The biorefinery is an important approach for the current needs of energy and chemical building blocks for a diverse range of applications, that gradually may replace current dependence on fossil-fuel resources. Among other primary renewable building blocks, 5-hydroxymethylfurfural (HMF) is considered an important intermediate due to its rich chemistry and potential availability from carbohydrates such as fructose, glucose, sucrose, cellulose and inulin. In recent years, considerable efforts have been made on the transformation of carbohydrates into HMF. In this critical review we provide an overview of the effects of HMF on microorganisms and humans, HMF production and functional group transformations of HMF to relevant target molecules by taking advantage of the primary hydroxyl, aldehyde and furan functionalities.

An efficient, simple, scalable and atom efficient method for the synthesis of 2,5-dihydroxymethylfuran (DHMF) and 5-hydroxymethylfuranoic acid, as sodium salt (HMFA), in 80% yield from 5-hydroxymethylfurfural (HMF) in water using NaOH (0.9 eq.) via a Cannizzaro reaction is described. Both the building blocks DHMF and HMFA were successfully isolated merely using selective crystallisation.