Anhydrous Potassium Hydroxide Research Articles

Characterization of new polyether-diols with different molar masses and modality prepared by ring opening polymerization of oxiranes initiated with anhydrous potassium hydroxide

Several new polyether-diols were prepared by ring-opening polymerization of monosubstituted oxiranes in the presence of anhydrous potassium hydroxide. 1,2-Butylene oxide (BO), styrene oxide (SO), isopropyl glycidyl ether (IPGE), allyl glycidyl ether (AGE), phenyl glycidyl ether (BGE), p-methoxyphenyl glycidyl ether (MPGE) and benzyl glycidyl ether (BGE) were chosen as monomers. Macrocyclic ligands complexing metal cations, i.e. coronand 18C6 or cryptand C222 were used as activators in these systems. All polymerizations were carried out in tetrahydrofuran solution at room temperature. Molar mass (Mn) and dispersity (Mw/Mn) of the polymers obtained with KOH depends on the kind of monomer, initial concentration of the initiator and the presence and kind of ligand or water. For example, PBO-diols prepared without ligand are bimodal and for the main fraction Mn > Mcalc. However, after addition of 18C6 polymers are unimodal and unexpectedly have much higher Mn = 13,700–15,800 and very low dispersity (Mw/Mn = 1.04–1.08). Mn of PBO-diols decrease with increase of [KOH]o and do not change at [BO]o = 2.0–9.0 mol/dm3. Addition of C222 results in Mn decrease of PBO-diols. Similar effects were observed in the polymerization of PAGE-diols and PPGE-diols. In the polymerization of SO, PGE, MPGE and BGE initiator efficiency (f) is high and Mn < Mcalc. Polymodality of some polymers obtained was discussed in term of the formation of various species propagating with different rate constants.Graphical abstractPolyether-diols synthesized using anhydrous hydroxide as initiator.

On biodiesels from castor raw oil using catalytic pyrolysis

In the present work, different types of castor biodiesels were synthesized by using slow pyrolysis process of raw castor oil in the presence of different types of catalysts. These catalysts as anhydrous sodium hydroxide (NaOH), alumina (Al2O3), sodium carbonate (Na2CO3), potassium hydroxide (KOH) and molecular sieve catalyst zeolite (ZMS-5) combined with anhydrous sodium hydroxide (ZMS-5 combined with NaOH) were used for yielding these biodiesels. So, the effects of variation of the catalyst type and its concentration on both yield of castor biodiesels and the pyrolysis temperature ranges were investigated. It was noticed that through the pyrolysis process, two grades of synthesized biodiesels were obtained in the presence of different types of catalysts. The first at the start of the pyrolysis was yellowish one, termed as Castor Biodiesel Number 1 (CBD1). And the second type was brownish biodiesel, called as Castor Biodiesel Number 2 (CBD2), while the rest was the black and heaviest, termed as bio-mazot. It was found that the highest total yields of biodiesels were obtained in the presence of 1% by volume of both NaOH and ZMS-5 combined with NaOH. Thus, four biodiesels were yielded and termed as CBD1h, CBD2h, CBD1hz, CBD2hz. And the different physical properties of these four biodiesels were measured according to American Society of Testing Material (ASTM). Also, the chemical compositions of these four biodiesels were determined by using Gas Chromatography Mass (GC-Ms) spectrum as well as the functional groups using Infra-Red (IR) spectrum. In addition, the performance of a single cylinder four stroke direct injection compression ignition engine fueled by two different blends as 5 and 10% by volume of CBDh and CBDhz with gas oil was measured. Thus, the main conclusion was derived from both physical and chemical investigations as well as engine performance that these synthesized biodiesels could be used as a good alternative of gas oil.

Synthesis And Ionic Conductivity of Siloxane Based Polymer Electrolytes with Propyl Butyrate Pendant Groups

Hydrosilylation reactions of 2.4.6.8-tetrahydro-2.4.6.8-tetramethylcyclotetrasiloxane with allyl butyrate catalyzed by Karstedt's, <TEX>$H_2PtCl_6$</TEX> and Pt/C catalyst were studied and 2.4.6.8-tetra (propyl butyrate)-2.4.6.8-tetramethylcyclotetrasiloxane was obtained. The reaction order, activation energies and rate constants were determined. Ringopening polymerization of 2.4.6.8-tetra (propyl butyrate)-2.4.6.8-tetramethylcyclotetrasiloxane in the presence of <TEX>$CaF_2$</TEX>, LiF, KF and anhydrous potassium hydroxide in <TEX>$60-70^{\circ}C$</TEX> temperature range was carried out and methylsiloxane oligomers with regular arrangement of propyl butyrate pendant groups were obtained. The synthesized products were studied by FTIR and NMR spectroscopy. The polysiloxanes were characterized by wide-angle X-ray, gel-permeation chromatography and DSC analyses. Via sol-gel processes of oligomers doped with lithium trifluoromethylsulfonate or lithium bis (trifluoromethylsulfonyl)imide, solid polymer electrolyte membranes were obtained. The dependences of ionic conductivity of obtained polyelectrolytes on temperature and salt concentration were investigated, and it was shown that electric conductivity of the polymer electrolyte membranes at room temperature changed in the range <TEX>$3.5{\times}10^{-4}{\sim}6.4{\times}10^{-7}S/cm$</TEX>.

The influence of macrocyclic ligands and water on propylene oxide polymerization initiated with anhydrous potassium hydroxide in tetrahydrofuran

It was found that presence of macrocyclic ligands, such as coronand 18C6 and cryptand C222 influence unsaturation of polyethers obtained by the polymerization of propylene oxide (PO) initiated with highly dispersed anhydrous KOH in tetrahydrofuran at room temperature. Polymerization carried out at low initial concentration of PO and quenched with CH3I resulted in the polymers without terminal OH groups. In this case unsaturation is very high and is represented mainly by cis-propenyloxy starting groups due to isomerization of double bonds of allyloxy groups. The unsaturation increases in the presence of ligands. However, polymers synthesized at higher initial concentrations of PO possess OH terminal groups and addition of ligands diminishes unsaturation which is represented mainly by allyloxy starting groups. The highest molar mass of polymers obtained is Mn=9000. KOH⋅H2O/18C6 appeared to be also effective initiator giving the polymers which contain great amount of terminal OH groups and very low unsaturation; their molar masses are rather low (Mn=2400–2900).

ペロブスカイト型酸化物ナノキューブの作製

Synthesis of barium zirconate (BaZrO3) nanocubes with perovskite structure was carried out by the composite-hydroxide-mediated (CHM) approach. The synthesis was conducted using zirconium dioxide (ZrO2) as a zirconium-source starting material and barium hydroxide［Ba(OH)2］ as a barium-source starting material. Through the use of these starting materials, BaZrO3 was prepared with a mixture of anhydrous sodium hydroxide (NaOH) and potassium hydroxide (KOH) as the reaction medium at 170～230℃ for 0～72h. Measurement by X-ray diffraction (XRD) confirmed the presence of perovskite BaZrO3 and indicated that the lattice of the obtained BaZrO3 was cubic. The amount of BaZrO3 increased as the reaction temperature increased. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observation revealed BaZrO3 nanocubes. The results showed that BaZrO3 nanocubes could be shaped from ZrO2 and Ba(OH)2. In order to clarify the formation mechanism of the BaZrO3 nanocubes, various reaction conditions such as the processes of increasing, maintaining, and decreasing the temperature were investigated. BaZrO3 nanocubes with sharp-edged corners were formed via the CHM approach when the temperature was maintained at 230℃ for increasing periods of time.

Unprecedented dual reactivity of anhydrous potassium hydroxide in cascade cyclopropannelation/Haller–Bauer-scission/Grob-fragmentation reactions

We report an unprecedented type of reactivity of ‘anhydrous potassium hydroxide’ (‘APH’) in which it plays, over a large variety of related educts, sequentially the role of base and nucleophile. Some insight into the structure of reactive species as well as comparative reactivity of related reagents prepared by fusion of commercially available potassium hydroxide or by adding stoichiometric amount of water to potassium hydride is provided.

Stereochemical issues on the fragmentation of non-enolisable β-heterosubstituted-cyclopentanones with wet and anhydrous potassium hydroxide

Fragmentation by potassium hydroxide of non-enolisable β-mesyloxy-cyclopentanones fused to a cyclopropane ring in α′,β′-positions proceeds efficiently from derivatives possessing (i) an exo -mesyloxy group and an endo -methyl group on the cyclopropane ring and (ii) an endo -mesyloxy group and an endo -hydrogen on the cyclopropane ring. This reactivity has been tentatively correlated to an antiperiplanar arrangement of atoms and bonds involved in the process accessible from various stereoisomers owing the flexibility of the five-membered ring. Tandem Haller–Bauer- scission /Grob- fragmentation reaction of cyclopentanone bearing a leaving group in β-position involves antiperiplanar arrangements which can be also achieved from epimeric derivatives, probably due to the high flexibility of the five-membered ring. We have observed that epimeric compounds react at different rates if the leaving group is a halogen and leads to very different types of compounds when it is a mesyl group.

Contribution to the preparation of chitins and chitosans with controlled physico-chemical properties

In this paper, from many new examples, our approach on the preparation of chitins and chitosans with controlled physico-chemical characteristics was presented. The chitosan samples were prepared from α-chitin from crustacean shells and β-chitin from squid pens. The chitin deacetylation was carried out according to two methods using, respectively, as alkaline agent, the aqueous sodium hydroxide solution and anhydrous potassium hydroxide. The role of the source and of the process on the N-deacetylation reactions is confirmed. The effect of the addition of sodium borohydride or thiophenol within the reaction medium was studied. One of the parameters conditioning the physico-chemical characteristics of chitosan being in relation with the nature and the quality of original chitin, the role of this parameter was examined and the isolation process was discussed to put in evidence its advantages compared to other processes quoted in the literature by relying on new results.

Liquid/solid two-phase carbonization of low-molecular-weight chloro-/bromo-hydrocarbons

A novel liquid/solid two-phase reaction has been discovered that enables destruction of a series of low-molecular-weight chloro-/bromo-hydrocarbons to carbon-based materials. The solid phase is anhydrous potassium hydroxide and the liquid phase is a benzene or tetrahydrofuran solution of halide and contains a certain amount of tetrabutyl ammonium bromide (TBAB) as phase transfer catalyst. The structure of the carbon-based materials have been characterized by elemental analysis, Fourier transform infrared (FT-IR), FT-Raman, and X-ray photoelectron spectroscopies, and their morphologies have been examined by wide-angle X-ray diffraction and transmission electron microscopy. The results indicate that the products are amorphous nanoparticles and contain mainly elemental carbon. They consist of sp, sp2, and sp3 carbon atoms simultaneously and can be regarded as carbyne analogues. This work provides a convenient method for synthesizing new carbon-based materials in relatively high yields. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1510–1515, 2000

Carbonization of trichloroethanes with anhydrous potassium hydroxide

Chemical dehydrochlorination of 1,1,1- and 1,1,2-trichloroethanes with anhydrous potassium hydroxide (KOH) in the presence of a poly(ethylene glycol) oligomer as phase transfer catalyst leads to polymeric carbons with partly carbynoid structures. The FTIR spectra show a strong band at 2130 cm−1 and FT-Raman exhibits a strong line at around 1900 cm−1, either of which is interpreted as the CCC stretching mode of the linear carbon chain with alternating carbon–carbon triple and single bonds (polyyne). Carbons prepared by this technique are amorphous nanoparticles with diameters in the 30–50 range nm. After iodine doping they have dc conductivities of 10−3 S cm−1. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 185–189, 2000

Rigid-rod polyelectrolytes: carboxylated poly(para-phenylene)s via a novel precursor route

The synthesis of a soluble poly( para-phenylene) (PPP) derivative with two p-carboxyphenoxymethylene substituents in the 2,5-positions of every alternate phenylene moiety is described, transforming a bromomethylene-substituted precursor PPP in a two-step reaction sequence. Both of these steps, namely a Williamson reaction and an ester cleavage using anhydrous potassium hydroxide, occur selectively and almost quantitatively (>98%, n.m.r.). Structurally homogeneous, rigid-rod polyelectrolytes with 80–130 phenylene rings attached to each other may be obtained by this method.

Facile One-Pot Syntheses of 1-Allenylpyrroles

A number of pyrroles have been N-allenylated in reasonable to good yields by treatment with anhydrous potassium hydroxide and propargyl chloride, 2,3-dichloro-1-propene or 1,2,3-trichloropropane in anhydrous dimethyl sulfoxide.

Anionic Polymerization of Ethylene Oxide by Anhydrous Potassium Hydroxide

Abstract The heterogeneous anionic polymerization of ethylene oxide in tetrahydro-furan by anhydrous potassium hydroxide, prepared in situ by addition of an equivalent of water to potassium naphthalene, was studied. The effect of time of polymerization, degree of conversion, and monomer and catalyst concentration on the molecular weights was studied. The system was a living one with no chain transfer. The efficiency of the catalyst was low. The polymerization was faster than those previously reported using solid potassium hydroxide due to the high dispersion of the catalyst prepared in this manner. The rate of polymerization increased about threefold by addition of two equivalents of dimethylsulfoxide to the catalyst due to solvation effects.

Copolymerization of ethylene oxide and propylene oxide by anhydrous potassium hydroxide

AbstractEthylene oxide and propylene oxide have been copolymerized at low temperatures in the presence of anhydrous potassium hydroxide. The monomer reactivity ratios were found to be r(ethylene oxide) = 6.5 and r(propylene oxide) = 0.5.

A Study of the Polymerization of Propylene Oxide Catalyzed by Anhydrous Potassium Hydroxide

A Study of the Polymerization of Propylene Oxide Catalyzed by Anhydrous Potassium Hydroxide