Renewable nylon: 5‐Hydroxymethylfurfural (HMF), which can be obtained from renewable resources such as D‐fructose, was converted into caprolactone with very good overall selectivity in only three steps. The new route involves two hydrogenation steps to obtain 1,6‐hexanediol, which was oxidatively cyclized to caprolactone, and then converted into caprolactam.

1,6-hexanediol (1) is an important polymer precursor for the polyester industry. In this paper, exploratory catalyst screening studies on the synthesis of 1 from 1,2,6-hexanetriol (2) are described via two different routes. The latter is available by a two-step procedure from 5-hydroxymethylfurfural (HMF, 3), a promising bio-based platform chemical. In the first approach, the direct catalytic hydrodeoxygenation of 2 to 1 with heterogeneous catalysts and molecular hydrogen was explored. Best results were obtained using a Rh-ReO x /SiO 2 catalyst in water (180°C, 80 bar H 2 , 20 h reaction time), leading to full conversion of 2 and 73 % selectivity to 1, the main byproduct being 1,5-hexanediol (4). In a second approach, 2 was first converted to tetrahydropyran-2-methanol (2-THPM, 5) in quantitative yield using triflic acid as catalyst (125°C, 30 min). Various catalysts were explored for the subsequent ring opening/hydrodeoxygenation of 5 to 1 using a hydrogenation protocol and the best results were obtained with a Rh-ReO x /SiO 2 catalyst, viz. 96 % selectivity to 1 at 26 % conversion (120°C, 80 bar H 2 , 20 h).

Erneuerbares Nylon: 5‐Hydroxymethylfurfural (HMF), das aus erneuerbaren Quellen wie D‐Fructose zugänglich ist, wurde in nur drei Stufen mit einer sehr guten Gesamtselektivität in Caprolacton überführt. Dieser neue Ansatz umfasst zwei Hydrierungen, die 1,6‐Hexandiol liefern, und dessen oxidative Cyclisierung zu Caprolacton. Dieses wurde schließlich zu Caprolactam umgesetzt.

Hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) was studied by using mono- and bidentate p-cymene ruthenium(ii) N-heterocyclic carbene (NHC) complexes as catalyst precursors. In water, all complexes were found to be reduced in situ to form ruthenium nanoparticles (RuNPs) with a high hydrogenation activity. In organic solvents, complexes with monodentate NHC ligands also formed nanoparticles, while complexes with bidentate ligands gave rise to stable homogeneous catalysts with moderate hydrogenation activities.