5780-08-5Relevant academic research and scientific papers
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.
NATURE OF THE REDUCING AGENT AND MECHANISM OF THE REDUCTIVE CONDENSATION OF TRICHLOROMETHYLARENES WITH HYDROXYLAMINE AND HYDRAZINES IN PYRIDINE
Belen'kii, L. I.,Poddubnyi, I. S.,Krayushin, M. M.
, p. 726 - 736 (2007/10/03)
It was shown that during the reductive condensation of trichloromethylarenes with hydroxylamine or hydrazines in pyridine the event of reduction with replacement of one chlorine atom by a hydrogen atom occurs without the participation of hydroxylamine or hydrazine.The first step of the reaction is the formation of N-(α,α-dichloroarylmethyl)pyridinium chlorides, which are converted by the action of the chloride anion or a second pyridine molecule to the corresponding 4-substituted 1,4-dihydropyridines.The latter undergo further aromatization with transfer of hydrogen from the 4-position of the dihydropyridine ring to the benzyl dichloromethylene group and the formation of N-(α-chloroarylmethyl)-4-chloropyridinium chlorides or N-(α-chloroarylmethyl)-4-(pyridino)pyridinium dichlorides, which give the corresponding aldehydes in hydrolysis or products of reductive condensation under the action of hydroxylamine or hydrazines.
A new redox system: Trichloromethylarene - Pyridine base. On the mechanism of the synthesis of N-(4-pyridyl)pyridinium dichloride
Belen'kii, Leonid I.,Poddubnyi, Igor S.,Krayushkin, Mikhail M.
, p. 5075 - 5078 (2007/10/02)
A redox reaction of trichloromethylarenes with pyridines results in respective N-(α-chloroarylmethyl)-substituted pyridinium chlorides which give on hydrolysis aromatic aldehydes and 4-chloropyridines or 1,4'- bipyridinium salts.
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.
Process for preparing a methyl-substituted benzaldehyde
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, (2008/06/13)
Process for formylating an alkyl-substituted benzene using carbon monoxide and hydrogen chloride, in the presence of aluminum chloride catalyst, in a reaction mixture which includes chlorobenzene as a solvent, and process for oxidizing an alkyl-substituted benzaldehyde using oxygen, in the presence of an autoxidation initiator, in a reaction mixture which includes cyclohexanone as a reductant.
