Internal acidity scale and reactivity evaluation of chiral phosphoric acids with different 3,3′-substituents in Brønsted acid catalysis

NMR H-bond analysis reveals an offset of internal and external acidities of catalysts and allows for a detailed reactivity analysis.

Voltammetric Perspectives on the Acidity Scale and H+/H2 Process in Ionic Liquid Media

Nonhaloaluminate ionic liquids (ILs) have received considerable attention as alternatives to molecular solvents in diverse applications spanning the fields of physical, chemical, and biological science. One important and often overlooked aspect of the implementation of these designer solvents is how the properties of the IL formulation affect (electro)chemical reactivity. This aspect is emphasized herein, where recent (voltammetric) studies on the energetics of proton (H+) transfer and electrode reaction mechanisms of the H+/H2 process in IL media are highlighted and discussed. The energetics of proton transfer, quantified using the p Ka (minus logarithm of acidity equilibrium constant, Ka) formalism, is strongly governed by the constituent IL anion, and to a lesser extent, the IL cation. The H+/H2 process, a model inner-sphere reaction, also displays electrochemical characteristics that are strongly IL-dependent. Overall, these studies highlight the need to carry out systematic investigations to resolve IL structure and function relationships in order to realize the potential of these diverse and versatile solvents.

Ecological phytocoenotic characteristics of Platanthera bifolia (L.) Rich. within the territory of Nature Reserve «Bylina» in Kirov Region

Ecological-phytocoenotic confinement of Platanthera bifolia in conditions of middle taiga subzone of Kirov Region was investigated. Studied coenopopulations are restricted mostly to spruce-birch, pine and rarely to spruce phytocoenoses. Herbaceous-shrub cover includes 78 species of vascular plants with dominance of Maianthemum bifolium L., Vaccinium myrtillus L. , Vaccinium vitis-idaea L., Hieracium pilosella L., Equisetum sylvaticum L. , Pyrola rotundifolia L. , Linnaea borealis L. , Trientalis europaea L. , etc . Populations age spectres are in most cases normal and incomplete. Ontogenesis of P. bifolia has pregenerative and generative periods as well as juvenile, immature, virginile and generative age stages. Ecological positions of the species within Bylina Nature Reserve are given by Tsyganov scales. It was shown that P. bifolia is a mesobiont species. Maximum potential of P. bifolia is marked on soil acidity scale (11,54%) and illumination scale (11,51%). Estimation of habitat ecological conditions for P. bifolia was accomplished with Ellenberg scales. It was defined that P. bifolia is characterised by significant ecological amplitude. It is a subcontinental, semi-shade species which prefers semi-wet soils with moderate acidity and moderate nutritients richness. According to hemeroby parameters, P. bifolia can be considered a species that survives insignificant and moderate anthropogenic influence in the studied area.

A unified view to Brønsted acidity scales: do we need solvated protons?

The most comprehensive solvent acidity scale spanning 28 orders of magnitude of acidity was measured in the low-polarity solvent 1,2-dichloroethane (DCE).