Bio-based Surfactants by Homogeneous Catalysis – Approaches to Process Development

Surfactants are amphiphilic molecules that enable dissolving otherwise immiscible phases. Fields of application include household and industrial detergents, personal care products and food additives. There is an ever rising awareness for ecological concerns on side of the consumer as well as the manufacturer. Taking this into account, complex expectations regarding the feedstock, production and chemical and biological properties of the surfactants are present. For instance, a renewable feedstock is an important argument for sustainability, but should be evaluated in the context of competition with food production. This could make the exploitation of new feedstocks, like turpentine, for surfactant synthesis reasonable. To synthesize surfactants hydrophobic chains are to be coupled with hydrophilic groups. In the present work it was examined to which extent the tool of homogeneous catalysis is suitable for reaching these goals while meeting the above mentioned criteria. Regarding the opposing polarities of the components this is a challenging task. Transition metal catalyzed reactions that are not yet part of the industrial production of surfactants are applied to substrates that allow for a direct or indirect access to amphiphilic structures. These substrates should be preferentially based on a renewable feedstock. Regarding process development, not only effective conversions had to be found, but also ways to embed them into a process that ideally includes product purification and recycling of the transition metal catalyst. The elaborated results demonstrate that polar groups can effectively be linked to non-polar building blocks. The sugar-based aminopolyol N-methylglucamine can be coupled to non-polar tails, e. g. terpenes or olefins, via telomerization or hydroaminomethylation reactions. Hydroamination is of particular usefulness in the conversion of terpenes with short-chain amines. Employing the respective carbamates enables the combination of an effective recycling concept with an efficient product purification; products can subsequently be functionalized to nitrogen-based surfactants.