Glycerol is one of the most crucial by-products in the production of biodiesel, and owing to its oversaturation in the market, several synthetic strategies have been developed to transform it into other higher value-added products such as glycerol carbonate, epichlorohydrin, 1,3-propanediol, etc. Amongst them, glycerol carbonate is considered to be the most valuable product. Considering the facile separation and reusability of catalyst, heterogeneous base catalysts have attracted considerable attention due to the obvious advantages over Brϕnsted acid and homogeneous base catalysts in the transesterification of glycerol. Herein, we will give a short overview on the recent development of the heterogeneous catalysis in the transesterification of glycerol with dialkyl carbonate. Focus will be concentrated on the heterogeneous base catalysts including alkaline-earth metal oxides (MgO, CaO, and mixed oxides), hydrotalcites, zeolites, clinoptilolites, organic bases, etc. Their catalytic mechanisms during the heterogeneous process will be elucidated in detail.

A palladium-catalyzed intramolecular reductive amination of ketones with weakly nucleophilic sulfonamides has been developed, providing facile access to a range of chiral sultams with up to 99% enantioselectivity.

An enantioselective hydrogenation of cyclic iminium salts has been successfully realized by employing [Ir(COD)Cl]₂ and chiral diphosphine ligands as catalyst, furnishing chiral N-alkyl tetrahydroisoquinolines and N-alkyl tetrahydro-β-carbolines with up to 96% ee and 88% ee, respectively. The hydrogenation provides a direct, simple and efficient protocol toward chiral tertiary amines. Meanwhile, asymmetric hydrogenation at the gram scale was also conducted smoothly without loss of reactivity and enantioselectivity.

A series of micro-sized MgO catalysts with various morphologies have been prepared by varying the reaction temperature and stirring time during precipitation, and were investigated for the production of glycerol carbonate from the transesterification of glycerol with dimethyl carbonate. In contrast to other morphologies of MgO (e.g., rod-like, spherical, flower-like and nest-like), trapezoidal MgO demonstrated a superior performance with a yield of glycerol carbonate of more than 99%. Various techniques including N₂ physical adsorption, XRD, CO₂ chemical adsorption and EDS revealed that the unique catalytic activity of trapezoidal MgO was related to its lower specific surface area, bigger crystallite size, weaker surface basicity and fewer Mg atom vacancies compared to the other morphologies of MgO. The experimental conditions (e.g., the catalyst amount, solvent, reaction temperature and molar ratio between glycerol and dimethyl carbonate) were also found to play crucial roles in determining the yield of glycerol carbonate. Furthermore, CO₂-TPD profiles and FT-IR spectra indicated that the weak surface basic sites occurring at 150 °C and the CO₃ ²⁻ stretching vibration around 1448 cm⁻¹ were responsible for the catalytic activity of the developed trapezoidal MgO in regeneration.

Phenol is an important chemical material that is widely used in industry. Currently, phenol is dominantly produced by the well-known three-step cumene process, which suffers from severe drawbacks. Therefore, developing a green, sustainable, and economical strategy for the production of phenol directly from benzene is urgently needed. In recent years, the photocatalytic hydroxylation of benzene to phenol, which is economically feasible and could be performed under mild conditions, has attracted more attention, and development of highly efficient photocatalyst would be a key issue in this field. In this review, we systematically introduce the recent achievements of photocatalytic hydroxylation of benzene to phenol from 2015 to mid-2022, and various heterogeneous photocatalysts are comprehensively reviewed, including semiconductors, polyoxometalates (POMs), graphitic carbon nitride (g-C₃N₄), metal–organic frameworks (MOFs), carbon materials, and some other types of photocatalysts. Much effort is focused on the physical and chemical approaches for modification of these photocatalysts. The challenges and future promising directions for further enhancing the catalytic performances in photocatalytic hydroxylation of benzene are discussed in the end.