Sustainable Catalytic Synthesis for a Bio‐Based Alternative to the Reach‐Restricted N‐Methyl‐2‐Pyrrolidone

Abstract

The catalytic conversion of biomass and its derivatives into valuable chemicals requires efficient, energy saving, and sustainable technologies. In this work, a variety of bifunctional catalysts are prepared combining immobilized metal nanoparticles and acid solid materials featuring Lewis or Brønsted acidity. The catalytic systems are tested in the reductive amination of bio‐derived levulinates with primary amines, using hydrogen as clean reducing agent, to obtain N‐substituted‐5‐methyl‐2‐pyrrolidones, which are proposed as substitutes for the widely used, REACH‐restricted solvent N‐methyl‐2‐pyrrolidone. The overall process is studied in depth to identify the best combination of metal and acid functionalities to be used in one‐pot and one stage. Pt immobilized onto the Brønsted solid acid Aquivion is shown to be the most efficient catalyst, with a productivity of N‐heptyl‐5‐methyl‐2‐pyrrolidone of 7.9 mmolgcat−1 h−1 reached at full conversion and 98.6% selectivity, under 120 °C, 4 bar H2 pressure and solvent‐free conditions.

The green solvent: a critical perspective

“…Levulinic acid can provide routes to a series of downstream products (at least on the research or small technical scale) including γ-valerolactone , 2-methyltetrahydrofuran and alkyl levulinates . A 3-step synthetic route from bio-derivable alkyl levulinates leads to a series of N - substituted 5-methylpyrrolidones (Barbaro et al 2020 ). The N - heptyl derivative (RN 69343-70-0) has a bp of 94–95 °C at 1.0 torr.…”

“…Most of these have been assembled from various compilations and data sets used in the computerised identification and selection of solvents with particular characteristics and are discussed in “ Solvent selection and design: empirical database and computational methods ” section. Some materials cited as green in additional papers [and from one website ( http://www.xftechnologies.com/solvents )] are also included (Bankar et al 2013 ; Barbaro et al 2020 ; Bauer and Kruse 2019 ; Bergez-Lacoste et al 2014 ; Byrne et al 2017 ; Byrne et al 2018 ; Calvo‑Flores et al 2018 ; Christy et al 2018 ; Clark et al 2017a ; Cseri and Szekely 2019 ; Di Girolamo et al 2021 ; Diorazio et al 2016 ; Driver and Hunter 2020 ; Estévez 2009 ; Gevorgyan et al 2020 ; Ho et al 2020 ; Hu et al 2014 ; Jessop et al 2012 ; Jin et al 2017 ; Kobayashi et al 2019 ; Lee et al 2017 ; Linke et al 2020 ; Marcel et al 2019 ; Moity et al 2014a , b ; Mudraboyina et al 2016 ; Murray et al 2016 ; Pellis et al 2019 ; Piccione et al 2019 ; Qian et al 2021 ; Samorì et al 2014 ; Shahbazi et al 2020 ; Shakeel et al 2014 ; Sherwood et al 2016 ; Strohmann et al 2019 ; Tobiszewski et al 2015 ; Vinci et al 2007 ; Wypych and Wypych 2014 , 2019 ; Yang and Sen 2010 ; Yara-Varón et al 2016; Zhenova et al 2019 ).…”

Effect of Phosphorus Precursor, Reduction Temperature, and Support on the Catalytic Properties of Nickel Phosphide Catalysts in Continuous-Flow Reductive Amination of Ethyl Levulinate

“…Reductive amination of LA or levulinates with primary amines over heterogeneous metal catalysts using molecular hydrogen as a reducing agent is a promising method for the synthesis of N-substituted-5-methyl-2-pyrrolidones [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], which are an alternative to the carcinogenic solvent N-methyl-2-pyrrolidone (NMP) used in large volumes in industry [3]. Due to the high cost and limited availability of precious metals, the use of non-noble metal catalysts is of particular interest [1,[20][21][22][23][24][25].…”

“…In the case of EL, the process begins with the condensation of EL and amine to the corresponding imine, which reacts with hydrogen over metal sites to form 4-aminopentanoate, and further intramolecular amidation leads to pyrrolidone. The conversion of imine can 2 of 11 also occur via imine-enamine equilibrium, followed by the elimination of EtOH and hydrogenation to the desired product [9,13,17,24]. At the same time, hydrogenation of EL with the subsequent cyclization gives γ-valerolactone (GVL) in a side reaction (Scheme 1).…”

“…A positive role of acid sites on the surface of the support material in achieving a high pyrrolidone yield was observed, which is associated with the acceleration of EL amination and cyclization steps [9][10][11][12][13][14]21,25]. Nickel phosphides are attracting increased attention as bifunctional catalysts due to the presence of both metal and acid sites [26][27][28].…”