The efficacy of the claycop system in the nitration and the dinitration of toluene has been investigated.Comparison of regioselectivity and of rate constant with homogeneous nitric acid nitration was made. The use of ion-exchanged montmorillonite clay as a catalyst for acetyl nitrate nitration was studied. The system was found to enhance Para selectivity in the nitration of toluene and to catalyse the reaction. Additionally, the catalyst was shown to be recyclable. The reaction of toluene was too fast to allow kinetic study. However, kinetic study was possible,using chlorobenzene as substrate.Again, the system was found to decrease both the reaction time and the o-/ p- ratio. It was possible to demonstrate a dependence of rate constant upon mass of clay. The effect of the counter ion was investigated and the use of trifluoroacetyl anhydride was studied. A new system for aromatic nitration has been developed in this work using zeolite with dinitrogenp entoxide.A series of zeolites were screened in the nitration of onitrotoluene, with the H-faujasites showing the quickest reaction times and highest degree of regioselectivity. The silica/ alumina ratio of the faujasite used was varied and this was shown to have an effect on regioselectivity. However, reactions were too fast for kinetic study. The faujasite/ dinitrogen pentoxide system was used in the nitration of some deactivated benzenes using these substrates allowed kinetic studies to be made and the order in each component to be determined. It was found that nitration was zeroth order in dinitrogen pentoxide, that the reaction obeyed a first order rate law, and that the first order rate constant was proportional to the mass of zeolite used. Comparison of the relative rates of nitration of 1-chloro-2-nitrobenzene1, -chloro-4-nitrobenzene and nitrobenzeneb y this system to the relative rate constants of nitronium ion nitration was made. The similarity suggested that the mechanism of nitration by faujasite/d initrogen pentoxide might involve nitronium ion transfer.Amongst the H-faujasites of different silica/ alumina ratio, the rate constant was shown to increase with the aluminium content. A mechanism is proposed in which zeolite protons (present in proportion to the aluminium atoms) are first replaced by nitronium ions. The latter are transferred to the aromatic in the rate-determining step. The use of non-chlorinated solvents and the recycling of zeolite were both studied, and the nitration of 2,6-dinitrotoluene was attempted. The use of the faujasite/ dinitrogen pentoxide system was extended to the nitration of nitrogen containing aromatic heterocycles direct C-nitration of quinolone was not possible, only N-nitration. However, pyrazole was converted to 1,4-dinitropyrazole quickly and cleanly under mild conditions. It was shown that the N-nitration occurred instantly, followed by slower C-nitration. The kinetics of the second nitration were studied and comparison with deactivated benzenes was made.

No description available.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Call number: LD2668 .T4 1959 R46

Doctor of Philisophy (PhD) / Despite their early discovery, relatively few classes of ruthenium dinitrogen complexes are known. This work describes the successful coordination of dinitrogen to the electron-rich alkylphosphine cores [RuCl(dmpe)2]+ and [RuCl(depe)2]+ by chloride abstraction from both the cis and trans dichloro derivatives. One such complex, trans-[RuCl(N2)(dmpe)2](BArF24), possesses the most activated ruthenium νNN reported to date. A variety of chloride abstraction agents were tested on the cis and trans isomers of [RuCl2(P-P)2] (P-P = dmpe, depe) with the choice of abstracting agent, anion and solvent all found to significantly affect the outcome. Reaction with silver triflate and trimethylsilyl triflate was found to give dichlororuthenium(III) products, which could be readily reduced to the ruthenium(II) starting materials with common reducing agents, as well as by alcohols and hydrazine. The use of thallium triflate avoided oxidation and led to the formation of the crystallographically characterised polymeric incorporation product, [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] from trans-[RuCl2(dmpe)2] and the interesting chloride-bridged ruthenium dimer cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 from trans-[RuCl2(depe)2]. Anion exchange of the complex [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] with the non-coordinating anion tetrakis(3,5-bis(trifluoromethyl)phenyl)borate resulted in removal of thallium from the system and coordination of dinitrogen to give trans-[RuCl(N2)(dmpe)2](BArF24). Cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 was found to readily react with a variety of small ligands and gave products such as cis-[RuCl(CO)(depe)2](OTf), cis-[RuCl(NCMe)(depe)2](OTf), cis-[RuCl(CNtBu)(depe)2](OTf), cis-[RuCl(NH3)(depe)2](OTf), cis-[RuCl(N3)(depe)2], and trans-[RuCl(η2-H2)(depe)2](OTf). A preliminary X-ray single crystal structure analysis was conducted on the complex cis-[RuCl(CNtBu)(depe)2](OTf). The thallium(I) salt Tl(BArF24) was found to be an efficient chloride abstraction agent under mild conditions. Reactions with cis- and trans-[RuCl2(depe)2] and cis-[RuCl2(dmpe)2] furnished dinitrogen complexes of the form cis-[{RuCl(P-P)2}2(μ-N2)](BArF24)2, whilst reaction of trans-[RuCl2(dmpe)2] with Tl(BArF24) led to the stable five-coordinate complex trans-[RuCl(dmpe)2](BArF24). Vapour diffusion techniques applied to a solution of cis-[{RuCl(depe)2}2(μ-N2)](BArF24)2 gave rise to crystals of trans-[RuCl(N2)(depe)2](BArF24), on which preliminary X-ray molecular structure analysis was performed. Reactions of both cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 and trans-[RuCl2(dmpe)2] with high pressure (140 psi) dinitrogen at 140 150°C in methanol or tetrahydrofuran resulted in solvent carbonyl abstraction to afford trans-[RuCl(CO)(depe)2](OTf) and trans-[RuCl(CO)(dmpe)2](Cl) from the depe and dmpe complexes respectively. The molecular structure of trans-[RuCl(CO)(dmpe)2](Cl) was determined via single crystal X-ray structure analysis.

Nitrogen-fixation is an essential biochemical reaction involving the reduction of inert, atmospheric dinitrogen (N2) into biochemically accessible ammonia (NH3). Organisms that are capable of this process are collectively called “diazotrophs” and are ubiquitous in marine and terrestrial environments. Despite the wide distribution, little is known about the biological nature of the diverse groups of diazotrophs. This study was designed to address the influence of light and nutrients on nitrogen fixation and growth in several marine diazotrophic symbioses collectively termed “Diatom-Diazotroph Associations (DDAs).” The organisms of interest included the diatoms Hemiaulus haukii Grunow and Hemiaulus membranaceus Cleve, and their diazotrophic endosymbiont Richelia intracellularis Schmidt. The study included acetylene reduction assays, growth rate, and nutrient analysis experiments on both associations in order to better understand the similarities and differences within and between the two DDAs. The results indicate distinct differences in nitrogen fixation rates within and between the species. In the nitrogen addition experiment, the “no added nitrogen” treatment had the highest N2-fixation rate (N2-fixmax = 7.43 x 10-5 nmols N2 heterocyst-1min-1), followed by the added nitrate treatment (N2-fixmax = 6.49 x 10-5 nmols N2 heterocyst-1min-1) and the added ammonium treatment (N2-fixmax = 3.79 x 10-5 nmols N2 heterocyst-1min-1). The maximum growth rate occurred in the “added ammonium” treatment (0.42 divisions day-1), which had a higher percentage of asymbiotic cells than the two other treatments. The maximum recorded rate of N2-fixation for H. haukii was 7.43 x 10-5 nmol N2 heterocyst-1min-1 and the maximum value of N2-fixation for H. membranaceus was 1.88 x 10-4 nmol N2 heterocyst-1min-1. The maximum growth rate for H. haukii was 0.99 divisions day-1, and 1.06 divisions day-1 for H. membranaceus. Growth followed light saturation kinetics in H. haukii with a compensation light intensity (IC) of 10 µmol quanta m-2sec-1 and saturation light intensity (IK) of 100 µmol quanta m-2sec-1. H. haukii and H.membranaceus expressed light saturation kinetics in N2-fixation. N2-fixation was generally limited to the light period, with no evidence of a morning or evening enhancement. The DDAs grew solely on N2-fixation and did not use nitrate. This study contributes to current knowledge of DDAs and their role in global marine nitrogen fixation. / text

Doctor of Philisophy (PhD) / Despite their early discovery, relatively few classes of ruthenium dinitrogen complexes are known. This work describes the successful coordination of dinitrogen to the electron-rich alkylphosphine cores [RuCl(dmpe)2]+ and [RuCl(depe)2]+ by chloride abstraction from both the cis and trans dichloro derivatives. One such complex, trans-[RuCl(N2)(dmpe)2](BArF24), possesses the most activated ruthenium νNN reported to date. A variety of chloride abstraction agents were tested on the cis and trans isomers of [RuCl2(P-P)2] (P-P = dmpe, depe) with the choice of abstracting agent, anion and solvent all found to significantly affect the outcome. Reaction with silver triflate and trimethylsilyl triflate was found to give dichlororuthenium(III) products, which could be readily reduced to the ruthenium(II) starting materials with common reducing agents, as well as by alcohols and hydrazine. The use of thallium triflate avoided oxidation and led to the formation of the crystallographically characterised polymeric incorporation product, [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] from trans-[RuCl2(dmpe)2] and the interesting chloride-bridged ruthenium dimer cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 from trans-[RuCl2(depe)2]. Anion exchange of the complex [{trans-[RuCl2(dmpe)2]•Tl(OTf)}n] with the non-coordinating anion tetrakis(3,5-bis(trifluoromethyl)phenyl)borate resulted in removal of thallium from the system and coordination of dinitrogen to give trans-[RuCl(N2)(dmpe)2](BArF24). Cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 was found to readily react with a variety of small ligands and gave products such as cis-[RuCl(CO)(depe)2](OTf), cis-[RuCl(NCMe)(depe)2](OTf), cis-[RuCl(CNtBu)(depe)2](OTf), cis-[RuCl(NH3)(depe)2](OTf), cis-[RuCl(N3)(depe)2], and trans-[RuCl(η2-H2)(depe)2](OTf). A preliminary X-ray single crystal structure analysis was conducted on the complex cis-[RuCl(CNtBu)(depe)2](OTf). The thallium(I) salt Tl(BArF24) was found to be an efficient chloride abstraction agent under mild conditions. Reactions with cis- and trans-[RuCl2(depe)2] and cis-[RuCl2(dmpe)2] furnished dinitrogen complexes of the form cis-[{RuCl(P-P)2}2(μ-N2)](BArF24)2, whilst reaction of trans-[RuCl2(dmpe)2] with Tl(BArF24) led to the stable five-coordinate complex trans-[RuCl(dmpe)2](BArF24). Vapour diffusion techniques applied to a solution of cis-[{RuCl(depe)2}2(μ-N2)](BArF24)2 gave rise to crystals of trans-[RuCl(N2)(depe)2](BArF24), on which preliminary X-ray molecular structure analysis was performed. Reactions of both cis-[{Ru(depe)2}2(μ-Cl)2](OTf)2 and trans-[RuCl2(dmpe)2] with high pressure (140 psi) dinitrogen at 140 150°C in methanol or tetrahydrofuran resulted in solvent carbonyl abstraction to afford trans-[RuCl(CO)(depe)2](OTf) and trans-[RuCl(CO)(dmpe)2](Cl) from the depe and dmpe complexes respectively. The molecular structure of trans-[RuCl(CO)(dmpe)2](Cl) was determined via single crystal X-ray structure analysis.

Formic acid and nitric acid have been found to contribute to aerosol formation and are key components of acidity in the troposphere. Tropospheric measurements of these species are often limited, resulting in major uncertainties when assessing their effects on the climate. Current global chemistry-transport models significantly under-predict formic acid concentrations, particularly in the mid-to-high latitudes of the Northern Hemisphere. Furthermore, large discrepancies exist in the role played by dinitrogen pentoxide on nitric acid production between two recently documented models assessing the global nitric acid budget. In order to accurately constrain the budget of these acids in the mid-to-high latitudes of the Northern Hemisphere, it is crucial that these uncertainties are addressed. In this work, airborne measurements of formic acid, nitric acid and dinitrogen pentoxide are presented from across different regions of the Northern Hemisphere to investigate direct and indirect sources contributing to the formic acid and nitric acid regional budgets. Measurements were collected using a Chemical Ionisation Mass Spectrometer (CIMS) fitted to the Facility for Atmospheric Airborne Measurements (FAAM) BAe-146 aircraft. Formic acid measurements within the European Arctic during March and July 2012 would indicate ocean sources dominate over terrestrial sources irrespective of seasonality. CH2I2 photolysis and oxidation was hypothesised as a marine source of formic acid. Modelled estimates would indicate the CH2I2 reaction route may represent a significant summer marine source of formic acid within the Fenno-Scandinavian Arctic. Additionally, low altitude aircraft measurements taken within the Fenno-Scandinavian Arctic over regions occupied by wetlands in August 2013 were used to calculate a formic acid surface flux. Results would suggest formic acid emission from wetlands may represent up to 37 times greater than its globally inferred estimate. A flux measurement conducted over a comparable region in September 2013 observed a negative flux, indicating a change of this region from a net source to a net sink of formic acid. The inconsistency of this regional wetland source confirms the need for in-depth studies on formic acid emission from wetlands, in order to better understand its contribution to the regional and global formic acid budget. In a separate study, significant daytime elevations of N2O5 and HNO3 concentrations were observed within identified biomass burning plumes off the eastern coast of Canada. In-plume correlations between N2O5 and HNO3 concentrations observed within these environments suggest N2O5 was acting as additional daytime source of gaseous HNO3 when subjected to photolytically-limited conditions. This result has important implications to ozone production and provides evidence for an additional daytime source of nitric acid, which must be included in chemistry models calculating the global nitric acid budget.

xvi, 233 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The coordination chemistry of iron with N 2 is becoming increasingly important as chemists try to find alternative routes to the production of ammonia. Current biological and industrial processes use iron to catalyze the formation of ammonia from N 2 ; however, huge amounts of energy are required for this conversion. Understanding how dinitrogen and other intermediates of dinitrogen reduction interact with iron could lead to energy efficient processes for the production of ammonia. This dissertation explores the synthesis and reactivity of an iron dinitrogen complex that reacts with acid to produce ammonia at room temperature and pressure. This dissertation also explores the progress toward determining the mechanism of this reaction in hopes of improving the yields of ammonia. Chapter I describes both the biological nitrogen fixation process and the industrial production of ammonia and provides an in-depth look at progress toward an alternative route to ammonia using iron complexes described in the literature thus far. Chapter II details the synthesis, characterization, and reactivity of dihydrogen and dinitrogen complexes of iron. These complexes are precursors to the active ammonia producing complex and are among a handful of dihydrogen and dinitrogen complexes that have been structurally characterized. Chapter III explores the synthesis and stability of Fe(DMeOPrPE) 2 N 2 . This complex produces ammonia and hydrazine upon protonation with a strong acid. Optimizing the yield of ammonia from this protonation is also described. Chapter IV discusses the synthesis and reactivity of several complexes of iron containing intermediates relevant to dinitrogen reduction, including diazene (N 2 H 2 ), hydrazine (N 2 H 4 ), and ammonia. By studying these intermediates, a mechanism of ammonia formation from the protonation of Fe(DMeOPrPE) 2 N 2 is proposed that may also provide insights into the mechanism of nitrogenase. Chapter V provides a summary of this research. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Darren Johnson, Chairperson, Chemistry; David Tyler, Advisor, Chemistry; Michael Haley, Member, Chemistry; Kenneth Doxsee, Member, Chemistry; Scott Bridgham, Outside Member, Biology

Development of effective pollution control strategies for urban areas requires accurate predictive models. The ability of models to correctly characterize the atmospheric chemistry, meteorology, and deposition rely on accurate data measurements, both as input and verification of output. Therefore, the measurement techniques must be sensitive, accurate, and capable of resolving the spatial and temporal variations of key chemical species. The application of a sensitive in situ optical absorption technique, known as cavity ring-down spectroscopy, will be introduced for simultaneously measuring the nitrate radical and dinitrogen pentoxide. The cavity ring-down spectrometer was initially designed and constructed based on the experiments by Steven Brown and Akkihebal Ravishankara at the National Oceanic and Atmospheric Administration. The instrument design has since undergone many revisions before attaining the current instrumentation system. Laboratory observations provide verification of accurate N2O5 and NO3 detection with measurements of the nitrate radical absorption spectrum centered at 662 nm, effective chemical zeroing with nitric oxide, and efficient thermal decomposition of N2O5. Field observations at a local park provided further confirmation of the instruments capability in measuring N2O5 and NO3. However, detection limits were too high to detect ambient NO3. Effective and frequent zeroing can easily improve upon the sensitivity of the instrument. Determination of the source of the polluted air masses detected during these studies was unknown since the typical southerly winds from Houston were not observed. Since deployment in the field, instrumentation modifications and laboratory measurements are underway for preparation of the SOOT campaign in Houston, Texas starting April 15, 2009. Current modifications include automation of the titration with a solenoid valve and an automated filter changer. Wall losses and filter transmission for NO3 and N2O5 will be determined through laboratory measurements in coincidence with and ion-drift chemical ionization mass spectrometer prior to the SOOT project. Potential modifications to improve upon the instrument are suggested for future endeavors.