Search results for "Salt"
showing 10 items of 1157 documents
Chemodiscrimination of Olefin Bonds Through Cross‐Metathesis Reactions – Synthesis of Functionalized β‐Lactam and β‐Amino Acid Derivatives
2019
Diastereoselective synthesis of fluorinated, seven-membered beta-amino acid derivatives via ring-closing metathesis.
2003
[reaction: see text] Cis and trans seven-membered gamma,gamma-difluorinated beta-amino acid derivatives (III) have been prepared with a sequence that starts with imidoyl halides (I), which are condensed with suitable ester enolates to give intermediates (II). These, in turn, can be cyclized by means of a ring-closing olefin metathesis reaction and the product stereoselectively reduced to yield compounds (III) in good overall yields.
Studien zum Vorgang der Wasserstoffübertragung 46. Zur kathodischen Spaltung von Alkyl- und Cycloalkyl(triphenyl)-phosphoniumsalzen; Abhängigkeit der…
1977
Die kathodische Spaltung von Methyl-, Butyl- und einiger Cycloalkyl(triphenyl)phosphoniumsalze wurde potentiostatisch und galvanostatisch durchgefuhrt. Beim Methyl(triphenyl)-phosphoniumsalz hangt die prozentuale Zusammensetzung der Spaltprodukte: Triphenylphosphin und Methyl(diphenyl)phosphin sowohl vom Potential als auch von der Temperatur ab, die sich ihrerseits wieder gegenseitig beeinflussen. Zusatze unterschiedlich strukturierter quartarer Ammoniumsalze als Leitsalz verandern das prozentuale Verhaltnis (C6H5)3P/(C6H5)2PCH3 nicht, wohl aber der Zusatz von Essigsaure, welche die Bildung von Methyl(diphenyl)phosphin begunstigt. - Bei den Cycloalkyl(triphenyl)phosphoniumsalzen mit Cyclohe…
Group 4 and Group 8 unbridged metallocene derivatives with a pendant fluorenyl group. X-ray structure of 1,1â²-bis[2-(2-fluorenyl)propyl]ferrocene
1999
Abstract The action of one equivalent of BuLi on 2-cyclopentadienyl-2-fluorenylpropane (C5H5CMe2C13H9) led to the monoanionic salt LiC5H4CMe2C13H9. This anion was reacted with Fe2Cl4(THF)3, TiCl3(THF)3, ZrCl4, HfCl4 or CpZrCl3, DME and, in a mixture with CpLi, with Fe2Cl4(THF)3 affording the corresponding metallocenes and metallocene dichlorides. The X-ray structure of Fe(η5-C5H4CMe2C13H9)2 is described. The first results about the reactivity of the fluorenyl group are reported together with the synthesis of Zr(η5-C5H5)[η5-C5H4CMe2-η5-C13H8Rh(cod)]Cl2, which has been tested using hydroformylation and cyclotrimerisation catalysis.
Macrocyclic (1,3)- and (1,4)-benzena-(1,4)-piperazinacyclophanes
1995
New large, up to 45-membered macrocycles were synthesised from piperazine and m- and p-2,6-bis(bromomethyl)xylene under high dilution conditions. X-ray structures of compounds 3a, 4a, 5a, and 8b were determined. Surprisingly, none of the macrocycles prepared showed any inclusion properties towards small guest molecules. Instead, the compounds were found to self-organize during the packing process into larger structures due to the complementary of the molecular skeletons. In the crystalline state 3a forms nets, where the macrocycles are bound by HCH…N interactions to each other. 4a exits in a dimeric structure, which, in turn, further extends to a sheet structure. The positively charged phan…
Amino acid-based cholinium ionic liquids as sustainable catalysts for pet depolymerization
2021
Chemical recycling to monomers is one of the key strategies in tackling the issues deriving from persistent plastic pollution in the environment, and poly(ethylene terephthalate) (PET) is among the most used polymers in modern society. In this context, we herein describe the glycolysis of PET to bis-hydroxyethyl terephthalate (BHET), promoted by basic cholinium salts differing for the anions, also comprising amino acid anions. We investigated the optimal reaction conditions, finding that the best-performing catalyst is [Ch][Gly], in the presence of which a conversion of 85% and a yield of 51% are achieved at 150 °C after 6 h, from PET deriving from a clear water bottle. We used our protocol…
Phase transitions and distortion of [BiCl6]3- octahedra in (C3H5NH3)3[BiCl 6] - DSC and single-crystal X-ray diffraction studies
2004
The DSC diagram of tris(allylammonium) hexachlorobismuthate(III), (C3H5NH3)3[BiCl6], revealed three anomalies at 152, 191 and 299 K. The structure of the salt was determined at 200 and 315 K, below and above the high-temperature phase transition at 299 K. In both phases the crystals are monoclinic. At 200 K the space group is C2/c whereas at 315 K it is C2/m. The structures, at both temperatures, are composed of [BiCl6]3− octahedra and allylammonium cations. The organic and inorganic moieties are attracted to each other by a network of the N-H. . .Cl hydrogen bonds. The relationship between corresponding parameters of the unit cells has been found. The phase transition at 299 K, of the orde…
New conducting radical salts based upon Keggin-type polyoxometalates and perylene
2004
Three new radical salts, Per6[PMo12O40]·CH2Cl2 (1), Per6[PMo12O40]·CH3CN (2), and Per9(NBu4)4[SiW12O40]2 (3) (Per = perylene), have been synthesised and their electrical and magnetic properties characterised. These three salts are diamagnetic and they behave as semiconductors with room temperature conductivities of 69, 3.6 and 0.85 S cm−1. While salt 2 presents hole-type conduction and 3 exhibits electron-dominated electrical transport properties, salt 1 shows at 150 K an abrupt change in the thermal dependence of the electrical conductivity and the Seebeck coefficient suggesting a phase transition.
A new macrocyclic dipyrazolate salt of diazatetraester structure able to efficiently and selectively interact with psychotropic phenethylammonium sal…
2002
Abstract The equilibrium stability constants (Ks) of a series of ammonium pyrazolate complexes [L22−]2RN(R′)H2+ (7, R′=H and 8, R′=Me) formed from a new macrocyclic disodium dipyrazolate salt of diazatetraester structure 6[L22−] 2Na+ and ammonium salts [RNH3+X− or RN(Me)H2+X−] of psychotropic drugs and neurotransmitter catecholamines has been evaluated by electrochemical methods in DMSO solution. The resulting Ks values demonstrate that in general, the diazatetraester crown-derived dipyrazolate salt 6 exerts a stronger complexing effect over phenethylammonium ions than that of the dioxatetraester crown-derived disodium dipyrazolate salt 2 previously reported. Interestingly, complexes formed…