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The protolysis of o-benzoic acid derivatives (OBAD), m/p-benzoic acid derivatives (BAD) and salicylic acid derivatives (SAD) in a micelle of dodecylammonium chloride (DAC) have been studied by the ultrasonic relaxation absorption method. The relaxation absorption was larger than in tetradecyltrimethylammonium bromide (TTAB) micellar solution owing to the electrostatic force of NH 3 + in DAC. The rate constants (γ 2 k f , k b ), apparent dissociation constant (K a =k b /γ 2 k f ) and volume change (ΔV) on protolysis were determined. The dependence of the rate constants on pK a in the BAD–DAC system was the same as in the OBAD–DAC system, but differed from those obtained in aqueous solution or in a TTAB micellar solution. The pK a of OBAD in a TTAB micellar solution exceeded that in aqueous solution but in a DAC micellar solution it was less than in aqueous solution. The results, in comparison with those in a TTAB micellar solution, are discussed, based on differences in the electrostatic force of the DAC and TTAB micelles.

Using defatted and SH-blocked bovine serum albumin (BSA), measurements of differential scanning calorimetry (DSC) have been made at pH 7 on the complexes of BSA and a series of sodium alkyl sulfates used were sodium decyl sulfate (SDeS), sodium octyl sulfate (SOS), sodium hexyl sulfate (SHS) and sodium ethyl sulfate (SES). Results obtained were compared with those on the system BSA-sodium dodecyl sulfate (SDS) studied previously. Two peaks P1 and P2 existed in the DSC curve of BSA. These peaks originate in the heat-induced transition of BSA. The pattern of DSC curve changed with the amount of the ligand added, i.e. with the molar mixing ratio ligand/BSA (1). The change for systems BSA-SDeS, BSA-SOS and BSA-SHS was qualitatively the same as that for the system BSA-SDS (2). Interestingly, SES, which is not a surfactant, interacts with BSA. The change for the system BSA-SES was qualitatively the same as that for the system BSA-Na2SO4. All alkyl sulfates suppressed the heat-induced transition at lower concentrations. A linear relationship was obtained for the plots of log(D/A)1 versus log CMC, where (D/A)1 is the molar mixing ratio of anionic surfactant (D) to BSA (A) at which the most heat-stable complex is formed. This suggests that the hydrophobic force has a serious effect on the formation of heat-stable complexes.

Base equilibria of arginine (basic amino acid) in the absence of a micelle and then in a micellar solution of sodium dodecyl sulfate (SDS) have been studied by ultrasonic absorption measurements. Forward (γ 2 k f ) and backward (k b ) rate constants, the apparent base dissociation constant K b (=k b /γ 2 k f ), and the volume change (ΔV) for the reaction were obtained. Micellar effects for arginine were greater than those for a neutral amino acid measured previously. This is discussed in terms of total charge of the amino acids. Similar experiments were carried out for aspartic acid (acidic amino acid)-cationic micelle of dodecyl-ammonium chloride (DAC). Relaxation was considered due to the protolysis of aspartic acid. A slightly lower micellar effect than that for an aromatic carboxylic acid-dodecylammonium chloride (DAC) system was noted. ΔV was smaller than that for an aromatic carboxylic acid with the same pK a

Ultrasonic relaxation absorption has been measured in aqueous solutions of amino acids (tryptophan, leucine, glycine, phenylalanine, asparagine) in the absence and in the presence of micelles of sodium dodecylsulphate. The relaxation absorption was ascribed to the base equilibrium of amino acids, and the rate constants, the base dissociation constant, and the volume change of the reaction were obtained. The smaller micellar catalytic effect for the base equilibrium of amino acids, compared to those of amines and ammonia was ascribed to the electrostatic effect of the carboxylate group. The reaction mechanism, including the interactions of amino acid and the SDS micelles, were discussed.

Measurements of differential scanning calorimetry (d.s.c.) have been made on the complex bovine serum albumin (BSA)-sodium dodecyl sulphate (SDS) under various conditions. There are two peaks P1 and P2 in the d.s.c. curve for BSA at pH 7 and in the absence of NaCl, indicating the presence of the heat-induced transition of BSA. There are three peaks P1, P2 and P3 in the curve for the system with the molar mixing ratio SDS/BSA = 1. With the increase in the amount of SDS, the peak P3 grows at the expense of P1 and P2. There is only a single peak P3 in the curve for the systems SDS/BSA > 7, and no peak at SDS/BSA = 50 and 100. There is a single peak P12 in the curve for BSA at pH 7 and in the presence of 0.05 m NaCl, indicating that the heat-induced transition is suppressed. There are two peaks P12 and P3 for the systems SDS/BSA = 1–5; the area ratio of the peak P3 to P12 increases with the increase in the amount of SDS. There is only a single peak P3 when SDS/BSA > 7, and no peak at SDS/BSA = 50. It is concluded that the peak P3 is a product of SDS regardless of the presence or absence of NaCl. Values of thermal denaturation temperature ( T d ) and enthalpy (Δ H ) of thermal denaturation indicate that the complex AD 12 (A = BSA, D = SDS) is in the most thermostabilized state. It is suggested that some of the higher-order structures of BSA are reorganized by the binding of 12 SDS so as to make the BSA molecule the most compact and thermostable. D.s.c. curves of AD 1 have been measured in the pH range 3–11. Patterns change depending on the pH-induced conformational change of BSA. It is emphasized that the pattern is different below and above pH 5.6 or the isoionic point of BSA. The reason for this is discussed.

Using defatted and SH-blocked bovine serum albumin (BSA), measurements of differential scanning calorimetry (d.s.c.) have been made mainly in NaSCN solution. BSA undergoes a heat-induced conformational transition in a particular range of pH and ionic strength and is separated into two thermally independent units, each of which has different thermostability in acidic and alkaline pH regions. Comparisons were made of the pH dependencies of the enthalpy of thermal denaturation (delta H) and the temperature of thermal denaturation (Td) in 0.01 M NaSCN with those in 0.01 M NaCl. It has been found that the stabilizing effect of NaSCN on BSA is larger than that of NaCl at pH 3.5-8, and that the heat-induced transition occurs by the electrostatic repulsive forces among the positively charged amino acid residues in a segment Arg 184-Arg 216 containing Trp 212 and the primary binding sites of anions. At ionic strength 0.01, the relative effectiveness of anions in suppressing the heat-induced transition and increasing the thermostability of BSA follows the order ClO4- - greater than or equal to SCN- greater than I- greater than SO4(2-) greater than Br- greater than Cl-. At ionic strength 0.1, the heat-induced transition is suppressing in all the salt solutions, and a Td increase follows the order ClO4- greater than or equal to SCN- greater than I- greater than Br- greater than Cl- greater than or equal to SO4(2-). Thus, the highly chaotropic ions thermostabilize BSA more markedly than kosmotropic ions in the low and moderate salt concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

The base dissociation of ammonia has been studied by an ultrasonic absorption method in both the absence and presence of SDS micelle in aqueous solution, and kinetic parameters were obtained. The micellar catalyzed reaction mechanism, including the interactions of ammonium ion with SDS micelles, are discussed.

Using defatted and SH-blocked bovine serum albumin (BSA), the measurement of differential scanning calorimetry (d.s.c.) was performed in the range pH 3-11 and ionic strength 0.001-1 M. The shape of the d.s.c. curve was classified into four regimes: (i) the curve with no peak, (ii) that with a peak, (iii) that with a peak having a shoulder, and (iv) that with two peaks. The presence of two peaks was interpreted by the concept of 'heat-induced transition'. The BSA molecule is composed of two domains, thermodynamically independent owing to the formation of a crevice in BSA in a particular range of pH and ionic strength; this gives two peaks in the d.s.c. curve. The enthalpy (delta H) from the d.s.c. curve was plotted against pH and against the NaCl concentration. The value of delta H increased with the increase in the ionic strength in the pH range 5.6-9.0. The temperature of thermal denaturation (the temperature of the peak maximum, Td) was raised with the increase in the ionic strength in the pH range 4.5-9.0, but was lowered in the pH range 3.5-4.0. BSA was stabilized in the neutral-alkaline pH range by the presence of NaCl, but was destabilized in the acidic pH range.

Ultrasonic relaxation absorption has been observed in aqueous solutions of ortho-benzoic acid derivatives (OBAD) in the presence of a micelle of tetradecyltrimethylammonium bromide (TTAB). Relaxation absorptions were ascribed to the protolysis of acids on the surface of the micelle. The apparent dissociation constant (pKa=kb/γ2kf), rate constants (γ2kf, kb) and volume change (ΔV) for the reactions were determined. The dependence of rate constants on pKa for OBAD was compared with that for meta- and para-benzoic acid derivatives (BAD). It was especially noticeable that the dissociation of OBAD in the micellar solution is depressed more than that in aqueous solution. This can be explained as due to electrostatic effects, the polarity of solution and solvation in the TTAB micellar solution. The dependence of ΔV of OBAD on pKa was also compared with that of BAD. The result was considered to be due to differences in solute–solvent interactions and the situation around OBAD and BAD in the micellar solution.

The protolysis of carboxylic acids has been kinetically studied by the ultrasonic absorption method in the presence of tetradecyltrimethylammonium bromide (TTAB) micelles in aqueous solution. The carboxylic acids studied were classified into two categories, one capable of formation of intramolecular hydrogen bond, namely the salicylic acid derivatives (SAD) and the other which cannot form the bond, namely the benzoic acid derivatives (BAD). The rate constant (γ2kf, kb), the apparent dissociation constant (Ka), and the volume change of the reaction (ΔV) were obtained. Different Ka dependences of the rate constants observed for SAD and BAD are discussed in relation to the effect of intramolecular hydrogen bond. pKa dependences were also observed for ΔV of SAD and BAD. These dependences are larger than those in aqueous solution. This result was attributed to the change of arrangement of water molecules around the solute in micellar solution and aqueous solution.

The kinetics of the protolysis of aromatic carboxylic acids solubilized in a micelle of dodecylpyridinium chloride has been studied by the ultrasonic relaxation absorption measurements. The rate constants are dependent on the acid dissociation constant K a and the results are interpreted by means of the Bronsted catalysis law. The micellar catalytic effect is discussed in comparison to those in the acid and base equilibria of carboxylic acids and amines in the micellar solutions. The volume change of the reaction is also found to be dependent on K a .

Ultrasonic absorption was measured in hexane solutions of octylammonium alkanoates (nonanoate, decanoate, dodecanoate, and tetradecanoate). The value of critical micelle concentration (CMC) was determined to be 0.02 M (1 M=1 mol dm−3) for all the surfactants. The excess ultrasonic absorption, observed in the solutions above the CMC, was ascribed to the association-dissociation of the monomer to and from the micelle. From the concentration dependences of the ultrasonic parameters, the mean aggregation number of the micelle, the rate constants, and the enthalpy change of the above reaction were obtained. These results were discussed in relation to the shape of the reversed micelle and the solute-solvent interactions.

Micellar catalytic effects on the base dissociation of methylamine have been studied by ultrasonic absorption method. The dissociation constant, the rate constants, and the volume change of the reaction were obtained in the absence and in the presence of SDS. The micellar catalytic effects observed for methylamine was smaller than those for amines of long alkyl chain, which was ascribed to the facts that the former is incorporated into the micellar ionic atmosphere in the concentrated micellar solution while the latters are solubilized into micelles.

The 13C chemical shifts of 4-amino- and 4-arylamino-1, 2-naphthoquinones measured in DMSO-d6, pyridine-d5 and a D2O solution of NaOD indicated that the predominant tautomer in neutral solvents is the 1, 2-dioxo-4-amino-naphthalene (Ia) form, while that in weak basic solvents is the 1-oxo-2-hydroxy-4-imino-naphthalene (Ib) form and that in an aqueous solution of NaOH is the anion of the Ib form. The electronic spectrum of 4-anilino-1, 2-naphthoquinone measured in a mixture of EtOH and 0.05M H3SO4 (1 : 4 by volume) indicated that its tautomeric form in an aqueous strong acid solution is the Ia form and that the compound is hydrolyzed quickly to produce 2-hydroxy-1, 4-naphtho-quinone. The magnitudes of substituent effects observed in the electronic spectra of 4-(4'-substituted)-anilino-1, 2-naphthoquinones measured in EtOH were found to be smaller than those measured in pyridine. This difference was considered to provide confirmation that the predominant tautomer in neutral solvents is the Ia form. The theoretical π-π* transition energies of 4-arylamino-1, 2-naphthoquinones were calculated for both the Ia and the Ib forms by means of Pariser-Parr-Pople type molecular orbital calculations.

The ultrasonic relaxation absorption has been measured in aqueous solution of dipentylamine, dihexylamine, dioctylamine, N-methylphenethylamine, and N-ethylbenzylamine in the presence of the sodium dodecyl sulfate(SDS) micelle. The relaxation absorption has been ascribed to the base equilibrium of the amines on the surface of the micelle: RR′NH2++OH−\oversetkf\undersetkb\ightleftharpoonsRR′NH+H2O. The rate constants γ±2kf, kb, the apparent base dissociation constant Kb (=kb⁄γ±2kf), and the volume change in the base equilibrium ΔV were obtained, where γ± is the mean activity coefficient for RR′NH2+ and OH−. The dependence of the rate constants on Kb revealed that, in the detailed mechanism of the base equilibrium of the amines, RR′\underset(I)NH2++OH−\oversetk12\undersetk21\ightleftharpoons(RR′NH\underset(II)2+···OH−)\oversetk23\undersetk32\ightleftharpoonsRR′N\underset(III)H+H2O, the rate-determining step is the proton-transfer process, (II) \ightleftharpoons (III). The pKb values of the secondary amines ...

Hydrolyse de methyl-1 heptylamine, tetramethyl-1,1,3,3 butylamine, phenyl-4 butylamine, phenyl-3propylamine phenethylamine et benzylamine en presence de micelles de laurylsulfate de Na

The theoretically proposed structures of activated complexes in polarographic redox reactions of unsaturated organic compounds were shown to be valid without exception in the cases of the oxidation reactions examined. Additional data supporting the validity of the assumption for reduction reactions were also obtained. The MASP-HMO method was very useful for the calculation of π-stabilization energies of para- and meta-disubstituted aromatic compounds.

Two crystalline color reaction products were isolated from the reaction mixture of butylurea with 1-phenyl-1, 2-propanedione in dioxane containing HCl. One of them (A) was found to be identical with 1, 3'-dibutyl-5, 5'-diphenyl-2, 2'-dioxo-4, 4'-diimidazolylmethane (I) which was isolated previously. The other one (C) was found to be isomeric with compound (B) which was also isolated previously. It was found that the only difference between B and C is the positions of their butyl side chains. In order to decide the positions of the side chains of B and C, the differences between the physico-chemical properties expected to be shown by 3, 3'-dibutyl-(II) and by 1, 1'-dibutyl-5, 5'-diphenyl-2, 2'-dioxo-4, 4'-diimidazolylmethane (III) were estimated theoretically. From the results of this estimation the structures II and III could be assigned to B and C, respectively.

Etude de la relaxation dans des solutions d'acide benzoique (et ses derives) en presence du chlorure de dodecylammonium. La relaxation est attribuee a la protolyse de l'acide carboxylique sur la surface de la micelle. Parametres cinetiques

The interaction between imidazole and p-benzoquinone in acetonitrile was investigated at both low temperature (below 0°) and room temperature. The step of formation of the charge-transfer complex between two intact molecules could not be detected. Instead, the two compounds were found to react with each other fairly quickly at room temperature to form 2, 5-bis (imidazol-1-yl) hydroquinone, 2, 3-bis (imidazol-1-yl) hydroquinone and hydroquinone.

The out-of-plane CH deformation vibrations of the aromatic ring of the tetralin series normally appear in almost the same frequency region as in the corresponding benzene series, and their frequencies are regularly shifted by the type of substituents attached to the aromatic ring with a few exceptions. All compounds which have an isolated CH group in the aromatic ring exhibit fairly strong absorption bands around the 800 cm−1 region, which may be associated with the aromatic ring. Carbonyl and hydroxyl groups in the peri-position of tetralone are strongly chelated, showing frequency shifts in their stretching vibrations.

The ultrasonic absorptions of Aerosol OT in dodecane solution were measured in the frequency range 5–95 MHz at various temperatures. An excess absorption caused by single relaxation was observed above the second critical micelle concentration. This is attributed to the conformational change in structure of two kinds of Aerosol OT micelles, since the maximum excess absorption per wave length depends on the concentration and temperature. The thermodynamic and kinetic parameters were determined in relation to the reaction.

Hydrolyse de methyl-1 heptylamine, tetramethyl-1,1,3,3 butylamine, phenyl-4 butylamine, phenyl-3propylamine phenethylamine et benzylamine en presence de micelles de laurylsulfate de Na

A method for quantitative determination of nano gram level of benzo[a]pyrene (BP) in foodstuffs using tritiated BP (3H-BP) was described. Extracts from foodstuffs, having been added a certain amount of 3H-BP, were fractionated by column chromatography on Florisil, and thinlayer chromatography on acetylated cellulose. Concentration and radio activity of BP in the final fraction were determined by fluorescence spectrometry and liquid scintillation. Recovery ratio of each experiment was obtained by comparing the radio activities of added 3H-BP and separated BP. Concentration of BP in the sample analyzed was calculated from the amount of isolated BP and the recovery ratio in each experiment. A quantitative limit of BP by this method was 0.2 ppb when 50 g of sample was used.By this method, contents of BP in each sample of Tenpura oil, salad oil, flour, and polished rice were determined as 0.6, 0.2, 0.1, and