Furanic platform chemicals derived from renewable plant biomass offer a multitude of potential applications in materials science and the chemical industry, positioning them as promising alternatives to nonrenewable petrochemical feedstock products. However, the relatively low stability of the pseudoaromatic furan core poses a significant challenge because of the limited range of available reaction conditions for the preparation and subsequent chemical modification of these furanic platforms. In this review, our focus lies on investigating the stability of 5-(hydroxymethyl)furfural (HMF), one of the most extensively studied platform chemicals, with the aim of identifying optimal conditions for its synthesis and further functionalization. The goal of this study is to delineate the limits of renewable furan stability by identifying optimal conditions with minimal tarring and the occurrence of side reactions, a crucial aspect for both ongoing laboratory research and the development of reactors for large-scale production of HMF derivatives in the industry.