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The aldol condensation of furfural and acetone followed by hydrodeoxygenation into bio-jet fuel range alkanes and bio-polyester diols has attracted intensive interest in recent years. Such sequential reactions require a careful tailoring of one or more catalysts consisting of metal and acid–base active sites that can efficiently promote the two step cascade aldol condensation and hydrodeoxygenation. Here, we have begun developing a prominent base catalyst for mild aldol condensation of furfural and acetone by synthesizing acid–base bifunctional MgAl-SBA-15 and further modifying it with potassium. The catalyst with the highest basic site loading of 0.27 mmol g−1 showed a furfural conversion of 83% and 99% total selectivity to products comprising 54% 4-(2-furyl)-4-hydroxy-butan-2-one (FAc-OH, a C8 alcohol intermediate) and 23% of each 4-(2-furyl)-3-buten-2-one (FAc) and 1,4-pentadiene-3-one,1,5-di-2-furanyl (F2Ac) (C8 and C13 aldol condensation products, respectively) after 3 hours of reaction, at 50 °C. Though a higher loading of potassium causes severe blockages of mesopores and inaccessible acid sites, the catalyst could still be regenerated by open-air calcination and be re-used for considerable cycles with fair catalytic performances. Overall, the present study can be the stepping stone for future investigations on further tuning of non-interfering active sites in SBA-15 to promote an efficient one-pot transformation of furfural and acetone via the two-step cascade aldol condensation and hydrodeoxygenation.

The application of the conventional zeolites has been limited due to its large crystal size (micrometer) and also due to the microporosity (size < 2nm). Hence, this study has been conducted to produce enhanced nanozeolites to overcome the above mentioned limitations. Herein, two microporous nanozeolites namely Beta and ZSM-5 were synthesized via hydrothermal method. Moreover, the enhanced hierarchical nanozeolites have been produced via a green solvothermal approach with the following attributes such as narrow particle size distribution and appropriate mesopores. The synthesis was based on reducing the growth of zeolite crystals by surface silanization of zeolitic seeds using organosilane (hexadecyltrimethoxysilane) as a growth inhibitor. The activities of these nanozeolites and hierarchical nanozeolites were evaluated with catalytic hydroprocessing of oleic acid to green diesel by incorporating Ni metals on these supports. Moreover, extensive characterizations and initial rate investigation were conducted to determine the nature of acid sites and their structuralfunctional relationship in selective hydrodeoxygenation (HDO) of octanoic acid. The results showed hydrothermally synthesized nanozeolites were made of globular aggregates with broader particle size distributions (48-1273 nm for zeolite Beta) and (60-135 nm for zeolite ZSM-5). A much smaller and narrower distributions of globular aggregates of hierarchical nanozeolites are formed using solvothermal approach with sizes of 65–120 nm (for Beta using acetone) and 30-100 nm (for ZSM-5 using 1-decanol). These globular aggregates are actually made by quite smaller primary nanounits ranging 4–11 nm size. The hierarchical nanozeolites exhibited secondary porosity, especially larger mesopores found in zeolite Beta (with pore diameter 8.1 nm) due to efficient functionalization of HDTM in polar solvent environment (acetone). Whereas, moderate mesopores observed in zeolite ZSM-5 (with pore diameter 7.8 nm) caused by the

Here, we focused on a simple enzymatic epoxidation of alkenes using lipase and phenylacetic acid. The immobilised Candida antarctica lipase B, Novozym 435 was used to catalyse the formation of peroxy acid instantly from hydrogen peroxide (H2O2) and phenylacetic acid. The peroxy phenylacetic acid generated was then utilised directly for in situ oxidation of alkenes. A variety of alkenes were oxidised with this system, resulting in 75–99% yield of the respective epoxides. On the other hand, the phenylacetic acid was recovered from the reaction media and reused for more epoxidation. Interestingly, the waste phenylacetic acid had the ability to be reused for epoxidation of the 1-nonene to 1-nonene oxide, giving an excellent yield of 90%.

In view of the emerging importance of enzyme as a promising biocatalyst in fine organic synthesis, we focused on the synthesis of epoxides for their potential applications in chiral synthesis, including asymmetric synthesis and optical resolution of racemates. Epoxides are increasingly used as intermediates in many industrial processes and have wide applications in food, polymer and pharmaceutical formulations due to their excellent ability to facilitate ring opening reactions to various desirable functional groups. The enzymatic synthesis of epoxides has received much attention for its clean production due to its high-regioselectivity and low production of by-products. Furthermore, hydrogen peroxide (H2O2) as green oxidant and mild operating temperature, hence, low energy requirement, are becoming two important advantages of this enzymatic reaction. Herein, we describe an improved enzyme-facilitated epoxidation of a simple alkene (1-nonene) using a conventional water bath shaker. The lipase was used to catalyse the formation of peroxy acids instantly from H2O2 and various perhydrolysis substrates. The peroxy acid generated was then utilised directly for in-situ oxidation of 1-nonene to 1-nonene oxide. Various reaction parameters affecting the synthesis of epoxide, including the nature of peroxy acids, organic solvents, enzyme’s sources, enzyme concentrations, reaction temperatures, initial concentrations and rate additions of the H2O2, stirring rates (rpm), and amounts of H2O2 and peroxy acid, were investigated. Highest conversion was achieved using phenylacetic acid as an oxygen carrier. 1-nonene was converted most efficiently with maximum yield of 97% by Novozym 435, an immobilised Candida antarctica lipase B (CALB) and chloroform as reaction media. A minimum amount (1.4% w/w, 19 mg) of Novozym 435 was needed to maintain the catalytic activity (190.0 Ug-1). The highest yield was successfully obtained within 12 h reaction time at optimal synthesis conditions (35°C

Herein, an efficient epoxidation of 1-nonene is described. In a simple epoxidation system, commercially available Novozym 435, an immobilized Candida antarctica lipase B, and hydrogen peroxide (H2O2) were utilized to facilitate the in situ oxidation of phenylacetic acid to the corresponding peroxy acid which then reacted with 1-nonene to give 1-nonene oxide with high yield and selectivity. The aliphatic terminal alkene was epoxidised efficiently in chloroform to give an excellent yield (97%–99%) under the optimum reaction conditions, including temperature (35 °C), initial H2O2 concentration (30%), H2O2 amount (4.4 mmol), H2O2 addition rate (one step), acid amount (8.8 mmol), and stirring speed (250 rpm). Interestingly, the enzyme was stable under the single-step addition of H2O2 with a catalytic activity of 190.0 Ug−1. The entire epoxidation process was carried out within 12 h using a conventional water bath shaker.