Process for the preparation of alkyldiamines
View Patent ↗Provided is a process for preparing alkyl diamine compounds in high purity. The process utilizes an alkyl amine compound during the reduction of a nitroamine, resulting in reduction of the concentration of undesired byproducts.
1. A process for preparing an alkyl diamine compound of formula I:
wherein n is an integer from 1 to 5; R 1 and R 2 are independently H or C 1 -C 6 alkyl, or R 1 and R 2 together with the carbon to which they are attached form C 3 -C 12 cycloalkyl; and R 3 and R 4 at each occurrence are independently H or C 1 -C 6 alkyl, the process comprising reducing a corresponding nitroamine compound, wherein the reduction is conducted in the presence of an alkylamine compound of formula II:
wherein R 5 is H or C 1 -C 6 alkyl and R 6 is C 1 -C 6 alkyl.
2. The process of claim 1 wherein n is 1.
3. The process of claim 1 wherein R 3 and R 4 are H.
4. The process of claim 1 wherein R 1 and R 2 are independently C 1 -C 3 alkyl.
5. The process of claim 1 wherein R 1 and R 2 together with the carbon to which they are attached form C 5 -C 6 cycloalkyl.
6. The process of claim 1 wherein the alkyl diamine compound of formula I is 2-methyl-1,2-diaminopropane, 1-amino-cyclopentanemethanamine, 1-amino -cyclohexanemethanamine, or 2-amino-2-methyl-1-aminobutane.
7. The process of claim 1 wherein R 5 is H and R 6 is C 1 -C 6 alkyl.
8. The process of claim 1 wherein the alkylamine compound of formula II is n-propylamine.
9. The process of claim 1 wherein the reduction is carried out with hydrogen gas in combination with a hydrogenation catalyst.
10. A process for preparing 2-methyl-1,2-diaminopropane, the process comprising: hydrogenating 2-nitro-2-methyl-l-propylamine in the presence of hydrogen gas, a hydrogenation catalyst, and n-propylamine.
11. A composition comprising 2-methyl-1,2-diaminopropane and less than 0.6 weight percent of its N-methylated derivative prior to distillation, wherein the composition is prepared by the process of claim 10 .