Heterogeneous Pt Catalysts for Reductive Amination of Levulinic Acid to Pyrrolidones

Abstract

Supported platinum catalysts have been studied for the reductive amination of levulinic acid (LA) by H2 to N-alkyl-5-methyl-2-pyrrolidones under solvent-free conditions. The activity depends on the type of metal (Pt, Re, Pd, Rh, Ru, Cu, Ni), support material, and coloaded oxides of transition metals (V, Cr, Mo, W, Re). In 24 kinds of catalyst tested, Pt and MoO X (molybdenum oxide) coloaded TiO2 (Pt-MoO X /TiO2) shows the highest activity. Pt-MoO X /TiO2 is effective for reductive amination of LA with wide varieties of amines under mild conditions (3 bar of H2, 100 °C, solvent-free) to give high isolated yield of pyrrolidinones and shows higher turnover number (TON) than previously reported catalysts for reductive amination of LA with an aliphatic amine. The catalyst can be separated from the reaction mixture by filtration, and the recovered catalyst can be reused. This is the first general and reusable heterogeneous catalytic system for the reductive amination of LA. On the basis of mechanistic studies, high activity of Pt-MoO X /TiO2 can be attributed to acid–base interaction between the acid sites of Pt-MoO X /TiO2 and carboxyl groups in LA and an intermediate.

A Multiphase Protocol for Selective Hydrogenation and Reductive Amination of Levulinic Acid with Integrated Catalyst Recovery

“…[31] Homogeneous and heterogeneousc atalysts (i.e.,A u/ZrO 2 , Pt-MoO x /TiO 2 ,C -coated Ni nanoparticles, Ir/SiO 2 -SO 3 H, and Ru-, Ir-, and In complexes) prove active for the reaction, by using either FA in at ransfer hydrogenation or H 2 or even hydrosilanes as reductants. [31] Homogeneous and heterogeneousc atalysts (i.e.,A u/ZrO 2 , Pt-MoO x /TiO 2 ,C -coated Ni nanoparticles, Ir/SiO 2 -SO 3 H, and Ru-, Ir-, and In complexes) prove active for the reaction, by using either FA in at ransfer hydrogenation or H 2 or even hydrosilanes as reductants.…”

“…[31] Homogeneous and heterogeneousc atalysts (i.e.,A u/ZrO 2 , Pt-MoO x /TiO 2 ,C -coated Ni nanoparticles, Ir/SiO 2 -SO 3 H, and Ru-, Ir-, and In complexes) prove active for the reaction, by using either FA in at ransfer hydrogenation or H 2 or even hydrosilanes as reductants. [31] To cope with these problems, the present MP approach was explored for the modelr eaction of LA with cyclohexylamine. [31] To cope with these problems, the present MP approach was explored for the modelr eaction of LA with cyclohexylamine.…”

“…An important issue was the need to minimize the presence of water because of its adverse effects on the reaction. [31,33,35,38] To disfavort he formation of GVL during the MP process, we envisaged adding FA,w hich is known to selectively inhibit the adsorption of LA on Ru/C (see the previous section). For example, at 130 8Ca nd 15 bar H 2 ,i fa ne quimolar aqueous solution of LA and CyNH 2 (3.6 mmol each;t otal volume = 5mL) was set to react in the presence of 5% Ru/C (28 mg) and i-octane (5 mL), LA was quantitatively converted after 16 h, yieldingamixtureo fG VL (83 %), CyMP (9 %), and other derivatives (8 %i nt otal) the structures of which were assigned by GC-MS and comparison with literature data (Scheme 5, furtherd etails are in the Supporting Information, Figure S9).…”

“…Such ad ramatic change was ascribed to concurrent effectsi nferred by examining the accepted mechanismsf or catalytic reductive amination, [31,33,34,38] and comparing the structures of co-products designated as "others" in Table 2. Such ad ramatic change was ascribed to concurrent effectsi nferred by examining the accepted mechanismsf or catalytic reductive amination, [31,33,34,38] and comparing the structures of co-products designated as "others" in Table 2.…”

Chemicals from Biomass: Chemoselective Reductive Amination of Ethyl Levulinate with Amines

“…In Table 5 can be seen that aromatic amines with electron withdrawing groups (entries [11][12][13], are more reactive than aromatic amines with electron donating substituents (entries 4-10) which required longer reaction times in order to reach good yields (92-98%). Moreover, when a substituent at the 2 position of aniline is present, a strong decrease in selectivity to 5-methyl-2-pyrrolidone is observed.…”