Synthesis and Photochromism of 3-(2,6-dichlorophenyl)-1-(Naphthalen-1-yl)Prop-2-en-1-one (Part II)

Abstract

A practical and environmentally friendly method for the design of unique chalcone 5N and chromene 5NR in high yields is provided by reacting 2,6-dichlorobenzaldehyde with 1-acetonaphthone. The matching chromene 5NR was also made possible by the photochromism of 5N using a UV-Visible spectrophotometer. The structure of the obtained chalcones 5N was established by using IR, 1H NMR, 13C NMR and LC-MS. The advantages of photochromism method are very cheap, available, non-toxic, easy work-up, improved yields and the product of the reaction is very pure. Moreover, photochromism and kinetic of the target product were studied using irradiation with xenon (XL) lights using different solvents such as chloroform (CHF), acetone (ACT), and ethyl acetate (ETAC). It has been found that CHF was the best solvent of photochromism for 5N unlike ETAC which has poor reaction, while in ACT chromene did not produce. The synthesis compound 5N was the faster one to get photostationary state 91 min at (λmax 503nm) in CHF, in other hand ETAC was the slowest (1730 min) solvent used for 4NR chromene formation.  The chromene 5N was the faster returning back to chalcone in dark reaction (DR) 3.5 days when decreases the concentration in CHF. The rate constant (k) at the DR when using XL light was 0.0155, furthermore XL light produce a maximum yield (20%).