Recent Advances and Challenges in the Valorization of a-Pinene toward Value-Added Chemicals

The transformation of abundantly available bioresources into specialty chemicals, particularly as consumer products, remains an important pursuit in chemical research. In this sense, the valorization of bio-oil strategies that utilize stable and easy-to-handle chemical entity not only creates application-oriented products but also helps in avoiding the usage of toxic and hazardous chemical sources. Recently, the valorization of a-pinene (readily/naturally available terpenic compounds) has been explored to prepare a wide range of processes to access perfumery products and remains fast-growing research for industrial and societal applications. Considering the valorization of a-pinene, challenges for the synthetic and selective preparation of perfumery chemicals are centered around the design of the catalyst and the setting up of the precise reaction conditions. Extensive research is employed using diverse catalytic approaches to utilize a-pinene to prepare important perfumery intermediates. In this review, the state-of-the-art, recent advances and challenges in the utilization of a-pinene are reviewed, emphasizing two main products, i.e., a-campholenic aldehyde and carveol via a-pinene oxide isomerization, and discussed the pertinent role of various homogeneous and heterogeneous catalytic systems.