41902-42-5Relevant articles and documents
Templating Influence of Molecular Precursors on Pr(OH)3 Nanostructures
Hemmer, Eva,Cavelius, Christian,Huch, Volker,Mathur, Sanjay
, p. 6267 - 6280 (2015/07/15)
Four new praseodymium alkoxo and amido compounds ([Pr3(μ3-OtBu)2(μ2-OtBu)3(OtBu)4(HOtBu)2] (1), [Pr{OC(tBu)3}3(THF)] (2), [PrCl{N(SiMe3)2}2(THF)]2 (3), and [PrCl{OC(tBu)3}2(THF)]2 (4)) were synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Application of these compounds in solvothermal synthesis of praseodymium oxide/hydroxide nanostructures showed their templating influence on the morphology and phase composition of the resulting solid-state materials. Differential reactivity of the chosen alkoxide ligands toward water and the different arrangements of metal-oxygen units in the studied precursor compounds strongly influenced the kinetics of hydrolysis and cross-condensation reactions as manifested in the morphological changes and phase composition of the final products. Thermal decomposition studies of 1-4 confirmed their conversion into the corresponding oxide phases. Activation of compounds 1, 2, and 4 by either a base or a stoichiometric amount of water showed the distinct influence of their chemical configuration on the obtained nanopowders: whereas 1 solely produced nanorods of Pr(OH)3, 2 predominantly formed a mixture of rod-shaped and spherical particles. The solvothermal decomposition of 4 resulted in Pr(OH)2Cl or PrOCl due to the presence of Cl ligands in the molecular precursor. The resultant materials were thoroughly characterized to demonstrate the relationship between precursor chemistry and the processing parameters that are clearly manifested in the morphology and phase of the final ceramics. (Chemical Equation Presented).
Synthesis of sterically hindered long-chain alkenols via organolithium compounds
Helaja, T. Tuulamari,Loefgren, Barbro,Hase, Tapio
, p. 352 - 355 (2007/10/03)
The synthesis of sterically hindered primary, secondary and tertiary alcohols is reported. An unsual monoalkylation/reduction occurs on treatment of a fully α-substituted methyl carboxylate with t-BuLi. A mechanism not involving a ketone intermediate but a β-H abstraction from t-BuLi prior to or after alkylation is proposed.
Complexes of the Lanthanides, I. - Solvent-Free Alkoxide Complexes of Neodynium and Dysprosium. Crystal and Molecular Structure of trans-Bis(acetonitrile)tris(tri-tert-butylmethoxy)neodynium
Herrmann, Wolfgang A.,Anwander, Reiner,Kleine, Matthias,Scherer, Wolfgang
, p. 1969 - 1980 (2007/10/02)
The first lanthanide complex 3a is obtained from the sterically demanding silanol (tC4H9)3SiOH ("silox", 1a) and Nd2>3 (2a).Similarly, the bulky alcohols "tritox-H", tri-tert-butylmethanol (1b), and "ditox-H", di-tert-butylmethanol (1c), react with 2a to give the corresponding alkoxide complexes Nd(tritox)3 (3b) and 2 (3c), respectively.Under the same conditions Dy2>3 (2b) yields the homoleptic ditox derivative 6.The new complexes are all very soluble in aliphatic hydrocarbons.They show a very different thermal stability as, for example, expressed in their sublimation behaviour. Key Words: Lanthanide alkoxides, siloxides / Neodynium complexes / Dysprosium complexes / Thermochemistry
Reactions of Dialkylmagnesium-Salt Mixtures with Ketones: Increasing the Ratio of Addition to Reduction
Richey, Herman G.,DeStephano, Joseph P.
, p. 3281 - 3286 (2007/10/02)
The reduction of the ketone to a secondary alcohol that accompanies addition in reactions of ketones and dialkylmagnesium compounds can be lessened by first adding an appropriate salt to the dialkylmagnesium compound.With favorable salts and reactant stoichiometries, reduction is eliminated in reactions of dipropylmagnesium with diisopropyl ketone or di-tert-butyl ketone.In reactions of di-tert-butylmagnesium and di-tert-butyl ketone, reduction always predominates, although some addition does occur.Salts observed to have significant effects are potassium methoxide, (Me2NCH2)2CHOK, sodium methoxide, lithium methoxide, lithium tert-butoxide, tetrabutylammonium bromide, and benzyltriethylammonium chloride.Stoichiometry has significant effects on product composition, the least reduction product generally resulting when the ratio of salt to diorganomagnesium compound is at least one.The fundamental significance of the effects of stoichiometry and of the relative effects caused by different salts is obscured, however, by the heterogeneity of many of the systems.Magnesiate ions, such as (R2MgOMe)2 2-, are thought to be the organomagnesium species responsible for reactions that proceed without reduction.
Olefins from Crowded Carbonyl Compounds with tert-Butyllithium (tert-Butylmagnesium Chloride)/Thionyl Chloride. Study of Carbocationic Reaction Intermediates and Rearrangement-Cleavage under Stable Ion Conditions Using 13C NMR Spectroscopy
Olah, George A.,Wu, An-hsiang,Farooq, Omar,Prakash, G. K. Surya
, p. 1792 - 1796 (2007/10/02)
Crowded carbonyl compounds when reacted with tert-butyllithium or tert-butylmagnesium chloride followed by thionyl chloride treatment give in an one-pot reaction olefins in good to excellent yields.In the case of highly crowded tertiary systems the reaction occurs either by rearrangement followed by the loss of a tert-butyl group (as isobutylene) or rearrangement accompanied by deprotonation, indicating the carbocationic nature of the process.The nature of the intermediate carbocation and their cleavage-rearrangement process was probed in SbF5/SO2ClF solution of thecorresponding alcohols under stable ion conditions using 13C NMR spectroscopy.
SYNTHESE EN SERIE ENCOMBREE. PREPARATION DE L'ACIDE DITERTIOBUTYL-METHYLACETIQUE tBu2MeCCOOH ET DE QUELQUES COMPOSES CETONIQUES DERIVES DE CETTE STRUCTURE
Dubois, Jacques-Emile,Zhang, Ben Li,Lion, Claude
, p. 4189 - 4194 (2007/10/02)
The synthesis of tBu2MeCCOOH, which is among the most sterically hindered known acids is described.Only Newman's sequence via tBu2C=O, tBu2MeCOH, tBu2C=CH2, tBu2CHCH2OH, tBu2CHCOOH, tBu2CHCOCl and tBu2C=C=O, which has been optimized in this work by a direct access to tBu2CHCOOH, permits the preparation of tBu2MeCCOOH.The condensation of the corresponding chloride with a Grignard reagent yields new highly-hindered ketones tBu2MeCCOR wich by alkylation give more substituted structures.The limitations of each method have been studied in this work.
