Friedel-Crafts chain extension

Arsenic pentafluoride effects a Friedel-Crafts chain extension and cross-linking in PPV. The electrical conductivity takes place by a variable-range hopping mechanism. 

The Friedel-Crafts alkylation reaction has long been an extremely important method of introducing alkyl side-chains into aromatic species. This area has been extensively reviewed652,653. Recent developments have been few, but it has been noted recently that... 

Multiple intramolecular ring closures of aryl-substituted unsaturated long chain alcohols, acids, acid chlorides and ethers in the presence of Friedel-Crafts catalysts have been extensively employed to synthesize polynuclear hydroaromatic hydrocarbons and polycyclic ketones. This is illustrated by two examples shown in equations (112) and (113). The application of stereospecific cycloalkylations in approaching the synthesis of complex organic molecules has been reviewed by Barclay. ... 

The cationic polymerization of styrene has been known since the 1960s using Lewis acids or strong protic acids as initiators leading to fast, uncontrolled polymerization due to extensive proton transfer reactions to, for example, counteranion, solvent, monomer, or polymer. In addition, chain transfer occurs as a result of an intramolecular Friedel-Craft reaction of the carbocation with the penultimate monomer unit, resulting in an indane chain end and the release of a proton that can reinitiate a new polymer chain as illustrated in Scheme 8.13. 

Synthesis (s. a. C-Chain extension. Condensation, Friedel-Crafts ketone synthesis, Oxalic ester -)... 

HCPs [12, 15] represent a family of robust microporous organic materials which are low cost and mainly prepared by the Friedel-Crafts alkylation reaction. The permanent porosity in HCPs is a result of extensive crosslinking reactions which prevent the polymer chains from collapsing into a dense, non-porous state. Such highly... 

If the Friedel-Crafts alkylation in Eq. (10) is inhibited and instead deprotonation of the carbocationic intermediate takes place exclusively, then the resulting polymer will be linear and have unsaturated instead of cyclic units in the main chain. Mechanistically, this case is an extension of the selective linear dimerization of styrene (Eq. (11)), which can be regarded as a polyaddition reaction involving protonation of the carbon-carbon double bond of the monomer and subsequent P-proton elimination from the dimer cation (of. Sect. 3.2) ... 

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