Abstract
<p>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<sub>2</sub>B<sub>9</sub>H<sub>11</sub>)2Me]. 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.</p>
Highlights
Some published studies of exchange reactions in blends of conventional industrial polyesters indicate the possibility of producing new polymer materials with valuable properties [1,2,3,4]
It was been found that non-catalytic trans-esterification reaction 1 follows first-order kinetics at a 20fold molar excess of butyl benzoate at temperatures 523 K, 538 K, 548 K and 563 K [8]
Was found to be only 50% in 24 hours. This prompted us to look for efficient catalytic systems for transesterification reactions
Summary
Some published studies of exchange reactions (included trans-esterification) in blends of conventional industrial polyesters indicate the possibility of producing new polymer materials with valuable properties [1,2,3,4]. Using of the inhibitors may expect to stabilize the mixtures of polyesters during their processing and application The objective of this investigation was to find new and efficient catalysts and inhibitors in order to control reactivities of ester groups during the process of trans-esterification. On the first stage of this work the model reaction of trans-esterification of n-butylbenzoate with phenyl-p-chlorobenzoate in the molar ratio of 20:1 (reaction 1) has been studied (Scheme 1) In order to determine the influence of the chemical structure on the activity of ester groups, the reaction of di-n-butylterephthalate with different p-substituted derivatives of phenylbenzoate (20:1 molar ratio) has been studied (reaction 2 − Scheme 2). The estimated error in the observed reaction rate constant (k0) is equal to be 5%
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