Process for the preparation of diaminobutane

1. A process for preparing diaminobutane from ornithine, comprising steps of:

(i) preparing a reaction solution comprised of:

(a) a salt of ornithine and an acid; and

(b) an aldehyde, a ketone or a mixture thereof; in

(c) a solvent which comprises a dipolar aprotic organic solvent, and

(ii) heating the reaction solution to a temperature above 100° C. thereby inducing decarboxylation of the ornithine and formation of diaminobutane.

2. The process according to claim 1 , wherein the salt of ornithine is a salt of ornithine and an acid selected from the group consisting of hydrogen bromide, hydrogen chloride, hydrogen sulfate, hydrogen phosphate and hydrogen nitrate.

3. The process according to claim 2 , wherein step (i) comprises dissolving ornithine and an acid in the solvent to obtain a salt solution.

4. The process according to claim 1 , wherein the solvent comprises the dipolar aprotic organic solvent in an amount of at least 50 wt. %, relative to the total weight of the solvent.

5. The process according to claim 1 , wherein the solvent has a boiling temperature, measured at 0.1 MPa, of at least 150° C.

6. The process according to claim 1 , wherein step (ii) comprises heating the reaction solution to a temperature which is in a range of 140-250° C.

7. The process according to claim 1 , wherein the dipolar aprotic organic solvent has a dielectric constant of at least 10, determined by the method according to ASTM D924, at 20° C.

8. The process according to claim 1 , wherein the dipolar aprotic organic solvent is selected from the group consisting of dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetonitrile, dimethyl acetamide, and mixtures thereof.

9. The process according to claim 1 , wherein the solvent further comprises a protic organic solvent selected from the group consisting of alcohols.

10. The process according to claim 9 , wherein the protic organic solvent is selected from the group consisting of benzyl alcohol, cyclohexanol and mixtures thereof.

11. The process according to claim 1 , wherein the aldehyde is p-methoxybenzaldehyde.

12. The process according to claim 1 , wherein the ketone is 2-cyclohexenone.

13. The process according to claim 1 , wherein the aldehyde, ketone or mixture thereof is present in the reaction solution in an amount within a range of 0.01-0.50 mol %, relative to the molar amount of the ornithine salt.

14. The process according to claim 1 , wherein the salt of ornithine and acid is present in an amount within a range of 2-50 wt. %, relative to the total weight of the reaction solution.

15. A process for preparing diaminobutane from omithine, comprising steps of:

(i) preparing a reaction solution comprised of:

(a) a salt of ornithine and an acid; and

(b) p-methoxybenzaldehyde; in

(c) a solvent which comprises a protic organic solvent, a dipolar aprotic organic solvent or a mixture thereof, and

(ii) heating the reaction solution to a temperature above 100° C. thereby inducing decarboxylation of the omithine and formation of diaminobutane.

16. The process according to claim 15 , wherein the salt of omithine is a salt of ornithine and an acid selected from the group consisting of hydrogen bromide, hydrogen chloride, hydrogen sulfate, hydrogen phosphate and hydrogen nitrate.

17. The process according to claim 16 , wherein step (i) comprises dissolving ornithine and an acid in the solvent to obtain a salt solution.

18. The process according to claim 15 , wherein the solvent comprises the protic organic solvent, the dipolar aprotic organic solvent or the mixture thereof in an amount of at least 50 wt. %, relative to the total weight of the solvent.

19. The process according to claim 15 , wherein the solvent has a boiling temperature, measured at 0.1 MPa, of at least 150° C.

20. The process according to claim 15 , wherein step (ii) comprises heating the reaction solution to a temperature which is in a range of 140-250° C.

21. The process according to claim 15 , wherein the dipolar aprotic organic solvent has a dielectric constant of at least 10, determined by the method according to ASTM D924, at 20° C.

22. The process according to claim 15 , wherein the solvent comprises a dipolar aprotic organic solvent selected from the group consisting of dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetonitrile, dimethyl acetamide, and mixtures thereof.

23. The process s according to claim 15 , wherein the solvent comprises a protic organic solvent selected from the group consisting of alcohols.

24. The process according to claim 15 , wherein the solvent is selected from the group consisting of dimethylsulfoxide (DMSO), benzyl alcohol, cyclohexanol and mixtures thereof.