Single stage resolution/racemization of α-amino-ε-caprolactam

Claim 2

A process for effecting transformation of D,L-α-amino-ε-caprolactam complex with nickel(II) chloride to L-α-amino-ε-caprolactam complex with nickel(II) chloride which comprises: a. forming a supersaturated solution of said complex by mixing α-amino-ε-caprolactam with nickel(II) chloride and with nickel(II) hydroxide or nickel(II) alkoxide, in a solvent selected from C 1 C 4 alkanols and mixtures thereof, at a temperature below 120° C. and in proportions such that the molar ratio of α-amino-ε-caprolactam to nickel(II) is at least 3 and the molar ratio of hydroxide or alkoxide to nickel(II) is at least 0.01; b. containing said solution with seed crystals of L-α-amino-ε-caprolactam complex with nickel(II) chloride; and c. removing the grown crystals of said complex.

Claim 3

The process of claim 1 wherein the reaction temperature is in the range of about 40° to 95° C.

Claim 4

The process of claim 1 wherein the nickel(II) hydroxide or alkoxide is obtained by treating an alcoholic solution of NiCl 2 with a strongly basic or weakly basic ion exchange resin.

Claim 5

A process for effecting transformation of D,L-α-amino-ε-caprolactam to L-α-amino-ε-caprolactam hydrochloride comprising: a. admixing D,L-α-amino-ε-caprolactam with an ROH solution of Ni(OR) n Cl 2 -n , wherein R is methyl, ethyl, or iso-propyl and n has a value of from about 0.01 to about 1.00, in a molar ratio of α-amino-ε-caprolactam to Ni(II) of from at least 3:1 to about 10:1 b. contacting the resulting solution with seed crystals of the formula (L-ACL) 3 NiCl 2 .ROH; c. removing the grown crystals of (L-ACL) 3 NiCl 2 .ROH; and d. decomposing said grown crystals by reaction with hydrogen chloride in ROH wherein R in each instance is as defined above, and removing the L-α-amino-ε-caprolactam hydrochloride formed.

Claim 6

A process for effecting transformation of D,L-α-amino-ε-caprolactam to L-α-amino-ε-caprolactam hydrochloride comprising: a. admixing D,L-α-amino-ε-caprolactam with an ROH solution of Ni(OR) n Cl 2 -n , wherein R is methyl, ethyl, or iso-propyl and n has a value of from about 0.01 to about 1.00, in a molar ratio of α-amino-ε-caprolactam to Ni(II) of from at least 3:1 to about 10:1 b. contacting the resulting solution with seed crystals of the formula (L-ACL) 3 NiCl 2 .ROH; c. removing the grown crystals of (L-ACL) 3 NiCl 2 .ROH; and d. decomposing said grown crystals by reaction with hydrogen chloride in ROH wherein R in each instance is as defined above, and removing the L-α-amino-ε-caprolactam hydrochloride formed.

Claim 7

The process of claim 1 wherein the seed crystals of L-α-amino-ε-caprolactam-nickel(II) chloride complex are prepared by mixing a methanolic solution of L-α-amino-ε-caprolactam-nickel(II) chloride complex with an alkanol selected from ethanol and isopropanol

Claim 8

A continuous process for effecting transformation of D,L-α-amino-ε-caprolactam to L-α-amino-ε-caprolactam hydrochloride comprising the steps of: a. generating a solution of basic nickel(II) salt by treating an alcohol solution of NiCl 2 with a weakly basic ion exchange resin; b. admixing said solution with at least three moles of D,L-α-amino-α-caprolactam per mol of nickel(II) thereby producing alkoxide ions; c. evaporating the resulting mixture from step (b) in the presence of seed crystals of (L-ACL) 3 NiCl 2 .ROH, where R is ethyl or iso-propyl, and continuously removing the grown resolved (L-ACL) 3 NiCl 2 .ROH crystals; d. dissolving said grown crystals from step (c) in methanol; e. mixing from about 2 to about 25% of the resulting solution from step (d) with ethanol or iso-propanol and introducing the resulting slurry of fine (L-ACL) 3 NiCl 2 .ROH crystals as seed to step (c); and f. reacting the balance of the solution from step (d) with HCl, removing the L-ACL-HCl crystals produced and recycling the resulting mother liquor to step (a).

Claim 9

A continuous process for effecting transformation of D,L-α-amino-ε-caprolactam to L-α-amino-ε-caprolactam hydrochloride comprising the steps of: a. generating a solution of basic nickel(II) salt by treating an alcohol solution of NiCl 2 with a weakly basic ion exchange resin; b. admixing said solution with at least three moles of D,L-α-amino-α-caprolactam per mol of nickel(II) thereby producing alkoxide ions; c. evaporating the resulting mixture from step (b) in the presence of seed crystals of (L-ACL) 3 NiCl 2 .ROH, where R is ethyl or iso-propyl, and continuously removing the grown resolved (L-ACL) 3 NiCl 2 .ROH crystals; d. dissolving said grown crystals from step (c) in methanol; e. mixing from about 2 to about 25% of the resulting solution from step (d) with ethanol or iso-propanol and introducing the resulting slurry of fine (L-ACL) 3 NiCl 2 .ROH crystals as seed to step (c); and f. reacting the balance of the solution from step (d) with HCl, removing the L-ACL-HCl crystals produced and recycling the resulting mother liquor to step (a).

Claim 10

The process of claim 6 wherein the molar ratio of α-amino-ε-caprolactam to nickel(II) in step (c) is from 3.5 to 7.0.

Claim 11

The process of claim 6 wherein the molar ratio of alkoxide ion nickel(II) in step (c) is from 0.05 to 0.50.

Claim 12

The process of claim 6 wherein the alcohol of crystallization in step (c) and the alcohol employed in step (e) is ethanol.

Claim 13

The process of claim 6 wherein the alcohol of crystallization in step (c) and the alcohol employed in step (a) is isopropanol.

Claim 14

The process of claim 6 wherein the resin of step (a) after removal of the basic nickel(II) salt is regenerated with an alcohol solution of ammonia.

Claim 15

The process of claim 6 wherein after generation of the solution of basic Ni(II) salt in step (a), small amounts of Ni(II) are removed from the weakly basic ion exchange resin by treatment with an α-amino-ε-caprolactam alcohol solution and the resulting nickel(II) containing solution of α-amino-ε-caprolactam is introduced to step (b).