Aromatic ethers acylation acid mixture

The regioselective acylation of aromatic ethers with carboxylic acids (aromatic ether/carboxylic acid ratio =1) can be pafonned with an equimolecular mixture of trifluoroacetic anhydride adsorbed on the surface of alumina without any solvent [77]. The process can be applied, with nearly quantitative yields, to anisole and the three isomeric dimethoxybenzenes by using carboxylic acids. The authors outline that in the case of anisole, the acylation selectively occurs at the para position to the methoxy group. The reaction requires a large amount of alumina and trifluoroacetic anhydride, and consequently, it can only be appUed at the laboratory scale. The intervention of a mixed carboxyhc acidArifluoroacetic acid mixed anhydride intermediate is presumed. 

Table 3.5 Acylation of aromatic ethers with anhydrides in the presence of titanium(IV) monochlorotriflate-triflic acid mixture...

Acylation and alkylation of aromatic compounds. Benzophenones are obtained in good yield when a mixture of a phenolic ether and an alkoxybenzoic acid is treated with PPA prepared by stirring a mixture of 8 parts by weight of P2O5 and 5 parts by volume of 90% orthophosphoric acid (dl. 75) at 85° for 30 min. (Ayers and Denney ). Thus veratrole and vanillic acid afforded4-hydroxy-3,3, 4 -trimethoxybenzophenone. 

Fluoroalkyl chromone derivatives can be obtained from the base catalysed reaetion between 2,2-dihydropolyfluoroalkanoates and phenols. Initial loss of HF allows Michael addition of the phenol and subsequent cyclisation of the enol ether yields the heterocycle. m-Substituted phenols give the expected mixture of 5- and 7-substituted chromones, whilst dihydroxy aromatic compounds give polycyclic materials (94JFC263). In a more conventional approach Z-3-(aryloxy)-polyfluoroalkenoic adds, derived from Michael addition of phenols to polyfluoro-2-alkynoic acids, undergo intramolecular Friedel-Crafts acylation to 2-polyfluoro-alkylchromones (94JFC25). 

Maleic anhydride grafting (cont.) poly(styrene-co-divinylbenzene), 694 poly(styrene-co-isobutylene), 675, 689 poly(styrene-co-nfialeic anhydride), 676, 679 poly(vinyl acetate), 676, 694 poly(vinyl acetate-co-vinyl fluoride), 678 poly(vinyl alkyl ethers), 675, 679, 692, 701 poly(vinyl chloride), 683, 692, 693, 695, 702 poly(vinylidene chloride), 691 poly(vinyl toluene-co-butadiene), 689 radical—initiated, 459-462, 464-466, 471, 475, 476 radiation—initiated, 459, 461, 466, 471, 474 redox-initiated, 476 rubber, 678, 686, 687, 691, 694 to saturated polymers, 459-466, 475, 476 solvents used 460-463, 465, 466, 469, 474-476 styrene block copolymers, 679 tall oil pitch, 678, 697 terpene polymers, 679, 700 thermally-initiated, 462, 464-467, 469, 476 to unsaturated polymers, 459, 466-474 vapor-phase techniques, 464, 474, 475 to wool fibers, 476 Maleic anhydride monomer acceptor for complex formation, 207-210 acetal copolymerization, 316 acetone CTC thermodynamic constants, 211 acetone photo-adduct pyrolysis, 195, 196 acetylacetone reaction, 235 acetylenic photochemical reactions, 193-196 acrylamide eutectic mixtures, 285 acylation of aromatic acids, 97 acylation of aromatics, 91, 92 acylation of fused aromatics, 92, 95, 97, 98 acylation of olefins, 99 acylation of phenols, 94-96 acylic diene Diels-Alder reactions, 104-111, 139 addition polymer condensations, 503-505 adduct with 2-cyclohexylimino-cyclopentanedi-thiocarboxylic acid, 51 adducts for epoxy resins curing, 507-510 adduct with 2-iminocyclopentanedithiocarboxylic acid, 51... 

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