B. E. Ivanov

The effect of electrolytes on the reaction rates and acid-base equilibria in ionic micelles

The influence of a number of electrolytes on the micellar effect of cetyltrimethylammoniurn bromide (CTAB) in the hydrolysis ofp-nitrophenyl acetate (1) and bis(p-nitrophenyl) methylphosphonate (2) and in the course of the acid-base dissociation of thep-nitroanilide of bis(chloromethyl)phosphinic acid (3) has been examined. The activity of the salts studied increases in the following order: MeCOOK<K2CO3<KCl<KBr<KNO3<p-MeC6H4SO3K. It has been found that in the presence of electrolytes the catalytic effect of CTAB micelles in the hydrolysis reactions of esters1 and2 decreases, and the pKa value of anilide3 increases. The results obtained are interpreted in terms of the pseudophase model of micellar catalysis. The analysis of the experimental data carried out using logarithmic coordinates revealed a relationship between phase transitions in micellar catalysis and in micellization.

Basicity of o-aminomethylphenols in nonaqueous media

Summary1.The basicity of o-aminomethylphenols in nitromethane, acetonitrile, and ethanol is lower in comparison with benzylamines, which do not have any intramolecular hydrogen bonds.2.The influence of the intramolecular hydrogen bond on the basicity of the o-aminomethylphenols increases in the following series of solvents: ethanol<water<acetonitrile-nitromethane.3.Between the values of pKa of the o-aminomethylphenols and benzylamines in water, ethanol, nitromethane, or acetonitrile, linear correlations are obtained with slopes close to unity.4.The relationship between pKa in nitromethane and in acetonitrile is common for primary, secondary, and tertiary alkylamines, benzylamines, o-aminomethylphenols, anilines, and pyridine.

Kinetics of the reactions of p-nitrophenylbis(chloromethyl)phosphinate with primary and secondary amines

Study has been made of the kinetics of the reaction of p-nitrophenylbis(chloromethyl)-phosphinate with primary and secondary amines. Reaction proceeds through rupture of the ester bond at the P atom and is catalyzed by a second amine molecule. The reaction rate is determined by induction and steric effects in the amine substituents. The activation energy for the reaction with n-butylamine is negative.

Catalysis of the hydrolysis of di(p-nitrophenyl) methylphosphonate by polyamines

ConclusionsThe kinetics of the hydrolysis of di(p-nitrophenyl)methylphosphonate in aqueous solutions of triethylenetetramine and tetraethylenepentamine have been studied at various pH values. The catalytic rate constants for the neutral and monoprotonated forms of the polyamines are represented by the Brønsted equation as with the primary aliphatic amines and for the diprotonated forms they are represented together with the secondary aliphatic amines.

Hydrolysis of substituted 2-ethoxy-2-oxo-1-oxa-2-phosphoindans

Conclusions1.We synthesized a number of 2-ethoxy-2-oxo-1-oxa-2-phosphoindans with substituants in the benzene ring and studied their reactivity in neutral aqueous hydrolysis.2.It was shown that the rate constant for the hydrolysis of the phosphoindans is highly sensitive to a change in their structure, which sensitivity is determined by the dual effect of the substituents on the reaction center.

Tautomerism in the ortho-aminomethylphenols

Conclusions1.A tautomeric equilibrium is established between the neutral and zwitterion forms of the ortho-aminomethylphenols in aqueous solutions.2.Determination has been made of the tautomeric equilibrium constants and the acid-base equilibrium constants for the various forms of the ortho-aminomethylphenols.3.An equation for calculating the tautomeric equilibrium constant has been developed.

The influence of micellization ofn-decylamine on its basicity and reactivity toward carboxylic acid esters

Micellization ofn-decylamine in aqueous solution leads to substantial decrease in its pKa, and increase in its reactivity in the nucleophilic substitution ofp-nitrophenylic esters of carboxylic acids (up to 70 times compared to ethylamine which forms no micelles). The influence of cetylpyridinium bromide on the acid-base properties ofn-decylamine and its reactivity was investigated. It was found that the reaction withn-decylamine can be accelerated or retarded depending on the hydrophobicity of the esters. The quantitative characteristics of the mieellar catalytic processes were estimated.

Nucleophilic substitution in bis(4-nitrophenyl) ethyl phosphate in alkaline micellar solutions of 2-hydroxyethyldimethyloctadecylammonium bromide

A study was carried out on the mechanism of nucleophilic substitution in bis(4-nitrophenyl) ethyl phosphate (BNEP) in alkaline solutions of 2-hydroxyethyldimethyl-octadecylammonium bromide. In the presence of a 2-hydroxyethyl surfactant (Sur), nucleophilic properties of the 2-hydroxyethyl group, which is dissociated in alkaline media, are evident in addition to alkaline hydrolysis of the substrate. The second pathway arises beginning in the region of premicellar surfactant aggregates and is predominant in micellar solutions.

Alkylation reaction of amines by dimethyl phosphite

The alkylation reaction kinetics of a series of amines of different structures by dimethyl phosphite have been studied. Two-parameter correlation equations have been deduced, relating reactivity to steric and inductive effects of substituent s attached to the nitrogen atom in the amine; a Swain-Scott equation has also been deduced, establishing a correlation between the rate of alkylation and the nucleophilicity of the reaction site. When steric conditions at the nitrogen atom are fixed, as in the case of orthoaminomethylphenols, the reactivity follows a Brönsted equation.

Cetylpyridinium bromide-catalyzed reaction of ortho-aminomethylphenols with para-nitrophenyldiphenyl phosphate

Cetylpyridinium bromide micelles accelerate the reaction of paranitrophenyldiphenyl phosphate with orthoaminomethylphenol by more than an order of magnitude in aqueous micellar solutions. The rate constants for this reaction are, however, about 50 times lower in the micellar phase than in water, i.e., the principal factor responsible for micellar catalysis in this reaction is concentration of the reagent.