Dehydration Condensation Reaction Research Articles

One step electrochemical deposition and reduction of graphene oxide on screen printed electrodes for impedance detection of glucose

Graphene has emerged as one of the promising tools for bio-detections as it has high surface area with strong electrochemical properties. In present work, a sensitive electrochemical sensor based on the specific boronic acid-diol binding for glucose sensing was established. The sensor was consisted of 3-aminophenylboronic acid (APBA) and reduced graphene oxide (rGO). Before the modification of electrodes, graphene oxide (GO) and APBA composites (GO/APBA) were compounded by the dehydration condensation reaction. The rGO and APBA composites (rGO/APBA) were reduced from GO/APBA and deposited onto the screen printed electrodes through cyclic voltammetry, simultaneously. With the rGO/APBA functionalized electrodes, the glucose molecule could be detected in the range from 0.1mM to 50mM, which could satisfy the clinical application. In order to verify the sensitivity and selectivity of the rGO/APBA functionalized electrodes, GO/APBA, and rGO alone functionalized electrodes were also explored for glucose determination. Results showed that rGO/APBA modified electrodes possessed superior electron conductivity, which promoted the detection properties in impedance spectroscopy. In our study, an easy and simple cost-effective modification method was proposed by one step electrochemical reduction and deposition technique of rGO on screen printed electrodes. With specific modification, the rGO functionalized electrodes provided a sensitive and selective detection of biological analytes.

In situ implanting carbon nanotube-gold nanoparticles into ZnO as efficient nanohybrid cathode buffer layer for polymer solar cells

ZnO, plasmonic gold nanoparticles and conductive carbon nanotubes were combined by in situ growing to improve the light absorption and the electron mobility and the performance of polymer solar cells. Gold nanoparticles decorated carboxylic CNT (CNT-Au) was prepared by simple dehydration-condensation reaction. While CNT provides the template for the in situ growth of ZnO to form homogeneous film with less defects and higher conductivity, gold nanoparticles induce the surface plasmon effect to increase the light absorption. Compared to the bare ZnO, ZnO@CNT-Au nanohybrids could increase photo-generated excitons, decrease the charge recombination and facilitate the electron collection. In consequence, the power conversion efficiency of inverted polymer solar cell based on thieno [3,4-b]thiophene/benzodithiophene (PTB7) [6,6]:– phenyl C71-butyric acid methyl ester (PC71BM) was improved to 7.9% by adopting ZnO@CNT-Au as cathode buffer layer.

ChemInform Abstract: N‐Boc‐Aminals as Easily Accessible Precursors for Less Accessible N‐Boc‐Imines: Facile Synthesis of Optically Active Propargylamine Derivatives Using Mannich‐Type Reactions.

We developed a facile and practical synthesis of N-Boc-aminals, which can be used as precursors for less accessible N-Boc-imines. Aminals were obtained via simple dehydration condensation reactions of t-butyl carbamate (BocNH2) and various aldehydes in acetic anhydride, followed by filtration and washing with hexane. The obtained N-Boc-alkynylaminals could be successfully applied in enantioselective Mannich-type reactions, catalyzed by chiral phosphoric acids, to afford optically active propargylamine derivatives.

Preparation of Fe3O4/poly(l‐glutamic acid) microspheres and their adsorption of Cu(II) ions

ABSTRACTFe3O4/poly(l‐glutamic acid) (P‐l‐Glu) magnetic microspheres were synthesized in an l‐glutamic acid solution by coprecipitation and a dehydration condensation reaction and were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and ζ‐potential measurement. P‐l‐Glu was coated on the surface of Fe3O4 microspheres. The average particle diameter of Fe3O4/P‐l‐Glu was 388 nm and dispersed homogeneously in water. The adsorption of Cu(II) ions on Fe3O4/P‐l‐Glu was further studied. The effect of different pH values and reaction times on the adsorption of Fe3O4/P‐l‐Glu was discussed. The adsorption equilibrium was reached in 40 min, and the maximum adsorption for Cu(II) ions was more than 500 mg/g; this value occurred at pH 8 in water. The adsorption dynamic process fit the Freundlich isotherms well, and the adsorption kinetics followed the adsorption mechanism of the pseudo‐second‐order equation, which was the main complexation reaction. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43730.

N-Boc-aminals as easily accessible precursors for less accessible N-Boc-imines: facile synthesis of optically active propargylamine derivatives using Mannich-type reactions

We developed a facile and practical synthesis of N-Boc-aminals, which can be used as precursors for less accessible N-Boc-imines. Aminals were obtained via simple dehydration condensation reactions of t-butyl carbamate (BocNH2) and various aldehydes in acetic anhydride, followed by filtration and washing with hexane. The obtained N-Boc-alkynylaminals could be successfully applied in enantioselective Mannich-type reactions, catalyzed by chiral phosphoric acids, to afford optically active propargylamine derivatives.

One-step microwave synthesis of N-doped hydroxyl-functionalized carbon dots with ultra-high fluorescence quantum yields.

A one-step microwave synthesis of N-doped hydroxyl-functionalized carbon dots (CDs) with ultra-high fluorescence quantum yields (QYs) of 99% is reported. These ultra-high QY CDs were synthesized using citric acid and amino compound-containing hydroxyls like ethanolamine and tris(hydroxylmethyl)aminomethane. Amino and carboxyl moieties can form amides through dehydration condensation reactions, and these amides act as bridges between carboxyl and hydroxyl groups, and modify hydroxyl groups on the surface of the CDs. The entire reaction can be carried out within 5 min. When the molar ratio of reactants is 1 : 1, the hydroxyl and graphitic nitrogen content is the highest, and the synergy leads to a high ratio between the radiative transition rate and nonradiative transition rate as well as a high QY. The developed pathway to N-doped hydroxyl-functionalized CDs can provide unambiguous and remarkable insights into the design of highly luminescent functionalized carbon dots, and expedite the applications of CDs.

Boronic acid-DMAPO cooperative catalysis for dehydrative condensation between carboxylic acids and amines.

Arylboronic acid and 4-(N,N-dimethylamino)pyridine N-oxide (DMAPO) cooperatively catalyse the dehydrative condensation reaction between carboxylic acids and amines to give the corresponding amides under azeotropic reflux conditions. This cooperative use is much more effective than their individual use as catalysts, and chemoselectively promotes the amide condensation of (poly)conjugated carboxylic acids. The present method is practical and scalable, and has been applied to the synthesis of sitagliptin and a drug candidate.

Synthesis and catalytic property of facet-controlled Co3O4structures enclosed by (111) and (113) facets

Co3O4 microparticles, with many smooth quadrihedrons on the surface, were hydrothermally synthesized under the influence of EDTA2− anions. Due to the excellent chelating and capping ability of EDTA2−, the as-obtained Co3O4 microparticles were mainly enclosed by (111) and (113) facets or their equivalent facets. On the basis of condition-dependent experiments, a dehydration condensation reaction assisted by the limitation effects of EDTA2− adsorbed on the surfaces of Co3O4 was proposed to explain the growth process of the cubic crystalline Co3O4 microparticles. The as-obtained Co3O4 microparticles could catalyze the thermal decomposition of ammonium perchlorate (AP) effectively due to the exposure of the high energy facets.

Design of Microporous Material HUS-10 with Tunable Hydrophilicity, Molecular Sieving, and CO2 Adsorption Ability Derived from Interlayer Silylation of Layered Silicate HUS-2.

The attractive properties of zeolites, which make them suitable for numerous applications for the energy and chemical industries and for life sciences, are derived from their crystalline framework structures. Herein, we describe the rational synthesis of a microporous material, HUS-10, utilizing a layered silicate precursor, HUS-2, as a structural building unit. For the ordered micropores to be formed, interlayer pillars that supported the original silicate layer of HUS-2 were immobilized through the interlayer silylation of silanol groups with trichloromethylsilane and a subsequent dehydration-condensation reaction of the hydroxyl groups on the preintroduced tetrahedral units. An actual molecular sieving ability, enabling the adsorption of molecules smaller than ethane, was confirmed in the ordered micropores of HUS-10. The hydrophilic adsorption could also be controlled by changing the number of methyl and hydroxyl groups in the immobilized interlayer pillars. In addition, when the adsorption behaviors of CO2, CH4, and N2 on HUS-10 were compared to those on siliceous MFI and CDO zeolites with approximately the same pore diameter, the CO2 adsorption capacity of HUS-10 was comparable. Conversely, because of the adsorption inhibition of CH4 and N2, HUS-10 exhibited larger CO2/CH4 and CO2/N2 adsorption ratios relative to those of MFI and CDO zeolites. These results reveal that the unique microporous framework structure presented by the rational structural design using the layered silicate precursor HUS-2 has the potential to separate CO2 from gas mixtures.

Facile preparation of cyclodextrin-grafted chitosans and their conversion into nanoparticles for an anticancer drug delivery system

A facile method of preparing cyclodextrin-grafted chitosan (CyD-g-CS) by means of the carboxymethlation of cyclodextrins and the dehydration-condensation reaction to chitosan was developed. In this method, crude product containing ~10% of the carboxymethylated-cyclodextrin was subjected to the grafting reaction without further purification. The product (CyD-g-CS) was finally purified by dialysis. Furthermore, doxorubicin-capturing nanoparticles composed of CyD-g-CS and sodium triphosphate were prepared.

Dehydration Condensation Reaction in Inorganic Chemistry

Dehydration Condensation Reaction in Inorganic Chemistry

Solventless Organic Reactive Crystallization at Mild Conditions

Solid state mixtures of two reactants, 2-hydroxy-1-naphthaldehyde and 2-aminobenzonitrile, were melted at a temperature even lower than both the melting points. And dehydration condensation reaction occurred in the melt to give reaction product N-(2-cyanophenyl)-2-hydroxy-1-naphthadimine. Since the melting point of the product was higher than the reactants, self-crystallization of the product occurred. Usefulness of this one-pot synthesis and crystallization method for industrial application was described.

Synthesis, structure, and characterization of glyoxal‐urea‐formaldehyde cocondensed resins

ABSTRACTTo decrease the formaldehyde emission of urea‐formaldehyde (UF) bonded products at source, monomethylol urea (MMU) was chosen to react with glyoxal (G), a nonvolatile and nontoxic aldehyde, to prepare a novel glyoxal‐urea‐formaldehyde (GUF) cocondensed resin. The GUF resins were synthesized with different MMU/G molar ratios, and the basic properties were tested. The GUF resins were characterized by ultraviolet‐visible spectroscopy, Fourier transform infrared spectroscopy, carbon‐13 nuclear magnetic resonance spectroscopy and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI‐TOF‐MS). The results show that the synthesized GUF resins remain stable for at least 10 days at ambient temperature. Conjugated structures, and large amounts of OH, NH, CN, and CO groups with different levels of substitution exist in the GUF resin. There are two repeating motives in the MALDI‐TOF‐MS spectrum of the GUF resin, one of 175 ±1 Da and a second one of 161 ± 1 Da. Moreover, the peaks due to the dehydration condensation reaction of MMU also appear in the spectra. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41009.

Efficiency Enhancement in ZnO:Al-Based Dye-Sensitized Solar Cells Structured with Sputtered TiO2Blocking Layers

We explored new strategies for efficiency enhancement in dye-sensitized solar cells (DSSCs) by combining dehydration–condensation reactions with sputtering deposition methods. The photoanodes were realized by means of low-temperature preparation of mesoporous TiO2 films on thin undoped TiO2 compact (blocking) layers on ZnO:Al (AZO) substrates and sensitization with ruthenium dye, N719. For photoanodes fabrication, an 8 μm thick mesoporous film of TiO2 and an under critical thermal budget, applied before dye loading (≤200 °C: i.e., 150 °C for the TiO2 mesoscopic layer and 200 °C for the TiO2 blocking/AZO bilayer), were employed, which renders the overall process competitive for the applications. The structural properties of the sputtered TiO2/AZO bilayer were optimized, and a cell efficiency as high as the 4.6%, above the current literature limit for AZO-based DSSC (3.8% for 10 μm thick mesoporous layers sintered at 450 °C and sensitized with N719), was achieved at T ≤ 200 °C. With the proposed scheme for the photoanode structure and using, instead, a conventional thermal treatment at 500 °C (30 s), the cell efficiencies were further raised up to 4.9%. It was thus evidenced that the use of optimized materials for the cell architecture makes the AZO-based DSSC nowadays rising devices.

Refining and Mutual Separation of Rare Earths Using Biomass Wastes

Two different types of adsorption gels were prepared from biomass wastes. The first gel was produced from astringent persimmon peel rich in persimmon tannin, a polyphenol compound, which was prepared by means of simple dehydration condensation reaction using concentrated sulfuric acid for crosslinking. This adsorption gel was intended to be employed for the removal of radioactive elements, uranium (U(VI)) and thorium (Th(IV)), from rare earths. The second gel was prepared from chitosan, a basic polysaccharide, produced from shells of crustaceans such as crabs, shrimps, prawns, and other biomass wastes generated in marine product industry, by immobilizing functional groups of complexanes such as ethylendiaminetetraacetic acid and diethylentriaminepentaacetic acid (DTPA). This gel was developed for the mutual separation of rare earths. Of the two adsorption gels evaluated, the DTPA immobilized chitosan exhibited the most effective mutual separation among light rare earths.

Spiral Configuration of Nitroxide Radicals Along the Polypeptide Helix and Their Magnetic Properties

Poly(l-glutamic acid) (PLGA) derivatives PTPALG and PTPOLG, which contain 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals linked to PLGA via amide and ester bonds, respectively, were synthesized by the dehydration-condensation reaction. The main chains of both PTPALG and PTPOLG were found to adopt the right-handed α-helical conformation, and accordingly, the terminal side-chain nitroxide radicals adopted the spiral configuration synchronized with the helical conformation of the main chain. Polarized microscopy observations reveal that PTPALG exhibited the lyotropic liquid crystalline (LC) phase at greater than 7.5 wt % concentration in chlorinated solvents, whereas PTPOLG kept the anisotropic liquid phase at up to 10 wt % concentration. From the analysis of superconducting quantum interference device (SQUID) magnetometer and electron spin resonance (ESR) data, the magnetic properties of PTPALG and PTPOLG appeared to result from interchain spin–spin interactions between nitroxide• radicals rather than intrachain interactions. Interestingly, observation of the double quantum |Δms| = 2 line in a half-field region (g = 4.015) in the case of PTPALG revealed the doublet (S = 1/2) to triplet (S = 1) state conversion at around 6 K, exhibiting to be shifted the critical temperature in the sample evaporated the solvents from the LC phase. In contrast, PTPOLG retained its paramagnetic properties in the temperature range 4–200 K.

N-doped carbon nanowires synthesized from l-arginine for electrochemical application

N-doped carbon nanowires are synthesized by a simple impregnation method under low carbonization temperature. l-Arginine is adopted as carbon sources and nitrogen sources and SBA-15 is employed as hard template. The obtained carbon nanowires possess uniform and ultrafine diameter of around 6.5nm, in good accord with the pore size of the SBA-15 silica template. The probable mechanism is proposed that l-arginine is elongated to form long chains in the pore of SBA-15 through dehydration–condensation reaction. The as-synthesized carbon nanowires contain heteroatoms such as nitrogen and oxygen, which are very helpful to the pseudo-capacitance and the wettability of carbon materials. The experimental results demonstrate that N-doped carbon nanowires exhibit superior performance in supercapacitance properties.

Molecular-Chain Formation Induced by Infrared-Laser Light Observed in L-Cysteine and Potassium Dihydrogenphosphate

Each of amino acids and phosphate group is capable of forming a chain through repeating dehydration condensation reaction. We have observed Raman scattering spectra of L-cysteine (HSCH2CH(NH2)COOH) and potassium dihydrogenphosphate (KH2PO4 or KDP) before and after irradiation of one pulse of an erbium-doped yttrium aluminum garnet (Er:YAG) laser with its wavelength of 2.94 µm, duration of 0.2 ms, and peak power density of 0.4 MW/cm2. Extra peaks are observed in the spectra after the irradiation, which are not seen in the spectra before the laser irradiation. Comparison of the experimentally obtained spectra with the calculated ones of the chain compounds suggests that the laser light does induce such reactions.

Molecular-Chain Formation Induced by Infrared-Laser Light Observed in L-Cysteine and Potassium Dihydrogenphosphate

Each of amino acids and phosphate group is capable of forming a chain through repeating dehydration condensation reaction. We have observed Raman scattering spectra of L-cysteine (HSCH2CH(NH2)COOH) and potassium dihydrogenphosphate (KH2PO4 or KDP) before and after irradiation of one pulse of an erbium-doped yttrium aluminum garnet (Er:YAG) laser with its wavelength of 2.94 µm, duration of 0.2 ms, and peak power density of 0.4 MW/cm2. Extra peaks are observed in the spectra after the irradiation, which are not seen in the spectra before the laser irradiation. Comparison of the experimentally obtained spectra with the calculated ones of the chain compounds suggests that the laser light does induce such reactions.

Co-immobilization Mechanism of Cellulase and Xylanase on a Reversibly Soluble Polymer

Cellulase and xylanase from Trichoderma reesei were immobilized simultaneously on Eudragit L-100, a reversibly soluble polymer. The effects of polymer concentration and polymer precipitation pH on enzyme activity recovery were investigated at an enzyme complex concentration of 1%. The immobilization mechanism of cellulase and xylanase on the polymer was discussed. An activity recovery of 75% and 59% was obtained for the cellulase and the xylanase, respectively, under the condition of a polymer concentration at 2% and a polymer precipitation pH at 4.0. Most zymoproteins might be connected to the polymer by electrostatic attraction in a medium of pH 4.8. In addition, the covalent coupling between the zymoproteins and the polymer was demonstrated by the infrared spectrograms. It was suggested that dehydration-condensation reaction occurred between the zymoproteins and the polymer during the immobilization.