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.
The synthesis of fatty acid methyl esters (FAME) from sunflower oil and methanol was studied in a continuous centrifugal contactor separator (CCCS) using sodium methoxide as the catalyst. The effect of relevant process variables like oil and methanol flow rate, rotational speed and catalyst concentration was investigated and modelled using non-linear regression. Good agreement between experiments and model were obtained. At optimised conditions (oil flow rate of 31 mL/min, rotational speed of 34 Hz, catalyst concentration of 1.2%w/w and a methanol flow rate of 10 mL/min), the FAME yield was 94 mol% at a productivity of 2470 kg FAME /m 3 reactor .h. Proof of principle for the synthesis and subsequent refining of FAME in a cascade of two CCCS devices was also obtained. Relevant properties of the refined FAME obtained using this technology were determined and were shown to meet the ASTM specifications.Practical application: Synthesis and refining of sunflower biodiesel was successfully performed in a cascade of two CSSS devices. Besides for large scale biodiesel production, this technology has particularly potential to be applied in small mobile biodiesel units due to the compact size, robustness, flexibility in operation, and high volumetric productivity of the CCCS devices.
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