- A product analytical study of the thermal and photolytic decomposition of some arenediazonium salts in solution
-
Products of thermal and photochemical reactions of eleven arenediazonium tetrafluoroborates in various solvents have been analyzed. All compounds in most solvents undergo unimolecular heterolysis to give singlet aryl cations which are captured by solvent. This mechanism is dominant for arenediazonium ions without electron-withdrawing substituents in all solvents, and the only reaction observed in water. Additionally, appreciable yields of fluoroarenes are obtained by fluoride abstraction by the aryl cation from fluorinated solvents and from tetrafluoroborate in fluorinated solvents. Yields from photochemical processes are very similar to those from thermal reactions indicating that the main reactions proceed through common or very similar intermediates. Aryl cations formed from ion-paired diazonium ions may react with the counterion, but fragmentation of dissociated diazonium ions leads only to solvent-derived product. Some arenediazonium ions in some solvents undergo an alternative radical reaction leading principally to hydrodediazoniation. It is proposed that this reaction involves initial rate-limiting electron transfer from ethanol to the arenediazonium ion followed rapidly by homolysis of the resultant aryldiazenyl radical. Within the same solvent cage, the aryl radical then either abstracts an α-hydrogen from the ethanol radical cation generated in the first step to give the reduction product and protonated acetaldehyde, or combines with it at the oxygen to give a protonated aryl ethyl ether.
- Canning, Peter S. J.,Maskill, Howard,McCrudden, Katharine,Sexton, Brian
-
p. 789 - 800
(2007/10/03)
-
- Aromatic Fluoroalkoxylation via Direct Displacement of a Nitro or Fluoro Group
-
Nitro- and fluorobenzenes substituted with a range of electron-withdrawing groups readily undergo fluoroalkoxylation via direct displacement of the nitro or fluoro group.A number of compounds, which cannot be usefully prepared by direct displacement of a chloro group and which are otherwise inaccessible, have been synthesized.Yields and reaction conditions are comparable to those reported by other workers for reactions involving strong nucleophiles.
- Idoux, John P.,Madenwald, Mark L.,Garcia, Brent S.,Chu, Der-Lun,Gupton, John T.
-
p. 1876 - 1878
(2007/10/02)
-
- Aromatic Fluoroalkoxylation via Direct Aromatic Nucleophilic Substitution
-
The reaction of activated aryl and heteroaryl halides with fluorinated alkoxide anions is described.In all cases, substitution of the halogen by a fluoroalkoxy group was observed.The effect of solvent, time, temperature, the activating group, leaving group, and the nucleophile on this reaction is also discussed.
- Idoux, John P.,Gupton, John T.,McCurry, Cynthia K.,Crews, A. Donald,Jurss, Cindy D.,et al.
-
p. 3771 - 3773
(2007/10/02)
-