Tetrabutylammonium Iodide Research Articles

Epicyanohydrin: Polymerization by Monomer Activation Gives Access to Nitrile-, Amino-, and Carboxyl-Functional Poly(ethylene glycol)

Both homo- and copolymerization of the hitherto nonpolymerizable epoxide monomer epicyanohydrin (EPICH) with ethylene oxide (EO) have been studied, employing the monomer activation technique. Tetraoctylammonium bromide or tetrabutylammonium iodide was used as initiator combined with i-Bu3Al to activate the EPICH monomer. The EPICH content was varied from 4 to 16 mol %, yielding well-defined PEG-co-PEPICH copolymers with molecular weights Mn (SEC) ranging from 3700 to 8800 g mol–1. The nitrile groups of the resulting polyethers were further reduced or hydrolyzed to introduce amino, amide, or carboxyl groups at the polyether backbone, circumventing protecting group chemistry. Successful transformation of the functional groups was proven by SEC measurements, 1H NMR, 13C NMR, and FT-IR spectroscopy. These carboxyl-functional PEG copolymers are anionic polyelectrolytes consisting only of purely aliphatic polyether structures with carboxyl groups. The hydrolyzed PEPICH homopolymers represent the first polyether-based analogues of poly(acrylamide) and poly(acrylic acid). In pronounced contrast to poly(acrylic acid), carboxyl-functional PEPICH shows excellent aqueous solubility even at low pH.

Counterion-Mediated Ligand Exchange for PbS Colloidal Quantum Dot Superlattices.

In the past years, halide capping became one of the most promising strategies to passivate the surface of colloidal quantum dots (CQDs) in thin films to be used for electronic and optoelectronic device fabrication. This is due to the convenient processing, strong n-type characteristics, and ambient stability of the devices. Here, we investigate the effect of three counterions (ammonium, methylammonium, and tetrabutylammonium) in iodide salts used for treating CQD thin films and shed light on the mechanism of the ligand exchange. We obtain two- and three-dimensional square-packed PbS CQD superlattices with epitaxial merging of nearest neighbor CQDs as a direct outcome of the ligand-exchange reaction and show that the order in the layer can be controlled by the nature of the counterion. Furthermore, we demonstrate that the acidity of the environment plays an important role in the substitution of the carboxylates by iodide ions at the surface of lead chalcogenide quantum dots. Tetrabutylammonium iodide shows lower reactivity compared to methylammonium and ammonium iodide due to the nonacidity of the cation, which eventually leads to higher order but also poorer carrier transport due to incomplete removal of the pristine ligands in the QD thin film. Finally, we show that single-step blade-coating and immersion in a ligand exchange solution such as the one containing methylammonium iodide can be used to fabricate well performing bottom-gate/bottom-contact PbS CQD field effect transistors with record subthreshold swing.

Bu4NI Catalyzed C-N Bond Formation via Cross-Dehydrogenative Coupling of Aryl Ethers (Csp3-H) and Tetrazoles (N-H).

Intermolecular C-N bond formations via cross-dehydrogenative coupling (CDC) of aryl ethers and tetrazoles have been developed under a metal-free condition. In the presence of catalytic amount of tetrabutylammonium iodide (TBAI) and aqueous TBHP, aryl ethers coupled efficiently with tetrazoles to afford hemiaminal ethers. This strategy showed high level of regioselectivity for substrates possessing multiple sp(3) C-H bonds adjacent to the ethereal oxygen.

Organocatalytic Oxidative Amidation of Aldehydes with Tetrazoles to Construct 2,5‐Diaryl 1,3,4‐Oxadiazoles

AbstractA practical and metal‐free oxidative amidation of aldehydes with tetrazoles into 1,3,4‐oxadiazoles has been developed by employing tetrabutylammonium iodide (TBAI) as catalyst and tert‐butyl hydroperoxide (TBHP) as oxidant. A wide range of 2,5‐disubstituted 1,3,4‐oxadiazoles can be conveniently generated in moderate to good yields. Gram‐scale reaction was also realized in this catalytic system.

Effects of Ligands on Charge Generation and Recombination in Hybrid Polymer/Quantum Dot Solar Cells

Control of quantum dot surface chemistry offers a direct approach to tune the molecular interface between donor and acceptor constituents in hybrid bulk heterojunction photovoltaics incorporating organic semiconductors and colloidal quantum dots. We investigate the effects of altering the quantum dot surface chemistry via ligand exchange in blends of PbS quantum dots with the conjugated polymer poly((4,8-bis(octyloxy)benzo(1,2-b:4,5-b′)dithiophene-2,6-diyl)(2-((dodecyloxy)carbonyl)thieno(3,4-b)thiophenediyl)) (PTB1). We study organic ligands with both thiol and carboxylic acid functional groups including 1,2-ethanedithiol (EDT), 3-mercaptopropionic acid (MPA), and malonic acid (MA), in addition to inorganic halide ions such as tetrabutylammonium iodide (TBAI). We show that the different ligand treatments influence hybrid solar cell efficiency primarily through changes in open-circuit voltage (VOC) and fill factor (FF). We use photoinduced absorption (PIA) spectroscopy to probe the generation of long-lived...

Titanium Alkoxide Complexes as Catalysts for the Synthesis of Cyclic Carbonates from Carbon Dioxide and Epoxides

AbstractTitanium alkoxides can catalyze efficient and selective synthesis of cyclic carbonates through CO2 insertion into epoxides when tetrabutylammonium bromide or iodide is used as a cocatalyst. Of the series of synthesized titanium alkoxides, the most active catalyst was one bearing an aliphatic bidentate alkoxide ligand, and it produced propylene carbonate under benign conditions (100 °C, 15 bar CO2, 3 h) with turnover frequencies of up to 116 h–1. The effect of reaction parameters such as pressure, temperature, and catalyst/cocatalyst molar ratio were also studied in order to optimize the catalytic system.

ChemInform Abstract: Tetrabutylammonium Iodide‐Catalyzed Oxidative Coupling of Enamides with Sulfonylhydrazides: Synthesis of β‐Keto‐Sulfones.

AbstractA novel protocol for the catalyst‐ and base‐free synthesis of pharmaceutically interesting β‐keto sulfones is developed.

Densities, Sound Speed, and Viscosities of Some Amino Acids with Aqueous Tetra-Butyl Ammonium Iodide Solutions at Different Temperatures

Apparent molar volumes (V⌀), apparent molar isentropic compression (K⌀,s), and viscosity B coefficient of glycine, l-alanine, and l-valine in (0.01 and 0.03) mol·kg–1 aqueous tetrabutyl ammonium iodide (TBAI) solutions have been determined at temperatures (288.15, 293.15, 298.15, 303.15, and 308.15) K from their experimental density, ultrasonic speed, and flow time measurements, respectively. Partial molar volumes (V⌀0) and partial molar isentropic compression (K⌀,s0) have been determined from the above measurements. Further, these data were used to calculate the corresponding transfer parameters (ΔV⌀,s0 and ΔK⌀,s0), hydration number (nH), side chain group contributions of V⌀0, and viscosity B coefficients of the amino acids, partial molar expansibilities (E⌀0), (dB/dT), and related parameters. The trends of variations of experimental and computed parameters have been discussed in terms of solute–solvent interactions with an emphasis on structure-making and structure-breaking ability of the above amino ac...

Oxidative Coupling between Methylarenes and Ammonia: A Direct Approach to Aromatic Primary Amides

AbstractA direct oxidative amidation between methylarenes and aqueous ammonia using a tert‐butyl hydroperoxide and tetrabutylammonium iodide (TBHP/TBAI) oxidation system with co‐catalysis of iron(III) chloride has been developed. Both coupling partners were used in their native form to render prior functionalization unnecessary and afford a facile approach to aromatic primary amides.magnified image

Tert‐Butyl Hydroperoxide and Tetrabutylammonium Iodide‐Promoted Free Radical Cyclization of α‐Imino‐N‐arylamides and α‐Azido‐N‐arylamides

AbstractThe oxidizing system of tert‐butyl hydroperoxide (TBHP) and tetrabutylammonium iodide (TBAI) is capable of generating α‐(arylaminocarbonyl)iminyl radicals from ethyl 2‐(N‐arylcarbamoyl)‐2‐iminoacetates. These iminyl radicals preferably undergo intramolecular ipso attack on the benzene ring to give azaspirocyclohexadienyl radicals, which are readily captured by molecular oxygen under an oxygen atmosphere to yield azaspirocyclohexadienones. In the absence of oxygen, the reaction affords quinoxalin‐2‐one products. This oxidizing system is also effective to convert α‐aryl‐α‐azido‐N‐arylamides to the corresponding iminyl radicals under basic conditions (sodium tert‐butoxide, t‐BuONa), and the subsequent cyclization of these iminyl radicals results in the formation of azaspirocyclohexadienone products in high yields under an oxygen atmosphere. Plausible mechanisms are proposed to rationalize the experimental results, and factors influencing the reactions are discussed.magnified image

Theoretical investigation of the mechanism for the cycloaddition of CO2 to epoxides catalyzed by a magnesium(II) porphyrin complex.

The cycloaddition of CO2 to epoxides, catalyzed by Mg(TPP)/TBAI (TPP = tetraphenylporphyrin; TBAI = tetrabutylammonium iodide), was investigated using DFT methods. Epoxides with various substituents were studied to explore steric and electronic effects on the reaction mechanism. Computational results show that the cycloaddition proceeds according to a much easier mechanism in the presence of Mg(TPP) and TBAI than the mechanism that takes place when Mg(TPP) is used as the catalyst. A preference for the epoxide ring-opening to occur at the methine (Cα) or methylene (Cβ) carbon was noted. The ring-closing step leading to the formation of a five-membered carbonate is predicted to determine the reaction rate. For alkyl-substituted epoxides, the β pathway is favorable since steric factors are dominant; for epoxides with a strongly electron-donating group and styrene oxide, the reaction is mainly controlled by electronic factors and proceeds along the α pathway. When the epoxide has a strongly electron-withdrawing group (CF3), both steric and electronic effects play important roles. The calculated reactivity of epoxides with CO2 catalyzed by Mg(TPP)/TBAI is in good agreement with that observed experimentally.

Conductance studies of NaCl, KCl, NaBr, KBr, NaI, Bu4NI, and NaBPh4 in water + 2-propoxyethanol mixtures at 298.15 K

The molar conductances of sodium chloride (NaCl), potassium chloride (KCl), sodium bromide (NaBr), sodium iodide (NaI), tetrabutylammonium iodide (Bu4NI), and sodium tetraphenylborate (NaBPh4) in water + 2-propoxyethanol binary mixtures at T = 298.15 K were determined. Conductance values were analyzed using a low-concentration chemical model (lcCM). The ionic conductivities of Na+, K+, Bu4N+, Cl−, I−, Br−, and BPh4 − ions were determined using Fuoss–Hirsch’s assumption. The dependencies of the values of limiting molar conductance (Λ o), limiting ionic conductance of the individual anions (λ o ± ), and Walden products (Λ o ⋅ η and λ o ± ⋅ η) as a function of the composition of water + 2-propoxyethanol binary mixtures were discussed.

ChemInform Abstract: Metal‐Free, One‐Pot Synthesis of Allylic and Benzylic Esters via Decarboxylation and C—H Bond Activation.

A tetrabutylammonium iodide catalyzed method has been developed for the one-pot synthesis of allylic and benzylic esters from α-oxo carboxylic acids and alkenes/alkylbenzenes via decarboxylation and C–H bond activation. Various allylic and benzylic esters were obtained in good yield.

Effect of tetrabutylammonium iodide content on PVDF-PMMA polymer blend electrolytes for dye-sensitized solar cells

The influence of tetrabutylammonium iodide on the polyvinylidene fluoride-poly(methyl methacrylate)-ethylene carbonate (PVDF-PMMA-EC)-I2 polymer blend electrolytes was investigated and optimized for use in a dye-sensitized solar cell. The different weight ratios (50, 60, 70, and 80 %) of tetrabutylammonium iodide (TBAI)-added PVDF-PMMA-EC-I2 polymer electrolytes were prepared. The prepared solid polymer blend electrolytes were characterized by using various techniques such as Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and electrochemical impedance spectroscopy (EIS). The FT-IR spectra revealed the interaction among all composition of polymer electrolytes. The influence of TBAI salt on the ionic conductivity of polymer electrolytes was studied using electrochemical impedance spectroscopy. The polymer electrolyte containing 60 % of TBAI in PVDF-PMMA-EC-I2 showed the highest room temperature conductivity of 5.10 × 10−3 S cm−1. The fabricated DSSC using PVDF-PMMA-EC-I2 polymer electrolytes with 60 % of TBAI showed the best performance with a short-circuit current density of 8.0 mA cm−2, open-circuit voltage of 0.66 V, fill factor of 0.65, and the overall power conversion efficiency of 3.45 % under an illumination of 100 mW cm−2. Hence, the weight content of organic iodide salt in polymer electrolytes influences the overall performance of dye-sensitized solar cells.

Iodide Ion Pairing with Highly Charged Ruthenium Polypyridyl Cations in CH3CN.

A series of three highly charged cationic ruthenium(II) polypyridyl complexes of the general formula [Ru(deeb)3-x(tmam)x](PF6)2x+2, where deeb is 4,4'-diethyl ester-2,2'-bipyridine and tmam is 4,4'-bis[(trimethylamino)methyl]-2,2'-bipyridine, were synthesized and characterized and are referred to as 1, 2, or 3 based on the number of tmam ligands. Crystals suitable for X-ray crystallography were obtained for the homoleptic complex 3, which was found to possess D3 symmetry over the entire ruthenium complex. The complexes displayed visible absorption spectra typical of metal-to-ligand charge-transfer (MLCT) transitions. In acetonitrile, quasi-reversible waves were assigned to Ru(III/II) electron transfer, with formal reduction potentials that shifted negative as the number of tmam ligands was increased. Room temperature photoluminescence was observed in acetonitrile with quantum yields of ϕ ∼ 0.1 and lifetimes of τ ∼ 2 μs. The spectroscopic and electrochemical data were most consistent with excited-state localization on the deeb ligand for 1 and 2 and on the tmam ligand for 3. The addition of tetrabutylammonium iodide to the complexes dissolved in a CH3CN solution led to changes in the UV-vis absorption spectra consistent with ion pairing. A Benesi-Hildebrand-type analysis of these data revealed equilibrium constants that increased with the cationic charge 1 < 2 < 3 with K = 4000, 4400, and 7000 M(-1). (1)H NMR studies in CD3CN also revealed evidence for iodide ion pairs and indicated that they occur predominantly with iodide localization near the tmam ligand(s). The diastereotopic H atoms on the methylene carbon that link the amine to the bipyridine ring were uniquely sensitive to the presence of iodide; analysis revealed that an iodide "binding pocket" exists wherein iodide forms an adduct with the 3 and 3' bipyridyl H atoms and the quaternized amine. The MLCT excited states were efficiently quenched by iodide. Time-resolved photoluminescence measurements of 1 revealed a static component consistent with rapid electron transfer from iodide in the "binding pocket" to the Ru metal center in the excited state, ket > 10(8) s(-1). The possible relevance of this work to solar energy conversion and dye-sensitized solar cells is discussed.

TBAI-catalyzed oxidative cross-coupling of phenols and 2-aminoacetophenones.

An iodide-catalyzed oxidative cross-coupling between phenols and 2-aminoacetophenones has been developed. Using catalytic amounts of tetrabutylammoniumiodide (TBAI) as an iodine-containing catalyst and aqueous solutions of tert-butyl hydro-peroxide (TBHP) as the stoichiometric co-oxidant, a variety of α-phenoxylated 2-aminoacetophenones could be obtained in yields of up to 92% after remarkably short reaction times (20 min). This is a very rare example for an iodide-catalyzed intermolecular cross-coupling utilizing phenols. However, this efficient methodology could be further extended toward an intramolecular variant which gives direct access to a range of dihydro-4H-benzo[e][1,3]oxazin-4-ones.

Using neutral impact collision ion scattering spectroscopy and angular resolved X-ray photoelectron spectroscopy to analyze surface structure of surfactant solutions

In the present work, the surface structure of solutions of tetrabutylammonium iodide dissolved in formamide is in parallel analyzed by neutral impact collision ion scattering spectroscopy (NICISS) and angular resolved X-ray photoelectron spectroscopy (ARXPS). By NICISS, the concentration-depth profiles of the solute ions and solvent are achieved, whereas by ARXPS, those fraction-depth profiles are obtained. For the sake of convenient comparisons, the fraction-depth profiles are converted to concentration-depth profiles after the determination of the partial molar volume of the components. With those profiles, the surface structures of the solutions are mapped. The cations and anions distribute distinctly within the surface layer, indicating the complication of the surface structure of ionic surfactant solution. According to the definition of Gibbs dividing plane, the surface excesses of surfactant ions are determined. Those profiles and surface excesses obtained by two distinct methods are compared directly. The comparison shows good agreements in both items. The differences are also found during the comparison, and the causes are analyzed within the frame of the working mechanisms of those analytical techniques.

Electroanalytical Method for Determining Pyrogallol in Biodiesel in the Presence of a Surfactant

AbstractA sensitive, straightforward electroanalytical method for determining pyrogallol (PY) in biodiesel in the presence of a surfactant was developed using a voltammetric technique and screen‐printed electrodes. The influence of surfactant addition (sodium dodecyl sulfate (SDS), Triton X‐100 (TX‐100), cetyltrimethylammonium bromide (CTAB), tetrabutylammonium iodide (TBAI), tetrabutylammonium bromide (TBAB), or tetraethylammonium bromide (TEAB)) on the supporting electrolyte (0.04 mol L−1 BrittonRobinson buffer) was evaluated. Only CTAB significantly increased the oxidation peak current. Under optimal conditions, the method demonstrated linearity over the concentration range of 0.8–9.0×10−6 mol L−1, with limits of detection and quantification of 4.9×10−7 and 1.5×10−6 mol L−1, respectively. The results were satisfactory, relative to those obtained using high‐performance liquid chromatography (HPLC).

ChemInform Abstract: tert‐Butyl Hydroperoxide and Tetrabutylammonium Iodide‐ Promoted Free Radical Cyclization of α‐Azido‐N‐arylamides.

AbstractIt is demonstrated, that the reagent combination of tBuOOH and Bu4NI affects the oxidative cyclizations of α‐ethoxycarbonyl α‐azido‐N‐arylamides.

High-Performance Flexible Tandem Polymer Solar Cell Employing a Novel Cross-Linked Conductive Fullerene as an Electron Transport Layer

A novel thermally cross-linkable, n-doped conductive fullerene material is developed by incorporating tetrabutylammonium iodide (TBAI) as the dopant into an azidofullerene derivative PCBN3. The application of TBAI-doped cross-linked PCBN3 film as the electron transport layer (ETL) in polymer solar cells (PSCs) delivers several remarkable features, including easy solution-processability, reasonable electrical conductivity (2.8 × 10–3 S cm–1), good ambient and chemical stability, fine-tunability of the work function of the electrode, wide applicability in a variety of efficient polymers, relative weak thickness-dependent performance property, and moderate cross-linking temperature (∼140 °C). With this ETL, a single-junction solar cell based on the blend of poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) delivers a power conversion efficiency (PCE) up to 8.8...