Search results for "Lithium"

1980

Random quasi-phase-matched second harmonic generation in periodically poled lithium tantalate

2009

We experimentally observed and explained bulk second harmonic generation via random quasi-phase-matching, derived from a periodically poled lithium tantalate sample with a randomly patterned mark-to-space-ratio.

Surface periodic poling in congruent lithium tantalate

2006

The first demonstration of surface periodic poling of lithium tantalate at high voltages is reported. Periodic domain inversion with mark-to-space ratios close to the optimum 50:50 was successfully achieved down to micrometre periods with good uniformity and repeatability.

1990

The effect of lithium tert-butoxide (t-BuOLi) on rate constants and equilibrium constants of reactions involved in the initial stage of the anionic polymerization of methyl methacrylate (MMA) in tetrahydrofuran, initiated by methyl α-lithioisobutyrate (P) was investigated at 23 ± 3°C. Addition of t-BuOLi decreases the rate constants of initiation and propagation by one order of magnitude; the rate constants of termination by cyclization decrease by two orders of magnitude. This leads to an overall tenfold higher preference of propagation with respect to termination and explains the favourable effect of alkoxide in the polymerization reported earlier. Within experimental error, the equilibri…

A new strategy for the synthesis of highly functionalised fluorinated compounds by reaction of lithium dianions of carboxylic acids with perfluoroket…

2005

The reaction of perfluoroketene dithioacetal with lithium dienediolates of carboxylic acids proceeds at the ω position probably through an addition to the π system followed by elimination of the vinylic fluoride. The preparative value of this reaction depends strongly on the reaction and work-up conditions. The overall process lead to highly functionalised synthons containing a trifluoromethyl group.

Approaches to the preparation of carborane-containing carbosilane compounds.

2005

[Structure: see text] A novel type of carborane cluster assembly has been successfully prepared using carbosilane derivatives as a scaffold. Two synthetic routes have been used: One involves the reaction of a carbosilane containing terminal Si-Cl functions with the lithium salt of the phenyl-o-carborane, and the second one consists of a highly efficient hydrosilylation of tetravinylsilane with the corresponding carboranylsilane. The crystal structure of this carborane-containing carbosilane compound has been determined by X-ray diffraction.

Eine synthetische matrizenreaktion einer mischung von acrylsäureestern phenolischer mehrkernverbindungen; modell einer replicapolymerisation

1970

Mischungen der Acrylsaureester phenolischer Mehrkernverbindungen sowie zunachst unveresterter Verbindungen wurden einer synthetischen Matrizenreaktion unterworfen. Die so erhaltenen Verbindungsgemische liesen sich mit Lithiumborhydrid reduzierend spalten, so das neben den wiedergewonnenen phenolischen Mehrkernverbindungen Oligoallylalkoholmischungen entstanden. Deren Konzentrationsverhaltnisse waren mit einer geringen Streuung die gleichen wie jene der Acrylsaureester oder der phenolischen Mehrkernverbindungen in den Ausgangsmischungen. Mixtures of the acrylic esters of molecularly uniform polynuclear phenolic compounds and primarily not esterified compounds were cyclopolymerized. The so ob…

ChemInform Abstract: Remarkable Effect of Lithium Bromide in the Enantioselective Protonation with α-Sulfinyl Alcohols.

2010

Abstract The favourable effect of lithium bromide enhancing the facial enantioselectivity in the protonation of methyl tetralone enolate with α-sulfinyl alcohols is described. Theoretical calculations allow to propose a model to explain the stereochemical course of the protonation reaction.

Remarkable effect of lithium bromide in the enantioselective protonation with α-sulfinyl alcohols

1998

Abstract The favourable effect of lithium bromide enhancing the facial enantioselectivity in the protonation of methyl tetralone enolate with α-sulfinyl alcohols is described. Theoretical calculations allow to propose a model to explain the stereochemical course of the protonation reaction.

Die Reaktion von 1,4-Bis(1-phenylvinyl)benzol mit Lithium

1975

Die Reaktion von 1,4-Bis(1-phenylvinyl)benzol (1) mit Lithium in THF, die vorwiegend zu einem dimeren α,ω-Dien-dianion 3 fuhrt, wird diskutiert. Die durch Umsetzung des Dianions 3 mit Methanol, Kohlendioxid und Methyljodid erhaltenen Reaktionsprodukte 4, 6 und 7 werden durch ihre IR-, NMR- und Massenspektren charakterisiert. The reaction of 1,4-bis(1-phenylvinyl)benzene (1) with lithium in THF yielding predomaintly the dimeric α,ω-diene dianion 3 is discussed. The products 4, 6, and 7 resulting from the reaction of the dianion 3 with methanol, carbon dioxide and methyl iodide are characterized by IR, NMR and mass spectra.