An Efficient,Basic Resin-Mediated,One-Pot Synthesis of Dithiocarbazates Through Alcoholic Tosylates

A quick and efficient, one-pot synthesis of dithiocarbazates was accomplished in high yields by the reaction of various alcoholic tosylates of primary, secondary, and tertiary alcohols, with substituted hydrazines using an Amberlite IRA 400 (basic resin)/CS ₂ system. The reaction conditions are mild with simpler work-up procedures than previously reported methods.     

Novel Fluorinated Spiro [Indole-indazolyl-thiazolidine]-2,4′-diones: Design and Synthesis

The reaction of indol-2,3-diones ( 1a–i ) with 5-aminoindazole ( 2 ) has resulted in the formation of hitherto unknown 3-(indazol-5-yl)iminoindol-2-ones ( 3a–i ) in quantitative yields which, on 1,3-dipolar cyclocondensation with mercaptoacetic acid ( 4 ), has afforded a series of new spiro heterocycles, 3′-(indazol-5-yl) spiro[3H, indol-3, 2′ -thiazolidine]-2,4′-diones* ( 5a–i ).     

Kinetics of Polymerization of Methyl Methacrylate initiated by AIBN in the Presence of Acetophenone

The present investigation aims at estimating the retarding effect of acetophenone in the polymerization of methyl methacrylate initiated by α,α' -azobisisobutyronitrile in the temperature range of 50 to 80°C. The results are interpreted in terms of Tüdös kinetic parameter (β). The effects of varying concentrations of substrate, monomer, initiator, and salts have been investigated. A suitable reaction scheme and rate expression have been suggested on the basis of the experimental findings, and another kinetic parameter (K) to represent the reactivity of acetophenones toward the polymer radical has been obtained graphically.     

Curcumin,A Novel Natural Photoinitiator for the Copolymerization of Styrene and Methylmethacrylate

Curcumin (Cur), a natural colorant found in the roots of the Turmeric plant, has been reported for the first time as photoinitiator for the copolymerization of styrene (Sty) and methylmethacrylate (MMA). The kinetic data, inhibiting effect of benzoquinone and ESR studies indicate that the polymerization proceeds via a free radical mechanism. The system follows ideal kinetics (R_p α[Cur]^0.5[Sty]^0.97[MMA]¹). The reactivity ratios calculated by using the Finemann–Ross and Kelen‐Tudos models were r₁(MMA)=0.46 and r₂(Sty)=0.52. IR and NMR analysis confirmed the structure of the copolymer. NMR spectrum showing methoxy protons as three distinct groups of resonance between 2.2–3.75 δ and phenyl protons of styrene at 6.8–7.1 δ confirmed the random nature of the copolymer. The mechanism for formation of radicals and random copolymer of styrene and MMA [Sty‐co‐MMA] is also discussed.     

Hexavalent Chromium-Thioacetamide Redox System Initiated Polymerization of Acrylonitrile

Polymerization of acrylonitrile initiated by the Cr⁶⁺/thioacetamide redox system was studied in nitrogen atmosphere in the temperature range 35–45°C. The rate of polymerization and the rate of Cr⁶⁺ ion disappearance were measured. The effect of certain water-miscible organic solvents, neutral electrolytes, and complexing agents on the rate of polymerization was investigated. Chromic acid alone did not initiate the polymerization under deaerated and undeaerated conditions. Depending on the results obtained, a suitable kinetic scheme was proposed and various rate parameters were evaluated.     

The Synthesis of Poly(Dimethylsiloxane-b-Isobutylene-b-Dimethylsiloxane) and Poly-(Dimethylsiloxane-b-Isobutylene-b-Dimethylsiloxane) from Alcohol-Telechelic Polyisobutylenes

The purpose of these studies was to combine polydimethylsiloxane (PDMS) and polyisobutylene (PIB) sequences into novel triblock, PDMS-b-PIB-b-PDMS, and multiblock, (-PDMS-b-PIB-b-PDMS-)n, copolymers. The key toward syntheses was the definition of conditions for the initiation of living anionic polymerization of hexamethyl-cyclotrisiloxane (D₃) at the CH₂OLi termini of well-defined tele-chelic PIB sequences. Subsequent deactivation of living D₃ polymerization charges with Me₃ SiCl yielded the target triblock whereas stoichiometric amounts of Me₂ SiCl₂ gave the multiblock copolymer.     

Living Carbocationic Polymerization. VII. Living Polymerization of Isobutylene by Tertiary Alkyl (or Aryl) Methyl Ether/Boron Trichloride Complexes

Abstract

Colloidal palladium supported on a chelate resin containing iminodiacetic acid groups was prepared by refluxing the palladium chelate resin in methanol-water. Using the resin-supported colloidal palladium as a catalyst, cyclopentadiene was hydrogenated to cyclopentene in 97.1% selectivity at 100% conversion of cyclopentadiene under 1 atm of hydrogen in methanol at 30°C. Finely dispersed metal particles ranging from 10 to 60 Å in diameter were observed in the resin by electron microscopy. Both x-ray microanalysis for palladium and elution analysis of palladium ion with an aqueous solution of ethylenediaminetetraacetic acid disodium salt demonstrated the existence of large amounts of palladium ion complexes in the resin. The amount of palladium metal in the resin was estimated to be about 5% of the total palladium. Since the resin, after removal of most of the ionic palladium, exhibited almost the same catalytic activity as before, it was concluded that the finely dispersed metal particles are the active species in the catalyst.     

Nanocomposite blend gel polymer electrolyte for proton battery application

A proton-conducting nanocomposite gel polymer electrolyte (GPE) system, [35{(25 poly(methylmethacrylate) (PMMA) + 75 poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP))?+?xSiO₂}?+?65{1 M NH₄SCN in ethylene carbonate (EC) + propylene carbonate (PC)}], where x?=?0, 1, 2, 4, 6, 8, 10, and 12, has been reported. The free standing films of the gel electrolyte are obtained by solution cast technique. Films exhibit an amorphous and porous structure as observed from X-ray diffractometry (XRD) and scanning electron microscopy (SEM) studies. Fourier transform infrared spectrophotometry (FTIR) studies indicate ion–filler–polymer interactions in the nanocomposite blend GPE. The room temperature ionic conductivity of the gel electrolyte has been measured with different silica concentrations. The maximum ionic conductivity at room temperature has been observed as 4.3?×?10^?3?S?cm^?1 with 2 wt.% of SiO₂ dispersion. The temperature dependence of ionic conductivity shows a typical Vogel-Tamman-Fulcher (VTF) behavior. The electrochemical potential window of the nanocomposite GPE film has been observed between ?1.6 V and 1.6 V. The optimized composition of the gel electrolyte has been used to fabricate a proton battery with Zn/ZnSO₄·7H₂O anode and PbO₂/V₂O₅ cathode. The open circuit voltage (OCV) of the battery has been obtained as 1.55 V. The highest energy density of the cell has been obtained as 6.11 Wh?kg^?1 for low current drain. The battery shows rechargeability up to 3 cycles and thereafter, its discharge capacity fades away substantially.     

Radical Photopolymerization of Vinyl Monomers

Abstract

Photopolymerization is the initiation by light of a chain polymerization process. In the more general sense, photopolymerization implies the increase of molecular weight caused by light. Photopolymerization is not only useful for the detection and identification of photochemically produced free radicals; since photopolymerization reactions can be started or stopped at will by the simple expedient of turning on or off light, a means is provided for studying the nonsteady-state kinetics of polymerization [1]. Photopolymerization also allows for the subtle control of molecular weight and molecular weight distribution by varying the intensity of light. Photopolymerization can be confined to local regions since the light can be spatially controlled. Photopolymerization can be carried out at very low temperatures. Hence, chain-transfer processes leading to branched macromolecules will be absent. Photopolymerization at low temperature yields the low-energy stereospecific polymeric species, namely the syndiotactic configuration of the polymer [2]. Certain monomers can only be polymerized at low temperature, i.e., they have low ceiling temperatures; the photopolymerization offers this possibility [3]. Because photopolymerization need not be carried out at elevated temperatures, it has applications to biochemistry. One important application of the method is in disk electrophoresis [4]. Photopolymerization played an important role in the early development of polymer chemistry. One of the first procedures for polymerizing vinyl monomers was to expose the monomer to sunlight. Blyth and Hoffman [5] reported the polymerization of styrene by this method in 1845.