Telomerization is a versatile tool for synthesizing unsaturated ethers, amines and other molecules starting from 1,3‐dienes and respective nucleophiles. The homogeneously catalyzed reaction has been the subject of academic and industrial research for over 50 years, offering a broad variety of substrates, catalysts and process concepts. This Minireview presents the advances and developments in this field over the last decade. The focus was on the conversion of renewable resources, the synthesis of promising new products and the development of efficient process concepts to combine these.
A catalytic system was developed to enable the use of industrially available terpenes (e.g., β‐myrcene, β‐farnesene) in hydroaminomethylation to obtain renewable building blocks for surfactants in two steps. This homogeneously catalyzed tandem reaction includes both hydroformylation and enamine condensation steps, followed by hydrogenation. Under the optimized conditions, the Rh/1,2‐bis(diphenylphosphino)ethane catalytic system delivers products in high yields (70 %) after short reaction times (3 h) with unprecedentedly high turnover frequency (TOF) values for the hydroformylation of 1,3‐dienes of over 739 mol mol−1 h−1. This is the highest TOF reported to date for the hydroformylation of a 1,3‐diene. Furthermore, regioselectivities of 97 % and above were observed in the hydroformylation step, which is extraordinarily high for the conversion of 1,3‐dienes. The terpene‐derived amines obtained were further functionalized to quaternary ammonium compounds that were found to show surface activity quite similar to that of industrially available quaternary ammonium compounds. The hydroaminomethylation of terpenes achieves higher step efficiency than industrial means and makes use of an alternative, renewable feedstock to synthesize more environmentally friendly surfactants.
Biphasic water-based solvent systems
offer the opportunity of efficient
recycling of homogeneous catalysts. Water separates well from most
organic solvents; therefore, water-soluble catalysts can be immobilized
in this phase. Furthermore, water can substitute hazardous and environmentally
unfriendly organic solvents in these systems. Within industry only
the Ruhrchemie/Rhône-Poulenc process uses plain water to immobilize
the homogeneous catalyst for the hydroformylation of propene. Yet
for more hydrophobic substrates, no water-based system has been commercialized.
This review will summarize recent developments in the field of water-based
recycling strategies. Topics in this field are the intensification of the
mixing process, the use of thermomorphic solvent systems, and the
employment of several additives, like alcohols and surfactants. Continuously
operated processes for these recycling strategies will be presented
and discussed.
Turning down the bed for homogenous catalysts: the use of dimcarb as a reactive ionic liquid, offers the opportunity to carry out different homogeneously transition metal catalyzed aminations without using any solvent, while at the same time efficient catalyst recycling is possible.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.