Self-Catalyzed Deconstruction of Acid-Modified k‑Carrageenanfor Production of 5‑Hydroxymethyl Furfural

K-carrageenan is a major constituent of red seaweeds composed of inherent repeating sulfated galactan units having potential to produce 5-hydroxymethyl furfural (5-HMF). The presence of inherent alkali sulfate functionality leads to generate catalytically active acid sites on the backbone of k-carrageenan. In present study catalyst free synthesis of 5-HMF was studied by inducing acid active sites on alkali sulfated functionalities of k-carrageenan. The presence of –SO3H active sites on acid imparted k-carrageenan were accountable for self-catalytic property to deconstruct the k-carrageenan into galactose units and further dehydration into 5-HMF. Plausible mechanism for self-catalytic deconstruction of k-carrageenan into 5-HMF has been proposed. The comparative study of catalytic and non-catalytic reaction in DMSO resulted 43 % and 41% yield of 5-HMF, respectively. Of the tested solvents (DMF, DMSO, IPA, TBA and IAA) DMSO was found as a best solvent for deconstruction. Furthermore the ease of solvent recov...