5780-08-5Relevant articles and documents
A convenient synthesis of tri- and tetramethylbenzaldehydes from readily available phenols
Dhankher, Persis,Sheppard, Tom D.
supporting information, p. 381 - 384 (2014/03/21)
This letter describes a convenient synthesis of the six isomeric tri- and tetramethylbenzaldehydes, which are not readily available from major chemical suppliers. Formylation of readily available phenols via electrophilic aromatic substitution provides compounds containing the correct aromatic substitution pattern. ?Suzuki cross-coupling of the corresponding trifluoromethanesulfonates with methylboronic acid then provides the benzaldehydes as single isomers. Georg Thieme Verlag Stuttgart. New York.
Dual Reactivity of the Formyl Cation as an Electrophile and a Broensted Acid in Superacids
Tanaka, Mutsuo,Fujiwara, Masahiro,Ando, Hisanori
, p. 3846 - 3850 (2007/10/02)
The nature of the formyl cation in the Gattermann-Koch formylation was studied by comparing the formylation with the acetylation and sulfonation in CF3SO3H-SbF5 and FSO3H-SbF5, respectively.The results of the kinetic studies in CF3SO3H-SbF5 showed that the formyl cation has dual reactivity as an electrophile and as a Broensted acid.Upon comparing the formylation with the sulfonation in FSO3H-SbF5, it was found that the protonated aromatic compounds also act as Broensted acids to produce formyl cations.Therefore, the formylation has a priority over other typical electrophilic substitutions under conditions where most of aromatic compounds are protonated because the formyl cation is reproduced close to the aromatic compounds by the protonation of CO with not only superacids but also protonated aromatic compounds.
An Unexpected γ-Hydrogen Rearrangement in the Mass Spectra of Di-ortho-substituted Alkylbenzenes
Kingston, Eric E.,Eichholzer, John V.,Lyndon, Paul,MacLeod, John K.,Summons, Roger E.
, p. 42 - 47 (2007/10/02)
In contradiction of long-accepted mass spectrometric dogma, the site-specific γ-hydrogen rearrangement is observed in alkylbenzenes in which both ortho positions are blocked with methyl substituents.Mass spectrometric studies of a series of five trimethyl- and three tetramethylisopentylbenzenes have shown that this rearrangement is only suppressed to a significant degree in those compounds in which all three positions ortho and para to the isopenyl group are blocked.Deuterium labelling has confirmed the γ-site-specific origin of the migrating H atom while metastable studies have been used to investigate the mechanism of the rearrangement process.
