Dye conjugation to linseed oil by highly-effective thiol-ene coupling and subsequent esterification reactions

Linseed oil, a renewable material obtained from the ripened seeds of the flax plant, was conjugated with C. I. Disperse Red 1 to yield a coloured macromolecule in two experimentally-simplistic coupling steps. Firstly, the abundant presence of carbon-carbon double bonds in linseed oil was exploited to introduce carboxylic acid functionality to linseed oil via a thiol-ene reaction between linseed oil and 3-mercaptopropionic acid. C. I. Disperse Red 1 was then grafted to the carboxylic acid units now present via esterification, offering a coloured product in high yields. On average, 39.1% of the carbon-carbon double bonds in each linseed oil molecule were furnished with a C. I. Disperse Red 1 molecule. The remaining carbon-carbon double bonds may therefore be further exploited for chemical crosslinking, ensuring that the product formed is of potential significance as a coloured, bio-based, surface coating product.