Hydrated crystalline form of 2-acrylamido-2-methylpropane sulfonic acid

1. A method of manufacturing a hydrated crystalline form of 2-acrylamido-2-methylpropane sulfonic acid having a 2-theta powder X-ray diffraction diagram comprising peaks at 10.58°, 11.2°, 12.65°, 13.66°, 16.28°, 18.45°, 20°, 20.4°, 22.5°, 25.5°, 25.88°, 26.47°, 28.52°, 30.28°, 30.8°, 34.09°, 38.19°, 40.69°, 41.82°, 43.74°, and 46.04° degrees, all peak values being +/− 0.1°,said method comprising at least the following successive steps:

1) mixing 2-acrylamido-2-methylpropane sulfonic acid with an aqueous solution to form suspension A,

2) heating suspension A to produce a solution B of 2-acrylamido-2-methylpropane sulfonic acid,

3) cooling solution B to produce a suspension C of crystals, and

4) performing solid/liquid separation from suspension C and isolating crystals from suspension C from step 3) in the form of a composition comprising the hydrated crystalline form of 2-acrylamido-2-methyl propane sulfonic acid.

2. The method according to claim 1 , wherein in step 1) the ratio by weight between 2-acrylamido-2-methylpropane sulfonic acid and the aqueous solution is between 0.1:1 and 5.1.

3. The method according to claim 1 , wherein the aqueous solution of step 1) comprises at least 80% by weight of water and up to 20% by weight of organic solvent.

4. The method according to claim 1 , wherein the aqueous solution of step 1) comprises at least 80% by weight of water and up to 20% by weight of inorganic acid.

5. The method according to claim 1 , wherein during step 2), suspension A obtained in step 1) is heated to a temperature of between 50 and 120° C., to produce solution B.

6. The method according to claim 1 , wherein during step 3), solution B obtained in step 2) is cooled to a temperature of between −20 and 50° C.

7. The method according to claim 1 , wherein step 4) is conducted at a temperature of between −40 and 100° C.

8. The method according to claim 1 , wherein after step 4) the crystals of the hydrated crystalline form of 2-acrylamido-2-methylpropane sulfonic acid are not dried.

9. The method according to claim 1 , comprising:

1) mixing 2-acrylamido-2-methylpropane sulfonic acid with an aqueous solution for at least 1 minute to form suspension A, wherein the ratio by weight between 2-acrylamido-2-methylpropane sulfonic acid and the aqueous solution is between 0.2:1 and 3:1,

2) heating suspension A to a temperature of between 40 and 150° C. to produce a solution B of 2-acrylamido-2-methylpropane sulfonic acid,

3) cooling solution B to a temperature of between −40 and 100° C. for a period of between 1 and 1200 minutes, to produce a suspension C of crystals, and

4) performing solid/liquid separation from suspension C and isolating crystals of the from suspension C from step 3) in the form of a composition comprising the hydrated crystalline form of 2-acrylamido-2-methylpropane sulfonic acid, wherein the crystals represent between 40 and 99% by weight of the composition.

10. The method according to claim 1 , wherein the hydrated crystalline form of 2-acrylamido-2-methylpropane sulfonic acid presents a Fourier transform infrared spectrum comprising peaks at 3280 cm −1 , 3126 cm −1 , 1657 cm −1 , 1595 cm −1 , 1453 cm −1 , 1395 cm −1 , 1307 cm −1 , 1205 cm −1 , 1164 cm −1 , 1113 cm −1 , 1041 cm −1 , 968 cm −1 , 885 cm −1 , 815 cm −1 , and 794 cm −1 , all peak values being +/− 8 cm −1 .

11. The method according to claim 1 , wherein the hydrated crystalline form of 2-acrylamido-2-methylpropane sulfonic acid presents minimum ignition energy greater than 400 mJ.

12. The method according to claim 1 , wherein the hydrated crystalline form of 2-acrylamido-2-methylpropane sulfonic acid presents 4 thermal phenomena with the Differential Scanning calorimetry technique at 70° C., 100° C., 150° C. and 190° C., all +/− 10° C.

13. The method according to claim 1 , wherein the hydrated crystalline form of 2-acrylamido-2-methylpropane sulfonic acid has a water/2-acrylamido-2-methylpropane sulfonic acid molar ratio of 1:1.