Anacardic aldehyde

The cleavage of urushiol by catechol-2,3-dioxygenase has been studied (ref. 324) and the oxidation of anacardic aldehyde to urushiol with manganeses dioxide (ref. 325), an alternative to the Dakin reaction descibed some years ago (ref. 88). Experiments on the methylation of urushiol (refs. 88,89) Indicate that the 3-hydroxyl group reacts preferentially under mild conditions. Hydrogenated urushiol, 1,2-dihydroxy-3-pentadecylbenzene, reacted similarly to form 1-methoxy-2-hydroxy-3-... 

However, on account of the unavailability of the corresponding aldehyde, anacardic acid (8Z)-monoene Fig (2)-2 and Fig (2)-3, the (8Z,llZ)-diene were obtained by the alkylation route as described in [2],... 

A chemical/chromatographic method has been used to determine the first double bond position in the unsaturated anacardic acid constituents of Pistacia vera (ref. 9). The isolated constituent was methylated, dihydroxylated with performic acid, hydrolysed to remove some formate ester, oxidised with potassium periodate in acidic solution and the aldehydes formed reduced with sodium borohydride to the primary alcohols (refs. 226). The retention time of the aromatic product methyl 2-methoxy-6-(8-hydroxyoctyl)benzoate (C8 side chain) was compared with those of the Cl, C3, C7 and CIO synthetic analogues and from the linear plot of retention time against methylenic carbon chain length, the double bond could be readily assigned to the 8-position. Nevertheless mostly on account of limited sample availability and the time involved in purely synthetic verification. 

Reduction of isoanacardic aldehyde gave a methylol which could also be synthesised directly from cardanol together with formation of some of the 4,6-bis-methylol. The monomethylol compound isoanacardic alcohol was an effective solvent extractant for the borate anion (ref. 279, 293). The isomeric compound, anacardic alcohol (ref. 88) was similarly obtained from anacardic acid (ref. 180). This In conjunction with the teriary amine Aliquat 336 was highly effective for the solvent extraction of the borate anion (ref. 293). Both these substances were comparable in properties to the 2,6-bis(hydroxymethyl) derivatives of 4-t nonylphenol and to 4-t octyl-2-chloro-6-hydroxymethylphenol (ref. 294). 

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