Synthesis of Semiochemicals and Related Fine Chemicals from Cashew Nut Shell Liquid
This paper reports on syntheses of 3-hydroxybenzaldehyde (1) and tetradecanal (2) from the same renewable starting material (cashew nut shell liquid or CNSL), thus demonstrating the potential of the agro-waste cashew nut shells (CNS) as a source of valuable fine and industrial chemicals. The strategy employed in accomplishing the synthesis started with extraction of CNSL followed by isolation of anacardic acid (4) and decarboxylation to give cardanol (5). Compound 5 was hydrogenated followed by protection of phenolic group to give 3-pentadecylphenyl acetate (7). Benzylic oxidation of compound 7 followed by reduction and dehydration resulted into formation of 3-(pentadec-1-en-1-yl)phenol (9). Ozonolysis of compound 9 furnished tetradecanal (2) and 3-hydroxybenzaldehyde (1). Since the transformation of compound 1 to m-propylphenol (3) has been reported in literature, the synthesis of compound 1 from anacardic acid constitutes a formal synthesis of 3.
Keywords: semiochemicals isocardanol, 3-hydroxybenzaldehyde, m-propylphenol, tetradecanal