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Bei der Fluorierung von l,2,4,5-Tetramethylbenzol (III) mit Xenondi- fluorid (II) spielt der zugesetzte Katalysator eine wesentliche Rolle, mit HF erhalt in Abhangigkeit von der Stochiometrie die Fluorverbindungen (I) bzw. (IV).

Bei der Umsetzung mit Xenondifluorid erhalt man aus den Phenyl-cycloalkenonen (I) die isomeren Fluorverbindungen (II) und (III).

The photochemistry of fluoro-substituted aromatic and heteroaromatic molecules is reviewed. Investigations in this field of organic fluorine chemistry are summarized and some recent observations are presented. It is concluded that the fluorine atom is a convenient substituent for the elucidation of the reaction pathways of photochemical transformations of aromatic and heteroaromatic molecules.

2 + 2 photoaddition of cyclopentene to hexafluorobenzene in cyclohexane solution proceeds predominately via anti(85%) rather than syn attack (15%).

The fluorination of 9,10-dihydroanthracene and triptycene with xenon difluoride in the presence of hydrogen fluoride occurred at α and β position with β attack predominating over α attack, while the reaction with acenaphthene resulted in the formation of 2- and 4-fluorosubstituted products, regioselectivity being very little affected by the nature of the catalyst: hydrogen fluoride, boron trifluoride and pentafluorothiophenol. The fluorination of 1,2,3,4-tetrahydro-1,4-methanonaphthalene resulted in the formation of 6-fluoro-1,2,3,4-tetrahydro-1,4-methanonaphthalene, 6,7-difluoro-1,2,3,4-tetrahydro-1,4-methanonaphthalene and rearranged product 1-(2,2-difluoroethyl) indan.

A polymeric aryliodine(III) difluoride has been prepared and used to fluorinate several phenyl-sub-stituted olefins to their difluorides in high yields under mild conditions.

Halofluorination of 1,2-dihydronaphthalene with a mixture of N-chlorosuccinimide or N-bromosuccinimide or N-iodosuccinimide–hydrogen fluoride–pyridine in ether proceeds with Markovnikov type regioselectivity. The reaction is stereospecifically anti, the anti adduct isomerizing to syn products under the reaction conditions. The elimination of hydrogen halide under basic conditions occurs only from the syn adduct, thus forming 1-fluoro-3,4-dihydronaphthalene. Halofluorinations of 1,4-dihydronaphthalene also occur stereospecifically anti, and elimination under basic conditions gives naphthalene.

Xenon difluoride reacts with 1,1-diphenylethylenes in the presence of hydrogen fluoride or trifluoroacetic acid as catalyst to form the corresponding 1,2-difluoroacetic acid as catalyst to form the corresponding 1,2-difluoro-1,1-diphenylethanes in nearly quantitative yields.

The reaction of substituted (difluoroiodo)arenes with 1-phenyl-1-(m-chlorophenyl)ethylene results in 1,1-difluoro-1-(m-chlorophenyl)2-phenylethane, with 1-phenyl-1-(p-methoxyphenyl)ethylene in 1,1-difluoro-1-phenyl-2-(p-methoxyphenyl) ethane, and with 1-phenylcyclopentene and 1-phenylcyclohexene in rearranged gem-difluoro compounds. The reaction with norbornene results in three products: fluoronortricyclane (9–12%), 2-exo-7-syn-difluoronorbornane (75–86%), and 2-exo-7-anti-difluoronorbornane (5–15%) depending upon the substituent on the phenyl ring in (difluoroiodo)arenes.

Fluorination of 1,3-diketones with xenon difluoride in the presence of the insoluble cross-linked polystyrene–4-vinylpyridine complex with boron trifluoride and insoluble cross-linked polystyrene–4-vinyl-pyridine resins resulted in the formation of mono- and di-fluoro products, while reactions with enol acetates in the presence of hydrogen fluoride gave α-fluoroketones.

Photoaddition of indene or 1,2-dihydronaphthalene to hexafluorobenzene in cyclohexane solution results in the formation of cis-syn-cis-2 + 2-cycloadducts.