Long chain phenols—the thermal and oxidative deterioration of phenolic lipids from the cashew (Anacardium occidentale) nut shell

The thermal and oxidative deterioration of a mixture comprising the (15:0)‐, (15:1)‐, (15:2)‐ and (15:3)‐cardanols has been investigated by HPLC analysis. In air the oxidative deterioration is dependent on reaction time, unsaturated structure and temperature, being significant at 180°C and fairly extensive at 240°C. The reactivity of the constituents follows the sequence(15:3)‐cardanol > (15:2)‐cardanol > (15:l)‐cardanol > (15:0)‐(cardanol‐3‐pentadecylphenol). At 180°C, replacement of the aerial atmosphere by nitrogen retards the deterioration although in the upper range an inert atmosphere has only a marginal effect. The mixture and the individual cardanol constituents behave similarly. The results are relevant to distilllation procedures for purifying cardanol, to other unsaturated lipid systems and to the technical processing of the product known as technical cashew nut‐shell liquid from the cashew nut Anacardium occidentale L. Rate studies indicate that first order kinetics prevail in a nitrogen atmosphere. In air a second order rate of reaction was not always observed.