59813-05-7Relevant articles and documents
Synthesis and characterization of a new acid molten salt and the study of its thermal behavior and catalytic activity in Fischer esterification
Zaharani, Lia,Khaligh, Nader Ghaffari,Johan, Mohd Rafie,Gorjian, Hayedeh
, p. 7081 - 7088 (2021/05/03)
A new acid molten salt was prepared and its structure elucidation was conducted by FTIR, 1D NMR, 2D NMR, and mass spectrometry. Further support to elucidate the chemical structure of the 1H,4H-piperazine-N,N′-diium ring of the new acid molten salt was achieved by1H and13C NMR, and COSY analyses of 1H,4H-piperazine-N,N′-diium dibromide, which is synthesized and characterized for the first time in the current work. The analysis of FTIR and NMR spectra as well as pH and titrimetric analysis excluded the formation of [SO4]2?and the presence of an excess of H2SO4. Moreover, no distinguishing peak was detected for the acid proton of [HSO4]?in DMSO-d6. The thermal phase transition and thermal stability of the acid molten salt were also recorded, which approved the strong interaction between a dication and hydrogen sulfate anions. According to the acidity of the new molten salt, we encourage the study of its catalytic activity for the acetylation ofn-pentanol using glacial acetic acid. Pentyl acetate was obtained in 89.0% conversion and 78.0% isolated yield. The1H NMR spectrum of the residue showed an excess of HOAc together with molten salt, whereas the1H NMR spectrum of the upper phase exhibited pure pentyl acetate. After separation of the upper phase, the residue was concentrated and used in the next run without further purification. No significant changes in the chemical structure and catalytic activity of the new molten salt were observed even after the 5th run. Two chiral alcohols, including (?)-menthol and (+)-borneol, as well as α-tocopherol (α-TCP) were also acetylated with acetic acid in the presence of the new acid molten salt under optimized reaction conditions, which afforded the desired acetates in high yields.
Efficient diffusion-controlled ligand exchange crystal growth of isostructural inorganic-organic halogenidorhodates(III): The missing hexaiodidorhodate(iii) anion
Bujak, Maciej
, p. 1295 - 1302 (2015/05/20)
The monohydrates of piperazine-1,4-diium hexabromidorhodate(III) bromide and hexaiodidorhodate(III) iodide were obtained by a diffusion-controlled ligand exchange crystal growth method using a hydrochloric acid solution of rhodium(III) chloride trihydrate and piperazine, dissolved in hydrobromic and hydroiodic acid, respectively, separated by a layer of hydrohalic acid. Both inorganic-organic hybrids are defined by the general formula (C4H12N2)2[RhX6]X·H2O (X = Br, 1 or I, 2). They both crystallize in the orthorhombic Pnma space group, and they are isostructural with an isostructurality index above 95%. The cationic building blocks-piperazine-1,4-diium ions and the inorganic components-slightly distorted octahedral [RhX6]3- complexes, isolated X- anions and water of crystallization molecules are connected by related but different systems of interactions. The comparison of packing arrangements and interactions in the crystals of 1 and 2 with those in metal-free (C4H12N2)Br2·H2O, 3, and (C4H12N2)I2·I2, 4, clearly illustrates the occurrence and hierarchy of specific interactions: the bromide-containing structures are dominated by the O/N/C-H···X hydrogen bonds that are less pronounced or exchanged by the X···X halogen bonds in the corresponding iodide-containing structures. The structural features derived from the X-ray diffraction studies are confirmed by the solid-state IR and Raman spectroscopic results supported by the thermoanalytical analyses.
Initiation of Piperazine Ring Formation by Formaldehyde in Its Reaction with Nickel(II) N-(2-Aminoethyl)aziridine and N-(2-Haloethyl)ethylenediamine Complexes
Ukraintsev,Krasnov
, p. 128 - 131 (2007/10/03)
Reaction of [NiL2X2] (L′ = N-(2-haloethyl)ethylenediamine and L″ = N-(2-aminoethyl)aziridine; X = Cl, Br) with formaldehyde in methanol is studied. The major final products of the reaction with [NiL′2X2] are piperazine dihydrohalides and with [NiL″2X2], polymethylenepiperazine. Formally, formaldehyde does not participate in the first reaction. Possible reaction pathways explaining formaldehyde-induced formation of the piperazine ring are discussed.
