Ratio In Toluene Research Articles

Formation of Nitrogen-Doped Positively Curved Molecules by π-Extension.

Two nitrogen-doped positively curved aromatic molecules bearing doubly fused pentagonal rings were synthesized and characterized. Crystallographic analysis confirms the formation of a bowl-shaped structure, which is induced by the fusion of adjacent pentagons to the rigid aromatic planes. Both compounds demonstrate good photoluminescence. These electron-rich bowl-shaped molecules can associate with C60 to form complexes in 2:1 ratio in toluene with different association constants depending on the molecular dimension of the hosts.

Selective alcoholysis of lactide catalyzed by bulky Lewis pairs of tris(pentafluorophenyl)borane and phosphines

This study investigated the selective alcoholysis of lactide catalyzed by Lewis pairs, B(C6F5)3-phosphines. Among the phosphines examined in this study, tricyclohexylphosphine (Cy3P) exhibited both high activity and high selectivity in this system. The alcoholysis of l-lactide (L-LA) with benzyl alcohol by the B(C6F5)3-Cy3P system produced benzyl lactyllactate in high conversion (∼96%) with high selectivity (>91%) under the wide range of feed [L-LA]0:[alcohol]0 molar ratio in toluene at 100 °C. In this catalyst system, the reactions of L-LA with isopropyl alcohol or tert‑butyl alcohol were much slower than those with primary alcohols such as benzyl alcohol, 1-butanol, and ethanol. Thus, the high chemo-selectivity of the B(C6F5)3-phosphine systems should come from their steric hindrance which differentiates the reactivity to the primary hydroxy group and that to the secondary one.

Aluminium alkyl complexes supported by imino-phosphanamide ligand as precursors for catalytic guanylation reactions of carbodiimides.

Herein, we report the synthesis, characterisation, and application of three aluminium alkyl complexes, [κ2-{NHIRP(Ph)NDipp}AlMe2] (R = Dipp (2a), Mes (2b); tBu (2c), Dipp = 2,6-diisopropylphenyl, Mes = mesityl, and tBu = tert-butyl), supported by unsymmetrical imino-phosphanamide [NHIRP(Ph)NDipp]− [R = Dipp (1a), Mes (1b), tBu (1c)] ligands as molecular precursors for the catalytic synthesis of guanidines using carbodiimides and primary amines. All the imino-phosphanamide ligands 1a, 1b and 1c were prepared in good yield from the corresponding N-heterocyclic imine (NHI) with phenylchloro-2,6-diisopropylphenylphosphanamine, PhP(Cl)NHDipp. The aluminium alkyl complexes 2a, 2b and 2c were obtained in good yield upon completion of the reaction between trimethyl aluminium and the protic ligands 1a, 1b and 1c in a 1 : 1 molar ratio in toluene via the elimination of methane, respectively. The molecular structures of the protic ligands 1b and 1c and the aluminium complexes 2a, 2b and 2c were established via single-crystal X-ray diffraction analysis. Complexes 2a, 2b and 2c were tested as pre-catalysts for the hydroamination/guanylation reaction of carbodiimides with aryl amines to afford guanidines at ambient temperature. All the aluminium complexes exhibited a high conversion with 1.5 mol% catalyst loading and broad substrate scope with a wide functional group tolerance during the guanylation reaction. We also proposed the most plausible mechanism, involving the formation of catalytically active three-coordinate Al species as the active pre-catalyst.

Conjugated Bis‐Guanidines (CBGs) as β‐Diketimine Analogues: Synthesis, Characterization of CBGs/Their Lithium Salts and CBG Li Catalyzed Addition of B−H and TMSCN to Carbonyls

AbstractHerein, we report a range of conjugated bis‐guanidines (CBGs) L [L={(ArHN)(ArHN)C=N−C=(NAr)(NHAr)}; Ar=2, 6‐Me2 ‐ C6H3, (1), 2, 4, 6‐Me3−C6H2, (2), 2, 6‐Et2−C6H3, (3), 2, 6‐iPr2−C6H3, (4)]. These compounds can be easily accessed by the reaction between N,N′‐diaryl carbodiimide, and aq. ammonia in acetonitrile. Deprotonation of 1 with n‐BuLi in a 1 : 1 ratio in THF resulted in the formation of four coordinate lithium complex, [1Li ⋅ (THF)2] (5), while at the same reaction conditions, ligands 3 and 4 gave three coordinate lithium complexes, [3Li⋅THF] (6) and [4Li⋅THF] (7), respectively. However, both compounds 1 and 4 upon deprotonation with n‐BuLi in diethyl ether allowed [1Li⋅Et2O] (8) and [4Li⋅Et2O] (9), respectively, while compounds 1 and 3 in toluene afforded un‐solvated lithium complexes [1Li] (10) and [3Li] (11), respectively. Significantly, a reaction between compound 4 and n‐BuLi in a 1 : 1 ratio in toluene yielded sandwich lithium complex [4Li] (12). All new CBGs 1–4 and lithium salts of CBG, 5, 8, and 12 were characterized by single‐crystal X‐ray structural analysis. The compounds 5–12 were characterized by multinuclear magnetic resonance spectroscopy. Moreover, we have investigated the catalytic application of lithium salts of CBGs for the addition of B−H and TMSCN to carbonyls.

Controlled fabrication of polymer nanofibers via conventional free radical polymerization using diurea xerogel fibers as the templates

Polymer nanofibers with smooth surface were fabricated via conventional free radical polymerization of diurea type supramolecular gel fibers in cyclohexane. As the solvent polarity by using toluene increased, the product yield and fiber size increased, while the fibers changed from smooth to rough, together with more and more free particles. In the presence of polar methacrylic acid, both rough fibers and free particles were obtained when polymerized in cyclohexane. When nonpolar 2-(perfluoro-3-methylbutyl)ethyl acrylate (R-3420) was used, only polymer fibers with very smooth surface were formed. The morphologies of fluoropolymer samples changed from fibers to particles, while the fiber surface became rougher and rougher, as more and more ethanol was used. The hydrophobic fluoropolymer sample could extract toluene from water-toluene two-phase system. Compared with granular fluoropolymer samples, fibrous fluoropolymer samples displayed higher specific surface area and higher swelling ratio in toluene, and required a shorter time for toluene to flow through them.

Homodinuclear Lanthanide Complexes with the Divergent Heterotopic 4,4′‐Bipyridine N‐Oxide (bipyMO) Ligand

The synthesis of dinuclear molecular complexes [Eu2(dbm)6(bipyMO)2], 1, [Tb2(dbm)6(bipyMO)2], 2, [Eu2(tta)6(bipyMO)2], 3 [Eu2(hfac)6(bipyMO)3], 4, [Tb2(hfac)6(bipyMO)3], 5 is here reported (bipyMO = 4,4′‐bipyridine N‐oxide, Hdbm = dibenzoylmethane, Htta = thenoyltrifluoroacetone, Hhfac = hexafluoroacetylacetone). The products were obtained in mild conditions and with high yields reacting anhydrous lanthanide β‐diketonates and bipyMO in 1:1 or 1.5 molar ratio in toluene. X‐ray single crystal studies on 2, 3, 4 showed that the heterotopic ligands are hypodentate, bridging the two lanthanide centres exclusively through the oxygen atom. Photoluminescence studies show bright red emissions from europium derivatives with absolute quantum yields up to 44 %.

Compressing and Swelling To Study the Structure of Extremely Soft Bottlebrush Networks Prepared by ROMP.

To fully explore bottlebrush polymer networks as potential model materials, a robust and versatile synthetic platform is required. Ring-opening metathesis polymerization is a highly controlled, rapid, and functional group tolerant polymerization technique that has been used extensively for bottlebrush polymer generation but to this point has not been used to synthesize bottlebrush polymer networks. We polymerized a mononorbornene macromonomer and dinorbornene cross-linker (both poly(n-butyl acrylate)) with Grubbs' third-generation catalyst to achieve bottlebrush networks and in turn demonstrated control over network properties as the ratio of macromonomer and cross-linker was varied. Macromonomer to cross-linker ratios () of 10 to 100 were investigated, of which all derivative networks yielded gel fractions over 90%. Because of its amenability toward small samples, contact adhesion testing was used to quantify dry-state shear modulus , which ranged from 1 to 10 kPa, reinforcing that bottlebrush polymer networks can achieve low moduli in the dry state compared to other polymer network materials through the mitigation of entanglements. A scaling relationship was found such that , indicating that macromonomer to cross-linker ratio is a good estimator of cross-linking density. The swelling ratio in toluene, , was compared to dry-state modulus to test the universal scaling relationship for linear networks , and a measured exponent of -1.71 indicated good agreement. The synthetic platform outlined here represents a highly flexible route to a myriad of different bottlebrush networks and will increase the accessibility of materials critical to applications ranging from fundamental to biomedical.

Fabrication of Wood Fiber-rubber Composites with Reclaimed Rubber

This research investigated the use of reclaimed rubber (RR) from waste tires to partially replace the rubber compound (RC) when making wood fiber-rubber composites (WRCs). Ninety panels of WRC containing RR were manufactured with RR contents of 0% to 40%, mixing times of 6 min to 14 min, and vulcanizing temperatures of 150 °C to 170 °C. There were three steps, which were the fiber-rubber mixing, tabletting, and vulcanization molding processes. Four regression equations for the tensile strength, elongation at break, hardness, and rebound resilience as functions of the RR content, mixing time, and vulcanizing temperature were derived, and a nonlinear programming model was developed to obtain the optimum panel properties. It was found that when the RR content was within 20%, the wood fibers were well encapsulated and embedded in the RC/RR blends, and the processability of the WRCs were improved by adding RR. The incorporation of RR into the WRCs increased the average tensile strength and hardness by 33.9% and 2.3%, respectively, while the swelling ratio in toluene and 24-h water absorption were reduced by 13% and 42%, respectively.

Synthesis, Structural Characterization and Computational Studies of Bis(2-Ethylimidazole) Bis(Formato)Zinc(II)-Water (1/1)

The reaction of 2-ethylimidazole and zinc formate monohydrate in 1:2 ratio in toluene leads to the formation of bis(2-ethylimidazole)bis(formato)zinc(II)-water (1/1), [Zn(N2H8C5)2(OCHO)2]·H2O, 1 which has been characterized by several techniques, including elemental and thermal analyses, IR, 1HNMR and 13CNMR spectroscopies, single crystal X-ray diffraction and DFT studies. The results obtained show that this complex crystallizes in the orthorhombic crystal system of the Pbca space group, with cell parameters a = 14.7230(2) A, b = 7.3880(10) A, c = 29.0843(4) A, α = 90°, β = 90°, γ = 90°, V = 3163.73 A3 and Z = 8. The zinc center is bound to two molecules of 2-ethylimidazole, two formate molecules in a tetrahedral coordination geometry. One water of crystallization is present in the coordination sphere of the compound. Its molecular crystalline structure is strengthened by O/N-H…O, O-H…π, O-H…H, C-H…O, H…π, π…O and π…π interactions. The optimized structure, frontier molecular orbitals, global reactivity descriptors, molecular electrostatic potential, natural bond orbitals and the Mulliken atomic charges were investigated through theoretical studies.

Imidazolin-2-iminato ligand supported titanium(IV) aryloxo complexes – Syntheses and structures

We report the synthesis and structure of a series of mono-, bis- and tris- aryloxo titanium (IV) complexes supported by imidazolin-2-iminato ligands. The reaction of titanium imidazolin-2-iminato complexes [(ImRN)Ti(NMe2)3] [R=tBu (tert-butyl) (1a), Mes (mesityl) (1b) and Dipp (2,6-diisopropylphenyl) (1c)] with various substituted phenols in 1:1 M ratio in toluene afforded the corresponding mixed mono-aryloxo imidazolin-2-iminato titanium (IV) complexes of general formulae [(ImRN)Ti(NMe2)2(OAr′)] [(R=Mes, Ar′=2,6-tBu2C6H3 (2b), 2,4-tBu2-4-Me-C6H2 (3b), 2-Br-4,6-tBu2-C6H2 (4b), R=Dipp, Ar′=2,4-tBu2-4-Me-C6H2 (3c), 2-Br-4,6-tBu2-C6H2 (4c)]. Analogous reaction with 2 M of substituted phenols yielded the corresponding bis(aryloxo) imidazolin-2-iminato titanium (IV) complex [(ImtBuN)Ti(NMe2)(OAr′)2] [(Ar′=2-Br-4,6-tBu2-C6H2 (5a)]. The dimeric tris(aryloxo) imidazolin-2-iminato titanium (IV) complexes [{(ImRN)Ti(OAr′)2}2] [Ar′=4-tBuC6H4, R=tBu (6a) R=Mes (6b)] were obtained by treating complex 1a,b with 3mols of respective aryl alcohols. Complexes 2b, 3b, 3c, 4b, 4c, 5a and 6a were characterised using single-crystal X-ray diffraction analysis. The solid-state structures of all the complexes reveal that the Ti–Niminato bond in each case is kinetically stable and strong, due to bonding of the more electronegative oxygen atom to the titanium ion.

Synthesis and characterization of polyesters from renewable cardol

The preparation and thermal characteristics of new polyesters from cardol, a renewable monomer obtained as a by-product of the cashew industry, are reported. Cardol - a diol component of the natural product cashew nut shell liquid (CNSL) was isolated and reacted with adipoyl chloride and terephthaloyl chloride in a 1:1 molar ratio in hexane and toluene as solvents at 170 °C under nitrogen atmosphere. The cardol based polyesters [poly(cardyl adipate) and poly(cardyl terephthalate)] were produced in good yields of up to 63 and 54%, respectively. The polymers were analysed by FT-IR for functional groups elucidation and by combined thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for thermal stability. The cardol-based polyesters were thermally stable up to about 400 °C. The thermal stability of poly(cardyl terephthalate) was higher than that of poly(cardyl adipate) under similar conditions. All prepared polyesters were insoluble in common laboratory solvents at room temperature. KEY WORDS : Cashew nut shell liquid, Cardol, Polyesters, Renewable polymers Bull. Chem. Soc. Ethiop. 2016 , 30(2), 273-282. DOI: http://dx.doi.org/10.4314/bcse.v30i2.11

Heteroscorpionate Rare-Earth Catalysts for the Hydroalkoxylation/Cyclization of Alkynyl Alcohols

The chiral, enantiopure bis(pyrazol-1-yl)methane-based NNO-donor scorpionate ligands in the form of the alcohol compounds bpzbeH (bpzbe = 1,1-bis(3,5-dimethylpyrazol-1-yl)-3,3-dimethyl-2-butoxide), bpzteH (bpzte = 2,2-bis(3,5-dimethylpyrazol-1-yl)-1-p-tolylethoxide), and (R,R)-bpzmmH ((R,R)-bpzmm = (1R)-1-{(1R)-6,6-dimethylbicyclo[3.1.1]-2-hepten-2-yl}-2,2-bis(3,5-dimethylpyrazol-1-yl)ethoxide) have been used to obtain new NNO-heteroscorpionate yttrium and lutetium complexes. The reactions of bpzbeH, bpzteH (racemic mixtures), and (R,R)-bpzmmH (enantiopure compound) with [M{N(SiHMe2)2}3(thf)2] (M = Y, Lu) in a 1:1 molar ratio in toluene afforded the mononuclear bis(silylamide) complexes [M{N(SiHMe2)2}2(κ3-NNO)(thf)] (M = Y, Lu; 1–6), respectively. When the reaction was carried out with a 2:1 molar ratio (ligand to metal precursor) or with excess ligand, homoleptic complexes of the type [Y(κ3-NNO)2(κ-O-NN)] (κ3-NNO = κ-O-NN = bpzbe (7), bpzte (8)) were obtained. Compounds 1 and 3 were used as convenient st...

CHEMICAL DEGRADATION OF POLYURETHANE FOAM WASTE AND ITS CROSSLINKED NATURAL RUBBER

ABSTRACT The objective of this work was to use by-products from the chemical degradation of polyurethane foam waste (w-PUfd) and blend them with an epoxidized natural rubber (ENR), named PENR, for improving the mechanical properties of a Standard Thai rubber 5L (STR 5L). The swelling ratio in toluene of the PENR decreased as a function of w-PUfd content due to an increase in chemical interactions. After blending the PENR with the STR-5L and vulcanizing agents using two-roll mill and then compression molding at 150 °C, the effects of w-PUfd content in PENR on the properties of cured STR-5L were investigated. The cure rate index, tensile strength, and elongation at break of the cured STR-5L were improved after the addition of PENR. The swelling in toluene of cured STR-5L decreased as a function of w-PUfd in PENR. At 100 phr w-PUfd in PENR, the 20:80 PENR:STR-5L provided the highest tensile strength of ~23 MPa. These biodegradable, cured rubbers with w-PUfd content are environmental friendly and cost-effective products.

Encapsulation of Carbendazim with Epoxidized Natural Rubber/Sodium Alginate

This work aimed to study the properties of epoxidized natural rubber (ENR) having 19% mole epoxidation crosslinked with glutaraldehyde (GA) and its application in encapsulation of carbendazim (CAD). The swelling ratio in toluene and the elongation at break of cured ENR decreased with increasing dipping time in GA and the GA concentration. The weight loss of the sample after being buried in soil indicated its biodegradability. The blend of cured ENR with sodium alginate (NaAlg) which was then crosslinked by CaSUP2+/SUP or GA/CaSUP2+/SUP was sucessfully used for encapsulation of CAD. Results showed that the release rate of CAD was controlled by GA/CaSUP2+/SUP and ENR/NaAlg ratios.

Dialkyltin(IV)bis(O-tolyl/benzyldithiocarbonate) complexes: spectroscopic, thermogravemetric, antifungal and crystal analysis of n-Bu2Sn(S2COCH2C6H5)2.

Novel compounds of dimethyl- and dibutyltin(IV) with O-tolyl/benzyldithiocarbonates were successfully obtained by the reaction of Me(2)SnC(l2) and n-Bu(2)SnCl(2) with sodium salt of O-tolyl/benzyldithiocarbonates, [o-, m- and p-CH(3)C(6)H(4)OCS(2)Na and C(6)H(5)CH(2)OCS(2)Na], in 1:2 molar ratio in dry toluene. The structure of these newly synthesized complexes has been examined by elemental analysis, FT-IR, multinuclear NMR ((1)H, (13)C and (119)Sn) spectroscopy. The thermal behaviour of the complex (8) has been studied by TGA/DTA analysis. The complex (8), n-Bu2Sn(S2COCH2C6H5)2, crystallizes in the monoclinic space group C2/c, in which tin adopts a distorted octahedron or skew trapezoidal bipyramidal geometry accompanied by two n-butyl chains and the two dithiocarbonate ligands coordinated in an anisobidentate fashion. Antifungal activities against fungus Fusarium sp. of these organotin(IV) derivatives exhibited enhanced activity compared to the free ligands.

Synthesis of symmetrical and unsymmetrical subphthalocyanine dimers containing a hydroquinone bridge

Three novel hydroquinone-based symmetrically and unsymmetrically substituted subphthalocyanine (SubPc) dimers have been synthesized through the axial substitution of the macrocycle. The mono SubPc hydroquinone derivative (Hq-SubPc) first prepared acts as a nucleophile which replaces the chlorine atom of the second SubPc molecule to form the dimer. The dimers were obtained by reacting hydroquinone and the respective SubPcs in a 1:1 molar ratio in toluene at 180 °C in a pressure vessel. This new approach allowed stoichiometric quantities of reactants to be utilized. All dimers were characterized by 1 H NMR, 13 C NMR, UV-vis, fluorescence and mass spectral analysis.

Bi38 Oxocarboxylate Cages are Keplerates – Synthesis and Structural Characterization of Two Bi38 Oxocarboxylate Cages

AbstractThe reaction of 3,5‐dinitrobenzenecarboxylic acid with triphenylbismuth in a 1:1 stoichiometric ratio in toluene under reflux afforded two new Bi38 oxocarboxylate cages [Bi38(μ3‐O)22(μ4‐O)22(μ6‐O){3,5‐(NO2)2C6H3COO}20(OH)4(DMSO)16]·4DMSO·11H2O (1, DMSO = dimethyl sulfoxide) and [Bi38(μ3‐O)22(μ4‐O)22(μ6‐O){3,5‐(NO2)2C6H3COO}20(CH3COO)2(OH)2(DMF)10]·15DMF·20H2O (2, DMF = N,N‐dimethylformamide), which were obtained under different crystallization conditions. Compounds 1 and 2 are built from the coordination action of carboxylato, hydroxido, and oxido ligands and neutral solvent molecules. A detailed structural analysis of 1 reveals that the center of the core contains a {Bi6} octahedron, a Platonic polyhedron, which is encapsulated by another Platonic solid, viz., a {Bi8} cube. This entire assembly is further encapsulated by a truncated octahedral {Bi24} cage; the latter is an Archimedean solid. This structural arrangement of 1 classifies it along with Bi38 oxo cages as Keplerates, a structural family to which very few main‐group‐element‐containing compounds belong.

Preparation of Polymer Composite: Low Natural Rubber, Cassava Starch and Palm Fiber

The objective of this present work was to the preparation of polymer composite from low grade natural rubber (LNR), cassava starch (CSt) and palm fiber by using two-roll mill and then compression molding. The surface of palm fiber with different palm fiber lengths was analyzed by SEM. The tensile strength of the LNR/CSt composite containing 10% palm fiber with <425 µm fiber length was improved by addition of the 0.5 phr K2S2O8. After addition of K2S2O8, the swelling ratio in toluene of this composite was dramatically decreased. This is due to higher interaction between polymer matrix and fiber. The highest tensile strength and lowest swelling ratio in toluene of this composite was obtained with using palm fiber of < 425 µm in length.

Zirconium Complexes of Two Different Iminopyrrolyl Ligands – Syntheses and Structures

AbstractThe reaction involving N‐aryliminopyrrolyl ligand, 2‐((p‐Me‐C6H3N=CMe)–C4H3NH) (1a) (ImpMe‐H), and Zr(OtBu)4 in a 2:1 molar ratio in toluene at 90 °C afforded the corresponding bis(iminopyrrolyl) complex of zirconium, [(ImpMe)2Zr(OtBu)2] (2a) having two bidentate iminopyrrole groups in the coordination sphere. In contrast, the bulkier 2‐((2,6‐iPr2C6H3N=CH)–C4H3NH) (1b) (ImpDipp‐H) and Zr(OtBu)4 in a 1:1 molar ratio under the same condition yielded the corresponding mono(iminopyrrolyl) complex of zirconium, [(ImpDipp)Zr(OtBu)3(THF)] (2b), which contains only one bidentate iminopyrrole moiety in the coordination sphere. Both complexes were characterized by single‐crystal X‐ray diffraction analysis. The solid‐state structures reveal that the bulky iminopyrrole ligands cause a steric crowding around the zirconium ion along with three tert‐butoxide ligands attached to the central metal atom.

Oxidation of Carbene-Stabilized Diarsenic: Diarsene Dications and Diarsenic Radical Cations

Oxidation of carbene-stabilized diarsenic, L:As-As:L [L: = :C{N(2,6-(i)Pr(2)C(6)H(3))CH}(2)] (1), with gallium chloride in a 1:4 ratio in toluene affords the dicationic diarsene complex [L:As═As:L](2+)([GaCl(4)](-))(2) (2(2+)[GaCl(4)](2)), while oxidation of 1 with GaCl(3) in a 1:2 ratio in Et(2)O yields the monocationic diarsenic radical complex [L:AsAs:L](•+)[GaCl(4)](-) (2(•+)[GaCl(4)]). Strikingly, complex 2(•+) is the first arsenic radical to be structurally characterized in the solid state. The nature of the bonding in these complexes was probed computationally and spectroscopically.