Metathesis reactions of rapeseed oil-derived fatty acid methyl esters induced by monometallic and homobimetallic ruthenium complexes

Olefin Metathesis in Confined Spaces: The Encapsulation of Hoveyda-Grubbs Catalyst in Peanut, Square, and Capsule Shaped Hollow Silica Gels

In this study, Hoveyda-Grubbs 2nd generation (HG2) catalyst was encapsulated in hollow mesoporous silica gels with various morphologies (peanut, square, and capsule) by reducing the pore size of the mesoporous...

Preparation of Musk-Smelling Macrocyclic Lactones from Biomass: Looking for the Optimal Substrate Combination

Macrocyclic musk belongs to a well-known and valued class of the fragrance family. Originally, natural musks were obtained from rectal musk glands which often led to the death of the animals. Recently, a lot of effort was invested to obtain such macrocycles in a synthetic way. This research presents a study on the preparation of macrocyclic lactones with the musk scent by ring-closing metathesis (RCM) using biomass-derived starting materials: oleic and 9-decenoic acid. An experimental rule correlating the C-C double bond substitution pattern in the starting diene and the yield for the RCM macrocyclization was proposed.

Direct valorisation of waste cocoa butter triglycerides via catalytic epoxidation, ring-opening and polymerisation

BACKGROUND

Development of circular economy requires significant advances in the technologies for valorisation of waste, as waste becomes new feedstock. Food waste is a particularly important feedstock, containing large variation of complex chemical functionality. Although most food waste sources are complex mixtures, waste from food processing, no longer suitable for the human food chain, may also represent relatively clean materials. One such material requiring valorisation is cocoa butter.

RESULTS

Epoxidation of a triglyceride from a food waste source, processing waste cocoa butter, into the corresponding triglyceride epoxide was carried out using a modified Ishii-Venturello catalyst in batch and continuous flow reactors. The batch reactor achieved higher yields due to the significant decomposition of hydrogen peroxide in the laminar flow tubular reactor. Integral and differential models describing the reaction and the phase transfer kinetics were developed for the epoxidation of cocoa butter and the model parameters were estimated. Ring-opening of the epoxidised cocoa butter was undertaken to provide polyols of varying molecular weight (M_w = 2000-84 000 Da), hydroxyl value (27-60 mg KOH g^-1) and acid value (1-173 mg KOH g^-1), using either aqueous ortho-phosphoric acid (H ₃ PO ₄) or boron trifluoride diethyl etherate (BF ₃·OEt₂)-mediated oligomerisation in bulk, using hexane or tetrahydrofuran (THF) as solvents. The thermal and tensile properties of the polyurethanes obtained from the reaction of these polyols with 4,4'-methylene diphenyl diisocyanate (MDI) are described.

CONCLUSION

The paper presents a complete valorisation scheme for a food manufacturing industry waste stream, starting from the initial chemical transformation, developing a process model for the design of a scaled-up process, and leading to synthesis of the final product, in this case a polymer. This work describes aspects of optimisation of the conversion route, focusing on clean synthesis and also demonstrates the interdisciplinary nature of the development projects, requiring input from different areas of chemistry, process modelling and process design. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Remarkably Efficient Microwave-Assisted Cross-Metathesis of Lipids under Solvent-Free Conditions

Catalytic transformation of renewable feedstocks into fine chemicals is in high demands and olefin metathesis is a sophisticated tool for biomass conversion. Nevertheless, the large-scale viability of such processes depends on the conversion efficiency, energy efficiency, catalytic activity, selective conversion into desired products, and environmental footprint of the process. Therefore, conversions of renewables by using simple, swift, and efficient methods are desirable. A microwave-assisted ethenolysis and alkenolysis (using 1,5-hexadiene) of canola oil and methyl esters derived from canola oil (COME) and waste/recycled cooking oil (WOME) was carried out by using ruthenium-based catalytic systems. A systematic study using 1st and 2nd generation Grubbs and Hoveyda-Grubbs catalysts was carried out. Among all ruthenium catalysts, 2nd generation Hoveyda-Grubbs catalyst was found to be highly active in the range of 0.002-0.1 mol % loading. The conversions proved to be rapid providing unprecedented turnover frequencies (TOFs). High TOFs were achieved for ethenolysis of COME (21 450 min^-1 ), direct ethenolysis of canola oil (19 110 min^-1 ), for WOME (15 840 min^-1 ) and for cross-metathesis of 1,5-hexadiene with COME (10 920 min^-1 ). The ethenolysis of commercial methyl oleate was also performed with a TOF of 8000 min^-1 under microwave conditions.

The Future of Ethenolysis in Biobased Chemistry

The desire to utilise biobased feedstocks and develop more sustainable chemistry poses new challenges in catalysis. A synthetically useful catalytic conversion is ethenolysis, a cross metathesis reaction with ethylene. In this Review, the state of the art of ethenolysis in biobased chemistry was extensively examined using methyl oleate as a model compound for fatty acids. Allied to this, the ethenolysis of fatty acid, polymers and more challenging substrates are reviewed. To determine the limiting factors for the application of ethenolysis on biomass, the influence of reaction parameters were investigated and the bottlenecks for reaching high turnover numbers identified.

Ethenolysis: A Green Catalytic Tool to Cleave Carbon-Carbon Double Bonds

Remarkable innovations have been made in the field of olefin metathesis due to the design and preparation of new catalysts. Ethenolysis, which is cross-metathesis with ethylene, represents one catalytic transformation that has been used with the purpose of cleaving internal carbon-carbon double bonds. The objectives were either the ring opening of cyclic olefins to produce dienes or the shortening of unsaturated hydrocarbon chains to degrade polymers or generate valuable shorter terminal olefins in a controlled manner. This Review summarizes several aspects of this reaction: the catalysts, their degradation in the presence of ethylene, some parameters driving their productivity, the side reactions, and the applications of ethenolysis in organic synthesis and in potential industrial applications.