A lacunary interpolation algorithm on arbitrary points

Here, the following lacunary interpolation problem is considered: to find the polynomial which together with its second and third derivatives agrees on arbitrary points with the corresponding values of a given function. The representation of the polynomial depends on the solution of a linear algebraic system. The method is constructed on this observation. The error analysis shows that it behaves like the corresponding Lagrange interpolation problem with an equivalent number of conditions. Some applications are shown.     

Methylpyridylbenzimidazoles. Part I. Mono,bis-quaternary salts and related polymethyne dyes

The reaction of 2-(4-methyl-2-pyridyl)benzimidazole with long chain alkyl halides led to N-alkylation at the imidazole ring. The bases obtained were selectively quaternized at the azine and azole nitrogen atoms. The pyridinium salts gave the corresponding polymethyne dyes. Spectral (nmr and uv) and surface properties are briefly discussed.     

Synthesis,Surface Activity and Micelle Formation of Novel Cyanine Dyes

The synthesis, surface activity and micelle formation of three novel cyanine dyes with amphiphilic character is described. It is illustrated by combined surface tension and absorption measurements that in one case self-assembly is highly cooperative leading to aggregates with unique absorption properties.     

Effect of a proximal substituent on the triruthenium dodecacarbonyl-catalyzed reductive carbonylation of nitroarenes

Three nitroarenes were submitted to Ru₃(CO)₁₂-catalyzed reductive carbonylation in acetonitrile and in cis-cyclooctene. The main reaction products were the corresponding amines, ureas and six- or five-membered cyclization products. Optimization of the reaction varying the temperature, the CO pressure, the catalyst/substrate ratio and the reaction time and a statistical analysis of conversion and selectivity data allow to suggest a reaction mechanism in some reaction conditions.     

Acid-base titrations of substituted benzoic acids in micellar systems

The dissociation equilibria of substituted benzoic acids in cationic and anionic micellar systems, investigated potentiometrically, show pK shifts of less than 1.0 in cationic and 0.5–3 in anionic micelles. Visual titrations of otherwise insoluble acids in cationic micelles give satisfactory results.     

Enhancement of the ETS-10 titanosilicate activity in the shape-selective photocatalytic degradation of large aromatic molecules by controlled defect production

In recent times, it has been shown that the microporous ETS-10 titanosilicate can be used as a shape-selective photocatalyst for the decomposition of aromatic molecules (Chem. Commun. 2001, 2131). Its actual use on practical grounds is however discouraged by its too low activity, when compared with that of TiO(2) photocatalysts. In the present work, we show how an ad hoc mild treatment with HF enhances the activity of ETS-10 toward the photodegradation of large aromatic molecules that are unable to penetrate inside the zeolitic pores, such as 2,5-dichlorophenol, 2,4,5-trichlorophenol, 1,3,5-trihydroxybenzene, and 2,3-dihydroxynaphthalene (DHN). The photoactivity of the acid-treated materials is comparable or even greater than that of the nonselective TiO(2) catalyst. Moreover, the enhancement of the photoactivity is accompanied by a remarkable parallel increase of the shape selectivity, particularly toward DHN (k(DHN)/k(P) = 127, where P = phenol). A complete characterization (by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray aborption spectroscopy techniques) of a set of ETS-10 samples which have undergone a progressively severe HF treatment allows us to propose an explanation of the photocatalytic activity and selectivity of the modified materials.     

Living free‐radical polymerization of styrene under a constant source of γ radiation

Living polymerization of styrene was observed using γ radiation as a source of initiation and 1‐phenylethyl phenyldithioacetate as a reversible addition–fragmentation chain transfer (RAFT) agent. The γ radiation had little or no detrimental effect on the RAFT agent, with the molecular weight of the polymer increasing linearly with conversion (up to the maximum measured conversions of 30%). The polymerization had kinetics (polym.) consistent with those of a living polymerization (first order in monomer) and proportional to the square root of the radiation‐dose rate. This initiation technique may facilitate the grafting of narrow polydispersity, well‐defined polymers onto existing polymer surfaces as well as allow a wealth of kinetic experiments using the constant radical flux generated by γ radiation. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 19–25, 2002     

Partition equilibria of phenols between water and anionic micelles : Correlation with the Octanol/Water System

The partition equilibria of a series of thirty substituted phenols bearing different chemical groups between aqueous solutions and sodium dodecylsulfate micelles was investigated by using micellar high-performance liquid chromatography and by studying the variation of the acidity constant. The contribution of each substituent to the free energy of transfer from water to micelles was estimated. The group contribution approach is shown to be valid for polysubstituted compounds under well defined conditions. A comparison with partition coefficients obtained in classical two-phase system (1-octanol/water), frequently used as biochemical model systems, is discussed     

Kinetic determination of adrenaline,l-dopa and their mixtures with a stopped-flow spectrophotometric technique

Catecholamines (adrenaline and L-Dopa) can be determined by a stopped-flow spectrophotometric technique. For individual determinations, catecholamines are oxidized to the corresponding o-benzoquinones by hexachloroiridate(IV). Concentrations in the range 2·10^-4–2·10^-3 M can be determined with errors of about 2 %. For evaluation of mixtures, aminochromes are formed. The method allows a catecholamine concentration of about 5·10^-6 M to be determined in the presence of a ten-fold amount of another catecholamine, with a maximum error of about 10 %.