This review summarizes the recent developments in using QMAs in several regioselective transformations, including allylic substitution, multicomponent reactions, deoxyacylation, Wittig reaction, deuteration, aryloxylation, and [3+2] annulations. The review demonstrates that the production of C-C, C-X, C-P, and C-O bonds has significantly advanced with the invention of metal-free, cheap, and scalable techniques employing QMA as a starting material.

Catalysts play a vital role in various chemical industries. Homogeneous and heterogeneous catalysts have their specific advantages and disadvantages in terms of the tradeoff between efficiency and recyclability. Nanocatalysts can provide high efficiency as they operate practically in a homogeneous mode, but the recyclability remains a challenge. The concept of ‘dip catalysts’ was developed in this context; the nanocatalyst embedded within a swellable polymer matrix can effectively harmonize the advantages of homo and heterogeneous catalysts. A dip catalyst can be physically inserted in a reaction system to start the catalytic reaction, and retrieved to stop the reaction. By careful optimization of the nanocatalyst-polymer composition, the catalyst leaching can be prevented and the dip catalyst used in innumerable cycles. The dip catalyst can be monitored through the usage cycles using appropriate microscopy and spectroscopy tools, in order to assess the fate of the catalyst within. Since the discovery of this mode of catalysis, several applications have emerged in the literature. This article provides a brief overview of the concept of dip catalysts, their application and evolution.