Top Curr Chem (Z) (2018) 376:8 https://doi.org/10.1007/s41061-017-0177-9 1 3 REVIEW Chemical Valorization of Cashew Nut Shell Waste E. B. Mubofu 1  · J. E. Mgaya 1 Received: 24 February 2017 / Accepted: 6 November 2017 / Published online: 13 February 2018 © Springer International Publishing AG, part of Springer Nature 2018 Abstract Cashew nut shells are agro-wastes produced from cashew nut processing factories and contain about 30–35 wt% oil called cashew nut shell liquid (CNSL). This liquid is a mixture of four potential compounds, namely anacardic acid, cardanol, cardol and 2-methyl cardol. Various reactions have been developed to con- vert the components of cashew nut shell liquid into industrially important chemicals, and these materials are herein described. Such reactions employed in the transfor- mation include transfer hydrogenation reactions, isomerization reactions, metathesis reactions, carbonylation reactions, polymerization reactions, isomerizing metathesis reaction, and isomerizing carbonylation reactions. Through these descriptions, one realizes that cashew nut shells are not a waste, but they are rather a good source of a potential liquid, CNSL, which is a promising renewable resource for synthesizing various industrial chemicals. Keywords Cashew nut shells · Cashew nut shell liquid · Agro-wastes 1 Introduction Cashew (Anacardium occidentale) is a tree native to Brazil, and it was introduced to other parts of the world in the sixteenth century, mainly with the intention of soil conservation. From its intended purpose to check soil erosion, the crop became a major foreign exchange earner in most countries [1, 2]. It is primarily This article is part of the Topical Collection “Chemistry and Chemical Technologies in Waste Valorization”; edited by Carol Sze Ki LIN. * E. B. Mubofu ebmubofu@udsm.ac.tz; ebmubofu@gmail.com 1 Chemistry Department, University of Dar es Salaam, P.O. Box 35061, Dar es Salaam, Tanzania