Principal properties (PPs) for lanthanide triflates as Lewis‐acid catalysts

Abstract

A multivariate insight into lanthanide triflates descriptors allowed derivation of three principal properties (PPs). The first one resembling the lanthanide sequence in the periodic table, the second one reflecting the discontinuity in lanthanides properties, the so called 'gadolinium break', and the third one related to the change of coordination number of Ln ions in aqueous solution from nine to eight around Sm-Gd. Experimental support to the predicting ability of the above PPs as descriptors in the prediction of the yields for the synthesis of a-tocopherol from a selected set of four triflate catalysts (La, Eu, Er, Lu) was provided, opening new horizons for a rational selection in multivariate experimental design of Ln triflates catalysed organic reactions.

Upward Trend in Catalytic Efficiency of Rare‐Earth Triflate Catalysts in Friedel–Crafts Aromatic Sulfonylation Reactions

“…The variations in catalytic activity for the rare earth metal triflates is in strong agreement with the work of Fortuna et al [15] using principal component analysis (PCA) calculations. Briefly, PCA is a statistical technique that reduces the dimensionality of the original data set of variables by transforming it into a smaller set of uncorrelated variables that represents most of the information in the original set.…”

“…The use of t 1 and t 2 drastically facilitated further evaluation of the contribution of each original physiochemical property to the relative Lewis acidity of the corresponding lanthanoid compound. [15] The upward trend in the reaction yields ( Figure 3) is strongly correlated with the fluctuation of the first PP t 1 , which was transformed mostly from high and positive contributing loadings of atomic and ionic radii, as well as hydrolysis constant and rate, which are the most important factors that affect the Lewis acidity and, thus, the catalytic activity. The more active catalysts at the end of the series have smaller t 1 values while the less active catalysts at the beginning of the series have the highest ones.…”

“…Correlation of reaction yields obtained under optimal conditions (16 min irradiation time without byproduct formation), the radius of Ln 3 + ions, and the literature t 1 value. [15] higher pK h values of ErA C H T U N G T R E N N U N G (OTf) 3 , GdA C H T U N G T R E N N U N G (OTf) 3 further explains their stability and thus their lower catalytic activity compared with their neighbors. The salts at the beginning of the series, whose pK h values are high, have the lowest catalytic efficiency.…”

“…The hydrolysis constant suggests the referential state of the ion during reaction, and thus reflects the activity of the ion. Screening experiments carried out by Fortuna et al, [15] showed that metal ions with pK h values in the range 4-10 have good catalytic activity.…”

Gas principal properties as new compact descriptors for data-driven gas solubility modelling

“…The need for variables (descriptors) orthogonal to each other suitable for multivariate experimental design led to the derivation of principal properties (PPs), intrinsic properties representative of experimentally observable macroscopic descriptors for chemical entities. PPs, calculated as a principal component analysis (PCA) 1 scores from several experimentally measured physico-chemical properties, are nowadays available for solvents, 2,3 aldehydes and ketones, 2 amines, 2 Lewis acids, 2 lanthanide triflates, 4 aromatic substituents 5 and amino acids. [6][7][8][9] Principal properties for heteroaromatic moieties, based on aromaticity 10 and on 3D-GRID structural parameters 11 have also been reported.…”