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The mechanism of isobutylene initiation in the presence of ethylaluminum dichloride–proton donor (water, phenol, hydrochloric acid) complex catalysts is studied by the ab initio HF/3-21G method. The energetics of these reactions are estimated, and the values of their activation energy and thermal effects are obtained. It is established that among the studied catalysts, an increase in the activation energy of the initiation of isobutylene oligomerization is symbatic with the selectivity of this process from the C4 fraction. [ABSTRACT FROM AUTHOR]

In this article, for the first time, a systematic study of the mechanism of protonation of the following series of styrenes is carried out: styrene - p-methylstyrene - pethylstyrene - p-isopropylstyrene - p-tert-butylstyrene by classical quantum-chemical methods ab initio and DFT on α- and β-carbon atoms of the monomer. It is shown that both directions of proton attack are barrier-free. All reactions are exothermic, and the heat effects of the processes under study do not depend on the nature of the monomers under study when attacking the α-carbon atom, and when attacking Cβ, they decrease in the series of studied styrenes. [ABSTRACT FROM AUTHOR]

The experimental methods to estimate the main physico-chemical properties were worked out. Based on theoretical and experimental data we found that maximal sorptional ability of burn dressing equals the free volume of the dressing material, calculated from the value of the material density. We found that the study sorption ability water can be used as a model liquid instead of the blood plasma medium. Kinetic parameters were determined from the sorption curves. These parameters showed that the first aid burn dressings markedly differ in the value of the rate or liquid media sorption at stages close to the sorption limits. We established that the air penetrability parameter in wet state decreases abruptly by 2 - 3 orders of magnitude for the majority of tested dressings. This is due to the filling of porous space by liquid medium. The value of adhesive strength after the end of its action on the wound must not exceed 20 N/m. From the data obtained in this study we formulated the following criteria to estimate the efficiency of the first aid bum dressing: maximum sorptional ability for water must be at least 10 g/g; optimal thickness of dressings, fulfilling this value of sorptional capacity, must be ~ 5-10-3 m, the adhesive strength must not exceed 20 N/min, and the average diameter of open (connected) pores must not exceed 5-10-7 m. [ABSTRACT FROM AUTHOR]

For the first time, the mechanism of the reaction of 2,2,3,3-tetrafluoropropanol with thionyl chloride at the electronic level was studied using the classical quantum chemical method ab initio in the 3-21G basis. The reaction was studied in two directions. The first direction is synchronous simultaneous separation of chlorine and the formation of an O-S bond occurs. The second direction goes by the mechanism of the reaction of direct addition at the sulphur atom followed by the elimination of the chloride anion. It was found that the second direction is more energy-efficient than the first, since the reaction is barrier-free and the first direction-synchronous reaction has a barrier of more than 5 kJ/mol. [ABSTRACT FROM AUTHOR]

In this work, we performed a quantum-chemical calculation of a graphene oxide molecule by the MNDO method. An optimised geometric and electronic structure of this compound is obtained. It was found that the studied molecule, graphene oxide, belongs to the class of very weak Brönsted acids (pKa > 14). [ABSTRACT FROM AUTHOR]

For the first time, a quantum-chemical study of the initiation mechanism of the cationic polymerisation monomer p-methylstyrene in the presence of a complex catalyst of aluminum chloride -- hydrochloric acid in toluene with a stoichiometric composition of 1:1:4 by the ab initio method was performed. We showed that the energy barrier is 15 kJ/mol, and the thermal effect of the reaction is 113 kJ/mol. The reaction is of exotermic character and represents the usual acceptance of a proton from the complex catalyst AlCl3-HCl and its attachment to the most hydrogenated carbon atom C(1). [ABSTRACT FROM AUTHOR]

The first quantum-chemical study of the initiation mechanism of propylene in the presence of a complex chloride aluminium catalyst by the ab initio HF/6-311G** method was carried out with optimisation of the geometry in all parameters by a standard gradient method for attacks of the initiating particle on a-carbon monomer atoms. We showed that this reaction is barrier-like and exothermic. The mechanism of initiation is a coordinated process of SN 2-nucleophilic substitution. The energy barrier in the attack of the initiating particle on the a-carbon atom of propylene is 124 kJ/mol, the thermal effect of the reaction equals -49 kJ/mol. [ABSTRACT FROM AUTHOR]

The first quantum-chemical calculation of the molecules 22, 124 and 200 hexagons by the method MNDO was performed with optimisation of the geometry for all parameters by a standard gradient method. The optimised geometric and electronic structures of 22, 124 and 200 hexagons were obtained and their acid strength was theoretically evaluated (pKa = 33). It was found that the molecules belong to the class of very weak CH-acids (pKa > 14). [ABSTRACT FROM AUTHOR]

The first quantum-chemical study of the initiation mechanism of isobutylene in the presence of a complex chloride aluminium catalyst by the ab initio HF/6-311G** method was carried out with optimisation of the geometry in all parameters by a standard gradient method for attacks of the initiating particle on α-carbon monomer atoms. We showed that this reaction is barrier-like and exothermic. The mechanism of initiation is a coordinated process of SN²-nucleophilic substitution. The energy barrier in the attack of the initiating particle on the α-carbon atom of isobutylene is 97 kJ/mol, the thermal effect of the reaction equals 44 kJ/mol. [ABSTRACT FROM AUTHOR]

The first quantum-chemical study of the initiation mechanism of 4-methylpentene-1 in the presence of a complex chloride aluminium catalyst by the ab initio HF/6-311G** method was carried out with optimisation of the geometry in all parameters by a standard gradient method for attacks of the initiating particle on α-carbon monomer atoms. We showed that these reactions are barrier-like and exothermic. The mechanism of initiation is a coordinated process of SN 2-nucleophilic substitution. The energy barrier in the attack of the initiating particle on the α-carbon atom of 4-methylpentene-1 is 94 kJ/mol, the thermal effect of the reaction equals 52 kJ/mol. [ABSTRACT FROM AUTHOR]

The first quantum-chemical study of the initiation mechanism of p-isopropylstyrene in the presence of a complex boron fluoride catalyst by the classical ab initio method in the 6-311G** basis was carried out with optimisation of the geometry in all parameters by a standard gradient method for attacks of the initiating particle on α-carbon monomer atoms. It is shown that these reactions are barrier-like and exothermic. The mechanism of initiation is a coordinated process of SN²-nucleophilic substitution. The energy barrier in the attack of the initiating particle on the α-carbon atom of p-methylstyrene is197 kJ/mol, the thermal effect of the reaction equals 31 kJ/mol. [ABSTRACT FROM AUTHOR]