The objective of this study is to investigate the influences of the shape of grinding wheel to the teeth profile and the contact pattern of Curvic couplings. Firstly, the equations of concave and convex teeth profiles are successfully derived by using coordinate transformation technique. Then, assembly errors and shape parameters errors of the grinding wheel are introduced, and the error-involved teeth profiles equations are also obtained. Finally, the optimization technique is employed to find the optimized parameters of the grinding wheel such that Curvic couplings with prescribed proper mating conditions can be manufactured. The influences of the each parameter of grinding wheel with respect to the associated contact condition are also analyzed. The radii of grinding wheels for both concave and convex teeth, and the center distance between the grinding wheel and coupling blank are identified to significantly influence the contact area. A computer program for obtaining the optimum profile of grinding wheel involved error settings has been developed by using Visual Basic language.

Carbon-carbon (C-C) bond formation is among the most important processes in organic chemistry. Transition metal catalyzed C-C bond formation is an active research area that shows great potential due to high selectivity and relatively mild conditions. In Chapter 1, a new reaction for direct acylation of aryl halides is discussed. Specifically, the catalytic reaction between aryl halides/pseudohalides and aldehydes is explored. The choice of ligand, base, solvent, temperature, catalyst and substrates are important factors for optimizing this catalytic reaction. The various combinations of all these factors have, therefore, been examined by high-throughput screening (HTS) in order to develop the new C-C coupling reaction. In Chapter 2, a new methodology is reported in order to expand the scope of the Kumada-Corriu cross-coupling reaction. The strategy to achieve this goal is mechanistically based, matching oxidative addition rates with the rate of syringe pump addition of the Grignard to minimize the exposure of sensitive groups to the aggressive nucleophile. Aryl chlorides containing esters, amides, nitriles, pyrazines, carbamates, ketones, and other sensitive functionalities are all demonstrated to undergo chemoselective cross-coupling with this technique. The mechanistic reason for the effectiveness of this strategy is uncovered by continuous-infusion ESI-MS studies.

No description available.

The beta-decay interaction contains two terms which consist of invariant products of two scalars and two tensors respectively. The relative absolute magnitude of these two terms is fairly well established but there has been some controversy over their relative sign. In this thesis the form of the interaction is investigated by means of an analysis of the second-forbidden decay spectrum of Cs137 and it is concluded that the relative sign of the scalar and tensor terms is negative. / Thesis / Master of Science (MS)

Thesis advisor: James P. Morken / Internal allyl electrophiles were successfully implemented in a catalytic cross-coupling to allylB(pin) with high regiocontrol to afford multisubstituted 1,5-dienes bearing chemically differentiated olefins. Construction of alkenyl compounds with all carbon quaternary centers and high enantiomeric excess can be achieved in one step without the use of enantiomerically enriched chiral ligands. / Thesis (MS) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Because polypeptides present a repeating sequence of amide bonds, lactams provide good model compounds for investigating the angular dependencies of coupling constants over a range of rigid conformations. A number of ¹³C labeled lactams were synthesized to cover a range of dihedral angles; experimental and theoretical carbon-carbon and carbon-hydrogen coupling constants were obtained to give the relationships between the vicinal coupling constants ³J[C(O)-N-C-C], ³J[C(O)-N-C-H] and dihedral angle φ. Vicinal ¹³C-¹³C coupling constants for dihedral angles in the range of 90° to 180° were obtained unambiguously from the coupling between the carbonyl and carbons in the side chains of lactams. However, due to coupling via multiple paths, vicinal ¹³C-¹³C coupling constants for dihedral angles ranging from 0° to 90° were estimated by excluding the contributions from the geminal ²J[C(O)-C-C] or vicinal ³J[C(O)-C-C-C] couplings in the lactam rings. The experimental and theoretical results show that the angular dependence of vicinal ¹³C-¹³C coupling constants do not follow a simple Karplus type relationship, especially at small dihedral angles. It was found that geminal ²J[C(O)-N-C] were small ( < 0.3 Hz). However, the ²J[C(O)-N-C] in the cis arrangement are shifted to about 2.2 Hz in N-methyl substituted lactams while in the trans arrangement the values are about 4.4 Hz. Geminal ¹³C-¹³C coupling constants ²J[(C(O)-N-C)] also provide a useful tool in stereochemical studies.

No description available.

No description available.

No description available.

No description available.