Although glycerol has been a well-known renewable chemical for centuries, its commercial relevance has increased considerably in the last few years because of its rising inevitable formation as a by-product of biodiesel production. The present review gives a broad overview on the chemistry of glycerol starting from the classic esters and oligomers to new products like glycerol carbonate, telomers, branched alkyl ethers, propanediols and epoxides. In particular, the novel possibilities to control the numerous addition, reduction and oxidation reactions via heterogeneous, homogeneous and biocatalysis will be presented. A benchmark will be given to determine the products which will have the best chances of entering the market and which processes are currently most developed.
Currently, a shift towards chemical products derived from renewable, biological feedstocks is observed more and more. However, substantial differences with traditional feedstocks, such as their "hyperfunctionalization," ethical problems caused by competition with foods, and problems with a constant qualitative/quantitative availability of the natural products, occasionally complicate the large-scale market entry of renewable resources. In this context the vast family of terpenes is often not taken into consideration, although the terpenes have been known for hundreds of years as components of essential oils obtained from leaves, flowers, and fruits of many plants. The simple acyclic monoterpenes, particularly the industrially available myrcene, provide a classical chemistry similar to unsaturated hydrocarbons already known from oil and gas. Hence, this Review is aimed at reviving myrcene as a renewable compound suitable for sustainable chemistry in the area of fine chemicals. The versatility of the unsaturated C(10)-hydrocarbon myrcene, leading to products with several different areas of application, is pointed out.
An economically meaningful hydroformylation of long-chain olefins requires an efficient combination of both a high-yield reaction step and efficient catalyst recycling. The application of thermomorphic multicomponent solvent (TMS) systems allows for optimal reaction as well as catalyst-recycling conditions. In this work, the TMS concept was applied to the homogeneously rhodium-catalyzed hydroformylation of 1-dodecene in the TMS system dimethylformamide (DMF)/decane using Rh(acac)(CO) 2 /Biphephos as the catalyst system. Thermodynamic investigations focused on the influence of the olefin (hydroformulation educt) and the aldehyde (hydroformylation product) on the phase behavior of the TMS system. Temperature dependent liquid−liquid equilibrium (LLE) data were measured for the binary systems DMF/decane and DMF/1-dodecene and for the ternary systems DMF/decane/1-dodecene and DMF/decane/dodecanal. Additionally, the corresponding LLE data were modeled applying the Perturbed Chain Polar Statistical Associating Fluid Theory (PCP-SAFT) using a heterosegmented approach for modeling the long-chain aldehyde. On the basis of the LLE data, adequate working points for hydroformylation experiments in the TMS system were selected. In these experiments, aldehyde yields of up to 87% with an n/iso ratio of up to 99:1 were achieved. Moreover, the TMS system was successfully applied to catalyst recycling in eight recycling runs with a catalyst leaching of 7 ppm rhodium at lowest.
The carbon dioxide molecule has been of limited importance as a synthetic unit in organic chemistry. When it is coordinated to transition metals, however, completely new possibilities arise; CO2 can bond to metal complexes in a variety of ways and can enter into insertion and coupling reactions, or become catalytically attached to other substrates. The formation of CC bonds between carbon dioxide and unsaturated hydrocarbons under conditions of homogeneous catalysis makes available new synthetic routes to industrially interesting organic compounds.
The transition-metal catalyzed telomerization of 1,3-dienes with different nucleophiles leads to the synthesis of numerous products, such as sugar ethers, substituted lactones, or terpene derivatives, which can be applied in the cosmetic and pharmaceutical industry as well as in polymers and flavors. The reaction can be controlled by the choice of the catalytic system, the feedstock, and the reaction conditions. Since telomerization was developed in 1967, there have been many efforts to utilize this reaction. Herein we give an overview of the versatility of telomerization based on examples from research and industry, particular emphasis is placed on catalyst and process development as well as mechanistic aspects.
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