Selective separation of cyclopentane and cyclohexane derivatives with molecular size differences by polystyrene divinylbenzene resin DCE-3A

There are bottlenecks in the synthesis and purification of fine chemicals, such as high energy consumption and complex processes. Process optimization and green separation technology innovation are the key challenges for green chemistry and sustainable production. (S)-2,2-dimethyl-4-(2-hydroxyethyl)-1,3-dioxolane (dioxolane), as an important pharmaceutical and chemical intermediate, has limited its market application due to technical bottlenecks such as low synthesis efficiency and low purity. In this study, an efficient and green synthesis of dioxolane was established for the first time to avoid the generation of toxic chelated borate esters, and the purity of the product reached 99 %. Firstly, to address the low efficiency issue in dioxolane synthesis, we developed a novel synthetic route utilizing a tetrahydropyranyl (THP) protecting group strategy with (L)-malic acid as the starting material. Through response surface optimization of the key-step reduction reaction, the yield improved from 54 % to 91 %. Secondly, to address the problem of reduced purity caused by byproduct dioxane, we leveraged the size-matching effect between dioxane and the material, preparing seven materials with diverse physical structures via Friedel-Crafts alkylation. Notably, DCE-3A achieved selective separation of dioxolane and dioxane with a selectivity coefficient of 103.07. Through adsorption separation, dioxolane exhibited a purity of 99 % and a yield of 94 %, markedly outperforming the traditional derivatization separation method (purity 98 %, yield 50 %). In summary, the synergistic effect of the innovative protecting group strategy and the novel adsorbent achieved the efficient synthesis of dioxolane, offering a technical approach for the green synthesis of analogous compounds.