Utilization of natural cashewnut shell liquid for the synthesis of textile dyes

Anacardic acid derived azo dyes have been successfully prepared by coupling the acid or its salt with the diazonium salts from two isomers aminophenol. For long time. Cashew Nut Shell Liquid (CNSL) has been treated as a waste industrial by- product of cashew nut processing plants. However. chemical structures of its components show that they could be used for synthesis of textile dyes. This idea was tested by coupling of diazonium salts of 3-aminophenol and 4-aminophenol with anacardic acid or its salts. Natural CNSL was obtained by solvent extraction of cashew shells. its components were separated to obtain anacardic acid, which was then coupled with the diazonium salts. The average yield of the dyes was 44%. The UV-Vis absorption spectra was at 520 nm and at 295 nm for dyes of 3-aminophenol origin with saturated anacardic acid (3APSA) and the dyes of 4-aminophenol origin with saturated anacardic acid (4APSA) respectively. The FT-IR spectra for all the dyes had an absorption bands at 1450-1520 cm-1 indicating the presence of azo group. The dyes were tested for dyeing efficiency using 100% cotton and 35% cotton: 65% polyester. The total extents of fixations for 3APSA were 39% and 31% on the fabric with 1 00% cotton and 35% cotton: 65% polyester respectively. The fastness tests to washing showed that the best change in shade was 2/5 for 3APSA implying that the dye had fair fastness to washing. Generally, the successful preparation of the azo dyes from anacardic acid has proved that CNSL is not a waste; rather it is a raw material for dyes and other valuable products.