4046-09-7Relevant articles and documents
Water-Soluble Calixarenes as New Inverse Phase-Transfer Catalysts. Their Scope in Aqueous Biphasic Alkylations and Mechanistic Implications
Shoichi, Shimizu,Suzuki, Takashi,Shirakawa, Seiji,Sasaki, Yasuyuki,Hirai, Choichiro
, p. 370 - 378 (2007/10/03)
Alkylation reactions of active methylene compounds, alcohols and phenols with alkyl halides in aqueous NaOH solution can be carried out without the need for any added organic solvents in most cases. The water-soluble calix[n]arenes, which contain trimethylammoniomethyl groups on the upper rim, were used as inverse phase-transfer catalysts, resulting in the corresponding alkylated products in good to high yields. The scope of this methodology in aqueous biphasic alkylation reactions and the mechanistic implications are discussed.
Wanderungstendenzen cyclischer, polycyclischer und methylverzweigter Alkylreste bei der Beckmann-Umlagerung
Langhals, Heinz,Ruechardt, Christoph
, p. 3831 - 3854 (2007/10/02)
The migration aptitudes of polycyclic bridgehead groups, cycloalkyl groups as well as of β-, γ- and δ-branched alkyl groups in the Chapman variant of the Beckmann rearrangement were determined.From these data it is concluded that at transition state 2 the migrating group is not resembling a planarised carbenium ion R+, but rather a pentacoordinated carbonium ion structure.Because only small geometrical changes occur in the migrating group vertical stabilisation of charge at transition state is believed to have significant influence on the migration aptitudes.