Derivatives of Cardanol through the Ene Reaction with Diethyl Azodicarboxylate

Abstract

Cardanol is an alkyl/alkenyl phenolic material obtained from cashew nut shell liquid (CNSL), which is a byproduct of cashew nut processing. In an effort to develop new uses, cardanol was derivatized for the first time with diethyl azodicarboxylate (DEAD) through the ene reaction. The reaction was facile and required only the application of heat without a catalyst. Both conventional heating and microwave heating were shown to be effective; the latter entailed much shorter reaction time and substantial energy savings. The reaction product (a hydrazino-ester derivative of cardanol) was characterized by nuclear magnetic resonance (NMR). The product increased in viscosity with time and may be useful as a viscosifier in oil-based commercial formulations and as a synthon for further organic reactions.

Chemical Modifications and Applications of Cashew Byproducts - A Selective Review

“…Self-curing cardanol resins. In the second reaction, cardanol was reacted with diethyl azo dicarboxylate (also known as DEAD) 39 . DEAD is involved in many chemical reactions 40,41 .…”

“…In the second reaction, cardanol was reacted with diethyl azo dicarboxylate (also known as DEAD) . DEAD is involved in many chemical reactions. , It is commonly used as an activating reagent in the Mitsunobo reaction, such as the stereochemical inversion of secondary alcohols, aminations, and macrolactonizations.…”

“…In the ene reaction, as DEAD was inserted into the olefin, the double bond moved away from the point of insertion and became mostly trans in configuration. Subsequently, a Diels–Alder reaction occurred between the cis and the trans double bonds (Figure ), and the cardanol solution increased substantially in viscosity . Thus, this was a self-curing reaction, which might be useful for caulking, cement, and adhesive applications.…”

“…It is also a good reagent for pericyclic reactions; for example, it reacts readily with soybean oil. 42,43 The reaction of cardanol with DEAD was achieved easily by simply heating the reactants; no catalyst was needed 39 (Figure 3). Microwave heating was shown to involve less reaction time than conventional heating (5 min for microwave versus 6 h for conventional heat, both at 70 °C), thereby resulting in substantial energy savings.…”

Synthesis of Polycardanol Using BF3.O(C2H5)2 as Initiator: Influence of Polymerization Conditions on Reaction Products

“…The hydroxyl group of the phenol, the aromatic ring and the unsaturations of the aliphatic chain enable obtaining various types of functionalization of the cardanol molecules, making it a valuable starting material for the synthesis of various compounds, including polymers. 8,[15][16][17] The literature describes the polymerization of cardanol through different methods. Polycondensation of the material is achieved by the reaction of the phenol group with aldehydes, obtaining as a product novolac resins.…”