Photo-sensitive benzoxazine II: chalcone-containing benzoxazine and its photo and thermal-cured thermoset

Abstract

Chalcone-containing benzoxazine (BHP-a) was synthesized. Two procedures were applied to cure BHP-a, thermal curing of chalcone and oxazine moieties. Another one was photo curing the chalcone moiety, followed by thermal curing of the oxazine moiety.

Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers

“…Introduction of photoreactive functionalities, coumarin [ 208 , 209 , 210 , 211 ], chalcone [ 212 ], and bis-benzylidene as another smart feature in Bz monomer is reported. This created their capability for photodimerization [ 213 , 214 ] and exploration for self-healing applications.…”

Significant Efficacy of Desiccants in the Synthesis of Distyryl Ketones/Chalcones Bearing Phenolic Hydroxyl Groups

“…36−38 It was also adopted in the synthesis of distyryl ketones and chalcones under very mild conditions. 5,18,39 Unfortunately, boron trifluoride etherate is very sensitive to water, which leads to a rapid loss of catalytic activity during the reaction process. Therefore, a large amount of catalyst is needed, 40 though this will be accompanied by unavoidable side reactions of aldehydes and ketones.…”

“…Distyryl ketones and chalcones are generally synthesized by the Claisen–Schmidt reaction, in which benzaldehyde and methyl ketone undergo aldol condensation to form an unsaturated ketone in the presence of catalysts (Scheme a). To incorporate distyryl ketones or chalcones into different polymer resins including epoxy resins, benzoxazines, , polyethers or polyesters, benzaldehyde and methyl ketone bearing phenolic hydroxyl groups are often used as the reactants. For instance, the typical distyryl ketone 1,5-bis­(4-hydroxyphenyl) penta-1,4-dien-3-one (BHPDO) and the typical chalcone 1,3-bis (4-hydroxyphenyl) prop-2-en-1-one (BHPEO) (their chemical structures are depicted in Scheme b,c, respectively), which both contain two phenolic hydroxyl groups, have already been used in the preparation of photocurable resins. , …”

“…Recently, owing to the convenient operation and low cost, boron trifluoride etherate has been proposed as a high-efficiency catalyst in various organic synthesis reactions, including hydroboration–oxidation, cleavage and rearrangement of epoxides, esterification, cyclization, thioketalization, and ketalization. − It was also adopted in the synthesis of distyryl ketones and chalcones under very mild conditions. ,, Unfortunately, boron trifluoride etherate is very sensitive to water, which leads to a rapid loss of catalytic activity during the reaction process. Therefore, a large amount of catalyst is needed, though this will be accompanied by unavoidable side reactions of aldehydes and ketones. ,, Inspired by those previously used dehydrators, in this work, desiccants were introduced into the Claisen–Schmidt reaction to promptly remove the water produced when using boron trifluoride etherate as the catalyst.…”

Access to Densely Functionalized Chalcone Derivatives with a 2-Pyridone Subunit via Pd/Cu-Catalyzed Oxidative Furan–Yne Cyclization of N-(2-Furanylmethyl) Alkynamides under Air

“…Given that the aromatic furan ring is electron-rich and often acts as a nucleophile, we hypothesized that nucleopalladation of alkynes 1 bearing a pendant furan ring would generate vinylpalladium intermediate A , which could then couple with various partners to provide access to chalcone derivatives 2 , some of which show bioactivities and interesting photoelectronic properties (Scheme , eq 5). Chalcones are generally synthesized via aldol reactions between aldehyde and ketone substrates, but the preparation of the substrates tends to be difficult, requiring multiple steps if they are structurally complex and/or densely functionalized.…”