Renewable Surfactants through the Hydroaminomethylation of Terpenes

Abstract

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.

The Telomerization of 1,3‐Dienes – A Reaction Grows Up

“…Another terpene that is a promising building block for valuable chemicals is β‐farnesene, which has recently become available on a larger scale. It is produced by yeast fermentation and has attracted attention in both academic and industrial research and development. Since the large and bulky substituent is located at the 2 nd position, the 1,3‐diene unit is prone to conversion with nucleophiles, even during telomerization with amines .…”

Valorization of Biomass Derived Terpene Compounds by Catalytic Amination

“…Hydroformylation of the internal double bonds is much more difficult than the terminal bonds, thus it is not surprising that the examples mentioned above are related to isolated terminal double bonds. In the only reported hydroaminomethylation of a conjugated terpene [81] regioselectivity in hydroformylation was low along with low catalytic activity per se explained by formation of relatively stable η3-allyl-Rh complexes [78].…”

“…A few examples of hydroaminomethylation reaction with terpenes were reported including α-pinene [75], β-pinene [74], camphene [74], limonene [74,76,77], β-myrcene and β-farnesene [78] and naturally occurring allyl benzenes such as eugenol [79] and estragole [80]. Hydroformylation of the internal double bonds is much more difficult than the terminal bonds, thus it is not surprising that the examples mentioned above are related to isolated terminal double bonds.…”

Homogeneously Catalyzed 1,3‐Diene Functionalization – A Success Story from Laboratory to Miniplant Scale

“…Hydroformylation of β ‐myrcene was reported to yield different unsaturated C11‐aldehydes depending on the ligand . Our research group has found an efficient way to convert β ‐myrcene into an efficient surfactant via an enamine by means of hydroaminomethylation (Figure ) . Surfactants offer a wide range of applications, e. g. as a detergent and food additive as well as in oilfield chemistry…”

“…The combination of [Rh(cod)Cl] 2 (cod=1,5‐cyclooctadiene) with a 1,2‐bis (diphenylphosphino) ethane (DPPE) ligand shows product yields of 70 % after short reaction times of 3 hours. Furthermore, regioselectivities of 97 % were observed in the hydroformylation stage …”