Isomerization of butenes under the influence of nickel π-allyl complexes and free-anionic systems

Conclusions Crotylnickel chloride-chloranil complexes as well as BuLi-hexamethylphosphorustriamide systems cause chain isomerization of butenes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1414–1415, June, 1970.     

Catalytic properties of ion-exchanged carnegieite powders. Isomerization of n-butenes

The mist decomposition method was applied to the solgel type synthesis. Resulting carnegieite and its ionexchanged derivatives were tested by means of butene isomerization. Carnegieite showed weak but stable activity originating from its base sites. The results of the reaction suggested the development of more active sites by the magnesium ion exchange and new acid sites by the ammonium ion exchange. These are examined by acid-base measurements.

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Catalytic properties of Hf?Eu oxide fine crystalline powders. Isomerization of n-butenes

Catalytic properties of a series of HfO₂–Eu₂O₃ fine crystalline powders were examined by the isomerization of n-butenes. HfO₂ pretreated at 873 K showed a high activity. It decreased with the addition of the Eu component. The product distributions are discussed on the basis of the acid-base properties.

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HfO₂–Eu₂O₃ -. HfO₂, 873 K, . Eu. - .

     

Catalytic properties of the framework-structured zirconium-containing phosphates in ethanol conversion

Research on Chemical Intermediates - Aliphatic alcohols C1–C4 can serve as raw material for the production of essential organic products, such as olefins, aldehydes, ketones and ethers. For...     

Catalytic properties of sodium zirconium molybdate phosphates in methanol transformations

Molybdate phosphates Na_1?y Zr₂(MoO₄) _y (PO₄)_{3 ? y} (y = 0, 0.25, 0.5) having the NaZr₂(PO₄)₃ structure were prepared by the sol-gel method. The catalytic properties of the molybdate phosphates in dehydration and dehydrogenation of methanol in inert and oxidizing atmospheres were studied.     

Catalytic properties of complex oxide coatings on foamed nickel

Effect of the Ni/NiO composite support on the properties of catalytic systems based on cerium oxide and lanthanum manganite with various dopants was studied.     

Isomerization of 2-methyl-3-butenenitrile with (bis-diphenylphosphinoferrocene)nickel compounds: Catalytic and structural studies

The catalytic isomerization of 2-metyl-3-butenenitrile to 3-pentenenitrile was carried out by (dppf)Ni species (dppf = bis-diphenylphosphinoferrocene) in the absence and the presence of Lewis acids. Studies in solution reveal the intermediacy of Ni(II) allyl complexes. Addition of Lewis acids such as BEt₃ allow the crystallization and full characterization of the latter by X-ray diffraction studies.     

Etude microanalytique des phosphates de nickel

Résumé Par spectrographie d'absorption infrarouge, il a été possible d'interpréter les spectres des ortho, pyro, tri et polymétaphosphates de nickel simples et doubles, d'étudier le déplacement des bandes d'absorption par suite du remplacement partiel d'ions Ni²⁺ par des ions étrangers. Conjointement, les trois techniques expérimentales utilisées ont permis d'étudier les transformations subies par quelques uns de ces phosphates au cours de leur chauffage et de mettre ainsi en évidence la formation d'orthophosphate acide, NiHPO₄, dans certaines conditions, cette substance n'ayant pu être préparée à l'état de pureté par simple précipitation.

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Summary By means of infra red absorption spectrography, it is possible to interpret the spectra of the ortho-, pyro-, tri- and tetrapolyphosphates both simple and double, and to study the shifts of the absorption bands resulting from the partial replacement of Ni²⁺ ions by foreign ions. At the same time, the three experimental techniques employed have made it possible to investigate the transformations undergone by some of these phosphates when they are heated, and in this way reveal the formation of the acid orthophosphate NiHPO₄ under certain conditions. This material has heretofore not been obtained pure by simple precipitation.

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Zusammenfassung Durch absorptionsspektrographische Untersuchungen im Infrarot der einfachen und. Doppelsalze des Nickels mit Ortho- und Pyrophosphorsäure, Tri- und Polymetaphosphorsäure gelang es, deren Spektren zu interpretieren und die Verschiebung der Absorptionsbanden bei teilweisem Ersatz des Nickelions durch andere Ionen zu studieren. Gleichzeitig war es auf experimentellem Wege möglich, die Umwandlung einiger dieser Phosphate beim Erhitzen zu beobachten und dabei die Bildung von Nickelhydrogenorthophosphat, NiHPO₄, unter gewissen Bedingungen festzustellen. Diese Verbindung läßt sich durch einfache Fällung nicht in reinem Zustand herstellen.

     

Catalytic dealkylation of phosphates with binuclear boron compounds

The Salen(tBu) ligand and its derivatives were used to prepare binuclear boron complexes. These compounds have the formula, L(BBr2)2 (L = Salpen(tBu) and Salben(tBu)). These are formed from the reaction of the corresponding L[B(OMe)2]2 with BBr3. They represent a new type of binuclear boron compound. These compounds are active towards the dealkylation of many phosphates. They are also catalytically active with a stoichiometric amount of BBr3 to trimethylphosphate.     

烯烃及其衍生物催化异构反应的研究进展

烯烃及其衍生物异构化是一种利用碳碳双键沿骨架碳链发生位置迁移或顺反构型变换构建新烯烃的合成方法,对于有机合成、日用化学品合成、原料油应用和天然产物合成等均有着举足轻重的作用。本文综合论述了自1960年代以来烯烃及其衍生物异构化的五种催化体系的研究进展,重点结合笔者的研究工作,介绍光催化在有机化合物中碳碳双键异构反应中的应用及其发展趋势。     

Catalytic behavior in skeletal isomerization of linear butenes and acidic properties of ani-Pr2NH-templated sapo-11 molecular sieve

SAPO-11 samples were synthesized withi-Pr₂NH as a novel template, and applied in catalytic skeletal isomerization of linear butenes. More linear butenes were converted with increasing Si content in SAPO-11 samples, while theiso-butene selectivity was proportional to the Si content only in the lower reaction temperature region. The maximum yield ofiso-butene was achieved around 763 K. The acidic properties of SAPO-11 samples were studied by NH₃-TPD and IR spectroscopy. The strong acidity was due to the formation of Si domains in the framework lattice.     

Hydrogen adsorption in nanoporous nickel(II) phosphates

Hydrogen sorption in the nanoporous nickel phosphates VSB-1 and VSB-5 has been studied with a combination of BET, temperature programmed desorption (TPD), and inelastic neutron scattering (INS) measurements. H(2) BET isotherms for VSB-1 are similar to those seen in nanoporous zeolites, while VSB-5 adsorbs substantially more hydrogen due to a steep initial uptake at low partial pressures. TPD data show that hydrogen interacts strongly with VSB-5, with desorption peaks at 109 and 149 K in a nitrogen flow, whereas the absence of similar peaks for VSB-1 suggests a weaker interaction. INS spectra of the rotational tunnel transition of the adsorbed H(2) also reveal a strong interaction with the VSB-5 host. These data strongly suggest the existence of coordinatively unsaturated Ni(2+) sites accessible to H(2) molecules in the pores of VSB-5.     

Catalytic Regioselective Isomerization of 2,2-Disubstituted Oxetanes to Homoallylic Alcohols

The selective isomerization of strained heterocyclic compounds is an important tool in organic synthesis. An unprecedented regioselective isomerization of 2,2-disubstituted oxetanes into homoallylic alcohols is described. The use of tris(pentafluorophenyl)borane (B(C₆F₅)₃)_, a commercially available Lewis acid was key to obtaining good yields and selectivities since other Lewis acids afforded mixtures of isomers and substantial polymerization. The reaction took place under exceptionally mild reaction conditions and very low catalyst loading (0.5 mol %). DFT calculations disclose the mechanistic features of the isomerization and account for the high selectivity displayed by the B(C₆F₅)₃ catalyst. The synthetic applicability of the new reaction is demonstrated by the preparation of γ-chiral alcohols using iridium-catalyzed asymmetric hydrogenation.     

Asymmetric Synthesis of Trifluoromethylated Amines via Catalytic Enantioselective Isomerization of Imines

A new approach toward the asymmetric synthesis of optically active trifluoromethylated amines was enabled by an unprecedented, highly enantioselective catalytic isomerization of trifluoromethyl imines with a new chiral organic catalyst. Not only aryl but also alkyl trifluoromethylated amines could be obtained in high enantioselectivities.