Effect of omega-hydrogenation on the adsorption of fluorononanols at the hexane/water interface: Temperature effect on the adsorption of fluorononanols

The interfacial tensions (gamma) of the hexane solutions of 1H,1H-perfluorononanol (FDFC9OH) and its omega-hydrogenated analogue 1H,1H,9H-perfluorononanol (HDFC9OH) against water were measured as a function of temperature and concentration under atmospheric pressure in order to know the effect of omega-dipoles on the adsorption behavior of fluorononanols. The interfacial pressure (pi) versus mean area per adsorbed molecule (A) curves consist of two discontinuous changes among three different states: the gaseous, expanded, and condensed states. The A values at given pi in the gaseous and expanded states are larger for HDFC9OH than for FDFC9OH. The changes in partial molar entropy (s1(H) - s1(O)) and energy (u1(H) - u1(O)) of adsorption were evaluated. Their values are negative, and therefore, the alcohols have a smaller entropy and energy at the interface than in the bulk solution. Furthermore, the u1(H) - u1(O) value is more negative for HDFC9OH than for FDFC9OH in the expanded state and also in the condensed film just above the expanded-condensed phase transition point. This seems to be due to the following: (1) HDFC9OH may tilt from interface normal for omega-dipoles to interact effectively with water molecules in the interfacial region and to reduce their own repulsive interaction between neighbors arranging parallel in the adsorbed film. This leads to a lower value for HDFC9OH than for FDFC9OH. (2) The contact of omega-dipoles with hexane molecules in the bulk solution is energetically unfavorable, and thus, the u1(O) value of HDFC9OH is expected to be larger than that of FDFC9OH.     

Meromorphic approximation theorem in a Stein space

We prove the meromorphic version of the Weil–Oka approximation theorem in a reduced Stein space X and give some characterizations of meromorphically -convex open sets of X. As an application we prove that for every meromorphically -convex open set D of a reduced Stein space X with no isolated points there exists a family of holomorphic functions on X such that the normality domain of coincides with D. Mathematics Subject Classification (2000)  32E10, 32C15, 32E30, 32A19     

Charge-remote fragmentation characteristics of functionalized alkanes in high-energy collision-induced dissociation

In this study we report on high-energy, collision-induced dissociation processes leading to charge-remote fragmentations, using three alkyl cations, namely n-hexadecylpyridinium, n-hexadecyltriphenylphosphonium and n-hexadecyltriethylammonium, each with and without (2)H(2)-labelling at the C(9) position of the hexadecyl chain. The characteristic patterns corresponding to the formal elimination of alkane elements were observed, and the (2)H(2)-labelling at C(9) clearly affected only one charge-remote fragment ion of the homologous series. However, in addition to the expected fragment ion containing only one deuterium atom, a significant ion retaining two deuterium atoms was observed. MS/MS/MS experiments demonstrated clearly that the latter ion showed partial deuteration around the charge site, the level of deuteration depending on the structure of the original precursor cation. These results can be interpreted in terms of two novel, distinct mechanisms, one of which involves an excited state in an aromatic ring. Mixed-site fragmentation (MSF) ions were also observed from the phosphonium and ammonium ion precursors. We believe that the observation of the MSF process occurring at an sp(2)-hybridized center in the phosphonium series has not been reported previously. It thus becomes apparent that high-energy collisions leading to charge-remote reactions in fact lead to a broad range of pathways. Copyright 2000 John Wiley & Sons, Ltd.     

Preparation of viologen polymers from alkylene dipyridinium salts by cyanide ion

Polymers of viologen structure were prepared by oxidation of quinoid polymers obtained by the dimerization of alkylene dipyridinium salts with cyanide ion as catalyst. These polymers showed the behavior of polyelectrolytes and redox polymers that turn a deep blue when reduced chemically or electrically.     

Directed 2-azonia-[3,3]-sigmatropic rearrangements. a convenient preparation of substituted 1-azaspiro[4,5]decanes

3-Acetylpyrrolidines are prepared from 5-methyl-5-vinyloxazolidines in a reaction which involves a directed 2-azonia-[3,3]-sigmatropic rearrangement.     

Highly efficient method for oxidation of alcohol with tert -butyl hydroperoxide catalyzed by diaryl diselenide

In the presence of a catalytic amount of diphenyl diselenide (0.1–0.2 eq) $\text{tert}$-butyl hydroperoxide oxidized benzylic and primary allylic alcohols in high yields. Saturated alcohols were alo cleanly oxidized by the use of bis(2,4,6-trimethylphenyl) diselenide.