Synthesis of 1,3,5-tris(2-chloroethyl)- and 1,3,5-tris(2-iodoethyl)benzenes

A new method has been elaborated for the synthesis of 1,3,5-tris(2-chloroethyl)- and 1,3,5-tris(2-iodoethyl)benzenes based on the commercially available 1,3,5-tribromobenzene.     

Acid-base properties of silica-based ion-exchanger having covalently bonded aminodi(methylphosphonic) acid

Acid-base properties of an organophosphorous silica-based ion-exchanger with covalently bonded complexone groups—N-propylaminodi(methylphosphonic) acid (AdPA-SiO₂) were studied. By comparison of AdPA-SiO₂ chemical analysis and data of pH and conductometric titration it was demonstrated that the composition of immobilised layer differ from sample to sample and might consist of 60-88% aminodi(methylphosphonic) acid and 12-40% of residual aminopropyl groups. Regardless of the multifunctional nature of AdPA-SiO₂ interfacial layer, its acid-base properties can be predicted. All studied AdPA-SiO₂ samples have the properties of strong multiprotic H₄L acids with pK₁ < 2.6. Incomplete transformation of amino groups to aminodiphosphonic acid plays the key role in determination of the conditions of AdPA-SiO₂ ionisation in neutral and weak-basic media. Linear correlation was found for pK₂ and amine-to-acid conversion degree (ω) with pK₂ = 8.8 − 4.0ω. It allows us to determine the conditions of AdPA ionisation for all AdPA-SiO₂ samples. The established correlation can be used to check the quality (the degree of interfacial layer heterogeneity) of AdPA-SiO₂. The final measurable ionisation constant for AdPA-SiO₂, pK₃ = 7.9 ± 0.6 is 2-orders of magnitude higher then acidity constant for AdPA homogeneous analogue. It seems that such reduction is caused by increase of electro static interaction between movable counter-ions and negatively charged surface groups. Conductometric study of AdPA-SiO₂ also suggests firm fixation of counter-ions in the interfacial layer.     

Stereodynamics of 1,3,5-tris(trifluoromethylsulfonyl)-1,3,5-triazinane: experimental and theoretical analysis

Dynamic NMR of 1,3,5-tris(trifluoromethylsulfonyl)-1,3,5-triazinane reveals two dynamic processes: ring inversion leading to equilibrium between two degenerate rotamers of C_s symmetry (ΔG^≠ = 13.5 kcal/mol), and rotation about the S-N bond leading to equilibrium between the C_s (more stable) and C_3v (2.12 kcal/mol less stable) rotamers (ΔG^≠ = 13.0 kcal/mol).     

Organic glass-forming materials: 1,3,5-tris(naphthyl)benzene derivatives

The organic glass-forming materials 1,3-bis(1-naphthyl)-5-(2-naphthyl)benzene (2) and its partially deuterated analogue, 1,3-bis(1-naphthyl-d(7))-5-(2-naphthyl)benzene (2-d(14)), have been synthesized on a gram scale using Suzuki coupling reactions. Detailed spectroscopic studies afford complete NMR assignments (1H, 2H, 13C) for both compounds. Modest energy barriers for the interconversion of atropisomers (ca. 15 kcal/mol) result in a propensity for these materials to form supercooled liquids and glasses, rather than undergoing crystallization. The preparation of these materials enables detailed studies of physical properties of organic glasses and molecular diffusion in condensed phases.     

1,3,5-Trimethyl-1,3,5-tris(hexafluoroalkyl)cyclotrisiloxanes. Basicity of ethoxysilanes and cyclosiloxanes

1,3,5-Trimethyl-1,3,5-tris(hexafluoroalkyl)cyclotrisiloxanes were synthesized by hydrolytic polycondensation of methyl(hexafluoroalkyl)dichlorosilanes, and 1,1,3,3,5-pentamethyl-5-(trifluoromethyltrifluorobicyclo[2.2.1]heptyl)cyclotrisiloxane was synthesized by heterofunctional condensation. The effect of hexafluoroalkyl substituents at the silicon atom on the reactivity of the siloxane bonds has been studied.     

An efficient and facile one-pot synthesis of structurally unique 2,4,6-tris(arylchalcogeno)-1,3,5-triazine and 1,3,5-tris(arylchalcogeno)-2,4,6-trimethylbenzene

An efficient one-pot synthesis of a novel class of 2,4,6-tris(arylchalcogeno)-1,3,5-triazine (sulfur, selenium and tellurium) and 1,3,5-tris(arylchalcogeno)-2,4,6-trimethylbenzene (sulfur and selenium)-containing ligands has been developed based on the reaction of 2,4,6-trichloro-1,3,5-triazine and 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene with the corresponding arylchalcogenide anions generated in aqueous tetrahydrofuran.     

Supramolecular hydrogen‐bonded networks in adeninediium hemioxalate chloride and adeninium semioxalate hemi(oxalic acid) monohydrate

In 9H‐adenine‐1,7‐diium hemioxalate chloride, C₅H₇N₅²⁺·0.5C₂O₄²⁻·Cl⁻, (I), adenine is doubly protonated, while in 7H‐adenin‐1‐ium semioxalate hemi(oxalic acid) monohydrate, C₅H₆N₅⁺·C₂HO₄⁻·0.5C₂H₂O₄·H₂O, (II), adenine and one oxalate anion are both monoprotonated. In (I), the adeninium cation forms R₂²(8) and R₁²(5) hydrogen‐bonding motifs with the centrosymmetric oxalate anion, while in (II), the cation forms R₂¹(6) and R₁²(5) motifs with the centrosymmetric oxalic acid molecule and R₁²(5)and R₂²(9) motifs with the monoprotonated oxalate anion. Linear hydrogen‐bonded trimers are observed in (I) and (II). In both structures, the hydrogen bonds lead to the formation of two‐dimensional supramolecular hydrogen‐bonded sheets in the crystal packing. The significance of this study lies in the analysis of the interactions occurring via hydrogen bonds and the diversity seen in the supramolecular hydrogen‐bonded networks as a result of such interactions.     

Hydrogen bonded framework structures constructed from 2-(pyridyl N-oxide) methylphosphonic acid ligands and erbium(III)

Syntheses for 2-(pyridyl N-oxide) methylphosphonic acid, 1-H, and 2-(pyridyl N-oxide) hydroxymethylphosphonic acid, 4-H, are described, and the crystal structures of both ligands are presented. Combination of these ligands with freshly prepared erbium hydroxide results in the formation of the isostructural complexes Er(L(-))(3)(LH).8H(2)O. The crystal structure determinations of the complexes show that extensive hydrogen bonding links the individual eight coordinate Er(L(-))(3)(LH) molecular units into a 3-D structure.     

Synthesis and spectroscopic properties of 1,3,5-tris(arylalkynyl)-2,4,6-trimethoxybenzenes

A number of C₃-symetric 1,3,5-tris(arylalkynyl)-2,4,6-trimethoxybenzenes which carry electron withdrawing aryl substituents at the acetylenic periphery and donating methoxy groups on the central benzene ring are prepared via Sonogashira coupling. The utility of two different synthetic routes is evaluated as well as the effect of the nature of the aryl and ethynyl starting compounds in the coupling reaction. Finally, a correlation between the substitution pattern of the alkynyl compounds and their UV-vis and fluorescence spectroscopic properties is established.     

Trisubstituted 1,3,5-triazines 3. Synthesis of substituted 2,4,6-tris(hydroxyiminomethyl)-1,3,5-triazines

Previously undescribed substituted 2,4,6-tris(hydroxyiminomethyl)-1,3,5-triazines, including 2,4,6-(1,3,5-triazinetriyl)trinitrolic acid, have been synthesized.For Communication 2, see [1].N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 117913. Institute of Chemical Physics in Chernoglovka, Chernoglovka, Moscow Oblast, 142432, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 76–78, January, 1999.     

Reactions of 1,3,5-tris(fluorosulfonyl)benzene with some nucleophilic reagents

The reactions of 1,3,5-tris(fluorosulfonyl)benzene 1 with nucleophilic agents were investigated. It was found that morpholine, β,β,β-trifluoroethanol in the presence of triethylamine and sodium azide formed corresponding 1,3,5-trisulfonyl derivatives. In contrast, nucleophiles such as aniline, thiourea, and potassium thiocyanate do not react with compound 1 even in excess and under moderate heating. The conditions for the selective fluorine atom substitution in one SO₂F group with morpholine, DMAP and aniline in the presence of triethylamine as well as in two SO₂F groups with DMAP were found. Anionic σ-complex of compound 1 with nitromethane was isolated as individual compound.