Hydroformylation of branched olefins catalyzed by Co2(CO)8 for synthesis of branched alcohol ethoxylates and their surfactant properties

Abstract

Branched-chain surfactants have lower equilibrium surface tension, superior wettability and emulsifying performance, making them suitable for exclusive applications. Linear α-olefins are rich in coal-based Fischer–Tropsch synthesized liquid products and are promising building blocks for the synthesis of branched-chain surfactants via dimerization and subsequent C=C bond functionalization. Herein, a new series of branched ethoxylate non-ionic surfactants (MDC6E n ) were prepared using 2-butyl-1-octene (1-hexene dimer, DC6), obtained by the dimerization of coal-based Fischer-Tropsch synthesized 1-hexene, as the hydrophobe via hydroxylation and ethoxylation. In particular, the hydroxylation of DC6 was carried out in a one-pot tandem hydroformylation and hydrogenation over unmodified Co2(CO)8 under mild conditions (140 °C and 4–8 MPa, CO:H2 = 1:1). A thorough investigation of their surfactant properties was carried out, including equilibrium surface tension, dynamic surface tension, foaming properties, wetting power, and emulsifying power. The results indicate that MDC6E9 performs comparably to a commercially available branched-chain surfactants, the iso-tridecyl alcohol ethoxylates (MULTISO 1390). This research provides a new direction for the synthesis of branched nonionic surfactants using Fischer–Tropsch synthesized products, further promoting the development of coal-based fine chemicals.