NMR studies of the exchange reactions of CH3CN.BX3 with excess CH3CN /|nJoseph Fogelman. -- 260 St. Catharines, Ont. : [s. n.],

Exchange reactions between molecular complexes and excess acid or base are well known and have been extensively surveyed in the literature(l). Since the exchange mechanism will, in some way involve the breaking of the labile donor-acceptor bond, it follows that a discussion of the factors relating to bonding in molecular complexes will be relevant. In general, a strong Lewis base and a strong Lewis acid form a stable adduct provided that certain stereochemical requirements are met. A strong Lewis base has the following characteristics (1),(2) (i) high electron density at the donor site. (ii) a non-bonded electron pair which has a low ionization potential (iii) electron donating substituents at the donor atom site. (iv) facile approach of the site of the Lewis base to the acceptor site as dictated by the steric hindrance of the substituents. Examples of typical Lewis bases are ethers, nitriles, ketones, alcohols, amines and phosphines. For a strong Lewis acid, the following properties are important:( i) low electron density at the acceptor site. (ii) electron withdrawing substituents. (iii) substituents which do not interfere with the close approach of the Lewis base. (iv) availability of a vacant orbital capable of accepting the lone electron pair of the donor atom. Examples of Lewis acids are the group III and IV halides such (M=B, AI, Ga, In) and MX4 - (M=Si, Ge, Sn, Pb). The relative bond strengths of molecular complexes have been investigated by:- (i) (ii) (iii) (iv) (v] (vi) dipole moment measurements (3). shifts of the carbonyl peaks in the IIIR. (4) ,(5), (6) .. NMR chemical shift data (4),(7),(8),(9). D.V. and visible spectrophotometric shifts (10),(11). equilibrium constant data (12), (13). heats of dissociation and heats of reactions (l~), (16), (17), (18), (19). Many experiments have bben carried out on boron trihalides in order to determine their relative acid strengths. Using pyridine, nitrobenzene, acetonitrile and trimethylamine as reference Lewis bases, it was found that the acid strength varied in order:RBx3 > BC1 3 >BF 3 • For the acetonitrile-boron trihalide and trimethylamine boron trihalide complexes in nitrobenzene, an-NMR study (7) showed that the shift to lower field was. greatest for the BB~3 adduct ~n~ smallest for the BF 3 which is in agreement with the acid strengths. If electronegativities of the substituents were the only important effect, and since c~ Br ,one would expect the electron density at the boron nucleus to vary as BF3-bonding (20), (21) between the halogen and the boron atoms has been proposed as the predominating factor, i.e. ~rt- back-bond between a lone electron pair on the halogen and the vacant orbital on the boron site. The degree of back-bonding varies inversely as the bo~on halogen distance and one would therefore expect the B-F bond to exhibit greater back-bonding character than the B-Cl or B-Br bonds. Since back-bonding transfers electron density from substituent to the boron atom site, this process would be expected to weaken the Lewis acid strength. This explains the Lewis acid strength increasing in the order BF 3 BC1 3 BBr 3 . When the acetonitrile boron trihalide complex is formed, the boron atom undergoes ~_cbange of hybridization from sp2 to sp3. From a linear relationship between the heat of formation of ethyl acetate adducts and the shift in the carbonyl I.R. stretch, Drago (22) et al have proposed that the angular di~tortion of the X-B-X bonds from sp2 (12 ) to sp3 (10 hybridization is proportional to the amount of charge transferred, i.e. to the nature of the base, and they have rejected the earlier concept of reorganization energy in explaining the formation of the adduct bond (19).

Primary structure and expression studies of the dihydrofolate reductase gene (DFRI) of Saccharomyces cerevisiae

The nucleotide sequence of a genomic DNA fragment thought previously to contain the dihydrofolate reductase gene (DFR1) of Saccharomyces cerevisiae by genetic criteria was determined. This DNA fragment of 1784' basepairs contains a large open reading frame from position 800 to 1432, which encodes a enzyme with a predicted molecular weight of 24,229.8 Daltons. Analysis of the amino acid sequence of this protein revealed that the yeast polypep·tide contained 211 amino acids, compared to the 186 residues commonly found in the polypeptides of other eukaryotes. The difference in size of the gene product can be attributed mainly to an insert in the yeast gene. Within this region, several consensus sequences required for processing of yeast nuclear and class II mitochondrial introns were identified, but appear not sufficient for the RNA splicing. The primary structure of the yeast DHFR protein has considerable sequence homology with analogous polypeptides from other organisms, especially in the consensus residues involved in cofactor and/or inhibitor binding. Analysis of the nucleotide sequence also revealed the presence of a number of canonical sequences identified in yeast as having some function in the regulation of gene expression. These include UAS elements (TGACTC) required for tIle amino acid general control response, and "TATA H boxes as well as several consensus sequences thought to be required for transcriptional termination and polyadenylation. Analysis of the codon usage of the yeast DFRl coding region revealed a codon bias index of 0.0083. this valve very close to zero suggestes 3 that the gene is expressed at a relatively low level under normal physiological conditions. The information concerning the organization of the DFRl were used to construct a variety of fusions of its 5' regulatory region with the coding region of the lacZ gene of E. coli. Some of such fused genes encoded a fusion product that expressed in E.coli and/or in yeast under the control of the 5' regulatory elements of the DFR1. Further studies with these fusion constructions revealed that the beta-galactosidase activity encoded on multicopy plasmids was stimulated transiently by prior exposure of yeast host cells to UV light. This suggests that the yeast PFRl gene is indu.ced by UV light and nlay in1ply a novel function of DHFR protein in the cellular responses to DNA damage. Another novel f~ature of yeast DHFR was revealed during preliminary studies of a diploid strain containing a heterozygous DFRl null allele. The strain was constructed by insertion of a URA3 gene within the coding region of DFR1. Sporulation of this diploid revealed that meiotic products segregated 2:0 for uracil prototrophy when spore clones were germinated on medium supplemented with 5-formyltetrahydrofolate (folinic acid). This finding suggests that, in addition to its catalytic activity, the DFRl gene product nlay play some role in the anabolisln of folinic acid. Alternatively, this result may indicate that Ura+ haploid segregants were inviable and suggest that the enzyme has an essential cellular function in this species.

Studies of nucleophilic attack on tris (pentafluorophenyl) phosphine and its oxides

The reaction of tris(pentafluorophenyl)phosphine [5] with the nucleophiles dimethyl formamide (DMF), hexamethylphosphoric triamide (HMPA), diethyl formamide (DEF), hexaethylphosphoric triamide (HEPA), hydrazine, N,N-dimethyl hydrazine (in presence and/or absence of KF), phenylhydrazine, ammonium hydroxide, formamide, aniline, sodium hydrogen sulfide, and hexaethylphosphorous triamide was investigated. The reaction of [5] with DMF and HMPA gave the same product, namely tris-[4-(N,N-dimethylamino)-2,3,5,6-tetrafluorophenyl]phosphine [12] but in higher yield in the case of HMPA. Compound (5] also reacted with DEF to give tris[4-(N,N-diethylamino)-2,3,5,6-tetrafluorophenyl] phosphine [14]. When [51 was treated with HEPA, it gave a mixture of bis(pentafluorophe~yl)-(N,N-diethylamino-tetrafluorophenyl)phosphine, pentafluorophenyl-bis-(N,N-diethylamino-tetrafluorophenyl)phosphine and tris (N,N-diethylamino-tetrafluorophenyl)phosphine. Treatment of [5] with aqueeus hydrazine solution in excess ethanol gave tris(4-hydrazo-2,3,4,6-tetrafluorophenyl)phosphine [1s1 in high yield while reaction with aqueous hydrazine led to C-P cleavage and production of tetrafluorophenyl hydrazine. With N,N-dimethyl hydrazine, [5] gave tris(4-N,N-dimethylhydrazine-2,3,5,6-tetrafluorophenyl) phosphine {20j. The latter could be obtained in higher yield and shorter reaction time, by the addition of KF. The reaction of compound {51 with phenylhydrazine in THF gave bis(pentafluorophe~yl)-4-S-phenylhydrazino- 2,3,5,6-tetrafluorophenyl phosphine [22] in low yield. Reaction of [5] with ammonium hydroxide in THF at high pressure in the presence of KF gave tris-~4-amino-2,3,5,6-tetrafluorophenyl)phosphine [25]. Similarly, formamide led to a mixture of (C6F4NHZ)3P, (C6F4NHZ)ZPC6FS, (C6F4NHZ)ZPC6F4NHCHO, and C6F4NHZP(C6Fs)(C6F4NHCHO). When [5] was treated with aniline, a mixture of mono-, di-, and tri-substituted products was obtained. Sodium hydrogen sulfide in ethylene glycol/ pyridine led to C-P cleavage and the isolation of pentafluorobenzene and tetrafluorothiophenol. Reaction of [5] and its oxide [35] with different alkoxides in the corresponding alcohols led mainly to C-P bond cleavage products, with the exception of one case where sodium methoxide was used in ether, and which led to tris-(4-methoxy-2,3,9,6-tetrafluorophenyl)phosphine [37]. On the basis of various spectroscopic data, it was concluded that the para position in compound [5] was generally the favoured site of attack.

Studies of some cocondensations of nickel atoms with unsaturated organic ligands and with mixed ligand systems

The cocondensation of nickel with a number of unsaturated ligands was studied, as was the cocondensation with a number of mixed ligand systems. Enamines were found not to react with nickel while acrylonitrile was polymerized. In the mixed ligand syst.ems different products were obtained than when the ligands were cocondensed individually. Cocondensations of benzyl halide/allyl halide mixtures gave unstable products that were not observed when the halides were cocondensed individually. The effect of Kao-Wool insulation on nickel/benzyl halide cocondensations was found to be significant. Kao-Wool caused the bulk of the benzyl halide to be polymeri zed to a number of poly-benzylic species. An alkali metal reactor was designed for the evaporation of sodium and potassium atoms into cold solutions of metal halide and an or ganic substrate. This apparatus was used to synthesize Ni(P¢3 )3' but proved unsuccessful for synthesizing a nickel-enamine compound.

Studies of tetrahedral haloboron cations of pyridines and aliphatic tertiary amines

The preparation of the haloboron cations D2BF2 + and DD'BF 2+, where D=R3N or a pyridine, has been systematically . 19 11 studied uS1ng F and B n.m.r. Both types of amines form numerous difluoroboron cations by heavy halogen displacement from D.BF 2X (X=CI,Br) adducts. Previously, D.BFX2 (X=CI,Br) adducts of aliphatic tertiary amines were unreactive towards cation formation. However, with the more-reactive pyridines, D.BFX 2 adducts formed new monofluoroboron cations D2BFX+ In non-fluorinated D.BX Y3 systems for n -n both pyridines and R3N, haloboron cations of type D2BX2 + and D2BXY+ can be similarly prepared. FAB-MS studies of ionic salts of our haloboron cations resulted in m/z peaks characteristic of D2 BX2 + and its f ragmentation products. These results s upport our n.m.r. solution s t u d ies. Pairwise interaction n . m.r . parameters for tetrahedral boron halide species were def i ned, then used to assist confirmation of our haloboron cations.

Synthesis and spectral studies of methyl heterocylic systems

2-Carboxy-2?-methyldiphenyl sulfide was prepared by the Ullmann reaction and cyclodehydrated by sulfuric acid to afford 4-methylthioxanthone. 1-Methylthioxanthone was separated from the reaction mixture obtained upon cyclodehydration of 2-carboxy-3f-methyldiphenyl sulfide. In addition, 1-, 2-, 3- and 4-methylthioxanthone 10,10-dioxides were synthesized by oxidation of the corresponding thioxanthones. o-, m- and p-N-Tolylanthranilic acids were prepared by the Ullmann reaction and used as precursors for the preparation of 1-, 2- and 4- methyl-9-chloroacridine and finally 1-, 2-, 3- and 4-methylacridone. High resolution, 60 MHz PMR spectra were obtained on the four monomethyl isomers of xanthone, thioxanthone, thioxanthone 10,10-dioxide and acridone, and on 1-, 2- and 4-methyl-9-chloroacridine. For some compounds, coupling of all three different aromatic protons to the methyl was observed, two of the couplings typically being smaller than the third. With the large (ortho) coupling being on the order of 0.5 to 1.0 Hz, it was necessary to decouple the aromatic part of the spectrum. The magnitude of the ortho benzylic constant may be related to an incomplete Tr-bond delocalization in the molecules.

X-ray diffraction studies of muscle : observations on the anterior byssus retractor muscle of Mytilus edulis and the insect flight muscle from Sarcophaga bullata

The interfilament spacing of the anterior byssus retractor muscle from Mytilus edulis was studied as the muscle was extended. It was found that variations in this spacing were very small and consistent with the hypothesis that the interfilament spacing was independent of the extension of the muscle. It was observed that the interfilament spacing was dependent on the osmolarity of the bathing medium. In concentrated solutions of the artificial seawater, the interfilament spacing decreased; while in dilute solutions of artificial seawater, it was observed that the interfilament spacing was increasing. X-ray diffraction patterns were obtained from fresh, and glutaraldehyde fixed, specimens of insect flight muscle from Sarcophaga bullata. There patterns were in general agreement with previous X-ray diffraction studies of insect flight muscle. A reflexion G at 93A was observed and interpreted as arising from diffraction in the mitochondria. Specimens of dried insect flight muscle produced a diffraction pattern consisting of arc and ring reflexions. This was interpreted as suggesting an ordered arrangement of cristae, in the mitochondria from these muscles.

Nuclear magnetic resonance studies of boron trihalide complexes of 1,1-BIS (dimethylamino) ethylene and related bases

Boron tribalide complexes of 1,1-bis(dimethylamino)ethylene (DME) , t etramethylurea (TMU), tetramethylguanidine (TMG) , and pentamethylguanidine (PMG) and also mixed boron t r ihalide adducts of DME have been investigated by 1H and 19F NMR spectroscopy. Both nitrogen and the C-Q-H carbon of DME are possible donor a toms to boron trihal ides but complexation has been found to occur only at carbon of DME. The initial adduct acts as a Bronsted acid and gives up a proton to free DME in solut ion. A side reaction in the DME-BF, system gives rise to trace amounts of a complex aSSigned as (DME)2BF2+. (DME)2BF2+ is produced in much larger quantities in t he DME-BF3-BC13 and DME-BF,-BBr, systems by reaction of free DME with DME:BF2X (X = Cl, Br). Restricted r otation about the C-N bonds of TMUlBC13 and n1U:BBr3 has been observed at low temperatures. This complements previous work in this system and confirms oxygen donation of TMU to boron trihalides . Restricted rotation at low temperatures also has been observed in DMEboron trihalide systems

Anti-Oedipus en-procés : a comparative analysis of Kristeva and Deleuze & Guattari

The present thesis is an attempt to bring into dialogue what appear to be two radically different approaches of negotiating subjectivity in late Western Modernity. Here the thought of Julia Kristeva as well as Gilles Deleuze and Felix Guattari are fully engaged. These thinkers, the latter two being considered as one, have until now remained strangers to one another. Consequently much confusion has amassed concerning their respective philosophical, as well as social/political projects. I take up the position that Deleuze and Guattari's account of subjectivity is a commendable attempt to understand a particular type of historical subject: late modern Western man. However I claim that their account comes up short insofar as I argue that they lack the theoretical language in order to fully, and successfully, make their point. Thus I argue that their system does not stand up to its own claims. On the contrary, by embracing the psychoanalytic tradition - staying rather close to the Freudian and Kleinian schools of thought - I argue that it is in fact Kristeva that is better equipped to provide an account of this particular subject. Considerable time is invested in fleshing out the notion of the Other insofar as this Other is central to the constitution of subjectivity. This Other - insofar as this Other is to be found in Kristeva's notion of the chora -- is something I claim that Deleuze and Guattari simply undervalued.

Unveiling Shi’i Religious Identities: Case Studies of Hijab in Culturally Homogeneous Canadian Schools

This qualitative case study explored 10 young female Shi’i Muslim Arabic-Canadian students’ experiences associated with wearing the Hijab (headscarf) within their home, community, and predominantly White Canadian public elementary school environments. The study integrated several bodies of scholarly theories in order to examine the data under a set of comprehensive lenses that more fully articulates and theorizes on the diversity of female Shi’i Muslim Canadian students’ experiences. These theories are: identity theories with a focus on religious identity and negative stereotypes associated with Muslims; feminism and the Hijab discourses; research pertaining to Muslims in school settings; and critical race theory. In order to readdress the dearth of information about Shi’is’ experiences in schools, this study provides an in-depth case study analysis in which the methodology strategies included 10 semi-structured in-depth interviews, 2 focus-group meetings, and the incorporation of the researcher’s fieldnotes. Data analysis revealed the following themes corresponding to participants’ experiences and values in their social worlds of home, community, and schools: (a) martyrdom and self-sacrifice as a means for social justice; (b) transformational meaning of the Hijab; (c) intersectionality between culture, religion, and gender; and (d) effects of visits “back home” on participants’ religious identities. Additional themes related to participants’ school experiences included: (a) “us versus them” mentality; (b) religious and complex secular dialogues; (c) absence of Muslim representations in monocultural schools; (d) discrimination; (e) remaining silent versus speaking out; and (f) participants’ strategies for preserving their identities. Recommendations are made to integrate Shi’i Muslim females’ identity within the context of Islam and the West, most notably in relation to: (a) the role of Muslim community in nondiverse settings as a space that advances and nurtures Shi’i Muslim identity; and (b) holistic and culturally responsive teaching that fosters respect of others’ religiosity and spirituality. This study makes new inroads into feminist theorizing by drawing conceptual links between these previously unknown connections such as the impact of the historical female exemplary role model and the ritual stories on the experiences of Muslim females wearing the Hijab.

Fluorescence Studies of Photosystem II Fluorescence Quenching During Desiccation

Poikilohydric organisms have developed mechanisms to protect their photosynthetic machinery during times of desiccation. In hydrated conditions nonphotochemical quenching (NPQ) mechanisms are able to safely dissipate excess excitation energy as heat, but mechanisms of NPQ associated with desiccation tolerance are still largely unclear. In the lichen Parmelia sulcata, photosystem protection has been associated with an energy quenching energetically coupled to PSII and characterized by a fast-fluorescence decay lifetime, and long-wavelength emission. The present study compares the relative ability of green algae and lichens to recover photosynthetic activity after periods of desiccation using steady state fluorescence emission spectroscopy, and picosecond time-resolved fluorescence decay measurements. It was determined that desiccation induced quenching involves an antenna quenching mechanism with similar characteristics appearing in both P. sulcata and green algae. Algae isolated from lichens suggest symbiosis in the lichen appears to enhance this naturally occurring phenomenon and provide greater protection during desiccation.

Structural, Magnetic and Thermal Studies of Ce1-xEuxCrO3 Nano-Powders

A new series of nano-sized Ce1-xEuxCrO3 (x = 0.0 to 1.0) with an average particle size of 50 - 80 nm were synthesized using a solution combustion method. Nano-powders Ce1-xEuxCrO3 with the canted antiferromagnetic property exhibited interesting magnetic behaviours including the reversal magnetization and the exchange bias effect. The effect of europium doping as the ion with the smaller radius size and different electron con figuration on structural, magnetic and thermal properties of Ce1-xEuxCrO3 were investigated using various experimental techniques, i.e. DC/AC magnetic susceptibility, heat capacity, thermal expansion, Raman scattering, X-ray photoemission spectroscopy, transmission/scanning electron microscopy, X-ray powder diffraction and neutron scattering. An exchange bias effect, magnetization irreversibility and AC susceptibility dispersion in these samples confirmed the existence of the spin disorder magnetic phase in Ce1-xEuxCrO3 compounds. The exchange bias phenomenon, which is assigned to the exchange coupling between glassy-like shell and canted antiferromagnetic core, showed the opposite sign in CeCrO3 and EuCrO3 at low temperatures, suggesting different exchange interactions at the interfaces in these compounds. The energy level excitation of samples were examined by an inelastic neutron scattering which was in good agreement with the heat capacity data. Neutron scattering analysis of EuCrO3 was challenging due to the large neutron absorption cross-section of europium. All diffraction patterns of Ce1-xEuxCrO3 showed the magnetic peak attributed to the antiferromagnetic Cr3+ spins while none of the diffraction patterns could detect the magnetic ordering of the rare-earth ions in these samples.

DFT Studies of the Organocatalytic Aldol Reaction and a Frustrated Lewis Pair

The computational study, and in particular the density functional theory (DFT) study of the organocatalytic α-chlorination-aldol reaction and the chiral backbone Frustrated Lewis Pair (FLP) system served as a valuable tool for experimental purposes. This thesis describes methods to consider different transition states of the proline- catalyzed α-chlorination aldol reaction to determine the reasonable transition state in the reaction between the enamine and α-chloro aldehydes. Moreover, the novel intramolecular Frustrated Lewis pair based on a chiral backbone for the asymmetric hydrogenation of imines and enamines was designed and the ability of hydrogen splitting by this new FLP system was examined by computational modeling and calculating the hydrogen activation energy barrier.

Comparative statement of different classes of trade passing downward through the Welland Canal at Port Colborne during the years 1857-1861

Comparative statement of different classes of trade passing downward through the Welland Canal at Port Colborne during the years 1857-1861 (1 page, hand drawn chart), Jan.25, 1862.