Lanthanum isopropoxide

Save M, Schappacher M, Soum A (2002) Controlled ring-opening polymerization of lactones and lactides initiated by lanthanum isopropoxide, 1 general aspects and kinetics. Macromol Chem Phys 203 889-899... 

Carboxylation reaction of active methylene compounds with lanthanoid system was first attained by using a lanthanoid complex obtained from the reaction between lanthanum isopropoxide (LalO Prlj) and 2 equiv of phenyl isocyanate (Ph-N=C=0). Under CO2 at atmospheric pressure, phenylacetonitrile, an active methylene compound (equimolar with respect to LalCyPrlj), was effectively... 

Chiral bases made by treatment of (i )-BINOC with a combination of lanthanum isopropoxide and sodium tert-butoxide have been used in asymmetrical Michael reactions to produce products with 92% ee.134... 

But, Yukawa et al. used lanthanum isopropoxide/BINOL system, 128, for the catalysis of asymmetric aza-Morita-Baylis-Hillman reaction (reaction 7.28), in which the electron-deficient alkenes, 129, reacted with... 

Indium isopropoxide, ln(0 Pr)a, actually Ins0(0 Pr)is Lanthanum isopropoxide, ... 

Fig 1 Chemical structure of initiators used in ROP of lactones and lactides.n) stannous oc-toate, b) aluminum isopropoxide, c) lanthanide isopropoxide. Lanthanum atoms are represented by gray circles and oxygen atoms by white circles. The black circle represents the bridging oxygen atom connecting all lanthanum atoms. Alkyl groups are omitted for clarity... 

Use of less basic triphenylsiloxide ligands also allowed the isolation of mononuclear complexes (Table 1) [46,47]. In addition to the silylamide route, anhydrous nitrates and isopropoxides were employed as synthetic precursors (Eqs. 1,2). The siloxide bridges in the solvent-free dimeric systems Ln2(OSiPh3)6 are readily disrupted by donor solvents like THF, OP Bu3 or DME. The m s-THF adducts of lanthanum, cerium (Fig. 5) and yttrium adopt an approximately /ac-octahedral geometry. 

Lu et al. prepared dense ceramic fibers of PbixLa,Ti03 (PLT, x = 0-0.2) by a sol-gel method from lead acetate trihydrate, lanthanum acetate, and titanium isopropoxide in triethanolamine and acetic acid, followed by solvothermal treatment in a mixture of xylene and triethylamine at 200°C for 12 h. They reported... 

Pyrroles. Imines and nitroalkenes undergo condensation to afford 1,3,4-trisubsti-tuted pyrroles. For the promotion of this reaction, samarium(ni) isopropoxide is better than several other Sm compounds and isopropoxides of lanthanum and ytterbium. 

The impetus for low temperature aldol processes in the absence or minimization of organic solvent has resulted in several new approaches. For example, Dewa et al. describe an aldehyde-ketone condensation catalyst that can be suspended in water, prepared by reacting lanthanum tris(isopropoxide) with anthracenebisresorcinol (ABR). A polymeric aquo complex with several 1,2-linked ABRs and two (LaOH) + groups is formed, coordinating 30 water molecules and relatively stable to decomposition. The base strength of this complex approached that of aqueous NaaCOs. 

Tripathi, U. M., Singh, A., and Mehrotra, R. C., Synthesis and characterization of some heterometallic isopropoxides of lanthanum with zirconium. Polyhedron, 10, 949 (1991). 

PZT and PLZT. The development of polycrystalline lead lanthanum zir-conate-titanate (PLZT) electronic ceramic monoliths, which fully transmit incident light, requires methods for controlling stoichiometry, impurity content, porosity, grain size, and so on. Alkoxy-derived PLZT powders were prepared by hydrolytic decomposition of mixed-metal alkoxides [40]. The Zr and Ti alkoxides were synthesized by the ammonia method, and the lanthanum tris-isopropoxide was synthesized by the metal/alcohol reaction method, which were described in the previous section. The Pb alkoxide was prepared by the reaction of anhydrous lead acetate, Pb(C2H302)2, with sodium isoamyloxide, NaOCsHn [40] ... 

Similarly, preparation of anhydrous and/or unsolvated lanthanide tris-acetylacetonates remained a challenge till 1965, as the efforts to remove ligated water from Ln()S-dik>3.2H2O (obtained from aqueous media) led to hydrolyzed products. However, pure tris-j6-diketonates of lanthanum, praseodymium, and neodymium could be easily synthesized by the reactions of their alkoxides (methoxides/isopropoxides) with 3 equivalents of acetylacetone (acacH) ... 

The methoxides and ethoxides of lanthanoids are insoluble solids. The derivatives of phenols and higher alcohols are amorphous or crystalline substances soluble in common organic solvents. Some of them (isopropoxides, tert-butoxides and derivatives of 2,6-di-tert-butylphenols) are sublimed in vacuum at 190-250 C. The cerium tetra-alkoxides with tertiary-radicals appear to be distillable liquids. The mixed alkoxide of lanthanum La(0C3H7-i)2(0CH2C4H70) containing the residue of tetrahydrofurfuryl alcohol OCH2C4H7O and the isopropoxy groups remains liquid at room temperature [14]. 

The study of the complexes formation between zirconium isopropoxide and iso-propoxides of Sc, Y, and La [54, 111] has shown that all three rare earth metals form the compound of Ln[Zr(OR)5]3 composition. However only the yttrium and lanthanum derivatives have been isolated as individual complexes. 

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