Gas-phase acylation reactions. Substrate and positional selectivity of free acetylium ions toward methylbenzenes

Journal Article · Wed Apr 23 04:00:00 EST 1980 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00529a039· OSTI ID:7128255

Speranza, M; Sparapani, C

Free acetylium ions, obtained in the diluted gas state from the ..gamma.. radiolysis of CH/sub 3/F-CO mixtures, have been allowed to react with methylbenzenes, in the pressure range 380 to 760 Torr, and in the presence of a gaseous base (NH/sub 3/). The gaseous cation has been confirmed to be unreactive toward benzene and toluene, whereas it acetylates the xylenes and the other selected polymethylated benzenes. The relative rates of acetylation have been determined in competition experiments, using mesitylene as the reference substrate. The mechanism of acetylation and subsequent isomerization is discussed, and the substrate and positional selectivity of the free CH/sub 3/CO/sup +/ ion are evaluated, together with its intrinsic steric requirements. Comparison of the gas-phase results with those of related condensed-phase reactions, involving CH/sub 3/CO/sup +/ salts as one of the reactive species, reveals no basic mechanistic differences. Some observed reactivity and selectivity discrepancies, in particular those concerning acetylation of toluene, aro-tho- and m-xylene, and hemimellitene, are outlined and their possible causes considered.

• Research Organization: CNR, Rome, Italy
• OSTI ID: 7128255
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 102:9; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ACETYL RADICALS
ACYL RADICALS
ACYLATION
ALKANES
AROMATICS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
ELECTROMAGNETIC RADIATION
EXPERIMENTAL DATA
FLUIDS
FLUORINATED ALIPHATIC HYDROCARBONS
GAMMA RADIATION
GASES
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
INFORMATION
IONIZING RADIATIONS
METHANE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
TOLUENE
XYLENES