Browsing by Subject "Pyridine"
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Item Complexes of tetracyanoethylene with substituted pyridines(Texas Tech University, 1969-05) Goodin, Richard DonNot availableItem Item Paramagnetic resonance and optical spectra of some divalent group I-B metal pyridine complexes(Texas Tech University, 1966-08) Frazier, John PedenNot availableItem Spectroscopic Studies of Pyridine and its Isotopomer, 2-Fluoro- and 3-Fluoropyridine, 1,3-Butadiene and Its Isotopomers(2012-02-14) Boopalachandran, PraveenkumarThe infrared, Raman and ultraviolet spectra of pyridine-d0 and pyridine-d5 were recorded and assigned with a focus on the low-frequency vibrational modes in the S1(n,pi*) electronic excited state. An energy map for the low-frequency modes was constructed and the data for the v18 mode allowed a highly anharmonic one-dimensional potential energy function to be determined for the S1 excited state. In this S1(n,pi*) state, pyridine is quasi-planar and very floppy with a barrier to planarity of 3 cm^-1. The infrared, Raman and ultraviolet spectra of 2-fluoropyridine (2FPy) and 3-fluoropyridine (3FPy) have been collected and assigned. For 2FPy about 150 bands were observed for the transitions to the vibronic levels of the S(pi, pi*) state at 38,030.4 cm^-1. For 3FPy more than a hundred absorption bands associated with the S(n,pi*) state at 35,051.7 cm^-1 and about forty broad bands associated with the S(pi, pi*) state at 37,339 cm^-1 were observed. The experimental work was complemented by ab initio calculations and these also provided calculated structures for 2FPy, 3FPy, and pyridine. They showed that the fluorine atom on the ring participates in the pi bonding. The gas-phase Raman spectra of 1,3-butadiene and its 2,3-d2, 1,1,4,4-d4, and d6 isotopomers have been recorded with high sensitivity in the region below 350 cm-1, in order to investigate the internal rotation (torsional) vibration. The data for all the isotopomers were then fit using a one-dimensional potential energy function of the form V = (1/2)Sigma(Vn(1-cos (phi))). The energy difference between trans and gauche forms was determined to be about 1030 cm^-1 (2.94 kcal/mol), and the barrier between the two equivalent gauche forms to be about 180 cm^-1 (0.51 kcal/mol), which agrees well with high-level ab initio calculations. The results from an alternative set of assignments also fits the data quite well are also presented. Combination and hot band series involving the v13 torsional vibration of the trans rotamer were observed for each of the butadiene isotopomers. In addition, the high signal to noise of the Raman spectra made it possible to detect several dozen bands of the gauche rotor which makes up only about 2% of the molecules at ambient temperature.Item Synthesis of complanadine A and phthaloyl peroxide-mediated oxidations of alkenes and arenes(2013-05) Yuan, Changxia; Siegel, Dionicio R.; Anslyn, Eric V.; Willson, Grant C.; Liu, Hung-Wen; Humphrey, Simon M.The natural product complanadine A has shown promise in regenerative science, promoting neuronal outgrowth by inducing the secretion of growth factors from glial cells. Through the use of tandem, cobalt-mediated [2+2+2] cycloaddition reactions two synthetic routes have been developed with different sequences for the formation of the unsymmetric bipyridyl core. The regioselective formation of each of the pyridines was achieved based on the inherent selectivity of the molecules or by reversing this inate regioselectivity through the addition of Lewis bases. This strategy has been successfully employed to provide laboratory access to complanadine A as well as structurally related compounds possessing the lycodine core. Phthaloyl peroxide derivatives have the potential to function as organocatalysts for the dihydroxylation of alkenes. The development of an organocatalytic system for the syn-dihydroxylation of alkenes, using hydrogen peroxide as the stoichiometric oxidant, could minimize the waste and cost associated with the current industrial process. With new access to phthaloyl peroxide derivatives, this dihydroxylation method was improved with stoichiometric dichlorophthaloyl peroxide for the dihydroxylation of alkenes. Substituted phenols are broadly useful compounds, functioning as starting materials and end products in all areas of chemical industry. Since the initial discovery of phenol from coal tar advances have been made in the synthetic preparations of this class of compounds which possess a hydroxyl group appended to an aromatic hydrocarbon core. Ideally the synthesis of phenols is achieved through the direct installation of oxygen into an aromatic precursor, which is typically more abundant. In this thesis it is discussed how phthaloyl peroxide, in the absence of other reagents, enables the conversion of aromatic hydrocarbons to phenols even when the precursors possess functionality that is incompatible with strongly oxidizing conditions. The reaction is shown to proceed through a "reverse rebound" mechanism as opposed to the classical rebound mechanism, providing insight into the unique aryl selectivity of the chemical transformation.