New method of synthesis of polyphenylene type polymers using polycyclocondensation of ketals

Phenylene dendrimers and novel hyperbranched polyphenylenes as light emissive materials for blue OLEDs

“…A family of different cyclotrimers with this core was synthesized by this method and optical properties were studied [15]. These preparations are based on works summarized in a review article [16], described polyphenylenes and also cyclotrimers synthesis based on cyclocondensation of acetylaromatic compounds like acetophenone and derivatives in the presence of acidic catalysts to give exclusively 1,3,5-substituted triarylbenzenes [17,18].…”

Highly Branched Polyphenylenes with 1,3,5-Triphenylbenzene Fragments via Cyclocondensation of Acetylaromatic Compounds and Ni0-Catalyzed Dehalogenation: Synthesis and Light Emission

“…Some works, summarized in a review article, 10 described polyphenylene synthesis based on trimerization cyclocondensation of diacetylaromatic compounds and acetophenone in the presence of acidic catalysts to give exclusively 1,3,5-substituted triarylbenzenes. 43,44 Since 1,3,5-triphenylbenzene (1, TPB) is an important "building block" of branched polyphenylenes, there were attempts to optimize the synthesis of 1 starting from the early work by Wirth et al, 45 describing synthesis of 1,3,5-triphenylbenzene with no more than 50% yield by cyclocondensation of acetophenone in the presence of various acids. Further optimization of this reaction carried out with triethylformate as a ketalizing agent in benzene using gaseous HCl as a catalyst is described in refs 10 and 44.…”

“…Use of tetrachlorosilane in dry ethanol, resulting in HCl and tetraethoxysilane (the latter is a ketalizing agent), led to formation of 1,3,5-triphenylbenzene with a comparable yield. 46 Cyclotrimerization polycondensation of the equimolar amounts of diacetyl-and monoacetyl-containing benzenes results in the polymer where chain growth occurs due to interaction of three acetyl groups: 43 This reaction has two drawbacks: (i) it may lead to the gel formation and should be stopped before gelation occurs (by precipitation in ethanol), and (ii) a polymer contains many defect fragments due to side reactions. The major side reactions are an incomplete cyclization, i.e., dimerization instead of cyclization with formation of β-methylchalcone groups and formation of linear and cyclic vinylene-containing products and also pyrylium salts.…”

“…Some works, summarized in a review article, described polyphenylene synthesis based on trimerization cyclocondensation of diacetylaromatic compounds and acetophenone in the presence of acidic catalysts to give exclusively 1,3,5-substituted triarylbenzenes. , …”