Thesis (Ph. D.)--University of Iowa, 2007. / Supervisor: Douglas R. Flanagan. Includes bibliographical references (leaves 310-319).

Thesis (doctoral)--Friedrich-Wilhelms-Universität Berlin, 1842. / Interleaved with blank pages. Also available on the Internet.

Texte remanié de: thèse--Sc. phys.--Paris, 1968. / Extrait du "Journal de chimie physique" T. 65, 1968, n° 6, pp. 1129-1140 . Conservé sous la cote : [4° V. 25892 (134)].

The nmr spectra of 2,3-dihydro-1,4-diazepinium salts are discussed. From the magnitude of the coupling constants around the conjugated part of the molecules, a planar partial structure with complete electron delocalisation is indicated. The molecule as a whole adopts a half-chair configuration which rapidly inverts at room temperature. The effect of ring substitution on this exchange process is correlated with the size of the substituents. The mass spectra of a variety of 2,3-dihydro-1,4-diazepinium salts are reported. The molecular ion of the cation is only rarely observable due to thermal dissociation of the salt. The 1 2 major breakdown process involves the loss of the (N1-C2) fragment but other pathways are also considered. The factors governing some anomalous fragmentation patterns are discussed. The rates of bromination in methanol of a number of 2,3-dihydro-1,4-diazepinium salts were measured under first-order conditions, normally by stopped flow methods. Differences in rate of factors of up to 10000 between dihydrodiazepines with only alkyl or aryl substituents, are correlated with steric effects in the region of the reaction site, 5,6,7-Unsubstituted 2,3-dihydro-1,4-diazepinium salts are tedious to make by standard methods, Their facile preparation from l,5-diaryl-1,5-diazapentadienium salts under high dilution conditions, is discussed, and the scope of the synthesis was explored. The mechanism of the reaction was investigated using mono-amine model compounds. Attempts to prepare 5,7-dimethyl-dihydrodiazepinium salts by this method generally resulted in the formation of 2-methylimidazolines. The parent 2,3-dihydro-1,4-diazepinium perchlorate was obtainable by this high dilution synthesis in sufficient quantities for a study of its properties to be made. it is active towards electrophiles, giving 6-substitution products, and reacts with-nucleophiles at the 5(7) position. In contrast to 5,7" substituted dihydrodiazepines, the 6-halogeno derivatives are inert towards nucleophiles at the 6-positiono A series of 1,2-dihydropyrimidines was prepared, and the chemical and spectroscopic properties of these heterocycles are compared with those of the isoelectronic 2,3-dihydro-1,4-diazepines. Dihydropyrimidines show meneidic reactions with electrophiles at the 5-position, taut only 6-unsubstituted derivatives react with nucleophiles at the 6-position. A convenient synthetic route from 4-methyldihydropyrimidines to 5-methyldihydrodiazepinium salts is described. The effect of electronic perturbation on the 1,5-diazapentadienium system was investigated using series of 1,3-dimethyl-1,2-dihydro-2-oxo- and 2-thiopyrimidinium salts. Substitution reactions of 4,6-unsutastituted derivatives with electrophiles have been shown to proceed by alternative mechanisms; those pyrimidines with 4(6)-methyl substituents also show substitution reactions in the methyl groups. Stable adducts are formed by reaction of the 4,6-unsubstituted compounds with bases. The structure and chemical properties of these pseudobases are discussed. The electronic structure of 2,3-dihydro-1,4-diazepinium perchlorates and the other 1,5-diazapentadienium salts considered in this thesis, was investigated by 13C nmr spectroscopy.

The effect of some simple salts on the viscosity of formamide has been studied at a number of temperatures and interpreted in terms of ion-solvent interactions using the equation suggested by Jones and Dole. Further evidence to support the various conclusions drawn has been provided by application of Eyring's reaction rate theory to the viscosity processes in solution. The viscosities of binary mixtures of formamide and water, methanol or dimethylformamide have been investigated over the whole composition range and the ability of three semi-empirical models to describe these systems has been discussed. A new three parameter equation has been proposed. Finally the effect of sodium chloride on the binary mixture formamide/water has been considered. It has been shown that, in general, for viscosity measurements to be a useful tool for investigating ion-solvent and solvent-solvent interactions, it is important that the measurements be made at more than one temperature.

Class of 2012 Abstract / Specific Aims: Assess the stability and sterility of various extemporaneously compounded captopril solution in different storage conditions. Methods: Extemporaneously prepared captopril standards and solutions tested in a high performance liquid chromatography instrument collected data on stability. In addition, physical appearance, bacterial growth and pH data were also collected. Main Results: Stability data was assessed with extemporaneously prepared captopril solutions prepared with standardized captopril powder, captopril tablets and captopril tablets with ascorbic acid included. Stability was defined as retention of at least 90% of the initial captopril concentration. Overall, all preparations were stable when stored at 4°C but only the tablet preparation was stable when stored at 25°C and 40°C. No bacterial growth was observed with any of the captopril solutions. Conclusions: Extemporaneously prepared captopril solution appears to have a shelf-life of at least 28 days when stored at 4°C.

This thesis addresses the difficulty young children have making the transition from solving simple addition and subtraction problems with referential support to the formalised language of arithmetic ('what does one and one make?') (Hughes, 1981, 1986). Nine experiments are reported testing a total of 782 children between 4 and 5 years old on their use of strategic prompts in addition and subtraction. Results produced evidence for their significant positive impact, whether it be imagery, solving problems with their eyes closed or provision of a memory-check for the initial addend. Effectiveness was mainly on more difficult problems, particularly subtraction, with one mentalistic strategy generating results as effective as those using concrete referents. Five-and-a-half year old children were shown to have greater sensitivity overall to such prompts, whereas the younger children of around five years showed less sensitivity to the imagery-prompt, but like their older counterparts were most sensitive to prompts involving a memory-check. Referential support was also found to be effective when the older children were presented with written formal code notation. Furthermore, children were also found to be sensitive to implicit (rather than explicit) strategic prompts with child-initiated strategies, like 'fingers', most effective when chosen by the children themselves. Results are discussed in relation to how such explicit strategic prompts are effective, whether working directly or indirectly.

The thesis is presented in two parts. In part one, the excess thermodynamic properties have been determined for several binary liquid mixtures, with the aim of testing theories of liquid mixtures. The excess molar enthalpies, Hem, have been determined using an LKB flow microcalorimeter, and the excess molar volumes, Vem, have been determined using an Anton Paar densitometer. The HemS and VemS have been measured at 298.15 K for binary systems involving an alkanol (methanol, ethanol, I-propanol, 2-propanol) mixed with a hydrocarbon (l-hexene, I-heptene, l-octene, I-hexyne, I-heptyne, l-octyne, toluene, mesitylene, 0-, m-, or p-xylene, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane). The results show trends relating to the degree of unsaturation, or size, of component molecules as well as the position of the hydroxyl group on the alkanol. Measurements were also made on mixtures involving an (n-alkane + a pseudo-n-alkane) and ( a cYcloalkane + a pseudo-cycloalkane). Two theories of liquid mixtures were tested in this work. The first theory tested was the theory of Congruency. This theory was tested, by means of a null test, on a novel set of mixtures involving an n-alkane (hexane, heptane, octane, decane, dodecane) + a pseudo-nalkane,and mixtures of a cycloalkane (cyclopentane, cyclohexane, cycloheptane, cyclooctane)+ a pseudo-cycloalkane. Deviations from the theory was less than the experimental error for the (n-alkane + pseudo-n-alkane) mixtures. However, significant deviations were observed for the mixtures of (a cycloalkane + a pseudo-cycloalkane). The second theory tested was the Flory theory, which has been used to predict the excess molar enthalpies and excess molar volumes for the mixtures involving (a 1-alkene, or 1-alkyne, or methyl-substituted benzene) + an alkanol. The results show that the theory does not hold for hydrocarbon mixtures involving an alkanol. In the second part of this thesis, the partial molar volumes, at infinite dilution, of binary solution involving a solid solute (18-crown-6 ether, dibenzo-18-crown-6 ether, dicyclohexanov 18-crown-6 ether, 15-crown-5 ether, or cryptand-222) are determined in various solvents. The results were repeated with a view to determine the volume changes at infinite dilution upon complexation, ΔV∞ of the crown ether or cryptand with a metal halide salt, MX (NaCl, NaI, KCl, KI, CsCl, CsI). The ΔV∞ results were compared with results in the literature for cryptand-222 (c-222) and dibenzo-18-crown-6 ether (B₂CE6) complexed with MX, and the study was extended to include further MX complexes with c-222 and B₂CE6, as well as MX complexes with 15-crown-5 ether and dicyclohexano-18-crown-6 ether. ΔV∞ results were correlated with the Hepler prediction of the electrostriction solvent effect.

1. The apparatus used in this investigation is fully described, and a new method is outlined for the calibration of bridge resistances "in situ". 2. A chart is given for the accurate correction of weights in air to weights in vacuum for a range of temperatures extending from 10° to 28°C, and for pressures from 690 to 730 mm. 3. An automatic recycling still has been designed for the continuous production of "ultra-pure" water. This still is capable of delivering daily, in routine operation, 16 l. of water of conductivity less than 100 nm/cm after aeration with "C0₂- and NH₃-free" air. 4. A very soluble layer appears to form on the surface of' glass when it is dried; this layer is readily removed on contact with water. 5. The removal of carbon dioxide and of ammonia from aqueous solution by aeration with an indifferent gas has been fully investigated, and it has been shown that these gases can be completely eliminated by such a process. Whereas the carbon dioxide is removed fairly rapidly, however, the ammonia, whether present alone or together with carbon dioxide, only goes out of solution rather slowly. 6. It has been shown that ammonia is adsorbed from aqueous solution on the glass walls of the cell. 7. There does not appear to be any ammonium bicarbonate in the residual impurity left in the "ultra-pure" water obtained from the still; the impurity can, in fact, be regarded as neutral salt with sufficient accuracy for most purposes. 8. The resistance change which accompanies any variation in the rate of bubbling of the stirring gas through the water has been investigated, but no solution has been found as to the cause of this change. 9. A comparison has been made of the efficiency of different gases for stirring purposes, and it seems that, for general work, nitrogen is by far the most suitable of the common gases. 10. The extrapolation to be used for converting resistances to their values at infinite frequency appears ...

A kinetic study of the complex formation between chlororuthenate (II) species and the olefinic substrates, 1,1 difluoroethylene, fluoroethylene and acrylamide in aqueous hydrochloric acid solution has been carried out. The kinetics were studied either by measurement of gas uptake or by following spectrophotometrically at 680 mμ the disappearance of the blue Ru (II) species at experimental conditions in which ruthenium, olefin and chloride concentrations were varied. A two step process involving an initial dissociation of a chloride ligand seems likely for these systems, but a detailed discussion is limit ed by lack of information on the equilibria between chlororuthenate (II) species in solution. No evidence was obtained for hydrogenation by molecular hydrogen of the 1,1 difluoroethylene or fluoroethylene through a π-complex formed with the chlororuthenate (II) species. Catalytic hydration of these olefins to acetic acid and acetaldehyde respectively was however observed, and a mechanism is proposed to account for this; this appears to be the first, report of a transition metal catalysed hydration of olefins. Acrylamide was not hydrated but could be catalytically hydrogenated to propionamide; the kinetic data fit a well established mechanism. Similarities between the hydrogenation and hydration processes are pointed out. / Science, Faculty of / Chemistry, Department of / Graduate