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Terahertz line-images of surfactant-stabilized dodecane(C 12 H 26 )-brine emulsions are obtained by translating the emulsified region through the focus of a terahertz time-domain spectrometer, capturing a time-domain waveform at each vertical position. From these images, relative dodecane content, emulsion size, and stability can be extracted to evaluate the efficacy of the surfactant in solvating the dodecane. In addition, the images provide insight into the dynamics of concentrated emulsions after mixing.

Transition state theory was originally developed in the 1930s as method for calculating chemical reaction rates in simple systems using energetic barrier heights. Unfortunately its usefulness in complex high dimensional chemical processes such as protein dynamics is severely mitigated by the approximate assumption that reacting systems do not recross the transition state. This approximation has been improved for simple systems in modern variational transition state theory (VTST), which gives a close upper bound to the true reaction rate. For complex systems, location of the VTST separatrix is still theoretically challenging. We propose the definition of all alternative transition state separatrix for systems with high friction which has the property that the escape rate through the separatrix gives the exact reaction rate for the system, without the need for recrossing corrections, and, surprisingly, without requiring the escaping trajectories to cross the reaction barrier. However, locating this separatrix presently does require considering trajectories crossing the barrier. In order to lessen the computational challenge associated with barrier crossing, we provide an automatic method to enhance sampling of trajectories crossing the reaction barrier derived from the mathematics of super symmetry. This method provides an effective "ensemble magnifying glass," statistically inducing additional sampling of configurations in regions with large probability flux but without affecting transition rates.

The objectives of this research problem were divided into several parts. The first objective was to develop a practical method of preparing 2,6-diamino-2,6-dideoxy-galactose. A second objective was to investigate the derivatives of benzyl-N-carbobenzoxy-α-D-galactosaminide. FInally, the third objective was to lay the groundwork for another possible route for the synthesis of 2,6-diamino-2,6-dideoxy-galactose other than the uronic acid route.

The purpose of this investigation was to prepare heterocyclic derivatives, bridging C-2 and C-3 of 2-amino-2-deoxy-D-hexopyranoses, useful as blocking groups in the preparation of aminosugar oligosaccharides and polysaccharides. The work reported herein is concerned with oxazolidones of 2-amino-2-deoxy-D-hexopyranoses (Figure 1).) There are no examples known, in which five or six-membered rings are fused in a trans-arrangement to five-membered furanose ring. However, although synthetic difficulties were observed, sic and five-membered rings were fused in a trans-arrangement to a sic-membered pyranose ring as pointed out before. In the case of our trans-diequatorially fused oxazolidones additional preparative difficulties were expected, because of the possibility of opening and recyclization of the less stable trans-oxazolidone to form the more stable cis-oxazolidone (39). The amino sugars that have the hydroxyl group at C-3 in the cis-position to the amino group, but otherwise the same structure as D-allopyranose and 2-amino-2deoxy-D-gulopyranose, respectively. Thus, it was considered expedient that oxazolidones of D-allosamine and D-glucosamine be investigated prior to the investigation of oxazolidones of D-glucosamine.

Although D-glucosamine has been found as a constituent of some antibiotics (28), very little research has been carried out in the area of synthetic preparations. Dutcher (7) recently reviewed the biochemical importance of this class of amino sugars as a constituent of complex antibiotic substances which compose the streptothricin family. For a complete elucidation of these antibiotics, it becomes necessary to investigate thoroughly the synthesis and reactions of the D-glucosamine compounds. Gross et al. (12) have succeeded in preparing the oxazolidone of α-D-glucosamine as well as some derivatives (13) of this compound. The present work reports an attempt to prepare the oxazolidone of β-D-glucosamine, its uronic acid, and some uronic acid derivatives. Of special interest is the uronic acid since uronic acids of other compounds have been used as intermediates for several types of reactions. One of the most interesting employments of such intermediates is the use of uronic acids for the indirect introduction of an omega-amino group (27, 29, 30, 33, 34) in syntheses of diamino sugars. Another use of uronic acids is in the so-called transposition reaction, as carried out by Fischer (9) on glucose and later applied to amino sugars by Weidmann et al. (35). This series of reactions involves transposition of the C-1 carbonyl function to C-6 thereby converting 2-amino D-glucose to 5-amino L-gulose. Other uronic acid derivatives may prove useful in the future. This research problem may be divided into four categories; (i) preparation of a suitable starting material, (ii) an investigation of suitable methods for the preparation of the desired glucosamine compound, (iii) conversion of the glucosamine compound to the uronic acid, and (iv) preparation of the desired uronic acid derivatives.

Two different systems involving the dye rhodamine 6G (R6G) were studied using absorption spectrophotometric techniques. The first is a compound that forms when R6G, HgCl$\sb2,$ and KI are combined in aqueous solution at concentrations near 10$\sp{-5}$ m. The second involves the formation of an addition complex between 10$\sp{-5}$m R6G and 10$\sp{-3}$ to 10$\sp{-2}$m $\beta$-cyclodextrin ($\beta$-CD) in aqueous solution. When R6G, HgCl$\sb2,$ and KI are combined, the absorption spectrum shows a shoulder around 571 nm that is attributed to the formation of a complex. The formula for this compound was determined by two methods: (1) the mole ratio method, which results in a 1:1 ratio between Hg(II) and R6G, and (2) the method of continuous variations, which this work has extended for a three reactant system, resulting in a ratio of 3:1 between iodide and R6G. Therefore, the formula for the complex is proposed to be R6GHgI$\sb3$ in the range of concentrations under study. Thermodynamic constants for the formation of the R6GHgI$\sb3$ compound are determined. Mole ratio plots at temperatures ranging from 15$\sp\circ$C to 30$\sp\circ$C are used to determine the mole fraction equilibrium constants. The values for the constants are 6.74 $\times$ 10$\sp{26}$, 5.53 $\times$ 10$\sp{26},$ 1.67 $\times$ 10$\sp{26},$ and 1.31 $\times$ 10$\sp{26}$ at 15.0, 18.0, 25.0, and 30.0$\sp\circ$C, respectively. The changes in enthalpy, $\Delta$H$\sb{\rm x}$, and free energy, $\Delta$G$\sb{\rm x}$, are then determined from the mole fraction equilibrium constant. $\Delta$H$\sb{\rm x}$ is $-$80.8 kJ/mol, $\Delta$G$\sb{\rm x}$ is 150 $\pm$ 2 kJ/mol, and $\Delta$S$\sb{\rm x}$ is 233 $\pm$ 2 J/mol. The addition of R6G to $\beta$-CD results in a red shift of the absorption peak of R6G from 526 nm to 529 nm. When the concentration of $\beta$-CD is varied, an isosbestic point is observed at 528 nm. Two different methods were used to calculate the equilibrium constant of the R6G - $\beta$-CD complex. Both methods use the same absorbance data, which is obtained by varying the concentration of $\beta$-CD and keeping the R6G concentration constant. One involves a double reciprocal plot using the Benesi-Hildebrand equation. The second uses a non-linear least squares fit of the absorbance data to the hypothetical equilibrium equation to calculate the equilibrium constant. The equilibrium constant determined by the Benesi-Hildebrand equation is 36 $\pm$ 44. The non-linear least squares equilibrium constant is (1.2 $\pm$ 0.4) $\times$ 10$\sp2.$

The purpose of this research is the preparation and characterization of derivatives of benzyl N-carbobenzoxy-β-D-glucosaminiduronic acid. Previously the derivatives of benzyl N-carbobenzoxy-α-D-glucosaminid-uronic acid have been prepared by H. Weidmann and H. K. Zimmerman (32). The procedure upon which both these uronic acid syntheses is based has been developed with the utilization of platinum in the selective catalytic oxidation of both the benzyl α- and β-D-glucuronosides. The applicability of this research is in the development of new intermediates for the preparation of new diamino sugars or other natural products.

A novel epoxide ring opening of benzyl 3,4-anhydro-2-benzylox-carbonylamido-2-deoxy-β-D-allopyranoside(I) was affected by phenylboronic anhydride in toluene. One of the products was demonstrated to be benzyl 2-benzyloxycarbonylamido-2-deoxy-4,6-0-phenylboronate-β-D-gulopyranoside. Another product isolated, while not identified, had the properties of an anhydro-sugar different from the starting compound(I). Benzyl 6-0-acetyl-2-benzyloxycarbonylamido-2-deoxy-β-D-allopyranoside(II) also underwent epoxide ring opening in a reaction with phenylboronic acid. An isolated product had the properties of a benzyl 2-benzyloxycarbonyiamido-2-deoxy-D-hexoside different from compounds isolate in the reaction of I with the phenyboronate. This indicated the necessity for an unsubstituted 6-OH group in order for the boron compound to be involved in the ring opening. Supporting this view is the lack of reaction between the blocked benzyl 2,3-anhydro-4,6-0-benzylidene-α-D-allopyranoside and phenylboronic anhydride. The 2,3-epoxide ring of benzyl 2,3-anhydro-4,6-0-benzylidene-α-D-allopyranodie(III) was shown to be remarkably stable in a reaction with boron acetate in nitromethane. The product had retained the 2,3-epoxide ring under conditions that removed the benzylidene group. Trimethylsilyl azide was prepared in good yield in a mild and direct method. The azide was then used to prepare a new, low-melting, compound by dilation of the 6-OH group of I. The epoxide ring remained stable under these conditions The epimine ring of benyl 4,6-0-benzylidene-2,3-dideoxy-2,3-epimino-α-D-allopyranodie(IV) was found to be unreactive with phenylboronate. However IV was deaminated with HNO2 to give the 2,3-unsaturated to give benzyl 4,6-0-benzylidene-α-D-mannopyranoside. The purpose of this study was to test the reactivity of sugar epoxides toward novel, ring-opening reagents. The study is especially concerned with the opening of the epoxide ring of benzyl 3,4-anhydro-2-benzyloxycarbonylamido-2-deoxy-β-D-allopyranoside, which has been found to be quite stable.1 These reagents were also used in a comparative study of the reactivity of epimino rings of sugars. Epimino rings react in a manner analogous to eposice rings. They have also been found to be quite stable in sugars.2,15