Synthesis of Nonsymmetric Dibenzoyldihydromonobenzotetraazacyclo[14]annulenes as Transition Metal Hosts: X-ray Structure of 13,14-Benzo-3,10-di(p-chlorobenzoyl)-5, 8-dihydro-2,4,9,11-tetramethyl-1,5,8,12-tetraazacyclotetradeca-1,3,9,11-tetraene

In this paper, we evaluated the behavior of fibrous cerium (IV) acid phosphate (CeP) in insertion procedures involving a strong Lewis base (ethylamine) and a weak one (ɛ-caprolactam). In the former case, the procedure was performed by exposing a sample of CeP to a saturated amine atmosphere. Insertion was shown to be independent of the crystallinity of CeP, and the products showed strong host–guest interactions of the Coulombic type. Conversely, ɛ-caprolactam insertion was achieved by immersing CeP samples into its fused form. This process was dependent on the crystallinity of the inorganic solid, and host–guest interactions were characterized as involving hydrogen bonds.     

Calorimetric determination of H+/M+ (M=Na,K) ion exchange in γ-titanium phosphate

H⁺/M⁺ (M=Na, K) ion exchange on -titanium phosphate (-TiP) at 25°C and under static conditions has been studied. Titration and hydrolysis curves and the exchange isotherms were determined. The substitution was followed by X-ray diffraction. Direct calorimetric measurements were carried out at different degrees of conversion and the variation of the exchange enthalpy and the hydrolysis enthalpy of -TiP were obtained. The results are compared to the values of H° obtained in previous works from titration data.     

Calorimetric determination of H+/M+ (M = Li,Cs) ion exchange inγ-titanium hydrogen phosphate

H⁺/M⁺ (M = Li, Cs) ion exchange in-titanium phosphate (-TIP) at 25°C and under static conditions has been studied. Titration and hydrolysis curves and the exchange isotherms were determined. The substitution was followed by X-ray diffraction. Direct calorimetric measurements were carried out at different degrees of conversion and the variation of the exchange enthalpy was obtained. The shape of the calorimetric curves is discussed. The results are compared to the values of H ⁰ obtained from titration data.     

Thermal behavior of zinc γ-zirconium phosphate intercalation compounds

Summary The layered ion-exchangers γ-zirconium phosphate and γ-zirconium phosphate containing intercalated diamines, obtained by exchanging zinc ions, have been synthesized and characterized. Zinc ions are able to form coordination compounds between the layers of the host matrix and consequently form zinc complexes formed in situ. The zinc ions uptake, the thermal behavior and the structural characterization of the compounds obtained have also been examined. The thermal stability and X-ray spectra of these compounds depend on the type of isomeric diamine precursor. The zinc fully exchanged γ-zirconium phosphate is able to form ZnS particles in the host matrix. The X-ray spectra of this obtained material matched those of the initial γ-zirconium phosphate precursor.     

Mild N-deacylation of secondary amides by alkylation with organocerium reagents

Secondary amides are a class of highly stable compounds serving as versatile starting materials, intermediates and directing groups (amido groups) in organic synthesis. The direct deacylation of secondary amides to release amines is an important transformation in organic synthesis. Here, we report a protocol for the deacylation of secondary amides and isolation of amines. The method is based on the activation of amides with Tf₂O, followed by addition of organocerium reagents, and acidic work-up. The reaction proceeded under mild conditions and afforded the corresponding amines, isolated as their hydrochloride salts, in good yields. In combination with the C-H activation functionalization methodology, the method is applicable to the functionalization of aniline as well as conversion of carboxylic derivatives to functionalized ketones.     

Thermal behaviour of mixed Sn and Ge phosphates

Pure and mixed Ge and Sn hydrogenphosphates, prepared either by refluxing in 8M H₃PO₄ or by hydrothermal treatment at 180° or 300°C, have been characterized in terms of chemical composition and thermal behaviour and also tested as catalysts in the 1-butene isomerization, in order to correlate acidic properties with preparation method. Solid solutions for every composition in this system are formed only when using the refluxing method, as proved by X-ray and TG-DTA data. The hydrothermal treatments are strongly influenced by the hydrolysability of the Ge phosphate: in almost all the samples, where Ge was present, GeOHPO₄ was identified on TG-DTA curves by the endothermic H₂O weight loss at 700°–800°C. The acidic properties of the various materials decrease as GeOHPO₄ content increases.     

SrP3N5O: a highly condensed layer phosphate structure solved from a nanocrystal by automated electron diffraction tomography

The oxonitridophosphate SrP₃N₅O has been synthesized by heating a multicomponent reactant mixture that consisted of phosphoryl triamide OP(NH₂)₃, thiophosphoryl triamide SP(NH₂)₃, SrS, and NH₄Cl enclosed in evacuated and sealed silica‐glass ampoules up to 750 °C. The compound was obtained as nanocrystalline powder with needle‐shaped crystallites. The crystal structure was solved ab initio on the basis of electron diffraction data by means of automated electron diffraction tomography (ADT) and verified by Rietveld refinement with X‐ray powder diffraction data. SrP₃N₅O crystallizes in the orthorhombic space group Pnma (no. 62) with unit‐cell data of a=18.331(2), b=8.086(1), c=13.851(1) Å and Z=16. The compound is a highly condensed layer phosphate with a degree of condensation κ=1/2. The corrugated layers ${{{\hfill 2\atop \hfill \infty }}}The oxonitridophosphate SrP(3)N(5)O has been synthesized by heating a multicomponent reactant mixture that consisted of phosphoryl triamide OP(NH(2))(3), thiophosphoryl triamide SP(NH(2))(3), SrS, and NH(4)Cl enclosed in evacuated and sealed silica-glass ampoules up to 750 °C. The compound was obtained as nanocrystalline powder with needle-shaped crystallites. The crystal structure was solved ab initio on the basis of electron diffraction data by means of automated electron diffraction tomography (ADT) and verified by Rietveld refinement with X-ray powder diffraction data. SrP(3)N(5)O crystallizes in the orthorhombic space group Pnma (no. 62) with unit-cell data of a=18.331(2), b=8.086(1), c=13.851(1) ? and Z=16. The compound is a highly condensed layer phosphate with a degree of condensation κ=?. The corrugated layers (∞)(2){(P(3)N(5)O)(2-)} consist of linked, triangular columns built up from P(O,N)(4) tetrahedra with 3-rings and triply binding nitrogen atoms. The Sr(2+) ions are located between the layers and exhibit six-, eight-, and ninefold coordination. FTIR and solid-state NMR spectra of SrP(3)N(5)O are discussed as well.     

Sorption studies of europium on cerium phosphate using Box-Behnken design

Amorphous cerium phosphate was prepared and characterized. Three-level Box-Behnken design (BBD) was employed to analyze the effect of process variables such as initial pH (2–6), contact time (60–180 min), and sorbent amount (0.05–0.15 g) on the sorption capacity of europium. Analysis of variance (ANOVA) revealed that the main effect of initial pH and sorbent amount has a substantial impact on the sorption of Eu(III). Probability F-value (F = 3 × 10^-3) and correlation coefficient (R2 = 0.97) point out that the model is in good accordance with experimental data. The maximum sorption capacity of Eu(III) was found to be 42.14 mg g^-1 at initial pH 6, contact time of 180 min, and a sorbent amount of 0.05 g. Sorption isotherm data was well explained by the Langmuir model and monolayer Eu(III) sorption capacity was obtained as 30.40 mg g^-1. Kinetic data were well described by the pseudo-second-order model. Thermodynamic data suggested that the process is endothermic and spontaneous.     

Unique charge ordering of manganese in a new mixed valent phosphate

A new mixed-valent manganese phosphate, , has been synthesized using hydrothermal method. Its monoclinic C2/c structure (a=12.5506(16) Å, b=10.4816(18) Å, c=13.6723(10) Å, β=103.758(11)°) forms a 3D framework of MnO₆ octahedra, MnO₅ trigonal bipyramids, PO₄ and PO₃OH tetrahedra. The main structural feature of this phosphate deals with its [Mn₄O₁₆]_∞ chains running along , which are interconnected through PO₄ and PO₃OH tetrahedra, forming intersecting tunnels running along [110], and [001]. The geometry of the [Mn₄O₁₆]_∞ chains and the charge ordering of manganese in the latter are unique: they consist of trimeric units of divalent manganese “” alternating with single trivalent Mn^IIIO₆ octahedra along . In each “” unit one central Mn^IIO₆ octahedron shares two opposite edges with two Mn^IIO₅ trigonal bipyramids. Along , one Mn(II) octahedron alternates with one Mn(III) octahedron by sharing one corner. The relationships between the structure of this unique charge ordered phosphate and other manganese phosphates are discussed.     

Indium-mediated mild and facile method for the synthesis of amides

Indium-mediated coupling reactions of acyl chlorides and amines for the synthesis of amide bonds are described. The reaction afforded high yields of the desired amides under mild and neutral conditions, and it was applicable also to the preparation of peptides without epimerization.     

Metal-free synthesis of amides by oxidative amidation of aldehydes with amines in PEG/oxidant system

A simple, inexpensive, and efficient one-pot synthesis of amide derivatives were achieved in good to excellent yields via the directly oxidative amidation of aldehydes with amines under PEG/Oxidant system.     

Formation and characterization of simple and mixed vesicles based on monomeric and oligomeric phosphate bipolar amphiphiles

Certain phosphate bipolar amphiphiles, both monomeric ( I and II ) and polymeric or rather oligomeric (poly- I and poly- II ), were used as basic materials for the preparation of simple and mixed vesicles. Specifically, it was found that oligomeric phosphate bipolar amphiphiles form stable vesicles in aqueous media. The same oligomeric bolaamphiphiles in mixture with their monomeric counterparts also form stable mixed vesicles with sonication; they are relatively less stable with the “thin film method.” Furthermore, it was shown that the method of spanning the membrane of didodecylphosphate vesicels with the dipolar amphiphile II is not effective for enhancing stability. © 1995 John Wiley & Sons, Inc.     

Sorption properties of natural clinoptilolite modified by Fe-containing solutions

Sorption properties of clinoptilolite tuff modified by Fe-containing solutions were studied. The absence of sorption of monocharged anions at any pH of the solution and a high sorption capacity (up to 2.0 to 2.5 mg-eq g^–1) for phosphate ions at pH 10 to 11.5 were shown. Desorption of phosphates by solutions of salts and mineral acids was studied.     

Sorption of amides by cationic exchange resins from nonaqueous solvents

Separation of weakly basic acetanilide, N-methylacetanilide, and N-n-propylacetanilide could not be accomplished using a conventional sulfonic acid resin and various mixed eluants containing methanol and acetonitrile. The chromatograms showed elution bands that were broad and tailed badly. However, with a new macroreticular resin, some separations were obtained with the same nonaqueous eluants that had been used with the conventional resin. Although separation of acctanilide from the two N-substitutcd acetanilides was almost complete, the separation of the two N-substituted compounds was not.Acetamides were separated from acetanilides because the former were not retained by the resin when a 1 :9 methanol-acetonitrile eluant was used.The two important parameters which render these separations possible are probably solvation and hydrogen bonding around tile sulfonic acid group of the resin and resin matrix attraction. Methanol is a better solvating liquid than acetonitrile. In acetonitrile the amide probably associates through the carbonyl with the sulfonic acid; in methanol this association does not occur.     

Scandium triflate catalyzed ester synthesis using primary amides

A scandium triflate (ScOTf)₃ catalyzed methodology has been developed to synthesize esters from primary amides. Various primary and secondary aliphatic alcohols have been shown to react in n-heptane with a range of primary amides for 24 h.     

Intercalation of heterocyclic compounds in α-zirconium phosphate: Imidazole,benzimidazole, histamine and histidine

The intercalation of imidazole and some organic species containing the imidazole ring, between the layers of crystalline zirconium phosphate has been investigated. Fourteen new, well-ordered intercalation compounds are obtained with the batch procedure at r.t. and/or 60°C. A mechanism of formation of the various compounds is proposed on the basis of the interaction between the guest molecules (with their dimensions and geometries) and the free PO₃OH groups available between the layers of the host. The new phases have been characterized by TG and X-ray methods.     

FeCl3-catalyzed Ritter reaction. Synthesis of amides

A safe and inexpensive synthesis of amides, from benzylic alcohols and nitriles and from t-butyl acetate and nitriles, using a Ritter reaction catalyzed by FeCl₃·6H₂O is described.     

Fe-exchanged clay catalyzed transamidation of amides with amines under solvent-free condition

Fe³⁺-exchanged montmorillonite is shown to be an effective and reusable heterogeneous catalyst for the transamidation of various amides and amines under solvent-free condition. The catalyst shows high yields and wide substrate scope.     

Synthesis of puleganic amides via a catalytically efficient two-step approach

Puleganic amides display interesting insect-repellent properties. A new synthetic route to this type of amide was developed involving an organocatalytic cyclization and metal-catalyzed hydrogenation in a one-pot protocol. An eco-friendly oxidative amination provided the puleganic amides with only one purification step and acceptable yields.     

A facile preparation of various N-heterocycles using amides and olefins

We herein report a one pot approach for the synthesis of various nitrogen containing heterocycles including: oxazolines, thiazolines, and dihydro dioxazines via the addition of amides to olefins in the presence of N-iodosuccinimide (NIS) and propionitrile at high temperatures. Thus, the reaction of aryl/heteroaryl amides, thioamides, N-hydroxybenzamide, and phenylurea with various olefins in the presence of NIS and propionitrile at 45 °C afforded the N-heterocycles in good to moderate yields. Reaction of the electron deficient tri-O-acetyl-d-glucal and tri-O-acetyl-d-galactal with benzamide and thiophene-2-carboxamide afforded the N-glycooxazolines in good yields. The newly made heterocycles were tested against various enzymes. Only 3,6-diphenyl-dihydro-1,4,2-dioxazine (1c) was found to moderately inhibit hexokinase II (hHK2).