Kinetic studies on the radical polymerization of acrylamide initiated by Mn3+–ethoxyacetic acid redox system

The kinetics of polymerization of acrylamide (AM) initiated by manganese(III) acetate–ethoxyacetic acid (EAA) redox system in aqueous sulphuric acid was investigated in the temperature range 35–45°C. The effects of variations in [monomer], [Mn³⁺], [EAA], [H⁺], and ionic strength on the rates of monomer disappearance (R_p) and Mn³⁺ disappearance (?R_m) were studied. The polymerization process is initiated by the free radical arising from the oxidation of ethoxyacetic acid by Mn³⁺ and terminated by the mutual combination of growing polymer radicals. Based on the kinetic results, a suitable reaction scheme is proposed and the rate expressions are derived. The study on degree of polymerization supports the proposed scheme for polymerization. The various rate and thermodynamic parameters are evaluated.     

Homopolymerization of Ethyl Methacrylate

The kinetics of polymerization of ethyl methacrylate initiated by manganese (III) in sulfuric acid have been investigated. The overall rates of polymerization (R_p), disappearance of manganic ion (-R_m), and degree of polymerization (X _n) were measured with variation in [monomer], [Mn³⁺], [H⁺], μ, and temperature. Various rate parameters and thermodynamic parameters were evaluated and are discussed.     

Polymerization of methyl methacrylate initiated by Mn(III)–glycerol redox system

The kinetics of thermal polymerization of methyl methacrylate initiated by the redox system Mn(III)–glycerol was studied in aqueous sulfuric acid in the temperature range of 30–40°C, and the rates of polymerization, R_p, and Mn³⁺ disappearance, etc., were measured. The effect of certain water-miscible organic solvents and certain cationic and anionic surfactants on the rates of polymerization has been investigated. A mechanism involving the formation of a complex between Mn³⁺ and glycerol whose decomposition yields the initiating free radical with the polymerization being terminated by the metal ion has been suggested.     

Phase-Transfer Catalysis: Free-Radical Polymerization of Methyl Methacrylate using K2S2O8-Quaternary Ammonium Salt Catalyst System. A Kinetic Study

Abstract

The kinetics of phase-transfer-agent-assisted free-radical polymerization of methyl methacrylate using K₂S₂O₈ as the water-soluble initiator and triethylbenzylammonium chloride (TEBA) as the phase-transfer catalyst (PTC) was investigated in toluene-water biphase media at 60°C. The effect of varying [MMA], [K₂S₂O₈], [TEBA], [H⁺], the ionic strength of the medium, and the temperature on the rate of polymerization (R _p) was studied. R _p was found to be proportional to [MMA]², [K₂S₂O₈]¹, and [TEBA]^0.5. Based on the kinetic results, a mechanism involving initiation of polymerization by phase-transferred S₂O₈ ^2- and termination by Q⁺ (quaternary ammonium ion) is proposed.     

Polymerization of Methyl Methacrylate: Kinetics of the Reaction Initiated by the Mn(III)-1,2-Propanediol Redox System

Kinetics of polymerization of methyl methacrylate initiated by Mn³⁺/1,2-propanedlol has been investigated in aqueous sulfuric acid at the temperature range of 25–35°C. The rate of polymerization (R_p) and the rate of manganic ion disappearance (-R_Mn) have been computed. The effects of organic solvents, certain cationic and anionic detergents, added electrolytes on the initial rate of polymerization, and maximum conversion have been examined. Depending on the kinetic results, a reaction scheme has been suggested involving the formation of a complex between Mn³⁺ and the alcohol, which subsequently decomposed in an unimolecular step to generate the initiating free-radical which initiates polymerization and termination of the growing polymer chain by metal ion.     

Aqueous polymerization of acrylonitrile initiated by manganese(III) pyrophosphate-thiocyanate redox system: a kinetic study

Summary The kinetics of aqueous polymerization of acrylonitrile monomer (M) initiated by the Mn^III-KNCS redox system have been studied under deaerated conditions in the temperature range 26–40 °C at constant ionic strength. The overall rates of polymerization and the disappearance of Mn^III were determined. The polymerization was initiated by the free radicals arising from the Mn^III-thiocyanate redox reaction. The rate of polymerization was investigated at various concentrations of monomer and initiator. The effects of varying [Mn^III], [NCS^–], pH, total [P₂O _inf7 ^sup4– ], added [Mn^II], metal ions, ClO _inf4 ^sup– , Cl^– and SO _inf4 ^sup2– were examined. Dependence of the rate of polymerization on temperature was studied and activation parameters were computed from an Arrhenius plot. A suitable kinetic scheme consistent with the observed results is proposed and discussed.     

Vinyl polymerization by cobaltic ions in aqueous solution. Part II. Polymerization of acrylonitrile and methyl acrylate

Polymerization of methyl acrylate in HClO₄ and HNO₃ was studied in the temperature range 10–15°C. The kinetics of the polymerization were found to be very simple, involving initiation and termination by cobaltic ions. Kinetic studies on polymerization of acrylonitrile in HClO₄ and HNO₃ revealed that water oxidation, and monomer oxidation were side reactions as in the case of methyl methacrylate. Experimental evidence favored the simultaneous initiation by Co³⁺ and CoOH²⁺ species. In H₂SO₄, certain unusual features were encountered. At low [Co³⁺], linear termination as well as termination by mutual combination occurred. Another interesting aspect was that CoSO₄⁺ initiated at low [Co³⁺]. This was unlike the case of other monomers in H₂SO₄. The rates of polymerization and rates of cobaltic ion disappearance were measured with respect to changes in [M], [Co³⁺], [H⁺], temperature, etc. The various rate constants were evaluated.     

Vinyl polymerization: Kinetics of Ce(IV)–acetophenone-initiated polymerization of acrylonitrile in acetic–sulfuric acid mixtures

The polymerization of acrylonitrile (M) initiated by the Ce(IV)–acetophenone (AP) redox pair has been studied in acetic–sulfuric acid mixtures in a nitrogen atmosphere. The rate of polymerization is proportional to [M]^3/2, [AP]^1/2 and [Ce(IV)]^1/2. The rate of disappearance of ceric ion,–R_Ce, is proportional to [AP], [M], and [Ce(IV)]. The effect of certain salts, solvent, acid and temperature on both the rates have been investigated. A suitable kinetic scheme has been proposed, and the composite rate constants k_p ²(k/k/_t) and k₀/k_i are reported.     

Metal Complexes with Macrocyclic Ligands. Part XXVIII.. Structures and stabilities of the Cu2+ complexes with 1,4,7-triazacyclononane-1-acetic acid

The potentiometric study of the complexation of 1,4,7-triazacyclononane-l-acetic acid ( 1 ) with Cu²⁺ (I = 0.5 (KNO₃), T = 25°) indicates the presence of the species [Cu( 1 )], [Cu( 1 )OH], [Cu( 1 )₂], and [(Cu( 1 ))₂OH], the stability constants of which are determined. The two complexes [Cu( 1 )]ClO₄ and [(Cu( 1 )₂)OH]ClO₄ were also characterized by X-ray structure analysis. In both cases, the Cu²⁺ ion is in a distorted square-pyramidal arrangement, penta-coordinated by the three N-atoms of the macrocycle, an O-atom of the carboxylate, and an additional O-atom either from a second carboxylate or from an OH^?, acting as a bridge between two metal centres.     

Polymerization of Acrylonitrile: Kinetics of the Reaction Initiated by the Mn3+-Cyclohexanol Redox System

The vinyl polymerization of acrylonitrile initiated by the redox system Mn³⁺-cyclohexanol was investigated in aqueous sulfuric acid in the temperature range of 30–45° C. The rate of polymerization R_p and the rate of Mn³⁺ ion disappearance were measured. The effects of certain water-miscible organic solvents and certain anionic, cationic, and nonionic surfactants on the rate of polymerization were investigated. Based on the results obtained, a suitable reaction mechanism involving the formation of a complex between Mn³⁺ and the alcohol, whose decomposition yields the initiating free radical with the polymer chain being terminated by the mutual combination of growing chains is suggested.     

Electro-initiated polymerization of acrylonitrile in aqueous acetic acid containing Mn(OAc)2·4H2O and CNCH2COOH

The electro-initiated polymerization of acrylonitrile initiated by the anodic oxidation of an aqueous acid solution (80% HOAc + 20% H₂O) containing Mn(OAc)₂ · 4H₂O/CNCH₂COOH has been investigated in the 30–40°C temperature range. The kinetics and mechanism of the process has been investigated as a function of variables and a suitable mechanism proposed. From the experimental observations the rate of polymerization is seen to be proportional to [An]^1.5I^0.5[Mn⁺²]^0.5 and [CAA]^0.5. The rate of polymerization gradually decreases at a higher applied current. The rate was independent of [CAA]^0.5. The rate of polymerization gradually decreases at a higher applied current. The rate was independent of CAA at high concentration. The average degrees of polymerization (P _n) increases with increasing AN and decreasing [CAA], [Mn⁺²] and applied current, I. The initiation is due to the anodic oxidation of Mn⁺²–CNCH₂COOH complex. Both the initiation of polymerization by the primary radical, viz., CN? C?? COOH as well as the oxidation of the primary radical at the electrode are equally significant reactions and neither can be neglected in comparison with the other. Predominant mutual termination accounts for all the observed data.     

Kinetics of polymerization of acrylonitrile initiated by the Mn3+-thioacetamide redox system

Kinetics of the polymerization of acrylonitrile has been investigated in aqueous sulfuric acid in a temperature range of 25–45°C. The rate of polymerization (R_p) and the rate of managanic ion disappearance, etc., have been measured. The effect of the various additives, such as water-miscible organic solvents, neutral electrolytes, complexing agents, and surfactants, on the rate has been thoroughly studied. A mechanism that involves the initial complex formation between the thiol form of the thioamide and Mn³⁺, whose decomposition yields the initiating free radical with the polymer chain terminated by mutual combination of growing radicals, has been suggested.     

Metal Complexes with Macrocyclic Ligands. Part XXXI. Protonation studies and complexation properties of tetraazamacrocyclic methylenephosphonates with earth-alkali ions

The three ligands 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonic acid) ( 1 ), 1,4,7,11-tetraazacyclotridecane-1,4,7,11-tetrakis(methylenephosphonic acid) ( 2 ), and 1,4,8,11-tetraazacyclotetradecane-1,4,8,1 1-tetrakis(methylenephosphonic acid) ( 3 ) have been synthesized by condensation of the corresponding macrocycles with formaldehyde and phosphorous acid. The protonation and stability constants with the earth-alkali ions have been determined at 25° and I = 0.1 M (Me₄)N(NO₃) by potentiometric titrations. Because of the high values of the first two protonation constants, ¹H-NMR measurements were necessary to determine them. Titrations in different supporting electrolytes (NaNO₃, KNO₃, RbNO₃, CsNO₃, and Me₄N(NO₃)) show that their choice is of paramount importance, as the above ligands can form complexes with alkali-metal ions. The potentiometric results for the earth-alkali ions show that beside mononuclear complexes of different degrees of protonation ([MLH_n], n = 0–4), also binuclear species are formed ([M₂LH_m], m = 0–2). It is interesting that 1 with the smallest macrocyclic ring has the greatest tendency to form binuclear complexes, which are so stable that they partially prevent the formation of the corresponding mononuclear species. For [ML], [MLH], [M₂L], and [M₂LH], the stability sequence is Mg²⁺ < Ca²⁺ > Sr²⁺ > Ba²⁺, whereas for [MLH₂], [MLH₃], and [MLH₄], the stability steadily decreases from Mg²⁺ to Ba²⁺.     

Polymerization of Acrylonitrile Initiated by the Thiourea-Mn3+ Redox System

Kinetics of vinyl polymerization initiated by the redox system thiourea-Mn³⁺ were investigated in the temperature range 30–40°C in sulfuric acid, and the rates of polymerization R_p and disappearance of Mn³⁺ have been measured. The effect of certain water-miscible organic solvents and anionic surfactant on the rates of polymerization was investigated. A mechanism involving the formation of a complex between Mn³⁺ and thiourea whose decomposition yields the initiating free radical with the polymerization terminated by mutual intraction of growing radicals is suggested.     

Tris-o-phenanthrolineiron(lll) Complex as a Photoinitiator of Acrylamide Polymerization

Abstract

The blue Tris-o-phenanthrolineiron(m) complex, Fe(phen)₃ ³⁺, formed in aqueous solution by oxidation of the red ferrous phenanthroline complex by nitric acid, is found to be a good photo-initiator of acrylamide (A.AM) polymerization. Systematic study of the kinetics of polymerization of acrylamide by Fe(phen) ₃ ³⁺ in aqueous nitric acid solution in the presence of light of Δ = 365 nm at room temperature showed that the rate of polymerization R_p was dependent on [A.AM]^1,5, [C] ^0,5, I^0,5, and [HCOOH], and the rate of Fe(phen) ₃ ³⁺disappearance, -R_c, was found to be proportional to [A.AM], [C], I, and [HCOOH], where [A.AM], [C] and [HCOOH] refer to the concentrations of acrylamide, Fe(phen) ₃ ³⁺, and formic acid, respectively, and I refers to light intensity. The kinetic observations are consistent with the interaction of the excited Fe(phen) ₃ ³⁺ with acrylamide molecule to produce a radical R. capable of initiation and also reduction of Fe(phen) ₃ ³⁺, to the stable Fe(phen) ₃ ²⁺. The results of the present study differ from those reported for photo initiation by ion pairs of the type Fe ³⁺X ^n- where ×= CI^?, Br^?, C₂O₄ ^2- OH^?, etc., which may be attributed to differences in the photo-behavior of the two systems.     

Polymerization of Acrylonitrile: Kinetics of the Reaction Initiated by the Redox System Mn3/Mannitol

Polymerization of acrylonitrile initiated by the redox system Mn³⁺/mannitol has been investigated in aqueous sulfuric acid in the temperature range 35–50°C. The rate of polymerization R_p and the rate of disappearance of Mn⁺³ (?R_M) were measured. The effect of certain water-miscible organic solvents, inorganic salts and complexing agents on the rate of polymerization have been investigated. Based on the experimental results, a suitable reaction mechanism is suggested involving the formation of complex between Mn³⁺ and the hydroxyl group of the substrate molecule, whose decomposition yields the initiating free radical; the polymer chain is terminated by the mutual combination of growing chains.     

Oxygen promoted radical polymerization of acrylonitrile in aqueous nitric acid. A kinetic study

The polymerization of acrylonitrile (AN) initiated by oxygen-ascorbic acid (AA)-ferric ion system was studied in dil. HNO₃ at 40°. The rate of polymerization, R_p, was found gravimetrically. In the [Fe³⁺] range, (2–5 × 10^?5 M, R_p was proportional to [AN]^{1.5 ± 0.05}, [O₂]^{0.5 ± 0.02} [AA]⁰ and [Fe³⁺]⁰; for [Fe³⁺] = (5–30) × 10^?5 M, it was proportional to [AN]^{1.8 ± 0.05}, [O₂]^{0.6 ± 0.02}, [AA]⁰ and [Fe³⁺]^{?0.9 ± 0.05}. A plausible reaction scheme is proposed and rate law presented to explain these results. R_p increased with ionic strength and [HNO₃] (up to ～0.25 M). An initial rate increase with temperature followed by a decrease was noticed. Chain lengths of the polymers were determined viscometrically.     

Comparative study of the absolute reactivity of vinyl monomers: Kinetics of polymerization of vinyl monomers initiated by Mn3+–thiodiglycolic acid redox system

The kinetics and mechanism of polymerization of methacrylic acid (MAA) and ethyl acrylate (EA) initiated by the redox system, Mn³⁺–thiodiglycolic acid (TDGA) were investigated in the 15–35°C temperature range. The polymerization kinetics of both the monomers followed the same mechanism, viz., initiation by primary radical and termination by Mn³⁺–thiodiglycolic acid complex. The rate coefficients k_i/k₀ and k_p/k_t were related to the monomer reactivity and polymer radical reactivity, respectively. It was observed that both monomer reactivity and polymer radical reactivity followed the same order, viz., EA > MAA. The polymer radical reactivity varied inversely with the Q values of the monomers.     

Electron transfer reaction in the chromium(VI)-manganese(II) system in the presence of ethylenediaminetetraacetic acid (EDTA)

Upon addition of Cr ^VI to a solution of ethylenediaminetetraacetic acid (EDTA) and Mn ^II, a transient species appears which has an absorption maximum at 500 nm. Kinetic studies of the outer-sphere oxidation of the Mn ^II-EDTA complex with the Cr ^VI-EDTA complex have been investigated by visible spectrophotometry at 25 °C. The formation of a transient species has been characterized spectrophotometrically and the encounter complex formation constants have been determined (K_OS = 1.75 × 10² and 1.66 × 10³ mol^-2 dm⁶ for [EDTA] and [Mn^II] variations, respectively). The effect of total [EDTA], [Mn^II], [Cr ^VI] and [HClO₄] on the rate of the reaction was determined. On addition of HClO₄, there is a decrease in the rate constants. The reaction product is the Cr^III-EDTA complex with λ_max = 400 and 550 nm. On the basis of the various observations and product characterization a most plausible outer-sphere mechanism has been envisaged.     

Kinetics and mechanism of polymerization of acrylonitrile by peroxomonosulphate

The kinetics of polymerization of acrylonitrile initiated by peroxomonosulphate (PMS) has been carried out in the temperature range 45–60°C at constant ionic strength of 0.50 mol dm^?3 under deaerated conditions. The rate of polymerization R_p has been investigated at various concentrations of monomer and initiator. The effects of [monomer], [initiator], [H⁺], ionic strength, temperature, and reducing agents (organic and inorganic substrates) on the rate of polymerization have been observed. Activation energy was found to be 15.2 kcal mol^?1.