2-Methyl cardol

The structures of anacardic acid, cardol, cardanol, and 2-methyl cardol are given in Fig. 9. Each component... 

This is one of the most widely distributed plants cultivated to obtain cashew nut. The phenolic lipid is only a by-product known as cashew nut shell liquid (CNSL). The nut, attached to the base of the cashew nut apple consists of an ivory-colored kernel covered by a thin brown membrane (testa) and enclosed by an outer porous shell, the mesocarp which is about 3 mm thick with a honey-comb structure where the reddish brown liquid (CNSL) is stored [91]. The major components of CNSL are a phenolic acid, anacardic acid, a dihydric phenol, cardol with traces of mono hydric phenol, cardanol, and 2-methyl cardol [92-95]. 

Anacardic acid Cardol Cardanol 2-Methyl cardol... 

CNSL is obtained as a by-product of the cashew nut industry, mainly containing anacardic acid 80.9%, cardol 10-15%, cardanol, and 2-methyl cardol (Fig. 10). CNSL occurs as a brown viscous fluid in the shell of cashewnut, a plantation product obtained from the cashew tree, Anacardium oxidentale (Bhunia, et al., 2000). CNSL is used in the manufacture of industrially important materials such as cement, primers, specialty coatings, p)aints, varnishes, adhesives, foundry core oils, automotive brake lining industry, laminating and rubber compounding resins, epoxy resins, and in the manufacture of anionic and non-ionic surface active agents. CNSL modified phenolic resins are suitable for many applications and perform improved corrosion and insulation resistance. 

The use of open-chain precursors for obtaining the benzenoid ring in anacardic and orsellinic acids has proved a fruitful approach. Ethyl 2-methoxy-6-methylbenzoate (synthesised through the Michael addition of ethyl acetoacetate virith but-2-en-al, followed by cyclisation and aromatisation), has been alkylated in an aprotic solvent after formation of the carbanion with lithium di-isopropylamide (refs. 113,114) to give the anacardic after hydrolysis and demethylation (a). In a similar way ethyl 2,4-dimethoxy-6-methylbenzoate (ethyl orsellinate), (formed from ethyl acetoacetate and ethyl crotonate followed by cyclisation aromatisation and methylation (ref. 115)), has been alkylated (ref. 116, 117). In this way the C.,5 orsellinic acid precursor [R = C14H29 in route (b)] of the component phenols in Anacardium occidentale has been synthesised (ref. 118) and the method indirectly affords another route to the cardol series. 

CNSL used in polymerisation with formaldehyde as for example in friction dusts may not require elaborate analysis. Nevertheless interest in the industrial chemical uses of phenolic lipids has led to a study of quantitative methods of analysis by a variety of chromatographic methods. For cashew phenols these were first based on GLC. Thus the (15 3), (15 2), (15 1) and (15 0) constituents of methyl anacardate, cardol and cardanol have been separated by GLC on PEGA columns (ref.206), the free phenols (anacardic acid as methyl anacardate) by GLC on SE30 (ref207) and the hydrogenated anf fully methylated phenols on Dexsil and PEGA columns (ref.208). A further number of stationary phases have been investigated... 

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