No abstract

A kinetic study of the alkylation reaction of deoxybenzoin (1) with alkylating agents 2 − 4, catalyzed by PHDB18C6 7 or [2.2.2,C10]cryptand 8, has been performed in chlorobenzene−aqueous (or solid) base (NaOH, KOH) two-phase systems, under liquid−liquid (LL) and solid−liquid (SL) phase-transfer catalysis (PTC) conditions. The results obtained seem to indicate a multistep mechanism where the ligand transfers the enolate from the interface to the bulk organic phase and the alkylation reaction is rate determining for all the process. The enolate reactivity strongly depends on the ligand and, to a lesser extent, on the base. The highest rate constant values are obtained under SL-PTC conditions and with [2.2.2,C10]cryptand 8, which realizes the best cation−anion separation and hence anion activation. In line with these data, UV−vis spectroscopic determinations of the complexed enolate (M+⊂Lig)R- exhibit bathochromic shifts of the absorption maximum wavelength (λmax) on changing from crown ether to cryptand. The distribution of the reaction products (O/C alkylation ratio) is also related to the different ability of the ligand to separate cation from anion in the ion pair.

No abstract

The palladium-catalysed homocoupling of aryl halides takes place in the presence of anhydrous, in situ generated, tetrabutylammonium fluoride (TBAF).

Summary: Functionalized perfluoropolyethers are investigated by infrared spectroscopy with the aim to give a quantitative estimate of the carboxylic acid groups species; since hydrogen bonded moieties have been observed, also the relative distribution of the associated species has been determined. The study is based both on measured and on theoretically predicted infrared intensities, as obtained by density functional theory (DFT) calculations on model systems.