Activated Zinc Powder Research Articles

Zinc Promoted Simple Synthesis of Z-Arnino Acids Under Neutral Conditions

Abstract: The introduction of benzyloxylcarbonyl (Z) group into amino acids is described at neutral pH using benzyloxylcarbonyl chloride and activated zinc powder. The reaction is simple, fast and clean. Thus the Z-amino acids are prepared in good yield and purity

Microwave-Assisted Synthesis of β-1,2,3-Triazolyl-α-amino Esters

The reaction of ethyl (p-methoxyphenylimino)acetate with propargyl bromide mediated by activated zinc powder afforded alkynyl amine, which was then reacted with a variety of organic azides using a microwave energy source, leading to β-1,2,3-triazolyl-α-amino esters in good yield.

Zinc powder-alkyl halide: a radical initiation system for living/controlled polymerization of vinyl monomers

An initiation system comprising activated zinc powder and alkyl bromide is presented for polymerization of vinyl monomers, including vinyl acetate (VAc). The polymerization was demonstrated to be effected in dry conditions at 70 °C and very sensitive to moisture. A radical mechanism was evidenced by spin-trapping method using TEMPO as capping agent and followed block copolymer formation. First order kinetics with respect to concentration of the monomers, methylmethacrylate(MMA), styrene and VAc, relatively long induction periods, and moderate polydispersities (PDI: 1.6–2.4) were determined as typical characteristics of the polymerization system in bulk conditions. The polymerization system was demonstrated to be living, as evidenced by chain extension of the poly (vinyl acetate) (PVAc) with MMA. A ZnBr radical fragment was proposed as key intermediate controlling the chain growth by reversible combination with the active chain ends. The system was also combined with typical copper-mediated atom transfer radical polymerization (ATRP), in which ATRP-growth polystyrene (PS) was directly used as macroinitiator to initiate VAc polymerization yielding block copolymer.

Alternative methods of obtaining silver from waste solutions using cementation

Thiosulphate leaching agent for silver is an alternative to cyanide leaching for certain types of refractory ores or secondary sources of the metal. Cementation of silver onto mechanically activated zinc powder after leaching is the most used method of the recovery of silver. The thiosulphate leaching of X-ray photos and cementation of silver by zinc from the solution are described in this paper. Application of cementation methods of processing silver from waste solutions represents economic as well as ecological importance for the whole society.

ChemInform Abstract: Solvent‐Free Addition Reaction of Propargyl Bromide and Aldimines Mediated by Activated Zinc Powder.

Zinc-mediated addition reactions of propargyl bromide with a variety of aldimines afforded the corresponding homopropargyl amines under solvent-free conditions. The methodology is solvent-free, cat...

Solvent-Free Addition Reaction of Propargyl Bromide and Aldimines Mediated by Activated Zinc Powder

Zinc-mediated addition reactions of propargyl bromide with a variety of aldimines afforded the corresponding homopropargyl amines under solvent-free conditions. The methodology is solvent-free, catalyst-free and involves a short reaction time (5 minutes).

N-Substitution Reactions of 20-π-Electron β-Tetrakis(trifluoromethyl)-meso-tetraphenylporphyrin

The N-substitution reactions of 20-π-electron β-text-rakis(trifluoromethyl)-meso-tetraphenylporphyrin 2 with α,ω-dibromoalkanes in N,N-dimethylformamide at room temperature in the presence of various bases gave a variety of N-substituted isophlorins, the nature of which depended on the chain length of α,ω-dibromoalkanes and the reaction conditions. When 1,4-dibromobutane was used, a fascinating N,N'-bridged isophlorin 14 was obtained. In the case of 1,3-dibromopropane or 1,5-dibromopentane, N-monoalkylated or N,N'-dialkylated isophlorins were produced under similar conditions. The reactions of these N-alkylated isophlorins with activated zinc powder were complicated and reduction, hydrolysis, elimination, and intramolecular cyclization were all observed.

Synthesis and Reactions of 20 π-Electron β-Tetrakis(trifluoromethyl)-meso-tetraphenylporphyrins

The 20 π-electron nonaromatic isophlorin 2 had been successfully isolated and thoroughly characterized and was formed by reduction of Cu(II) β-tetrakis(trifluoromethyl)-meso-tetraphenylporphyrin (Cu1) with activated zinc powder. However, the reaction utilizing Ni(II) β-tetrakis(trifluoromethyl)-meso-tetraphenylporphyrin (Ni1) as a substrate and Na2S2O4 as a reductant at 100 °C resulted in the formation of a porphydimethene 5. Subsequent N-methylation of the isophlorin 2 led to N-dimethylated isophlorin 3 or N-tetramethylated isophlorin 4 depending on the choice of the base used.

Synthesis and characterization of novel azo-bridged Zn(II) and Co(II) bisphthalocyanines

Metal phthalocyanines containing an unsymmetrically substituted nitro group were synthesized from 4-nitrophthalonitrile and the corresponding anhydrous metal salts ( Co ( OAc )2, Zn ( OAc )2) by the method of statistically mixed condensation reactions. The new type of metallo-bisphthalocyanine compounds connected by a N = N bridge was prepared from the reactions of respective nitro compounds with sodium hydroxide ( NaOH ) and activated zinc powder in a mixture of methanol ( MeOH ) and tetrahydrofuran (THF). The structures of these compounds were characterized by using 1 H NMR, IR, elemental analyses, UV-vis and magnetic circular dichroism spectroscopies.

Synthesis, characterization, conduction and gas sensing properties of novel multinuclear metallo phthalocyanines (Zn, Co) with alkylthio substituents

Compound 1 has been prepared by the reaction of 4-nitrophthalonitrile and 2-nitro-2-methyl-1,3-propanediol by the common method of nucleophilic substitution of an activated nitro group in an aromatic ring. Interesting binuclear metallophthalocyanines (M = Zn and Co), compounds 2 and 3, respectively, of a new type have been synthesized from compound 1, 4,5-bis(hexylthio)phthalonitrile, and the corresponding metal salts [Zn(OAc) 2 and CoCl 2] by the method of statistically mixed condensation. Compound 2 was converted to the tetranuclear zinc (II) phthalocyanine 4 by the reaction with NaOH solution and activated zinc powder in a mixture of MeOH and THF as the solvent. Impedance spectroscopy (IS) and d.c conductivity ( σ d.c) measurements were performed on spin coated films of these compounds as a function of temperature (290–400 K) and frequency (40–10 5 Hz.) The sensing properties for volatile organic compounds (VOCs) were also investigated. Although the d.c conductivity shows typical Arrehenius behaviour for compound 2, a discontinous point was observed in the slope of ln σ d.c versus 1/ T plot for compound 4. Unlike the films of 2 and 4, the d.c behaviour of compound 3 obeys the variable range hopping (VRH) model. At room temperature, a curved line was observed from the complex plane plots of impedance for all compounds. These curved lines transformed into a full semicircle with increasing temperature. The a.c conductivity of the films is represented by the form ω s . The dependency of the frequency exponent s on temperature suggests a correlated barrier hopping. A sensor using compound 4 as the sensing layer had the highest sensitivity for all volatile organic compounds investigated and showed complete reversibility even at room temperature. The results indicated that the film of compound 4 has potential as a sensitive coating for the monitoring of VOC vapours.

Copper(I) Chloride Cluster Complexes with Pentaphenyl‐Cyclopentaphosphane as Ligand

AbstractPentaphenylcyclopentaphosphane, c‐(P5Ph5) is conviently prepared from PhPCl2 and thermally activated zinc powder in thf. Hydrolysis of c‐(P5Ph5) in the presence of ZnCl2 gives to an equimolar distribution of PhPH2, PhP(=O)H2, and PhP(=O)(OH)H. Reaction of c‐(P5Ph5) with CuICl leads to the tetranuclear copper(I) chloride complex [Cu4(μ4‐Cl)2(μ2‐Cl)2{c‐(P5Ph5)}2] with a Cu4(μ4‐Cl)2(μ2‐Cl)2 cluster core and the hexanuclear [Cu6(μ3‐Cl)2(μ2‐Cl)2{c‐(P5Ph5)}2(thf)2]. Hydrolysis of the copper c‐(P5Ph5) complexes leads to significantly higher amounts of the primary phosphane oxide PhP(=O)H2.

Generation and Reaction of (N-Aryltrifluoroacetimidoyl)zinc Halide

Abstract (N-Aryltrifluoroacetimidoyl)zinc halides were easily generated at room temperature by the oxidative addition of imidoyl halides to activated zinc powder. [N-(2,6-Dichlorophenyl)- and N-(2,6-dimethylphenyl)trifluoroacetimidoyl]zinc halides react with aldehydes to give the corresponding alcohols smoothly in good to excellent yields. These adducts could be readily transformed to the α-amino ketones.

Acetylation and Debromination of Sydnones Accelerated by Ultrasound

AbstractIn the presence of a catalytic amount of 60% perchloric acid, 4‐acetyl‐3‐substituted sydnones were obtained more conveniently with greater yields by the sonochemical reaction of 3‐substituted sydnone with acetic anhydride. Some 4‐acetylsydnones which are difficult to synthesize by a known process were obtained in 17‐68% yields.4‐Bromo‐3‐(bromoaryl)sydnones with activated zinc powder dispersed in methanol were debrominated regioselectively by ultrasound in high yields (60‐96%). 3‐(2′‐/4′‐Amino‐3′,5′‐dibromophenyl)sydnone is synthesized easily from 3‐(2′/4′‐aminophenyl)sydnone by reduction, bromination and debromination subsequently.

A stereoselective synthesis of 1-phenyl-1-buten-3-yne and some 1-heteroaryl analogues.

Z-Enynes, RCHCHCCH (R= phenyl, 2-furyl, 2- and 3-thienyl and 3-pyridyl) can be obtained in ∼ 40% overall yields and with a stereoselectivity of > 95% by Pd/Cu-catalyzed cross-coupling of the readily available enyne sulfide HCCCHCHSC 2H 5 with RBr and RI, reduction of the products with activated zinc powder in ethanol and elimination of ethanethiol from the reduction products RCHCHCHCHSC 2H 5 with an excess of sodamide in liquid ammonia. In the case of the 2-pyridyl-substituted substrate the E-enyne HCCCHCH-2-pyridyl is isolated.

Preparation and reactions of 2-chloroperfluorocycloalkenylcopper reagents

1-Chloro-2-iodoperfluorocycloalkenes react with activated zinc powder in dimethylformamide solvent at room temperature to give 2-chloroperfluorocycloalkenylzinc reagents. Treatment of these organozinc reagents with copper(I) bromide at 0 °C or at room temperature provides a simple route to the corresponding 2-chloroperfluorocycloalkenylcopper. The yield is excellent. These organocopper reagents, which are stable at room temperature in the absence of oxygen and/or moisture, can be used for the production of C–C bonds via reactions with alkyl, aryl and acyl halides. Reaction of these organocopper reagents with acyl halides leads to previously unreported acylated polyfluorocycloalkenes.

Regio-and stereo-specific reduction of conjugated and non-conjugated triple bonds by activated zinc powder

Download options Please wait... Article information DOI https://doi.org/10.1039/C39840000735 Article type Paper Download Citation J. Chem. Soc., Chem. Commun., 1984, 735-736 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Regio-and stereo-specific reduction of conjugated and non-conjugated triple bonds by activated zinc powder M. H. P. J. Aerssens and L. Brandsma, J. Chem. Soc., Chem. Commun., 1984, 735 DOI: 10.1039/C39840000735 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Marc H. P. J. Aerssens Lambert Brandsma

Anthranilic acid: a new coreagent for the deblocking of 2,2,2-trichloroethylphosphate protecting groups

Deblocking of 2,2,2-trichloroethyl groups from 3′-terminal phosphodiesters has been achieved by treatment with activated zinc powder using the novel coreagent anthranilic acid. This deblocking procedure has been used in the construction of the guanosine-rich octadeoxyribonucleotide d(GGGGATC).

Reduction of β-Chlorovinylaldehydes with Zinc Powder

Treatments of β-chlorovinylaldehydes with zinc powder in ethanol selectively remove the β-chlorine atom to give the α, β-unsaturated aldehydes. However, the same treatments in nitrogen atmosphere and, preferably, by using the activated zinc powder lowered remark ably the yield of the α, β-unsaturated aldehydes and give the reductive dimer, 1, 2-di-(1-alkenyl) ethylene glycol, as major product.

Reductions of oxo-steroids with activated zinc powder

Reductions of oxo-steroids with activated zinc powder