Trithiocarbonate Research Articles

Stabilization and Release Characteristics of Heavy Metals in Desulfurization Sludge from Coal-Fired Power Plants

ABSTRACT The leaching risk of heavy metals from flue gas desulfurization (FGD) by-product sludge of coal-fired power plants is high, and there is an urgent need for effective treatment using solidification. In this paper, dithiocarbonates (DTC), 2,4,6-tri-mercapto-S-triazine trisodium salt (TMT-15) curing agent, fly ash and cement were used to cure the desulfurization sludge and study the environmental release characteristics of heavy metals before and after curing. The results show that all four curing agents had a good curing effect. The best chelating agent was DTC, and the best curing conditions were achieved at a liquid-to-solid ratio of 3:1 and a mass fraction of 8%. The leaching concentrations of As, Pb, Cd, Cr, Ni, Cu, Zn, and Hg were reduced by 87.95%, 100%, 85.29%, 86.17%, 70.11%, 95.06%, 90.28%, and 98.44%, respectively, after curing. In the environmental release characteristics test, the leaching concentrations of heavy metals in the cured sludge were lower than those of the original samples at different pH values and temperatures, indicating better stability. The mass fraction had the greatest effect on the leaching concentration of heavy metals, followed by the pH value and temperature.

A novel trithiocarbonate collector featuring high-temperature resistance for copper slag flotation

The nature of copper slag flotation is unique due to the high temperature in the flotation pulp and high metallic copper content in the feed. Despite its great potential for valorizing slag, copper slag flotation remains challenging due to the deactivation of traditional dithiocarbonate (DTC) collectors (e.g., butyl xanthate) under high temperatures. DTC collectors also respond poorly to the metallic copper due to the difficulty in forming stable chemical adsorption. In this work, possible deactivation mechanisms of DTC collectors are proposed, i.e., decomposition, oxidation and thermal desorption. A novel furfuryl trithiocarbonate (FTTC) collector was designed and synthesized. Spectral characterization using FT-IR, H-NMR and ion trap MS confirmed the molecular structure of the synthesized collector and its decomposition, oxidation and polymerization products at 55 °C. The novel collector features high-temperature resistance and high metallic copper recovery, as revealed by the single mineral flotation experiments of chalcopyrite, pyrite and metallic copper at both 25 °C and 55 °C. The high collecting ability and selectivity of our collector were explained by EHOMO and ELUMO values using first-principles calculations. Our work provides guidance for the design of collectors exhibiting high-temperature resistance for copper slag flotation, aims at constituting a meaningful contribution for unlocking potential copper resources in copper slag.

Photoimageable Organic Coating Bearing Cyclic Dithiocarbonate for a Multifunctional Surface.

We report the fabrication of photocross-linkable and surface-functionalizable polymeric thin films using reactive cyclic dithiocarbonate (DTC)-containing copolymers. The chemical functionalities of these material surfaces were precisely defined with light illumination. The DTC copolymers, namely, poly(dithiocarbonate methylene methacrylate-random-alkyl methacrylate)s, were synthesized via reversible addition-fragmentation chain transfer polymerization, and the reaction kinetics was thoroughly analyzed. The copolymers were cross-linked into a coating using a bifunctional urethane cross-linker that contains a photolabile o-nitrobenzyl group and releases aniline upon exposure to light. The nucleophilic attack of the aromatic amine opens the DTC group, forming a carbamothioate bond and generating a reactive thiol group in the process. The surface concentrations of the unreacted DTC and thiol were effectively controlled by varying the amounts of the copolymer and the cross-linker. The use of methacrylate comonomers led to additional reactive surface functionality such as carboxylic acid via acid hydrolysis. The successful transformations of the resulting DTC, thiol, and carboxylic acid groups to different functionalities via sequential nucleophilic ring opening, thiol-ene, and carbodiimide coupling reactions under ambient conditions were confirmed quantitatively using X-ray photoelectron spectroscopy. The presented chemistries were readily adapted to the immobilization of complex molecules such as a fluorophore and a protein in lithographically defined regions, highlighting their potential in creating organic coatings that can have multiple functional groups under ambient conditions.

Pyrolysis of (thio)carbonates via computation analysis

The regioselective production of alkenes from (thio)carbonates was calculated by MP2/6-31G(d) method via pyrolysis processes. Four (thio)carbonates were calculated in this paper. They are S-sec-butyl O-methyl thiocarbonate (I), O-sec-butyl S-methyl thiocarbonate (II), sec-butyl methyl thioncarbonate (III), and sec-butyl methyl dithiocarbonate (IV). Thirteen potential thermolysis routes were revealed for the pyrolysis of each substance, including nine routes to produce regioselective alkenes and four rearrangement/decompose alternatives. Among nine alkene generation routes, six-membered ring transition states via a two-step mechanism required the lowest energy, while the other routes exhibited higher energy barriers. The calculation results demonstrated an alkene distribution hierarchy of 1-butene [Formula: see text] E-butene [Formula: see text] Z-butene for substances I and II, and an order of E-butene [Formula: see text] 1-butene [Formula: see text] Z-butene for substances III and IV.

Mechanistic Study of Regio-Defects in the Copolymerization of Propylene Oxide/Carbonyl Sulfide Catalyzed by (Salen)CrX Complexes

Small quantities of regio-defects in a regio-/stereoregular polymer weaken its tacticity and properties. This work clarified the origin of the regio-defect in the process of synthesizing poly(monothiocarbonate) through the copolymerization of propylene oxide (PO) and carbonyl sulfide (COS) catalyzed by a (salen)CrCl complex accompanied by bis(triphenylphosphoranylidene)ammonium chloride ([PPN]Cl). Quantitative characterization results from the MALDI-TOF-MS and 1H (13C) NMR spectroscopy suggested that the chain transfer reaction resulted in the regio-defect in the final copolymer, i.e., tail-to-tail (T–T) diad and dithiocarbonate (DTC) unit. The chain transferring to water in the reaction system led to the production of a (salen)Cr–OH intermediate, which initiated the copolymerization via either attacking PO first to result in formation of a T–T diad or first activating COS to produce mercapto (−SH) end-capped dormant chains via decarboxylation, thus generating a DTC unit in the final product through anoth...

A computational study on the thermal decomposition of di(tri)thiocarbonates

Alkyl methyl di(tri)thiocarbonates can be thermally decomposed into alkenes. In this paper, theoretical calculations were used to calculate the thermal decomposition procedures. Six compounds, including ethyl, isopropyl and [Formula: see text] dithiocarbonate and trithiocarbonate, were examined. For each decomposition, nine possible paths were considered, including the paths leading to the desired alkene products, as well as rearrangement and elimination reactions. This calculation was performed with the MP2/6-31G(d) method. Wiberg bond indices were also calculated to further reveal the reaction progress.

Synthesis of hyperbranched polymers and hyperbranched block copolymers through “A2 + B3” click reaction

Long-chain hyperbranched and hyperbranched block polymers were synthesized through Cu catalyzed azide-alkyne cycloaddition (CuAAC) of A2 macromonomers with two alkyne groups and B3 coupling reagent with three azide groups. Polystyrene (PSt) homopolymers and block copolymers of styrene and butyl acrylate (P(St-b-BA-b-St)) with two alkyne groups were obtained via reversible addition-fragmentation chain transfer (RAFT) polymerization using a RAFT agent with two alkyne groups, S, S′-bis(α, α′-dimethyl – α″-propargyl acetate) trithio carbonate (BPTTC). Besides, the hyperbranched block copolymers were also prepared through the successive RAFT polymerization of BA with the hyperbranched PSt as RAFT agents. The evidence of 1H NMR, IR and GPC-Viscosity-MALLS measurements conformed the structure of the polymers. Dpws, the ratio of the weight average molecular weights of the hyperbranched polymers to those of the macromonomers, reached above 60 at most, calculated from MALLS measurement, which showed a high degree of the coupling reaction. The degree of branched of the hyperbranched polymers kept on increasing with the reaction time, according to the branching factor, g′.

The regioselective pyrolysis of (trithio)carbonate: A computational study

The regioselective pyrolysis of sec-butyl methyl (trithio)carbonate was calculated at the MP2/6-31G(d) level in the Gaussian program. Twelve possible pathways were calculated. Nine of them gave the desired alkene products, 1-butene, E-butene, and Z-butene, and the other three, the rearrangement products, sec-butyl methyl ether and butanone for sec-butyl methyl carbonate and sec-butyl methyl thioether and butane-2-thione for sec-butyl methyl trithiocarbonate. It was shown that the two-step mechanism, including the carbonyl oxygen- or thion sulfur atom-involved six-membered ring transition state, as rate-determining step, is a preferred mechanism of the pyrolysis. The calculated product distribution is consistent with the experimental data on the pyrolysis of sec-butyl methyl carbonate. The product distribution for sec-butyl methyl trithiocarbonate was also predicted by the MP2/6-31G(d) method.

Mechanisms of rearrangements of substituted thiocyclopropenes

220 There is an important task to study the structure and rearrangements of substituted dithioacyloxy and thiocyclopropenes, which can behave as precursors of new heterocyclic compounds and ligand systems for preparing metal complexes with catalytic properties and biological activity [1, 2]. Previously, we revealed the intramolecular migrations of thio groups around the three mem bered ring in 3 phenylthio 1,2,3 triphenylcyclopro pene (1), bis(1,2,3 triphenylcyclopropenyl) sulfide (2), and 1,2,3 triphenylcyclopropenyl O ethyl dithiocar bonate (3), using dynamic 1Н, 13С NMR (DNMR) spectroscopy and X ray diffraction analysis [3–7]. Activation free energies (Δ ) for the migration of phenylthio , cyclopropenylthio , and ethoxydithio carbonate groups around the triphenylcyclopropene ring, calculated from the line shape analysis of indi cator signals in 13C DNMR spectra of compounds 1–3, are 24.4 (C2D2Cl4), 24.1 (C2D2Cl4), and 17.8 (C6D5CD3) kcal/mol, respectively. Compound 3 where ethoxydithiocarbonate group migrates around the three membered ring at a high rate (k25°С = 0.43 s–1) may be attributed to a promising prototype of molecular rotary motors [8]. Available experimental data provide no possibility to establish the strict mechanism of fluctuating behav ior of these compounds, which may be associated with 1,3 or 3,3 sigmatropic (for –SC(OEt)S) shifts of thio groups or intermediate formation of a tight ion pair, triphenylcyclopropenium cation and RS– anion (R = 25 C G ≠ ° Ph, Ph3C3, C(OEt)S). To determine these mecha nisms, we studied the possible migration routes of thio groups in compounds 1–3 in the gas phase by the den sity functional theory (DFT) method at the B3LYP/6 311++G(d,p) level.

Convenient Route to Thiocarbonates from Alcohols, Thiols, and Triphosgene

An efficient and simple one-pot, three-component procedure has been introduced for the preparation of various thiocarbonates from thiols, alcohols, and triphosgene in dichloromethane.

Direct preparation of vesicles from one-pot RAFT dispersion polymerization

Abstract Various morphologies including spherical micelles, nanowires and vesicles have been prepared by reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of styrene (St) in methanol using S-1-dodecyl-S -(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (TC)-terminated poly(ethylene oxide) (PEO-TC) and 2,2′-azobis(isobutyronitrile) (AIBN) as chain transfer agent and initiator, respectively. GPC, 1H NMR, TEM and laser light scattering (LLS) were used to track the polymerization. The results showed that the block copolymers PEO-b-polystyrene (PEO-b-PS) were formed firstly in homogenous polymer solution, and then the spherical micelles were produced via polymerization-induced self-assembling. Continuous polymerization of the PS blocks induced the transition of spherical micelles into other morphologies. The polymerization-induced self-assembling and reorganization (PISR) were induced by chain length ratio increase of PS to PEO blocks. The concentration of St in methanol is also important factor to influence the formation of morphologies.

Formation of Vesicular Morphologies via Polymerization Induced Self‐Assembly and Re‐Organization

A facile and feasible strategy for the preparation of vesicular morphologies has been developed using reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymerization of styrene has been performed in a selected solvent, methanol, using S-1-dodecyl-S-(α,α'-dimethyl-α″-acetic acid)trithiocarbonate (TC)-terminated poly(4-vinylpyridine) as chain transfer agent and stabilizer. Various morphologies including spherical vesicles, nanotubes, and compound vesicles with different shapes are obtained by changing the feed ratios and reaction conditions. The final nanostructural materials are formed through formation of the block copolymers, self-assembly, and re-organization of the morphology in a one-pot polymerization. The latter two are induced by the propagation of PS blocks. The preparation of nanostructural materials can be performed at a concentration higher than 0.5 g · mL(-1) , thus this method offers a practical approach to prepare nanostructural materials on a large scale.

Theoretical studies on the relative reactivities of aryl thiol, thiono and dithio carbonates and carbamates

RHF, MP2 and DFT calculations were carried out for the unhydrated and explicitly solvated (by five water molecules) putative zwitterionic complexes formed in the aminolysis of oxo {(O, O)} and thio {(O, S), (S, O) and (S, S)} carbonates [MeO‒ C(˭Y)‒ Y′Ar] and carbamates [NH2‒ C(˭Y)‒ Y′Ar, where Y and Y′ are O or S] with ammonia. The reorganization energy of the carbonyl carbon from an sp2 to an sp3 center, i.e., the energy needed to form a zwitterionic tetrahedral intermediate, was inversely related to the experimental rate of the aminolysis of carbonates as Y and Y′ are varied, (O, S)<(O, O)<(S, S)<(S, O). For carbamates the reorganization energy is the highest and the solvation energy is the lowest among ester, carbonate and carbamate series, which is suggestive of the difficulty of zwitterionic intermediate formation and changeover to a concerted mechanism found experimentally for the aminolysis of the carbamates.

Acceleration effect of five‐membered cyclic dithiocarbonate on an epoxy–amine curing system

AbstractA bifunctional cyclic five‐membered dithiocarbonate (DTC), having a bisphenol A structure, was found to be an effective accelerator for a epoxy–amine curing system comprised of bisphenol A diglycidyl ether and amine‐terminated polypropylene glycol. The acceleration effect was evaluated by monitoring the time‐dependence of the storage modulus of the reaction mixture with a dynamic mechanical analyzer. The reactions involved in the curing system were investigated in detail by performing a series of model reactions using the corresponding monofunctional monomers. This investigation revealed that (1) DTC reacted with amine rapidly, (2) the reaction afforded the corresponding adduct having a thiourethane and thiol moieties, and (3) the thiol reacted rapidly with epoxide. The thiourethane moiety incorporated into the resulting adduct effectively catalyzed the reaction of epoxide and amine, and this catalysis was the predominant mechanism for the acceleration effect arisen by the addition of DTC. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4606–4611, 2007

Dithioesters and Trithiocarbonates as Anchoring Groups for the “Grafting-To” Approach

Dithioesters and Trithiocarbonates as Anchoring Groups for the “Grafting-To” Approach

Synthesis and crosslinking reaction of poly(thiourethane)s having a siloxane moiety in the side chain

AbstractPoly(thiourethane)s having a siloxane moiety in the side chain were synthesized with a 5‐membered cyclic dithiocarbonate (DTC) having a siloxane group as a building block. The synthetic pathway consisted of (1) an addition reaction of the DTC with diamines and (2) polyaddition reactions of the resulting dithiols with diisocyanates. The siloxane moiety in the polymer side chain underwent a self‐condensation reaction upon exposure to moisture, and this led to a successful crosslinking reaction of the poly(thiourethane). The crosslinking on a silicate surface was accompanied by condensation between the siloxane side chain of the polymer and the silanol group on the surface, giving the corresponding surface that was permanently coated with the crosslinked polymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6492–6502, 2005

A novel cyclic dithiocarbonate having siloxane moiety; Approach to curable siloxane oligomer

AbstractA novel 5‐membered cyclic dithiocarbonate (DTC) having a siloxane moiety, 5‐(3‐trimethoxysilylpropyloxymethyl)‐1,3‐oxathiolane‐2‐thione, was synthesized from the corresponding epoxide precursor by its cycloaddition with carbon disulfide. The siloxane group underwent condensation reaction by the treatment with water and a basic or acidic catalyst, to afford the corresponding oligomer having siloxane main chain and DTC pendant. The resulting oligomer was liquid and soluble in organic solvents such as THF and chloroform. Treatment of the oligomer with amines resulted in selective ring‐opening reaction of the DTC group, generating a thiol group, which underwent oxidative coupling reaction to make the oligomer successfully cured. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4422–4430, 2005

Adsorptive uptake of arsenic (V) from water by aquatic fern Salvinia natans

The sorption potential of the As (V) ion from aqueous solution has been studied using the water fern Salvinia natans as a scavenging candidate for aquatic arsenic. Sodium arsenate was used to prepare the stock solution of As (V). The diluted stocks with nutrient as sample solutions with As-free pond water were kept in different Perspex cells of a multiple chamber and for each concentration a varying amount of dry mass of the plants were nourished under adequate lighting for supporting the growth of the plants. The samples were drawn from each chamber at 24 h intervals up to 5 days and for each sample the residual As (V) was estimated by the silver diethyl dithio carbonate (SDDC) method. Test results indicate that the plant could effectively uptake As (V) between 0.25 and 2 mg l−1 to the extent of 74.8 to 54%, respectively, after 120 h contact time for a plant mass of 20 g l−1 at neutral pH. The experimental data were fitted well to both Langmuir and Freundlich isotherms. The effect of pH and biomass quantities on sorption rate have been also investigated along with some metabolic parameters.

Synthesis of a novel cyclic 5-membered dithiocarbonate (DTC) having hydroxy group and its application to terminal functionalization of polyurethane

A novel 5-membered cyclic dithiocarbonate (DTC) having a hydroxy group, 5-hydroxymethyl-1,3-oxathiolane-2-thione (DTC-OH), was synthesized from glycidol. On the basis of the highly efficient reaction of its hydroxyl group with isocyanate, a polyurethane having isocyanate terminals was modified with DTC-OH into a new type of polyurethane prepolymer having DTC-terminals, which was highly reactive with amines but tolerant to moisture.

ChemInform Abstract: A Convenient Method for the Preparations of Carboxamides and Peptides by Using Di(2‐pyridyl) Carbonate and O,O′‐Di(2‐pyridyl) Thiocarbonate as Dehydrating Reagents.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.