Organic Chemistry Commons^™

Synthesis And Characterization Of Transition Metal Scorpionate Complexes For Redox Shuttle Applications In Dye-Sensitized Solar Cells, Chase Lance

Honors Theses

Given the rising global energy demands, alternative renewable energy sources are currently being investigated. The most appealing renewable energy source is solar energy, and dye-sensitized solar cells (DSSCs) in particular are an attractive technology. DSSCs have traditionally utilized iodide/triiodide as the redox mediator couple, which exhibits high efficiencies and fast regeneration of the oxidized dye with little recombination. Recently, the use of alternative redox couples based on transition metal complexes has been studied as a promising substitute due to the tunable design of these complexes. In this study, tridentate tris(pyrazolyl)borate and tris(pyrazolyl)methane ligands with first-row transition metals were designed and …

A Study On The Modifications Of [2.2]Paracyclophane And Their Effects On The Enantioselectivity Of The Copper Catalyzed Cyclopropanation Reaction, Yousef Dawoud

Honors Theses

The use of chiral [2.2]paracyclophane Schiff-base ligands has been shown to induce enantioselectivity in the copper catalyzed cyclopropanation of styrene with diazoesters. ¹ Previous research by Dr. Masterson tested Schiff-base ligands based on 4- amino[2.2]paracyclophane with moderate enantioselectivity. In this project, the Schiff-base N- salicylidene-4-amino[2.2]paracyclophane, was modified by way of Grignard addition to the imine carbon and its enantioselective properties were explored with the copper catalyzed cyclopropanation. The methyl Grignard addition to N- salicylidene-4-amino[2.2]paracyclophane was successful in producing the amino alcohol and the amino alcohol was characterized. The amino alcohol was produced from the R enantiomer of the Schiff-base and …

Best Organic Chemistry Practices In The Midwest, Claire Van Der Bosch

Honors Theses

Organic Chemistry is a gateway course to a handful of courses in higher chemical education. Unfortunately, it is notorious for its high-fail, high-withdrawal, and high-drop rate and has a reputation for being time-consuming, with difficult concepts that are oftentimes new to students. It is often taught in a two-semester sequence, with the courses named Organic I and Organic II, and both courses have a lab component. At Western Michigan University, the fail rate for these two courses are 53.5% and 36.9%, respectively. Most higher education institutions are certified with the American Chemical Society (ACS) and given a skeleton of a …

Analysis Of Dl-Amino Acid Ratios In Eggshells Using Reverse Phase-High Pressure Liquid Chromatography, Gergana Milkova

Honors Theses

HPLC methodology was developed to determine the concentrations and ratios of D to L amino acids in emu and ostrich eggshells treated with heat at different temperatures . We aimed to determine an internal standard and how ratios were affected under different conditions. An HPLC method was determined that gave consistent retention times and satisfactory enantioseparation . Calibration curves for each amino acid were developed from single and multi-amino acid containing dilution series producing a model that most closely replicates the eggshell-extracted amino acids.

Generation And Reactions Of Cyclopropyl Vinylidene Carbenes, Nguyen Nhat Thu Le

Honors Theses

This study aimed to generate cyclopropyl methyl vinylidene carbene and cyclopropyl phenyl vinylidene carbene via photochemical routes. The precursors to these two carbenes were synthesized from phenanthrene by a two-step procedure. However, these precursors could not be fully purified because the second step generated many side products with similar properties as the precursors. A crude sample of each precursor were photolyzed with UV light in the range of 315 to 400 nm. Vinylidene carbenes are known to rapidly rearrange into alkynes, so the formation of these cyclopropyl vinylidene carbenes was monitored through the formation of their rearrangement products, cyclopropyl methyl …

An Exploration Of Pyrrole Groups On The Enantioselectivity Of Pig Liver Esterase, Brian Long

Honors Theses

Pig Liver Esterase (PLE) is a serine protease enzyme that can interact with one side of a diester to hydrolyze the ester to a carboxylic acid, and research has found that the level of hydrophobicity of side groups can impact the enantioselectivity of PLE hydrolysis.1, 2 The Jones Model is what current researchers use to model the active site of PLE, but the nature of its binding pockets, namely the Hydrophobic Long (HL) pocket, has been called into question.3 Dimethyl 2-((pyrrole-2-yl)methyl)-2-methylmalonate was prepared to be subjected to PLE hydrolysis to see whether enantioselectivity was found. Chiral HPLC revealed 25.32% enantiomeric …

Diastereoselective Synthesis Of 2,4,6-Trisubstituted Piperidines Via Aza-Prins Cyclization, John A. Hood

Honors Theses

The nitrogen heterocycles are shared amongst 59% of Food and Drug Administration (FDA) approved small molecule pharmaceuticals with the six-membered piperidine representing the most common moiety. Given the versatility and potential to yield derivatives with broad biological activities, the discovery of new chemical methods to generate these heterocycles in a more time and cost-efficient manner is desired. While there are existing racemic methods to access this class of molecule, the objective of this research is to pioneer a new novel six-step method to generate 2,4,6-trisubstituted piperidines with stereoselective control.

The first step is a condensation between a nonenolizable aldehyde and …

Silicon And Tin Substituted Halocyclopropanes: Approaches To New Carbenes And Strained Cyclic Allenes, Noura Srour

Honors Theses

Chloro(trimethylsilyl)carbene and chloro(trimethylstannyl)carbene were generated through photolysis of cyclopropanated phenanthrene precursors which were synthesized in two steps. The photolysis reactions were done in the presence of cis and/or trans-beta-methylstyrene. Though product peaks corresponding to the carbene-alkene adducts were observed in the GCMS, the yields were too low for their isolation and complete characterization. Density functional theory (DFT) calculations were performed on the stereoisomers of the precursor to Chloro(trimethylsilyl)carbene and the carbene itself. Surprisingly, Chloro(trimethylsilyl)carbene’s triplet state was found to be more stable than the singlet at this level of theory.

In a related project, (1-bromo-1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)trimethylstannane, was …

Photochemical Generation Of Carbenes And Ketenes From Phenanthrene-Based Precursors Part I: Dimethylalkylidene Part Ii: Diphenylketene, Tarini S. Hardikar, Tarini Hardikar

Honors Theses

Previous studies have shown that the photolysis of phenanthrene-based cyclopropyl precursors can generate carbenes. In this work, a novel phenanthrene precursor was synthesized and photolyzed to generate the dimethylalkylidene carbene, which was subsequently trapped by cyclohexene. The car- bene was not prone to an internal rearrangement as some other carbenes are, and instead favored the intermolecular addition reaction. The precursor also underwent a rearrangement via pericyclic processes. A theoretical analysis of the potential energy surface of the system is presented using coupled cluster and density functional methods. Preliminary analysis for the precursor via time-resolved laser flash photolysis (LFP) was performed. …

Investigation Of How Hydrogen Bonding Affects The Enantiomeric Excess Of Pig Liver Esterase Promoted Hydrolysis Of Pro-Chiral Substrates, Jacob E. Pruett

Honors Theses

Pig Liver Esterase is a cost effective enzyme for ester hydrolysis. In our group, it is vital for creating chiral molecules for the synthesis of unnatural amino acids of potential biological importance. It has been previously found that the enantiomeric excess (%ee) of the PLE hydrolysis reaction increases drastically with the addition of co-solvents that are able to both accept and donate hydrogen bonds. This research endeavors to see if substrates of enhanced hydrogen bonding ability also increase the stereoselectivity of PLE hydrolyses. Diester malonate was covalently linked with a furan ring in both the third and second position from …

Synthesis And Application Of (R)-3-Methylpyrrolidine-3-Carboylic Acid, Shelby D. Dickerson

Honors Theses

L-Proline is an amino acid widely used in pharmaceutical and biotechnological research due to its catalytic activity and biological relevance. L-Proline has been recognized and utilized as an organocatalyst, which allows cleaner, more sustainable reactions. However, one issue with L-proline is its low solubility in organic systems, limiting its reactivity and efficiency, especially when considering industrial research. Two reactions that utilize L-Proline are the Michael and Aldol but require 100 mol% of L-Proline and 30 mol% of L-Proline, respectively. This research will focus on the synthesis of an analogue of L-Proline utilizing inexpensive, commercially available reagents. A variety of organic …

Phenanthrene...With A Twist!, Nicholas S. Kim

Honors Theses

The twisted and sterically hindered 4,5-dibromophenanthrene, was synthesized from 2,6-dibromoiodobenzene in a four-step pathway, or from 1,3-dibromobenzene in a three-step pathway. Then, 4,5-dibromophenanthrene was subjected to a Kumada coupling, leading to the synthesis of an even more twisted 4-bromo-5-tert-butylphenanthrene. Computational studies using density functional theory were performed to compare experimental and theoretical characteristics of these compounds, such as dihedral angles, optimized structures, and transition state energy barriers.

The purpose of these experiments is to fill gaps in chemical databases, synthesize more pronounced twists in normally planar phenanthrene molecules, and to ultimately synthesize 4,5-bis-tert-butylphenanthrene, which may have …

Part I: Photochemical Generation Of Cyclohexyne From A Hydrocarbon Precursor Part Ii: A Triptycenyl Flower, Daniel Maurer

Honors Theses

Part I

Photolysis of phenanthrene-based methylenecyclopropane derivatives have previously been shown to generate alkylidenecarbenes, which readily rearrange to form alkynes. In this work, we show that photolysis of an analogous cyclic alkylidenecarbene precursor at ambi- ent temperature forms cyclohexyne via the putative cyclopentylidenecarbene, and can be trapped by dienes via a Diels-Alder reaction. Cyclohexyne and other strained cycloalkynes are of much interest to theoreticians and experimentalists alike. Results of coupled-cluster and DFT calculations on the potential energy surface of cyclopentylidenecarbene and the corresponding strained cyclohexyne are also presented. The photochemical generation of cy- clopentylidenecarbene, and thus cyclohexyne, from a hydrocarbon …

Experimental And Computational Study Of Methylphenylvinylidene And Its Rearrangements, Xi Yang

Honors Theses

In this study, the synthesis and properties were explored of the compound methylphenylvinylidene (MPV), a vinylidene carbene with methyl and phenyl groups as substituents. A phenanthrene-based precursor, 1-(1-phenylethylidene)-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene, was synthesized in three steps and was subjected to photolysis in C₆D₆ at ambient temperature. During photolysis, the MPV carbene rearranged into 1-phenylpropyne via a 1,2-phenyl shift, instead of 1,2-methyl shift, confirmed by photolysis of ¹³C-labeled precursor. This experimental result is consistent with computational results using the CCSD(T)/cc-pVTZ//B3LYP/6-31+G* method. The calculations suggest that the 1,2-phenyl shift in singlet carbene requires 3.8 kcal/mol to overcome …

Generation Of 2-Adamantylidenecarbene From A Phenanthrene-Based Precursor, Christine E. Wamsley

Honors Theses

This thesis examines the generation of 2-adamantylidenecarbene from a phenanthrene-based precursor. A three-step synthetic procedure was used to generate the 2-adamantylidenecarbene precursor, which subsequently underwent photolysis to produce 2-adamantylidenecarbene. This product was trapped with cyclohexene. No evidence of a ring expansion to 4-homoadamantyne was observed. It was also noted that the target precursor underwent rearrangement during photolysis, leading to the formation of an isomer containing a seven-membered ring. This isomer did not photolyze. Additionally, computational studies were performed using Gaussian 09. Geometries were initially optimized and then, the single point energies of the singlet and triplet carbene states were calculated. …

Experimental And Computational Investigation Of Selected Β-Hydroxy Carbenes, Joseph D. Deangelo

Honors Theses

The photolytic precursor to the sterically hindered β-bis(tert)-butanol carbene, 3-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)-2,2,4,4-tetramethylpentan-3-ol was prepared in three steps from phenanthrene. Photolysis of the precursor generates the desired β-hydroxy carbene, an intermediate, which subsequently rearranges into two different observed products from an intramolecular C-H insertion and alkyl shift. Four intramolecular mechanisms were ultimately considered to account for the possible rearrangement pathways. Computational studies using density functional theory are also presented.

In addition, the photolytic precursors to two cyclic β-hydroxy carbenes, 1-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)cyclopropan-1-ol and 1-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)cyclobutan-1-ol, were also prepared through different synthetic routes from phenanthrene. …

Analysis Of The Electron Withdrawing Capability Of Acetylene Groups For Promoting Nucleophilic Aromatic Substitution, Eric D. Braunstein

Honors Theses

It is well known that electron withdrawing groups, such as nitro or carbonyl groups, activate benzene rings for nucleophilic aromatic substitution. However, little research has been done to investigate the electron withdrawing capability of acetylene groups for substitution of aromatic halides. Experimental and computational investigations on the reactivity of halogenated phenylacetylenes with oxygen and other nucleophiles will be described.

Using Azahetercyclic Electrophiles To Synthesize Novel Bicyclooxacalixarenes And Oxacalix[2]N-Hexylnaphthalimide[2]Naphthyridines, Doug Rooke

Honors Theses

Various bicyclooxacalixarenes, tricyclooxacalixarenes and oxacalix[2]N-hexylnapthalimide[2]naphthyridines are synthesized via SnAr condensation. This research has involved synthesis optimization. The oxacalix[2]N-hexylnaphthalimide[2]naphthyridines have exhibited host-guest binding in fluorescence experiments. These compounds have been characterized by NMR spectroscopy as well as single crystal X-ray diffraction.

Photochemical Generation And Intramolecular Chemistry Of Β-Alkoxycarbenes, Kimberly Graves

Honors Theses

The photolytic phenanthrene-based precursors for both β-methoxycarbene and β-ethoxycarbene were synthesized with and without a deuterium label attached to the a carbon. The incorporation of this deuterium label allowed distinction between a 1, 2-H shift and a 1, 2-O shift pathway to the respective alkyl vinyl ether, without the influence of a primary kinetic isotope effect. Photolyses of these precursors gave rearrangement products of the expected β-alkoxycarbenes. In the case of β-methoxycarbene, no methyl vinyl ether was observed due to its volatility. However, the appearance of aldehyde peaks in the NMR spectra, from an apparent further rearrangement to acetaldehyde through …

Nickel Catalyzed Cyclizations Of Alkynyl-Etones And Their Application To The Formal Synthesis Of Pentalenic Acid, Kevin Schlosser

Honors Theses

Pentalenic acid is a very important molecule because it is a biosynthetic intermediate of pentalenolactone, which has antibiotic effects on Grampositive/ negative bacteria and pathogenic fungi. These effects are due to its ability to inhibit glyceraldehyde 3-phosphate dehydrogenase.1 However, the total synthesis of pentalenic acid is very lengthy.2 This project will begin the process of finding a more convenient route to pentalenic acid. Previously in this laboratory there have been experiments conducted in the cyclization of enones with nickel (0)3 It is hypothesized that this method can be used to shorten the preparation of pentalenic acid. As illustrated by the …

Determination Of The Rate Of Formation Of Hcn, Mitchell Hull

Honors Theses

Nitric oxide is a major air pollutant arising from fossil fuel combustion, yet the fuel contribution to its formulation is uncertain. Since, in combustion, fossil fuels undergo disintegration before oxidation takes place, the study of the pyrolsis of a model constituent of fossil fuels can shed light on NO formation. The rate of inert pyrolytic disappearance of pyridine and the rate of formation of the principal Nitrogen-containing pyrolytic product, HCN, was studied in an inert atmosphere. The rate constant for the formation of HCN and its temperature dependence were determined.