, and Br;
- comprising the sequential steps under exclusion of oxygen:
- a) nitrating 2,6-dihalotoluene (II)
- wherein each Z is independently Cl or Br, in a reaction mixture comprising oleum or SO3, nitric acid, and H2SO4
- wherein
- (i) the concentration of nitric acid is about 2.0 to about 2.3 moles per mole of 2,6-dihalotoluene;
- (ii) the concentration of SO3 is about 1 to about 3 moles per mole of 2,6-dihalotoluene;
- and
- (iii) the concentration of 2,6-dihalotoluene in the reaction mixture is between about 12 and about 24 weight percent;
- and
- wherein the temperature of the reaction mixture does not exceed 120° C.;
- thereby producing 2,6-dihalo-3,5-dinitrotoluene;
- b) directly separating the 2,6-dihalo-3,5-dinitrotoluene from the reaction mixture by filtration, while recycling the sulfuric acid mother liquor;
- c) washing the 2,6-dihalo-3,5-dinitrotoluene with water or acid then water, then with NH4OH, and then mixing it with glycol as a suspension;
- d) aminating the 2,6-dihalo-3,5-dinitrotoluene by heating the suspension formed in step (c) to a temperature in the range of about 100° C. to about 160° C. and contacting it with NH3(g), thereby converting the 2,6-dihalo-3,5-dinitrotoluene to 2,6-diamino-3,5-dinitrotoluene;
- e) directly separating the 2,6-diamino-3,5-dinitrotoluene from the reaction mixture by filtration, washing with glycol, then washing with water;
- f) forming a slurry of the 2,6-diamino-3,5-dinitrotoluene with water and transferring the slurry to a hydrogenation reactor containing a hydrogenation catalyst to form a reaction mixture;
- g) hydrogenating the 2,6-diamino-3,5-dinitrotoluene by contacting the reaction mixture formed in step (f) with hydrogen at a pressure in the range of about 0.31 to about 3.45 MPa and a temperature in the range of about 20° C. to about 100° C. to hydrogenate the 2,6-diamino-3,5-dinitrotoluene, thereby producing 2,3,5,6-tetraminotoluene;
- h) contacting the 2,3,5,6-tetraminotoluene produced in (g) with an aqueous solution comprising 1 to 6 equivalents of acid per mol of 2,3,5,6-tetraminotoluene, optionally heating the solution, thereby dissolving the 2,3,5,6-tetraminotoluene;
- i) filtering the reaction mixture, thereby removing the spent hydrogenation catalyst;
- j) forming and precipitating the 2,3,5,6-tetraminotoluene salt by adding an acid to the filtered reaction mixture, wherein the acid is selected from the group consisting of HCl, acetic acid, H2SO4, and H3PO4;
- k) cooling, filtering, washing and dissolving the precipitated 2,3,5,6-tetraminotoluene salt to form an aqueous solution thereof;
- l) combining the 2,3,5,6-tetraminotoluene salt solution with
- (i) 0 to 5 equivalents of an acid selected from the group consisting of HCl, acetic acid, H2SO4, and H3PO4;
- (ii) 0 to 5 equivalents of an organic base or an inorganic base;
- (iii) optionally, a buffer solution;
- and
- (iv) 0 to 5 equivalents of an XYTA source selected from XYTA and M2XYTA (Formula III)
- wherein M is K or Na, and wherein the molar ratio of XYTA to the 2,3,5,6-tetraminotoluene salt is from 1:1 to 1:1.1;
- thereby adjusting the pH of the mixture to between about 3 and about 10 and thereby producing and precipitating the complex generally described by Formula (I);
- and
- m) cooling, filtering, and washing the precipitated complex.
29 more elements
Dependencies are inferred from the claim text.