1,721,023 research outputs found
Synthesis of dihydropyridine and piperidine derivatives via an unexpected reaction of pyridine with acetyl chloride
Full text linkAcetyl chloride reacts with pyridine to give a mixture of N-acetyl-1,4- and 1,2-dihydropyridyl acetic acid (1a,b) after water quenching. The reactioninvolves the formation of a zwitterionic ketene enolate intermediate which results from
deprotonation of the acetyl moiety of the in situ formed N-acetyl pyridinium ion.The effect on the reaction outcome of different parameters as temperature, pyridine/acetyl chloride molar ratio, and as Lewis acids and triflate counterion presence has been studied in detail, and a reaction mechanism has been proposed
An unexpected reaction of pyridine with acetyl chloride to give dihydropyridine and piperidine derivatives
Full text linkApplication of IR and UV–VIS spectroscopies and multivariate analysis for the classification of waste vegetable oils
Full text linkDue to the ever-increasing worldwide interest in the exploitation of waste vegetable oils, the development of
analytical tools able to detect their adulteration with edible oils, is considered a priority for the scientific and
industrial community. In this work, edible and waste vegetable oils have been analysed by Fourier Transform-
InfraRed (FT-IR) and Ultraviolet-Visible (UV–VIS) spectroscopies and the corresponding spectral data subjected
to statistical multivariate analysis for classification purposes. In particular, Principal Component Analysis
(PCA) and Partial Least Square Discriminant Analysis (PLS-DA) were performed in order to develop an analytical
tool which is able to distinguish between edible and waste vegetable oil. Qualitative analysis of the spectra
suggested FT-IR and UV–VIS as the more suitable techniques to distinguish between wastes and edible samples.
Also, statistical multivariate analysis revealed that FT-IR-based methodology is more adequate for the target,
even if the elevated sensibility of the method produces an undesired distinction between edible oils of the same
type. Finally, further attempts on UV–VIS data obtained in reflection mode allowed to produce a good dataset
which after statistical treatment gave a clear differentiation between edible and waste oil samples
Monomerisation of [Rh2(1,3-Bis-(Diphenylphosphino)-Propane)2(μ2-Cl)2] Detected by Pulsed Gradient Spin Echo Spectroscopy and 31P Nmr Monitoring of Metathesis Experiments
No full textSynthesis and characterization of [Rh(PP)(PP)]X complexes (PP = DPPE or DPPP, X = Cl− or BF4-). Phosphine exchange and reactivity in transfer hydrogenation conditions
No full textThe synthesis of heteroleptic monomeric cationic Rh(I) bis-diphosphine complex [Rh(dppe)(dppp)]Cl (dppe = 1,2-bis-(diphenylphosphino)ethane and dppp = 1,3-bis-(diphenylphosphino)propane) was achieved by reaction between the neutral dimeric complex [Rh 2 (dppe) 2 (μ 2 -Cl) 2 ] and the dppp ligand. The corresponding complex [Rh(dppe)(dppp)]BF 4 was instead obtained from reaction between [Rh(dppe)(nbd)]BF 4 (nbd = bicyclo-[2.2.1]-hepta-2,5-diene) and the dppp ligand. Previous protocols had extended to the synthesis of the analogous homoleptic complexes containing two dppe or two dppp ligands. The structural analysis of such complexes conducted in the solid state by single-crystal x-ray crystallography and in solution by 31 P and 1 H NMR revealed a distorted square planar geometry where the anion and the cation are not bonded each other. Nevertheless, important differences in reactivity can be found if same complexes with different anions are compared, as in the case of the phosphine exchange reaction between [Rh(dppp) 2 ]X (X = Cl − , BF 4 − ) and the dppe ligand or in the case of the employment of such complexes as catalytic precursors for the transfer hydrogenation reaction from 2-propanol to acetophenone
Solvometallurgy as Alternative to Pyro- and Hydrometallurgy for Lithium, Cobalt, Nickel, and Manganese Extraction from Black Mass Processing: State of the Art
Full text linkThe rapid growth in lithium-ion battery (LIB) demand has underscored the urgent need for sustainable recycling methods to recover critical metals such as lithium, cobalt, nickel, and manganese. Traditional pyrometallurgical and hydrometallurgical approaches often suffer from high energy consumption, environmental impact, and limited metal selectivity. As an emerging alternative, solvometallurgy, and in particular the use of low-melting mixtures solvents, including deep eutectic solvents, offers a low-temperature, tunable, and potentially more environmentally compatible pathway for black mass processing. This review presents a comprehensive assessment of the recent advances (2020–2025) in the application of LoMMSs for metal recovery from LCO and NCM cathodes, analyzing 71 reported systems across binary, ternary, hydrated, and non-ChCl-based solvent families. Extraction efficiencies, reaction kinetics, coordination mechanisms, and solvent recyclability are critically evaluated, highlighting how solvent structure influences performance and selectivity. Particular attention is given to the challenges of lithium recovery, solvent degradation, and environmental trade-offs such as energy usage, waste generation, and chemical stability. A comparative synthesis identifies the most promising systems based on their mechanistic behavior and industrial relevance. The future outlook emphasizes the need for greener formulations, enhanced lithium selectivity, and life-cycle integration to support circular economy goals in battery recycling
Transfer hydrogenation from 2-propanol to acetophenone catalyzed by [RuCl2((η6-arene)P] (P = monophosphine) and [Rh(PP)2]X (PP = diphosphine, X = Cl-, BF−4) complexes)
Full text linkThe reduction of ketones through homogeneous transfer hydrogenation catalyzed by transition metals is one of the most important routes for obtaining alcohols from carbonyl compounds. The interest of this method increases when opportune catalytic precursors are able to perform the transformation in an asymmetric fashion, generating enantiomerically enriched chiral alcohols. This reaction has been extensively studied in terms of catalysts and variety of substrates. A large amount of information about the possible mechanisms is available nowadays, which has been of high importance for the development of systems with excellent outcomes in terms of conversion, enantioselectivity and Turn Over Frequency. On the other side, many mechanistic aspects are still unclear, especially for those catalytic precursors which have shown only moderate performances in transfer hydeogenation. This is the case of neutral [RuCl2(η6-arene)(P)] and cationic [Rh(PP)2]X (X = anion; P and PP = mono- and bidentate phosphine, respectively) complexes. Herein, a summary of the known information about the Transfer Hydrogenation catalyzed by these complexes is provided with a continuous focus on the more relevant mechanistic features
NMR Determination of Free Fatty Acids in Vegetable Oils
Full text linkThe identification and quantification of free fatty acids (FFA) in edible and non-edible
vegetable oils, including waste cooking oils, is a crucial index to assess their quality and drives their
use in dierent application fields. NMR spectroscopy represents an alternative tool to conventional
methods for the determination of FFA content, providing us with interesting advantages. Here the
approaches reported in the literature based on 1H, 13C and 31P NMR are illustrated and compared,
highlighting the pros and cons of the suggested strategies
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