Search results for "Lithium"

Rheological characterization of polycaprolactam anionically synthesized in the presence of lithium chloride

1980

Melt viscosity and dynamic-mechanical data are reported for samples obtained by anionic polymerization of caprolactam, in the presence of LiCl. The full body of results is essentially in line with those previously reported relative to mixtures of inorganic salts and commercial nylon 6, In particular a drastic-decrease of the melting point and of the rate of crystallization is confirmed as well as an increase of the glass transition temperature and of the melt viscosity. Some quantitative differences exist, which may be attributed to the different molecular weight distribution in the polymers employed in the present work.

The glass transition behaviour of salted nylon 6

1981

Glass transition measurements of nylon-6/lithium halides mixtures have been carried out in wide range of frequency with the aid of different experimental techniques. The results show an increase of the glass transition temperature when the salt is present and prove the larger effectiveness of lithium chloride with respect of lithium bromide. This effect, in line with the large reduction of the specific volume caused by the salt, is due to the formation of a pseudo-cross-linking between lithium ions and the carbonyl-oxygen groups of the polyamide.

Investigation on lithium/polymer electrolyte interface for high performance lithium rechargeable batteries

1997

Abstract Performance data of several linear and cross-linked polymer electrolytes are reported and the electrochemical criteria for the selection of electrolytes to be used in electric vehicle lithium metal batteries are discussed. Further, laboratory lithium cells with LiMn2O4 composite cathode were tested to ascertain the effective viability of these polymer in solid-state batteries and preliminary results are reported. This study clearly demonstrates the importance of a broad-based electrochemical characterization in selecting an electrolyte for lithium metal batteries.

2021

Water-in-salt systems, i.e., super-concentrated aqueous electrolytes, such as lithium bis(trifluoromethanesulfonyl)imide (21 mol/kgwater), have been recently discovered to exhibit unexpectedly large electrochemical windows and high lithium transference numbers, thus paving the way to safe and sustainable charge storage devices. The peculiar transport features in these electrolytes are influenced by their intrinsically nanoseparated morphology, stemming from the anion hydrophobic nature and manifesting as nanosegregation between anions and water domains. The underlying mechanism behind this structure-dynamics correlation is, however, still a matter of strong debate. Here, we enhance the apol…

Conjugate addition of organolithium reagents to α,β-unsaturated carboxylic acids

1999

Abstract Conjugate addition of primary, secondary, tertiary alkyl and phenyl lithium reagents to 2-alkenoic acids affords good yields of branched saturated carboxylic acids. Methyl groups at the α- and β-carbon of the 2-alkenoic acid decrease reactivity as acceptors, and foster deprotonation, respectively. The lithium enediolate resulting from the conjugate addition can react with electrophiles. PM3 calculations are in agreement with the substituent effects.

Pyrrole Studies XXVII.1Utilisation of 1-Methyl-2-pyrrolyl Lithium in the Synthesis of 1-Methyl-2-substituted Pyrroles

1982

Abstract Although metallation of 1-substituted pyrroles with alkyl lithium reagents to give the lithiated derivatives has been recorded by several research groups,4–6 only limited use has been made of these derivatives in the synthesis of 1,2-disubstituted pyrroles. Subsequent to ourinitial studies,7 it was reported that tetrahydrofuran was the solvent of choice for the formation of the mono-lithiated pyrrole derivative and that the rate of the metallation was accelerated by the presence of TMEDA.6 We had noted,7 however, that prolonged reaction of n-butyl lithium with 1-methylpyrrole in a 2:1 mixture of tetrahydrofuran:hexaneat ca 18°C in the absence of TMEDA gave 1-methyl-2-pyrrolyl lithi…

The role of association/complexation equilibria in the anionic polymerization of (meth)acrylates

1992

The kinetics of the anionic polymerization of methacrylates and acrylates in THF as well as the MWD of the polymers formed depend on the concentration of active centres and of additives, such as lithium halides and lithium alkoxides. These results are discussed on basis of multiple equilibria between non-associated, associated, and complexed ion pairs which are supported by viscosity measurements. The position of these equilibria determines the rate of polymerization, whereas the dynamics of interconversion determine the polydispersity. In the absence of additives the rate of monomer addition to non-associated ion pairs competes with the rate of association. Addition of lithium chloride mai…

1982

Studien zum Vorgang der Wasserstoffübertragung, 68. Die reduktive Überführung aromatischer Säurechloride in Diarylacetylene mit Lithiumamalgam in ein…

1983

Endioldiester A, die durch “Acylierende reduktive Dimerisierung” mit Lithiumamalgam (Li/Hg) nach (1) zuganglich sind, werden mit zwei weiteren Reduktionsaquivalenten nach (2) durch “Reduktive Eliminierung” in Acetylenderivate ubergefuhrt. Hierbei hat sich praparativ das Eintopfverfahren in der Zweistufenarbeitsweise bewahrt. Auch mit Natriumamalgam (Na/Hg) und Kaliumamalgam (K/Hg) gelingt die reduktive Eliminierung nach (2) sowohl von cis- als auch von trans-Endiol-diestern zu Acetylenverbindungen mit guten Ausbeuten. Voraussetzung fur den erfolgreichen Ablauf der Reaktion (2) ist die direkte Verknupfung von zwei Aromaten mit der C C-Doppelbindung in den Endiol-diestern. Endiol-diester mit …

Synthesis of [5]Rotaxanes Containing Bi- and Tridentate Coordination Sites in the Axis

2010

A new example of a linear [5]rotaxane has been synthesized by using the traditional "gathering-and-threading" approach but based on an unusual axle incorporating a symmetrical bis(bidentate) chelating fragment built on a 4,7-phenanthroline core. The stoppering reaction is particularly noteworthy since, instead of using a trivial bulky stopper as precursor to the blocking group, two semistoppered copper-complexed [2]pseudorotaxanes (namely [2]semirotaxanes) are used, which leads to the desired [5]rotaxane in good yield. The efficiency of the method relies on the use of "click" chemistry, with its very mild conditions, and on the protection by a transition-metal (copper(I)) of the various coo…