Design and Synthesis of Bio-based Amphiphiles from Lignocellulosic Biomass

In the pursuit of a carbon-neutral chemical industry, minimizing fossil feedstock consumption while integrating renewable carbon sources is imperative. Surfactants, inherently amphiphilic, pose challenges in separation and recovery processes. Given their essential role in daily applications, continuous improvement for sustainability, performance, and reduced environmental impact are required. Lignocellulosic biomass, the Earth's largest source of fixed carbon, offers a sustainable and economically attractive feedstock for bio-based chemicals. However, its recalcitrant nature poses challenges, particularly in efficiently utilizing all biomass fractions during conversion processes, often resulting in the underutilization or sacrifice of certain fractions. Additionally, reactions involving refined lignocellulosic sugars for amphiphilic products face issues such as low reaction selectivities and poor yields due to similar hydroxyl reactivity. These challenges are addressed through innovative approaches discussed in Chapter 3 and Chapters 4-5, which focus on integrated biomass conversion methods (functionalization-defunctionalization) and a novel sugar monoacetalization method (selective functionalization) employing size-selective zeolite catalysis, respectively.The "functionalization-defunctionalization" strategy aims to establish a direct pathway for generating surfactants from non-edible biomass fractions. By utilizing fatty aldehydes during fractionation, native polar functional groups are preserved while hydrophobic segments are introduced. Subsequent partial defunctionalization yields high-yield xylose- and lignin-based surfactants (29% w/w based on the total raw biomass and >80% w/w of these two fractions), exhibiting competitive or superior surface activity compared to fossil-based analogues.The "selective functionalization" method explores size-selective zeolite catalysis for high-yield, one-step synthesis of bio-based surfactants. Considering the molecular size difference between mono- and multi-substituted substrates, we leveraged the pore confinement effect of zeolite to enhance selectivity towards amphiphilic monoacetalized sugars/polyols. This highly selective, atomically efficient, and easily recyclable zeolite catalyzed reaction has the potential to facilitate the industrialization of acetal-containing bio-based surfactants.Lastly, renewable nonionic and anionic surfactant substitutes based on monoacetalized xylose are developed. Introducing carboxylic acid or sulfate groups yields anionic surfactants with performance comparable to widely-used counterparts, such as Sodium Dodecyl Sulfate (SDS) and Sodium Laureth Sulfate (SLES), offering potential sustainable commodity chemical alternatives. These methods highlight the viability of bio-based surfactants derived from lignocellulosic biomass as sustainable, carbon-neutral alternatives to traditional counterparts. These surfactants largely retained their original natural structures, exhibit comparable or superior performance while offering advantages such as biodegradability and reduced environmental footprint. By emphasizing the utilization of abundant and renewable feedstocks, this thesis contributes to the ongoing efforts towards a more sustainable and environmentally compatible chemical industry.