Non-equilibrium polycondensation (review)

Коршак, В.В.; Виноградова, С. В.

doi:10.1016/0032-3950(71)90012-8

Cited by 13 publications

(11 citation statements)

References 36 publications

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“…Therefore, it was necessary to continue search for new catalysts suitable for trans-esterification reactions. Literature reports that lanthanide compounds are effective catalysts for polymerization processes, due to coordination of lanthanide atom with the carbon-carbon double bond of the diolefin molecule [10]. Since this coordination is also possible in the carbon-oxygen double ester group's bond, the catalytic activity of such a compounds also could be expected in trans-esterification reactions.…”

Section: Resultsmentioning

confidence: 99%

Catalysis of Trans-esterification Reactions in Model Ester Mixtures

Васнев

Маркова

Uvarov

et al. 2017

Eurasian Chem. Tech. J.

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Model trans-esterification reaction of n-butylbenzoate with phenyl-p-chlorobenzoate in the molar ratio of 20:1 has been studied.In order to evaluate catalysts based on lanthanide system the activity of nyodymium compounds -neodymium acetate, neodymium acetylacetonate and nitrate complex with benzo-12-crown-4 (neodymium nitrate coronate) -has been studied in the model trans-esterification reaction of n-butylbenzoate with phenyl-pchlorobenzoate.The effect of the electronic structure of the metal on the catalytic activity of the coronates of lanthanum, cerium, praseodymium, neodymium, samarium, terbium and erbium nitrates has been studied.In order to estimate the optimum concentration of the catalysts, a study of the dependence of the transesterification reaction on concentration of neodymium nitrate coronate was carried out. An asymptotic nature of the concentration dependence on the catalytic activity of lanthanide compounds has been observed.In order to look for new classes of inhibitors of trans-esterefication reaction, the model trans-esterificatiom reaction of n-butylbenzoate with phenyl-p-chlorbenzoate has been studied in the presence of some carborane derivatives: cesium salts of bis-1,2-(dicarbollyl) complexes of iron, cobalt and nickel(3+) and bis-1,2(dicarbollyl)nickel(4+) [(C 2 B 9 H 11 ) 2 Me]. Some of these compounds were found to be effective inhibitors.The dependence of the constant rate of the model trans-esterification reaction of n-butylbenzoate with phenyl-p-chlorobenzoate on the concentration of cerium salt of bis-1,2-(dicarbollyl) complex of nickel has been studied to determine the optimum concentration of inhibitors.The influence of the ester chemical structure on the activity of ester groups in the trans-esterification activity has been determined in the reaction of di-n-butylterephthalate with different p-substituted derivatives of phenylbenzoate (phenyl-p-methoxybenzoate, phenyl-p-methylbenzoate, phenylbenzoate, phenyl-pchlorobenzoate, phenyl-p-nitrobenzoate, p-methoxyphenylbenzoate, p-methylphenylbenzoate, p-chlorophenylbenzoate, p-nitrophenylbenzoate, n-butylbenzoate, di-n-butylterephthalate) in presence of the samarium nitrate coronate.

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Section: Resultsmentioning

confidence: 99%

Catalysis of Trans-esterification Reactions in Model Ester Mixtures

Васнев

Маркова

Uvarov

et al. 2017

Eurasian Chem. Tech. J.

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“…When all the functional groups of the monomers are independent, the Shtraikhman-Beste equation [Eqn. (5)] is again valid for this process. However, when the intermonomer is introduced fairly slowly, high-molecular-weight products can be formed long before the reaction of the two monomers.…”

Section: Composition Of the Copolymers And Its Inhomogeneitymentioning

confidence: 83%

“…For initial compounds with interdependent functional groups, it is impossible to obtain mathematical formulae analogous to Eqn. (5) and the composition of the copolymer was calculated for individual specific instances on a computer 36 . However, it is noteworthy that the problem of the determination of the composition of the non-equilibrium homogeneous interbipolycondensation products with simultaneous introduction of all the initial compounds arises only when they are present in non-equimolar proportions whereupon the final reaction products are oligomers with a small number of units.…”

Section: Composition Of the Copolymers And Its Inhomogeneitymentioning

confidence: 99%

“…Hence it is clear that in equilibrium copolycondensation there is no need to determine the dependence of the statistical characteristics of the copolymer on the process conditions. This problem does however become very urgent for non-equilibrium copolycondensation, which is characterised by the absence of exchange and degradative reactions 5 . In this case the difference between the homophase and heterophase methods of carrying out the process, the chemical reactions of which may be complicated by the effects of diffusion and adsorption of the reactants on the interface, is shown particularly clearly.…”

Section: Introductionmentioning

confidence: 99%

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Non-equilibrium Copolycondensation in Homogeneous Systems

Васнев¹,

Кучанов²

1973

Russ. Chem. Rev.

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Theoretical and experimental data for the composition and structure (microheterogeneity) of copolymers obtained by nonequilibrium copolycondensation in homogeneous systems are considered. The effect of the relative reactivities of the comonomers, the reactivities of the first and second groups of the intermonomer, the order and duration of addition of the initial compounds to the reaction zone, and other factors on the composition and microheterogeneity of the copolymers has been demonstrated in relation to interbipolycondensation. The available experimental literature data have been compared with the results of calculations based on a quantitative theory of homogeneous copolycondensation. The bibliography includes 57 references. CONTENTS

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“…A similar approach is used in examining the chain of reversible reactions in polycondensation [15]. For the ith stage .…”

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confidence: 99%

Adsorption of vapors by amorphous polymers

Romankevich

2008

Fibre Chem

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The equation describing sorption of vapors by solutions of low-molecular-weight substances in the case of formation of solvates with a nonvolatile solvent can coincide in form with the BET equation. In calculating the specific surface area with the sorption value, it is necessary to determine the contributions of absorption (dissolution) processes in bulk and adsorption processes on the phase boundary to the overall sorption.The sorption characteristics [1-4] of fibres are used for assessing their performance properties, the specific surface area in particular (using the BET equation in particular), which suggests adsorption [2,3], and the intermolecular interaction, which suggests mutual solubility [4]. The shape of the dye sorption concentration curve is used for determining the mechanism of its sorption by a fibre [5]. Despite the evidence in support of an absorption mechanism of sorption of water by cellulose [6], the use of the BET equation for describing sorption of water by cellulose [3,7] is possible as an argument in support of an adsorption mechanism.The change in the chemical potential (Δμ 1 ) of a low-molecular-weight substance (LMC) dissolved in a polymer iswhere ϕ i i s the mole fraction of the component; z is the coordination number; χ is the Flory-Huggins parameter. When ϕ 2 → 1, the value of Δμ 1 → -∞, which ensures solubility at relatively low values of ϕ 1 . In the initial stages of sorption, the contribution of dissolution to the total amount of sorbed substance is unavoidable.We obtained an equation for the polymolecular absorption isotherm for solubility of the sorbate in the sorbent with formation of solvates. In sorption of LMC by a polymer, the interacting forces that affect the "lifetime" of the sorbate molecule in the adsorption layer or in the solvate are similar in nature. It is assumed that the active sites are fragments of macromolecules with sufficient intermolecular interaction energy for formation of solvates. The reaction of such active sites with the plasticizer dissolved in the amorphous polymer is accounted for by the rule of mole fractions.The quasichemical approach used previously for describing polymolecular adsorption [9, 10] and absorption [11,12] was used for deriving the absorption isotherm equation.Since solvation of the active sites in the polymer by the molecules of LMC is possible, the total amount of LMC in the polymer at equilibrium (C e ) is determined by the amount of LMC incorporated (a) and not incorporated in the solvates (C F ): C e = C F + a. Consider absorption of vapor of the substance into its solution with mole fraction n (LMC not contained in solvates) per 1 mole of active sites A, which is accompanied by solvation of "short-range" and "long-range" order [13]. The coordination number of the solvate is set equal to 1 (for example, the hydration number of the hydroxyl group in cellulose is equal to 1 [6]); the vapor pressure of the dissolved substance is determined by the relation p = np 0 , where p 0 is the vapor pressure of the LMC over the LMC in the...

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Non-equilibrium polycondensation (review)

Cited by 13 publications

References 36 publications

Catalysis of Trans-esterification Reactions in Model Ester Mixtures

Catalysis of Trans-esterification Reactions in Model Ester Mixtures

Non-equilibrium Copolycondensation in Homogeneous Systems

Adsorption of vapors by amorphous polymers

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