Method for continuously preparing N,N-Bis(2,2,6,6-Tetramethyl-4-piperidyl)-1,6-hexamethylenediamine

Patent metadata

Field	Value
Publication number	US-12084427-B2
Application number	US-202217740275-A
Country	US
Kind code	B2
Filing date	May 9, 2022
Priority date	May 9, 2022
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

Disclosed is a method of continuously preparing N,N-Bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine, which relates to chemical engineering. The Pt/C catalyst and the quartz sand are mixed uniformly and loaded to the continuous-flow fixed-bed reactor. Then, hydrogen gas and a substrate solution containing 2,2,6,6-tetramethyl-4-piperidinone and 1,6-hexanediamine are simultaneously fed to the micro-mixer and the continuous-flow fixed-bed reactor in sequence to undergo a continuous catalytic reductive amination to obtain the N,N-Bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine.

First claim

What is claimed is:

1. A method of continuously preparing N,N-Bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine using a continuous flow micro-reaction system, the continuous flow micro-reaction system comprising a micro-mixer, a continuous flow fixed-bed reactor and a gas-liquid separator communicated in sequence; and the method comprising:
(S1) mixing a quartz sand with a Pt/C catalyst uniformly followed by feeding to the continuous-flow fixed-bed reactor;
(S2) feeding hydrogen gas and a substrate solution containing 2,2,6,6-tetramethyl-4-piperidinone (II) and 1, 6-hexanediamine (I) to the micro-mixer for mixing to obtain a reaction mixture; and allowing the reaction mixture to flow into the continuous-flow fixed-bed reactor to undergo a continuous catalytic reductive amination reaction; wherein a flow ratio of the substrate solution to the hydrogen gas is adjusted such that a molar ratio of the substrate solution to the hydrogen gas in the micro-mixer is 1:(0.55-14); and
(S3) collecting the reacting mixture flowing out from the continuous-flow fixed-bed reactor followed by gas-liquid separation in the gas-liquid separator, isolation and purification 10 obtain target product N,N-Bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine (III); as shown in the following reaction scheme:

2. The method of claim 1 , wherein in step (S1), the Pt/C catalyst is added into the quartz sand; and the Pt/C catalyst is 1-30% by weight of the quartz sand; the Pt/C catalyst and the quartz sand both have a particle size larger than 20 mesh.

3. The method of claim 1 , wherein in step (S2), the substrate solution is prepared by dissolving 2,2,6,6-tetramethyl-4-piperidinone and 1, 6-hexanediamine in an organic solvent; and
the organic solvent is selected from the group consisting of methanol, ethanol, propanol, isopropanol, 1,2-propanediol, 1,3-propanediol, glycerol, n-butanol, sec-butanol, isobutanol, tert-butanol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentanol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, cyclopentanol, hexanol, cyclohexanol, heptanol, octanol, n-nonanol, decanol, ethylene glycol, diethylene glycol, polyethylene glycol, benzyl alcohol, phenol, toluene, xylene and a mixture thereof.

4. The method of claim 3 , wherein a molar ratio of the 1,6-hexanediamine to the 2,2,6,6-tetramethyl-4-piperidinone is 1:(1.5-5); and a concentration of the 1,6-hexanediamine in the substrate solution is 0.01-10 mol/L.

5. The method of claim 1 , wherein in step (S2), the micro-mixer and the continuous-flow fixed-bed reactor are both controlled at 20-180° C.

6. The method of claim 1 , wherein in step (S2), a residence time of the reaction mixture in the continuous-flow fixed-bed reactor is controlled to 0.1-60 min.

7. The method of claim 1 , wherein the micro-mixer is a static mixer, a T-type micro-mixer, a Y-type micro-mixer, a coaxial-flow micro-mixer or a flow-focusing micro-mixer.

8. The method of claim 1 , wherein the continuous-flow fixed-bed reactor is composed of one or more tubular continuous-flow fixed-bed reactors connected in series or in parallel; and an inner diameter of the one or more tubular continuous-flow fixed-bed reactors is 100 μm-50 mm.

9. The method of claim 1 , wherein N 2 is introduced into the gas-liquid separator at a pressure of 0.1-18 MPa; the continuous flow micro-reaction system further comprises a back-pressure valve; the back-pressure valve is connected to a port at the top of the gas-liquid separator; and the back pressure of the back-pressure valve is set to 0.1-15 MPa.

10. A continuous flow micro-reaction system for continuously preparing N,N-Bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine, comprising:
a feeding pump;
a gas mass-flow meter having a flow controller;
a one-way valve;
a micro-mixer;
a continuous-flow fixed-bed reactor;
a condenser;
a gas-liquid separator; and
a back-pressure valve;
wherein the continuous-flow fixed-bed reactor is filled with a Pt/C catalyst mixed uniformly with a quartz sand; and the Pt/C catalyst comprises 5% by weight of Pt;
the feeding pump is configured to feed a substrate solution containing 2,2,6,6-tetramethyl-4-piperidinone and 1,6-hexanediamine to the micro-mixer; the gas mass-flow meter is configured to feed hydrogen gas to the micro-mixer; the substrate solution and the hydrogen gas are mixed in the micro-mixer, and then flow into the continuous-flow fixed-bed reactor to undergo a continuous catalytic reductive amination reaction; the reacting mixture flowing out of the continuous-flow fixed-bed reactor flows into the condenser to be condensed, and then enters the gas-liquid separator to undergo gas-liquid separation, where waste gas is discharged through a port arranged on a top of the gas-liquid separator and the back-pressure valve, and the reaction mixture is discharged from an outlet at a bottom of the gas-liquid separator and collected, and subjected to isolation and purification to obtain a target product N,N-Bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine.

Assignees

• Univ Fudan

Inventors

• Chen Fener
• Lai Liangchuan
• Ye Baijun
• Jiang Meifen

Classifications

• B01J4/001

  Feed or outlet devices as such, e.g. feeding tubes · CPC title

• B01J4/008

  Feed or outlet control devices · CPC title

• B01J8/02

  with stationary particles, e.g. in fixed beds · CPC title

• B01J2219/00889

  Mixing · CPC title

• B01J19/0093

  Microreactors, e.g. miniaturised or microfabricated reactors (laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027) · CPC title