In one embodiment, the invention relates to processes for producing acesulfame potassium. In one embodiment, the process comprises the step of reacting a first reaction mixture to form an amidosulfamic acid salt such as a trialkyl ammonium amidosulfamic acid salt. The first reaction mixture comprises sulfamic acid, an amine, and smaller amounts, if any, acetic acid, e.g., less than 1 wt % (10000 wppm). In terms of ranges, the first reaction mixture may comprise from 1 wppm to 1 wt % acetic acid. The process further comprises the step of reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt. In preferred embodiments, the amidosulfamic acid salt formation reaction is conducted at ph levels from 5.5 to 7.0. The process further comprises the step of deriving the acesulfame-K from the acetoacetamide salt.
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10. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising:
sulfamic acid,
an amine, and
from 1 wppm to 1 wt % wppm acetic acid
to form an amidosulfamic acid salt;
(b) reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt;
(c) deriving the acesulfame potassium from the acetoacetamide salt,
wherein the acesulfame potassium has a yellowing index less than 5.
0. 124. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising: sulfamic acid, an amine, and from 1 wppm to 1 wt. % acetic acid to form an amidosulfamic acid salt;
(b) reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt;
(c) deriving the acesulfame potassium from the acetoacetamide salt,
wherein a molar ratio of amine to sulfamic acid in the first reaction mixture is from 1:1 to 1.05:1.
11. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising:
sulfamic acid,
an amine, and
from 1 wppm to 1 wt % wppm acetic acid
to form an amidosulfamic acid salt;
(b) reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt;
(c) deriving the acesulfame potassium from the acetoacetamide salt,
wherein a molar ratio of amine to sulfamic acid in the first reaction mixture is less than 1.06:1.
1. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising:
sulfamic acid,
an amine, and
from 1 wppm to 1 wt % wppm acetic acid
to form an amidosulfamic acid salt;
(b) reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt;
(c) deriving the acesulfame potassium from the acetoacetamide salt,
wherein a molar ratio of acetic acid to sulfamic acid in the first reaction mixture is less than 0.095:1.
0. 92. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising: sulfamic acid, triethylamine, and from 1 wppm to 1 wt % acetic acid to form a trialkyl ammonium amidosulfamic acid salt;
(b) contacting the amidosulfamic acid salt with diketene to form a second reaction mixture and reacting the second reaction mixture to form an acetoacetamide salt having a yellowing index less than 25;
(c) deriving the acesulfame potassium from the acetoacetamide salt.
0. 86. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising: sulfamic acid, triethylamine, and from 1 wppm to 1 wt % acetic acid to form a trialkyl ammonium amidosulfamic acid salt having a yellowness index less than 5;
(b) contacting the amidosulfamic acid salt with diketene to form a second reaction mixture and reacting the second reaction mixture to form an acetoacetamide salt;
(c) deriving the acesulfame potassium from the acetoacetamide salt.
0. 98. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising: sulfamic acid, triethylamine, and acetic acid at a ph from 5.9 to 6.8 to form a trialkyl ammonium amidosulfamic acid salt having a yellowing index less than 5;
(b) contacting the amidosulfamic acid salt with diketene to form a second reaction mixture and reacting the second reaction mixture to form an acetoacetamide salt;
(c) deriving the acesulfame potassium from the acetoacetamide salt.
0. 105. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising: sulfamic acid, triethylamine, and acetic acid at a ph from 5.9 to 6.8 to form a trialkyl ammonium amidosulfamic acid salt;
(b) contacting the amidosulfamic acid salt with diketene to form a second reaction mixture and reacting the second reaction mixture to form an acetoacetamide salt having a yellowing index less than 25;
(c) deriving the acesulfame potassium from the acetoacetamide salt.
0. 113. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising: sulfamic acid, an amine in a molar excess of 5 mol. % or less, and from 0.9 wt. % to 1 wt. % acetic acid to form an amidosulfamic acid salt, wherein the first reaction mixture is maintained at a ph of from 6.1 to 6.4;
(b) reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt;
(c) deriving the acesulfame potassium from the acetoacetamide salt,
wherein a molar ratio of amine to sulfamic acid in the first reaction mixture is from 1:1 to 1.05:1.
0. 85. A process for producing acesulfame potassium, the process comprising the steps of:
(a) reacting a first reaction mixture comprising: sulfamic acid, triethylamine, and from 1 wppm to 1 wt % acetic acid, at a molar ratio of acetic acid to sulfamic acid less than 0.095:1, at a molar ratio of amine to sulfamic acid less than 1.06:1, at an amine excess less than 6 mol %, to form a trialkyl ammonium amidosulfamic acid salt having a yellowing index less than 5;
(b) contacting the amidosulfamic acid salt and diketene to form a second reaction mixture and reacting the second reaction mixture at a ph from 5.5 to 7.0 to form an acetoacetamide salt having a yellowing index less than 45;
(c) reacting the acetoacetamide salt with a cyclizing agent to form a cyclic sulfur trioxide adduct; and
(d) hydrolyzing the cyclic sulfur trioxide adduct to form acesulfame-H; and
(e) neutralizing the acesulfame-H with potassium hydroxide to form the potassium acesulfame;
wherein the acesulfame potassium has a yellowing index less than 5.
2. The process of
reacting the acetoacetamide salt with a cyclizing agent to form a cyclic sulfur trioxide adduct;and
deriving the acesulfame potassium composition from the cyclic sulfur trioxide adduct.
3. The process of
hydrolyzing the cyclic sulfur trioxide adduct to form acesulfame-H; and
neutralizing the acesulfame-H with potassium hydroxide to form the potassium acesulfame.
5. The process of
6. The process of
7. The process of
9. The process of
contacting the amidosulfamic acid salt and diketene to form a second reaction mixture; and
reacting the second reaction mixture to form the acetoacetamide salt.
0. 12. The process of claim 1, wherein the acetoacetamide salt has a yellowing index less than 25.
0. 13. The process of claim 6, wherein the acetoacetamide salt has a yellowing index less than 25.
0. 14. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level ranging from 5.5 to 7.0.
0. 15. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level ranging from 6.1 to 6.4.
0. 16. The process of claim 13, wherein the ph of the first reaction mixture is maintained at a level ranging from 6.1 to 6.4.
0. 17. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level greater than 5.5.
0. 18. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level greater than 6.1.
0. 19. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level less than 6.8.
0. 20. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level less than 6.4.
0. 21. The process of claim 10, wherein the first reaction mixture comprises acetic acid in an amount from 10 to 900 wppm, based on the total weight of the sulfamic acid, amine, and acetic acid.
0. 22. The process of claim 10, wherein the first reaction mixture comprises acetic acid in an amount from 10 to 900 wppm, based on the total weight of the sulfamic acid, amine, and acetic acid.
0. 23. The process of claim 10, wherein the first reaction mixture comprises acetic acid in an amount less than 100 wppm, based on the total weight of the sulfamic acid, amine, and acetic acid.
0. 24. The process of claim 10, wherein the first reaction mixture further comprises solvent and wherein the first reaction mixture comprises acetic acid in an amount less than 0.175 wt %, based on the total weight of the sulfamic acid, amine, acetic acid, and solvent.
0. 25. The process of claim 20, wherein the first reaction mixture further comprises solvent and wherein the first reaction mixture comprises acetic acid in an amount less than 0.175 wt %, based on the total weight of the sulfamic acid, amine, acetic acid, and solvent.
0. 26. The process of claim 10, wherein the first reaction mixture comprises at least 35 wt % amine, based on the total weight of the sulfamic acid, amine, and acetic acid.
0. 27. The process of claim 10, wherein the first reaction mixture comprises from 1 wppm to 900 wppm acetic acid and from 35 wt % to 75 wt % amine, based on the total weight of the sulfamic acid, amine, and acetic acid.
0. 28. The process of claim 10, wherein the first reaction mixture comprises from 45 wt % to 85 wt % solvent, based on the total weight of the sulfamic acid, amine, acetic acid, and solvent.
0. 29. The process of claim 10, wherein the molar ratio of acetic acid to sulfamic acid in the first reaction mixture ranges from 0.001:1 to 0.06:1.
0. 30. The process of claim 10, wherein the molar ratio of amine to sulfamic acid in the first reaction mixture is greater than 1:1.
0. 31. The process of claim 29, wherein the molar ratio of amine to sulfamic acid in the first reaction mixture is greater than 1:1.
0. 32. The process of claim 10, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 5.
0. 33. The process of claim 10, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 2.
0. 34. The process of claim 29, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 2.
0. 35. The process of claim 10, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 0.5.
0. 36. The process of claim 10, wherein the acetoacetamide salt, as formed, has a yellowing index less than 25.
0. 37. The process of claim 10, wherein the acetoacetamide salt, as formed, has a yellowing index less than 10.
0. 38. The process of claim 10 wherein the acesulfame potassium has a yellowing index less than 3.
0. 39. The process of claim 32, wherein the acesulfame potassium has a yellowing index less than 0.5.
0. 40. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level ranging from 5.9 to 6.8, and wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 5.
0. 41. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level ranging from 6.1 to 6.4, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 5, and wherein the acetoacetamide salt, as formed, has a yellowing index less than 25.
0. 42. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level ranging from 6.1 to 6.4, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 2, wherein the acetoacetamide salt, as formed, has a yellowing index less than 10, and wherein the acesulfame potassium has a yellowing index less than 3.
0. 43. The process of claim 10, wherein the acetoacetamide salt, as formed, has a yellowing index and wherein the yellowing index of the acetoacetamide salt is less than the yellowing index of the acesulfame potassium.
0. 44. The process of claim 20, wherein the first reaction is conducted at a temperature greater than 25° C.
0. 45. The process of claim 10, wherein first reaction and the acetoacetamide salt formation reaction are conducted in the same reactor.
0. 46. The process of claim 10, wherein first reaction and the acetoacetamide salt formation reaction are conducted in different reactors.
0. 47. The process of claim 10, wherein the ph of the acetoacetamide salt formation reaction ranges from 5.9 to 6.8.
0. 48. The process of claim 10, wherein the ph of the first reaction mixture ranges from 5.9 to 6.8 and the ph of the acetoacetamide salt formation reaction ranges from 5.9 to 6.8.
0. 49. The process of claim 10, wherein the first reaction and the acetoacetamide salt formation reaction are conducted in separate reactors and wherein some of the amine from the first reaction is carried through to the reaction mixture of the acetoacetamide salt formation reaction.
0. 50. The process of claim 49, wherein the acetoacetamide salt formation reaction mixture comprises the amidosulfamic acid salt, and carried-through amine.
0. 51. The process of claim 10, wherein the ph of the acetoacetamide salt formation reaction is maintained at a level ranging from 5.5 to 7.0, wherein the acetoacetamide salt, as formed, has a yellowing index less than 10, and wherein the acesulfame potassium has a yellowing index less than 3.
0. 52. The process of claim 10, wherein the ph of the acetoacetamide salt formation reaction is maintained at a level ranging from 6.1 to 6.4, wherein the acetoacetamide salt, as formed, has a yellowing index less than 10, and wherein the acesulfame potassium has a yellowing index less than 3.
0. 53. The process of claim 10, wherein the first reaction is conducted at an amine excess of less than 6 mol %.
0. 54. The process of claim 10, wherein the first reaction is conducted at an amine excess of less than 3 mol %.
0. 55. The process of claim 10, further comprising: maintaining the ph of the first reaction by controlling the content of acetic acid and amine, and wherein the controlling comprises maintaining the concentration of acetic acid between 1 wppm and 1 wt % and the concentration of amine between 35 wt % and 75 wt %.
0. 56. The process of claim 10, wherein the acetoacetamide salt formation reaction comprises less than 0.157 wt % acetic acid, from 3 wt % to 45 wt % amidosulfamic acid salt, from 1 wt % to 30 wt % diketene, and from 45 wt % to 85 wt % solvent.
0. 57. The process of claim 10, wherein step (c) comprises:
reacting the acetoacetamide salt with a cyclizing agent to form a cyclic sulfur trioxide adduct; and
deriving the acesulfame potassium composition from the cyclic sulfur trioxide adduct.
0. 58. The process of claim 57, wherein the deriving comprises:
hydrolyzing the cyclic sulfur trioxide adduct to form acesulfame-H; and
neutralizing the acesulfame-H with potassium hydroxide to form the acesulfame potassium.
0. 59. The process of claim 10, wherein the amine comprises triethylamine.
0. 60. The process of claim 57, wherein the acetoacetamide salt formation reaction mixture comprises diketene in an amount from 1 wt % to 30 wt %, based on total weight of the acetoacetamide salt formation reaction mixture including solvent.
0. 61. The process of claim 53, wherein the acetoacetamide salt formation reaction mixture comprises from 3 wt % to 45 wt % of the amidosulfamic acid salt, from 1 wt % to 30 wt % of the diketene, and from 45 wt % to 85 wt % solvent based on total weight of the acetoacetamide salt formation reaction mixture.
0. 62. The process of claim 54, wherein the diketene is present in excess to the amount of the amidosulfamic acid salt.
0. 63. The process of claim 62, wherein the excess is less than 10 mol %.
0. 64. The process of claim 62, wherein the reacting of the first reaction mixture is conducted at a temperature from 0° C. to 25° C.
0. 65. The process of claim 10, wherein the ph of the first reaction mixture is maintained at a level ranging from 5.5 to 7.0, and wherein the acetoacetamide salt formation reaction is conducted in the presence of less than 0.157 wt % acetic acid, based on the total weight of the acetoacetamide salt formation reaction, and wherein the process produces at least 50 grams of acesulfame potassium per hour.
0. 66. The process of claim 64, wherein the ph of the first reaction mixture is maintained at 5.9 to 6.8, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 5, and wherein the acetoacetamide salt, as formed, has a yellowing index less than 25.
0. 67. The process of claim 64, wherein the ph of the first reaction mixture is maintained at a level ranging from 6.1 to 6.4, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 2, wherein the acetoacetamide salt, as formed, has a yellowing index less than 10, and wherein the acesulfame potassium has a yellowing index less than 3.
0. 68. The process of claim 65, wherein the ph of the first reaction mixture is substantially similar to the ph of the acetoacetamide salt formation reaction mixture.
0. 69. The process of claim 65, wherein the acetoacetamide salt, as formed, has a yellowing index less than 25, and the acesulfame potassium has a yellowing index less than 3.
0. 70. The process of claim 64, wherein the ph of the first reaction mixture is maintained at a level ranging from 5.9 to 6.8, wherein the amidosulfamic acid salt, as formed, has a yellowing index less than 5, and wherein the acetoacetamide salt, as formed, has a yellowing index less than 25.
0. 71. The process of claim 10, wherein the process produces at least 50 grams of acesulfame-K per hour, and wherein the first reaction is conducted at a temperature greater than 10° C.
0. 72. The process of claim 20, wherein the process produces at least 50 grams of acesulfame-K per hour, and wherein the first reaction is conducted at a temperature greater than 10° C.
0. 73. The process of claim 10, wherein the acetoacetamide salt formation reaction is conducted in the presence of less than 0.157 wt % acetic acid, and wherein the first reaction mixture comprises from 1 wppm to 900 wppm acetic acid, based on a total weight of the sulfamic acid, the amine, and the acetic acid.
0. 74. The process of claim 20, wherein the acetoacetamide salt formation reaction is conducted in the presence of less than 0.157 wt % acetic acid, and wherein the first reaction mixture comprises from 1 wppm to 900 wppm acetic acid, based on a total weight of the sulfamic acid, the amine, and the acetic acid.
0. 75. The process of claim 10, wherein the acetoacetamide salt formation reaction is conducted in the presence of less than 0.157 wt % acetic acid, and wherein the first reaction mixture comprises from 100 wppm to 1 wt % acetic acid, based on a total weight of the sulfamic acid, the amine, and the acetic acid.
0. 76. The process of claim 62, wherein the first reaction mixture further comprises solvent and wherein the first reaction mixture comprises the acetic acid present in an amount from 1 wppm to 150 wppm acetic acid, based on a total weight of the sulfamic acid, the amine, the acetic acid, and the solvent.
0. 77. The process of claim 76, wherein the molar ratio of the acetic acid to the sulfamic acid in the first reaction mixture is less than 0.095:1.
0. 78. The process of claim 76, wherein the amidosulfamic acid salt formation reaction mixture comprises from 3 wt % to 45 wt % amidosulfamic acid salt, from 1 wt % to 30 wt % diketene, and from 45 wt % to 85 wt % solvent, based on a total weight of the amidosulfamic acid salt formation reaction mixture.
0. 79. The process of claim 10, further comprising the step of:
maintaining the ph of the first reaction by controlling the content of acetic acid and amine in the first reaction mixture;
wherein the maintaining is achieved by maintaining a molar ratio of acetic acid to sulfamic acid at less than 0.095:1.
0. 80. The process of claim 79, wherein the ph of the first reaction mixture is maintained at 5.5 to 7.0.
0. 81. The process of claim 79, wherein the controlling comprises maintaining the concentration of acetic acid between 1 wppm and 1 wt % and the concentration of amine between 35 wt % and 75 wt %.
0. 82. The process of claim 10, wherein the reacting the amidosulfamic acid salt with diketene to form an acetoacetamide salt step is carried out in a second reaction mixture comprising less than 0.157 wt % acetic acid, from 3 wt % to 45 wt % amidosulfamic acid salt, from 1 wt % to 30 wt % diketene, and from 45 wt % to 85 wt % solvent, based on a total weight of the amidosulfamic acid salt formation reaction mixture.
0. 83. The process of claim 82, wherein first reaction and the acetoacetamide salt formation reaction are conducted in the same reactor.
0. 84. The process of claim 83, wherein the ph of the first reaction mixture is maintained at a level ranging from 5.9 to 6.8 and the ph of the second reaction mixture is maintained at a level ranging from 5.9 to 6.8.
0. 87. The process of claim 86, wherein the reaction of the first reaction mixture is conducted at an amine excess of less than 6 mol %.
0. 88. The process of claim 87, wherein the acetoacetamide salt formation reaction is conducted in the presence of less than 0.157 wt % acetic acid, and wherein the first reaction mixture comprises from 1 wppm to 900 wppm acetic acid, based on a total weight of the sulfamic acid, the amine, and the acetic acid.
0. 89. The process of claim 87, wherein the ph of the first reaction mixture is maintained at less than 6.8.
0. 90. The process of claim 87, wherein the acesulfame potassium has a yellowing index less than 3.
0. 91. The process of claim 88, wherein the acesulfame potassium has a yellowing index less than 3.
0. 93. The process of claim 92, wherein the reaction of the first reaction mixture is conducted at an amine excess of less than 6 mol %.
0. 94. The process of claim 93, wherein the molar ratio of acetic acid to sulfamic acid in the first reaction mixture ranges from 0.001:1 to 0.06:1.
0. 95. The process of claim 93, wherein the second reaction mixture further comprises ammonium acetate salt.
0. 96. The process of claim 93, wherein the acesulfame potassium has a yellowing index less than 3.
0. 97. The process of claim 95, wherein the acesulfame potassium has a yellowing index less than 3.
0. 99. The process of claim 98, wherein the acetoacetamide salt formation reaction is conducted in the presence of less than 0.157 wt % acetic acid, and wherein the first reaction mixture comprises from 1 wppm to 900 wppm acetic acid, based on a total weight of the sulfamic acid, the amine, and the acetic acid.
0. 100. The process of claim 98, wherein the acesulfame potassium has a yellowing index less than 3.
0. 101. The process of claim 99, wherein the acesulfame potassium has a yellowing index less than 3.
0. 102. The process of claim 98, wherein the second reaction mixture further comprises ammonium acetate salt.
0. 103. The process of claim 99, wherein the second reaction mixture further comprises ammonium acetate salt.
0. 104. The process of claim 100, wherein first reaction mixture is reacted at a ph from 6.1 to 6.4.
0. 106. The process of claim 105, wherein the molar ratio of acetic acid to sulfamic acid in the first reaction mixture ranges from 0.001:1 to 0.06:1.
0. 107. The process of claim 106, wherein the reaction of the first reaction mixture is conducted at an amine excess of less than 6 mol %.
0. 108. The process of claim 105, wherein the acetoacetamide salt formation reaction is conducted in the presence of less than 0.157 wt % acetic acid.
0. 109. The process of claim 106, wherein the acetoacetamide salt formation reaction is conducted in the presence of less than 0.157 wt % acetic acid.
0. 110. The process of claim 106, wherein the acesulfame potassium has a yellowing index less than 3.
0. 111. The process of claim 108, wherein the acesulfame potassium has a yellowing index less than 3.
0. 112. The process of claim 110, wherein first reaction mixture is reacted at a ph from 6.1 to 6.4.
0. 114. The process of claim 113, wherein step (c) comprises:
reacting the acetoacetamide salt with a cyclizing agent to form a cyclic sulfur trioxide adduct; and
deriving the acesulfame potassium composition from the cyclic sulfur trioxide adduct.
0. 115. The process of claim 114, wherein the deriving comprises:
hydrolyzing the cyclic sulfur trioxide adduct to form acesulfame-H; and
neutralizing the acesulfame-H with potassium hydroxide to form the potassium acesulfame.
0. 116. The process of claim 113, wherein the amine comprises triethylamine.
0. 117. The process of claim 113, wherein the amidosulfamic acid salt has a yellowing index less than 5.
0. 118. The process of claim 113, wherein the acetoacetamide salt has a yellowing index less than 25.
0. 119. The process of claim 113, wherein the first reaction mixture comprises from 45 wt % to 85 wt % solvent, based on the total weight of the sulfamic acid, amine, acetic acid, and solvent.
0. 120. The process of claim 113, wherein the molar ratio of amine to sulfamic acid in the first reaction mixture is greater than 1:1.
0. 121. The process of claim 113, wherein the diketene is present in excess to the amount of the amidosulfamic acid salt.
0. 122. The process of claim 113, wherein the diketene is present in excess in an amount of less than 10 mol. % to the amount of the amidosulfamic acid salt.
0. 123. The process of claim 113, wherein the process produces at least 50 grams of acesulfame-K per hour, and wherein the first reaction is conducted at a temperature greater than 10° C.
0. 125. The process of claim 124, wherein the acetic acid is present in an amount of from 0.9 wt. % to 1 wt. %.
0. 126. The process of claim 124, wherein the first reaction mixture is maintained at a ph of from 6.1 to 6.4.
0. 127. The process of claim 124, wherein step (c) comprises:
reacting the acetoacetamide salt with a cyclizing agent to form a cyclic sulfur trioxide adduct; and
deriving the acesulfame potassium composition from the cyclic sulfur trioxide adduct.
0. 128. The process of claim 127, wherein the deriving comprises:
hydrolyzing the cyclic sulfur trioxide adduct to form acesulfame-H; and
neutralizing the acesulfame-H with potassium hydroxide to form the potassium acesulfame.
0. 129. The process of claim 124, wherein the amine comprises triethylamine.
0. 130. The process of claim 124, wherein the amidosulfamic acid salt has a yellowing index less than 5.
0. 131. The process of claim 124, wherein the acetoacetamide salt has a yellowing index less than 25.
0. 132. The process of claim 124, wherein the first reaction mixture comprises from 45 wt % to 85 wt % solvent, based on the total weight of the sulfamic acid, amine, acetic acid, and solvent.
0. 133. The process of claim 124, wherein the molar ratio of amine to sulfamic acid in the first reaction mixture is greater than 1:1.
0. 134. The process of claim 124, wherein the diketene is present in excess in an amount of less than 10 mol. % to the amount of the amidosulfamic acid salt.
0. 135. The process of claim 134, wherein the excess of the diketene is less than 10 mol %.
0. 136. The process of claim 124, wherein the process produces at least 50 grams of acesulfame-K per hour, and wherein the first reaction is conducted at a temperature greater than 10° C.
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This application is a
Acetic acid is also present in the first reaction mixture. Acetic acid may react with the amine, e.g., triethylamine, to form a triethylammonium acetate. An exemplary reaction scheme that employs triethylamine as the amine is shown below.
H3C—COOH+N(C2H5)3→H3C—COO−·HN+(C2H5)3
In conventional processes, acetic acid is added to these reactants in higher amounts, e.g., in amounts greater than 1 wt % acetic acid. The addition of acetic acid affects the pH at which the reaction is conducted. The addition of amine to a mixture may increase the pH of the mixture to which the amines are added. Thus, in addition to acetic acid content, the presence of amine in the reaction mixture may also affect the pH at which the reaction is conducted. As such, the amine not only serves as a reactant, but may also adjust the pH of the reaction mixture. In one embodiment, the amine is present in amounts in excess of the stoichiometric amount. In one embodiment, the amidosulfamic acid salt formation reaction is conducted at an amine excess of less than 6 mol %, e.g., less than 5 mol % or less than 3 mol %. In the process of the present invention, however, less acetic acid is used in the first reaction mixture. Accordingly, less amine(s) are required to achieve the desired pH level, as compared to conventional reactions that employ higher amounts of acetic acid.
In one embodiment, the first reaction mixture comprises from 35 wt % to 75 wt % amine(s), e.g., from 45 wt % to 65 wt % or from 50 wt % to 60 wt %, based on the total weight of the first reaction mixture, excluding solvent. In terms of upper limits, the first reaction mixture may comprise less than 75 wt % amine(s), e.g., less than 65 wt % or less than 60 wt %. In terms of lower limits, the first reaction mixture may comprise at least 35 wt % amine(s), e.g., at least 45 wt % or at least 50 wt %. The first reaction mixture may also comprise a solvent. In one embodiment, the first reaction mixture comprises from 45 wt % to 85 wt % solvent, e.g., from 55 wt % to 75 wt % or from 60 wt % to 70 wt %. Exemplary solvents are discussed herein.
In one embodiment, the first reaction mixture has a molar ratio of acetic acid to sulfamic acid that is less than 0.095:1 e.g., less than 0.06:1, less than 0.01:1 or less than 0.001:1. In terms of ranges, the first reaction mixture may have a molar ratio of acetic acid to sulfamic acid in the range of 0.0001:1 to 0.095:1, e.g., from 0.001:1 to 0.06:1.
In one embodiment, a molar ratio of amine(s) to sulfamic acid in the first reaction mixture is greater than 1:1, e.g., greater than 1.02:1 or greater than 1.05:1.
The amine that is employed in this reaction may vary widely. Preferably, the amine comprises triethylamine. In one embodiment, the amine may be selected from the group consisting of trimethylamine, diethylpropylamine, tri-n-propylamine, triisopropylamine, ethyldiisopropylamine, tri-n-butylamine, triisobutylamine, tricyclohexylamine, ethyldicyclohexylamine, N,N-dimethylaniline, N,N-diethylaniline, benzyldimethylamine, pyridine, substituted pyridines such as picoline, lutidine, cholidine or methylethylpyridine, N-methylpiperidine, N-ethylpiperidine, N-methylmorpholine, N,N-dimethylpiperazine, 1,5-diazabicyclo[4.3.0]-non-5-en, 1,8-diazabicyclo-[5.4.0]-undec-7-en, 1,4-diazabicyclooctane, tetramethylhexamethylendiamine, tetramethylethylendiamine, tetramethylpropylendiamine, tetramethylbutylendiamine, 1,2-dimorpholylethan, pentamethyldiethyltriamine, pentaethyldiethylentriamine, pentamethyldipropylentriamine, tetramethyldiaminomethane, tetrapropyldiaminomethane, hexamethyltriethylentetramine, hexamethyltripropylenetetramine, diisobutylentriamine, triisopropylentriamine, and mixtures thereof.
Returning to the acetoacetamide salt formation reaction, amidosulfamic acid salt and an acetoacetylating agent are reacted to form the acetoacetamide salt. Preferably, the acetoacetylating agent is diketene, although other acetoacetylating agents may be employed, either with or without diketene.
In one embodiment, the resultant acetoacetamide salt may correspond to the following formula.
##STR00001##
where M+ is an appropriate metal ion,
Preferably, M+ is Li+ or N+R1R2R3R4. R1, R2, R3 and R4, independently of one another, may be organic radicals or hydrogen, preferably H or C1-C8 alkyl, C6-C10 cycloalkyl, aryl and/or aralkyl.
In one embodiment, the total number of carbon atoms in the ammonium ion in the ammonium salts is not more than about 20, in particular not more than about 10.
An exemplary reaction scheme that employs a trialkyl ammonium amidosulfamic acid salt and diketene as reactants and yields an acetoacetamide triethylammonium salt is shown below.
##STR00002##
In one embodiment, the reaction is conducted in the presence of a catalyst. The catalyst may vary widely. In some embodiments, the catalyst comprises one or more amines and/or phosphines. Preferably, the catalyst is triethylamine. In addition to triethylamine, other exemplary amine catalysts include the amines listed above with respect the amidosulfamic acid salt formation reaction. Exemplary phosphines include methyldiphenylphosphine, triphenylphosphine, tributylphosphine. In one embodiment, the acetoacetamide salt formation reaction takes place without a catalyst.
In one embodiment wherein the amidosulfamic acid salt formation reaction and the acetoacetamide salt formation reaction are conducted in separate reactors, a second reaction mixture comprises the amidosulfamic acid salt, the diketene, and the catalyst, e.g., triethylamine. Preferably, catalyst from the first reaction is carried through to the reaction mixture of the second reaction. The second reaction mixture is then subjected to conditions effective to form the acetoacetamide salt. Preferably, the second reaction mixture comprises essentially no acetic acid.
In one embodiment, the composition of the second reaction mixture may be similar to that of the first reaction mixture, discussed above. In one embodiment, when the weight of the solvent is taken into consideration in the weight percentage calculation, the second reaction mixture comprises less than 0.157 wt % acetic acid, e.g., less than 0.15 wt %, less than 0.10 wt %, less than 0.8 wt %, or less than 0.5 wt %, based on. In some embodiments, the second reaction mixture may further comprise from 3 wt % to 45 wt % amidosulfamic acid salt, e.g., from 13 wt % to 35 wt % or from 18 wt % to 30 wt %; from 1 wt % to 30 wt % diketene, e.g., from 1 wt % to 20 wt % or from 5 wt % to 15 wt %; and/or from 45 wt % to 85 wt % solvent, e.g., from 55 wt % to 75 wt % or from 60 wt % to 70 wt %. In a preferred embodiment, the reaction product of the amidosulfamic acid salt formation reaction provides the amidosulfamic acid salt component of the second reaction mixture. In addition to the above-mentioned components, the second reaction mixture may further comprise reaction by-products from the first reaction, e.g., (residual) ammonium acetate salt.
In one embodiment, the amount of acetoacetylating agent, e.g., diketene, should be at least equimolar to the reactant amidosulfamic acid salt. In one embodiment, the process may utilize a diketene excess less than 30 mol %, e.g., less than 10 mol %. Greater excesses are also contemplated.
The first and/or second reaction may employ an organic solvent. Suitable inert organic solvents are virtually all organic solvents which do not react in an undesired manner with the starting materials, final products and/or the catalysts in the reaction. The solvents preferably have the ability to dissolve, at least partially, amidosulfamic acid salts. Exemplary organic solvents include halogenated aliphatic hydrocarbons, preferably those having up to 4 carbon atoms such as, for example, methylene chloride, chloroform, 1,2-dichlorethane, trichloroethylene, tetrachloroethylene, trichlorofluoroethylene; aliphatic ketones, preferably those having 3 to 6 carbon atoms such as, for example, acetone, methyl ethyl ketone; aliphatic ethers, preferably cyclic aliphatic ethers having 4 or 5 carbon atoms such as, for example, tetrahydrofuran, dioxane; lower aliphatic carboxylic acids, preferably those having 2 to 6 carbon atoms such as, for example, acetic acid, propionic acid; aliphatic nitriles, preferably acetonitrile; N-alkyl-substituted amides of carbonic acid and lower aliphatic carboxylic acids, preferably amides having up to 5 carbon atoms such as, for example, tetramethylurea, dimethylformamide, dimethylacetamide, N-methylpyrrolidone; aliphatic sulfoxides, preferably dimethyl sulfoxide, and aliphatic sulfones, preferably sulfolane.
Particularly preferred solvents include methylene chloride, 1,2-dichloroethane, acetone, glacial acetic acid and dimethylformamide, with methylene dichloride being particularly preferred. The solvents may be used either alone or in a mixture.
In one embodiment, the reaction is conducted a temperature ranging from −30° C. to 50° C., e.g., from 0° C. to 25° C. The reaction pressure may vary widely. In preferred embodiments, the reaction is carried out at atmospheric pressure. The reaction time may vary widely, preferably ranging from 0.5 hours to 12 hours, e.g., from 1 hour to 10 hours. In embodiment, the reaction is carried out by introducing the amidosulfamic acid salt and metering in the diketene. In one embodiment, the reaction is carried out by introducing diketene and metering in the amidosulfamic acid salt. The reaction may be carried out by introducing the diketene and amidosulfamic acid and metering in the catalyst.
Once formed, the reaction product is preferably subjected to one or more purification steps. For example the solvent may be separated from the reaction product, e.g., via distillation, and the residue (mainly acetoacetamide-N-sulfonate) may be recrystallized from a suitable solvent such as, for example, acetone, methyl acetate or ethanol.
Cyclization, Hydrolyzation and Neutralization
The acetacetamide salt, in preferred embodiments, is reacted with a cyclizing agent to form a cyclic sulfur trioxide adduct. In one embodiment, the cyclization is achieved by using at least an equimolar amount of the cyclizing agent, e.g., sulfur trioxide, which may be dissolved in an inert inorganic or organic solvent. The sulfur trioxide is generally used in a molar excess, e.g., up to a 20 fold excess, or up to a 10 fold excess, based on the acetoacetamide salt. An exemplary cyclization reaction is shown below.
##STR00003##
The sulfur trioxide may be added to the reaction mixture either in the solid or the liquid form or by condensing in sulfur trioxide vapor. Preferably, a solution of sulfur trioxide in 1) concentrated sulfuric acid, 2) liquid sulfur dioxide, or 3) an inert organic solvent is used. In one embodiment, the reaction is carried out without a solvent. Suitable inert inorganic or organic solvents are those liquids which do not react in an undesired manner with sulfur trioxide or the starting materials or final products of the reaction. Preferred inorganic solvents include, but are not limited to liquid sulfur dioxide. Preferred organic solvents include, but are not limited to halogenated aliphatic hydrocarbons, preferably having up to 4 carbon atoms, such as, for example, methylene chloride (dichloro methane), chloroform, 1,2-dichloroethane, trichloroethylene, tetrachloroethylene, trichlorofluoroethylene; esters of carbonic acid with lower aliphatic alcohols, preferably with methanol or ethanol; nitroalkanes, preferably having up to 4 carbon atoms, in particular nitromethane; alkyl-substituted pyridines, preferably collidine; and aliphatic sulfones, preferably sulfolane. The processes may employ these solvents alone or in mixtures thereof.
In a preferred embodiment, the same solvent is used in both the acetoacetamide salt formation reaction and the cyclization reaction. As one benefit, the solution obtained in the acetoacetamide salt formation reaction, without isolation of the acetoacetamide salt formation reaction, may be used immediately in the cyclization.
In one embodiment, the reaction temperature for the cyclization reaction ranges from −70° C. to 175° C., e.g., from −40 ° C. to 10° C. The pressure at which the reaction is conducted may vary widely. In one embodiment, the reaction is conducted at a pressure ranging from 0.01 MPa to 10 MPa, e.g., from 0.1 MPa to 5 MPa. Preferably, the reaction is conducted at atmospheric pressure.
The acetoacetamide salt may be introduced to the reactor and the sulfur trioxide is metered into the reactor. In preferred embodiments, both reactants are simultaneously fed into the reactor. In one embodiment, sulfur trioxide initially introduced into the reactor and the acetoacetamide salt is added. Preferably, at least part of the sulfur trioxide is introduced into the reactor and, either continuously or in portions, acetoacetamide salt and (additional) sulfur trioxide are then metered in.
The cyclic sulfur trioxide adduct may be hydrolyzed and neutralized via conventional means. In cases where methylene chloride is used as the reaction medium, water or ice may be added, e.g., in a molar excess, based on the sulfur trioxide, to the cyclic sulfur trioxide adduct/sulfur trioxide solution. An exemplary hydrolysis reaction scheme is shown below.
##STR00004##
The addition of the water leads to a phase separation. The sweetener acid, acesulfame-H (6-methyl-3,4-dihydro-1,2,3-oxathiazin-4one 2,2-dioxide), which is formed via the hydrolysis, is present in the organic phase.
After the addition of water, the reaction solvent may be removed by distillation, and the acesulfame-H that remains in the organic phase may be extracted with a more suitable solvent. Suitable solvents are those which are sufficiently stable towards sulfuric acid and which have a satisfactory dissolving capacity. Other suitable solvents include esters of carbonic acid such as, for example dimethyl carbonate, diethyl carbonate and ethylene carbonate, or esters of organic monocarboxylic acids such as, for example, isopropyl formate and isobutyl formate, ethyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate and neopentyl acetate, or esters of dicarboxylic acids or amides which are immiscible with water, such as, for example, tetrabutylurea, are suitable. Isopropyl acetate and isobutyl acetate are particularly preferred.
The combined organic phases are dried with, for example, Na2SO4, and are evaporated. Any sulfuric acid which has been carried over in the extraction can be removed by appropriate addition of aqueous alkali to the organic phase. For this purpose, dilute aqueous alkali may be added to the organic phase until the pH reached in the aqueous phase corresponds to that of pure 6-methyl-3,4-dihydro1,2,3-oxathiazin-4-one 2,2-dioxide at the same concentration in the same two-phase system of extracting agent and water.
The neutralization of the acesulfame-H yields a non-toxic salt of acesulfame-H, e.g., acesulfame-K. In one embodiment, the neutralization is carried out by reacting the acesulfame-H with an appropriate base, e.g., potassium hydroxide. Other suitable bases include, for example, KOH, KHCO3, K2 CO3, potassium alcoholates. An exemplary reaction scheme using potassium hydroxide as a neutralizing agent is shown below.
##STR00005##
In one embodiment, the acesulfame-H may be neutralized and extracted directly from the purified organic extraction phase using an aqueous potassium base. The acesulfame-K then precipitates out, where appropriate after evaporation of the solution, in the crystalline form, and it can also be recrystallized for purification.
The crude amidosufamic acid salt composition in line 112 is directed to acetoacetamide salt formation reactor 104. Diketene is fed to acetoacetamide salt formation reactor 104 via line 114. The resultant reaction mixture in acetoacetamide salt formation reactor 104 is as discussed above. In acetoacetamide salt formation reactor 104, the amidosufamic acid salt and the diketene are reacted to yield a crude acetoacetomide salt composition, which exits reactor 104 via line 118. By controlling the feed rate of the amide(s), the reaction in acetoacetamide salt formation reactor 104 is maintained at the inventive pH levels. Although not shown, methylene dichloride may also be present in acetoacetamide salt formation reactor 104.
The crude acetoacetomide salt composition is directed to cyclization reactor 120. Sulfur trioxide is also fed to cyclization reactor 120 (via line 122 ). In cyclization reactor 120, the acetoacetamide salt in line 118 is cyclized and a cyclic sulfur trioxide adduct stream, which exits via line 124.
Line 124, which contains the cyclic sulfur trioxide adduct, is directed to hydrolysis reactor 126. Water is fed to hydrolysis reactor 126 via water feed 128. In hydrolysis reactor 126, the cyclic sulfur trioxide adduct is hydrolyzed to yield a crude acesulfame-H stream, which exits hydrolysis reactor 126 via line 130 and is directed to phase separation unit 132. Phase separation unit 132 separates the contents of line 130 into an organic phase 134 and an aqueous phase 136. Organic phase 134 comprises a major amount of the acesulfame-H in line 130 as well as solvent, e.g., methylene chloride. Aqueous phase 136 exits via line 137 and comprises triethylammonium sulfate, and optionally sulfuric acid and minor amounts of acesulfame-H. This phase may be further purified to separate and/or recover the acesulfame-H and/or the triethylammonium sulfate. The recovered acesulfame-H may be combined with the acesulfame from the organic phase (not shown).
The organic phase exits phase separation unit 132 and is directed to extraction column 138 (via line 140 ). Water is fed to extraction column 138 via water feed 142. The water extracts residual sulfates from the contents of line 140 and a purified acesulfame-H stream exits extraction column 138 via line 144. The extracted sulfates exit extraction column 138 via line 145.
Line 144 is directed to neutralization unit 146. Potassium hydroxide is also fed to neutralization unit 146 (via line 148 ). The potassium hydroxide neutralizes the acesulfame-H to yield a crude acesulfame-K product, which exits neutralization unit 146 via line 150. The crude acesulfame-K product stream comprises acesulfame-K, methylene dichloride, water, and potassium hydroxide. The crude acesulfame-K product stream in line 150 may be directed to further processing to recover purified acesulfame-K, which is shown exiting via stream 152. In addition to the purified acesulfame-K, methylene dichloride and potassium hydroxide may be separated from the crude acesulfame-K product stream, as shown by stream 154. The contents of stream 154 may be recovered and/or recycled to the process.
While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the Background and Detailed Description, the disclosures of which are all incorporated herein by reference. In addition, it should be understood that aspects of the invention and portions of various embodiments and various features recited below and/or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be appropriately combined with other embodiments as will be appreciated by one of skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention.
Mollenkopf, Christoph, Groer, Peter, Brietzke, Stephan, Bayer, Michael J.
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