Date of Award

2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Dr. Debasish Kuila

Abstract

Ultraviolet light absorber or stabilizer (UVLS) is one of the many additives that is incorporated into a polymer formulation which functions by preferentially absorbing the UV light to prevent its photodegradation. UVLS such as 2-hydroxyphenylbenzotriazole (2H-BZT) and its derivatives are commercially used UV-light absorbers in different polymers. The synthesis of 2H-benzotriazoles solely relies on the two-step azo-coupling of the diazonium salt and reductive cyclization where the former reaction suffers from poor yield.1 The presence of a phenolic hydrogen in the ortho position to the phenyl ring attached to the nitrogen atom on the benzotriazole imparts excellent photochemical stability to the molecule as the rapid intramolecular proton transfer renders the excited state “stable” and readily reverts to its ground state by dissipating the energy as heat. In designing the regioisomer of 2-(5’-acetyl-2’- hydroxyphenyl)-2H-benzotriazole, it is essential that this feature is not compromised. The aryl azide, 3’-azido-4’-hydroxyacetophenone was prepared from the two-step reduction-azidation of 3’-hydroxy-4’-nitroacetophenone with an isolated yield of 27%. The effect of different fluoride source on benzyne-azide click reaction was investigated. The fluoride-mediated benzyne-azide click reaction employing CsF/18-crown-6 afforded a product with a higher yield (66%) and significantly fewer side products. However, 1 H NMR suggested that 3’-azido-4’- phenoxyacetophenone was formed during the benzyne-azide click reaction, possibly due to the presence of the free –OH group.

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