The present invention relates to new bi-functional and polyfunctional bis-dioxolanes and bis-dioxanes. The present inventors have established that the bis-dioxolanes and bis-dioxanes of the invention are highly advantageous as building blocks, cross-linking and/or coupling agents in polymer engineering. They can be derived from biomass sources in a highly efficient manner. The production of the present bis-dioxolanes and bis-dioxanes from biomass has the particular advantage that it facilitates the introduction of desired functionality in a highly flexible manner. Hence, the present invention provides novel bi- or polyfunctional bis-dioxolanes and bis-dioxanes, their production from renewable (biomass) sources, as well as their use in the engineering of polymers.