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Continuous-flow synthesis of N,N′-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine (DTMPA) in a Micro fixed-bed reactor

Continuous-flow synthesis of N,N′-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine... An expeditious and efficient continuous-flow process is reported for the synthesis of N,N′-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine (DTMPA). The starting material 1,6-hexanediamine (HMDA) mixes with 2,2,6,6-tetramethyl-4-piperidinone (TAA), reacts with hydrogen in a micro fixed-bed reactor packed with 5% Pt/C catalyst to provide DTMPA in 85% isolated yield. The reaction rate in the flow system has been significantly improved (from 2 hours in batch to 12 minutes in flow) because of enhanced mass transfer. The purity of DTMPA from the continuous process is up to 97%. The effects of reaction temperature, pressure and initial concentration on product purity are investigated through the orthogonal method. The optimum conditions for the continuous-flow reaction are obtained as: molar ratio of TAA to HMDA is 2.1:1, reaction temperature is 70 °C, reaction pressure is 2 MPa and reaction time is 12 min. The reaction kinetics is investigated to be first order with respect to HMDA concentration and second order with respect to TAA concentration. Reaction rate constants are determined in the temperature range of 60–90 °C, and the activation energy is obtained as 26.2 kJ/mol. The continuous flow system enables efficient synthesis of DTMPA in gram-scale, corresponding to an overall productivity of 2.14 g/h after continuously running for over 8 hours successfully.Highlights• The continuous-flow reductive amination of 1,6-hexanediamine (HMDA) to generate hexanediamine piperidine (DTMPA) is carried out in a micro fixed-bed reactor successfully.• The optimum operation conditions are determined by orthogonal method, giving the target product with 85% isolated yield and 97% purity.• The reaction kinetics is investigated, reaction order, rate constants and the activation energy are obtained.• The productivity of the continuous-flow process to produce DTMPA is 2.14 g/hour, which is 5 times of that from the batch operation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Flow Chemistry Springer Journals

Continuous-flow synthesis of N,N′-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine (DTMPA) in a Micro fixed-bed reactor

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Publisher
Springer Journals
Copyright
Copyright © Akadémiai Kiadó 2022
ISSN
2062-249X
eISSN
2063-0212
DOI
10.1007/s41981-022-00230-4
Publisher site
See Article on Publisher Site

Abstract

An expeditious and efficient continuous-flow process is reported for the synthesis of N,N′-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine (DTMPA). The starting material 1,6-hexanediamine (HMDA) mixes with 2,2,6,6-tetramethyl-4-piperidinone (TAA), reacts with hydrogen in a micro fixed-bed reactor packed with 5% Pt/C catalyst to provide DTMPA in 85% isolated yield. The reaction rate in the flow system has been significantly improved (from 2 hours in batch to 12 minutes in flow) because of enhanced mass transfer. The purity of DTMPA from the continuous process is up to 97%. The effects of reaction temperature, pressure and initial concentration on product purity are investigated through the orthogonal method. The optimum conditions for the continuous-flow reaction are obtained as: molar ratio of TAA to HMDA is 2.1:1, reaction temperature is 70 °C, reaction pressure is 2 MPa and reaction time is 12 min. The reaction kinetics is investigated to be first order with respect to HMDA concentration and second order with respect to TAA concentration. Reaction rate constants are determined in the temperature range of 60–90 °C, and the activation energy is obtained as 26.2 kJ/mol. The continuous flow system enables efficient synthesis of DTMPA in gram-scale, corresponding to an overall productivity of 2.14 g/h after continuously running for over 8 hours successfully.Highlights• The continuous-flow reductive amination of 1,6-hexanediamine (HMDA) to generate hexanediamine piperidine (DTMPA) is carried out in a micro fixed-bed reactor successfully.• The optimum operation conditions are determined by orthogonal method, giving the target product with 85% isolated yield and 97% purity.• The reaction kinetics is investigated, reaction order, rate constants and the activation energy are obtained.• The productivity of the continuous-flow process to produce DTMPA is 2.14 g/hour, which is 5 times of that from the batch operation.

Journal

Journal of Flow ChemistrySpringer Journals

Published: Jun 15, 2022

Keywords: Continuous-flow synthesis; Reductive amination; Hexanediamine piperidine; Reaction optimization; Reaction kinetics

References