The dianion of cyclopentylidenemalononitrile (CPDM2-) can be characterized by dialkylation. The adducts formed in diallylation have been studied both experimentally and theoretically. Diallyl-CPDM has been characterized by 1H and 13C NMR, IR spectrum and by its fragmentation pattern in the mass spectrum. The chemical reactivity of CPDM2- is easily explained or predicted using the frontier molecular orbitals, FMO, calculated using MNDO method. The evidences from NMR, IR, MS and the prediction from MNDO calculation were highly consistent. The results indicate a very stable dianion having a pattern of reactivity that is observed experimentally and predicts the isomeric structure of its alkylation product, Diallyl-CPDM (Isomer A), consistent with MS, IR and NMR experiments.Cyclohexylidenemalononitrile dianion (CHDM2-) has been generated by two dimetalating systems, n-butyllithium/DMSO and Dimsyl/DMSO, and examined by 1H and 13C NMR in DMSO-d6. The 13C NMR spectra of CHDM2- has been interpreted by means of MNDO atomic charge, attached proton test APT, Nuclear Overhauser Effect and chemical shift reference data. The generation of this dianion is accompanied by appropriately characteristic changes in the 13C chemical shifts.MNDO calculations have been performed for all molecules of interest, and found to be useful and reliable for the study of Y-conjugated dianionsof cycloalkylidene-malononitriles. The correlation of MNDO atomic charge vs empirical 13C chemical shift was found to be linear for sp2 conjugated carbons of negative-charged nitriles and the empirical equation, s = 44.9p + 125.4, predicts chemical shifts with only 2.14% average percent error. With FORCE calculation, MNDO method can calculate the frequencies of CPDM and CHDM with only 0.65% average error which was superior than AM1 method (3.87%). Moreover, systematic MNDO calculations of over 30 nitrile molecules have been carried out giving; heats of formation, electronic energy, core-core energy, dipole moment and ionization potential.The conformation of CHDM2- has been analyzed with MNDO optimized geometry and found to have 45° twist within the Y-conjugated n-system of the dianion. Double-LithiumBridging-Structure, the simple model of dilithio-CHDM, has been proposed based on Ion Triplets Theory and MNDO charge distribution, and its electronic energy was calculated from the distances of point charges in this model. The results indicate that the Li counterion can stabilize the dianion. / Department of Chemistry

Thesis (Ph. D.)--Georgia State University, 2007. / Title from file title page. George Pierce, committee chair; E. Gilbert, Sidney Crow, committee members. Description based on contents viewed July 17, 2009. Includes bibliographical references (p. 124-135).

Thesis (M.S.)--Duquesne University, 2003. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 87-94) and abstract.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1950. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 124-125).

Thesis (MScEng)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Abstracted in Dissertation abstracts, v. 18 (1958) no. 3, p. 779. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 65-70).

Magister Scientiae - MSc / Geobacillus pallidus RAPc8 is a thermophilic nitrile-degrading isolate, obtained from thermal sediment samples of a New Zealand hot spring. The G. pallidus RAPc8 NHase gene has been cloned and expressed in E. coli. The recombinant NHase exhibits nitrile-degrading activity at 50 °C, capable of degrading branched, linear and cyclic heteroaromatic nitrile substrates. However, no activity was found on homoaromatic nitrile substrates such as benzonitrile. In the present study, high levels of activity on benzonitrile were detected with a double mutant βF52GβF55L. Kinetic analysis on the mutant enzyme showed an 8-fold decrease in KM with benzonitrile (0.3mM) compared to acrylonitrile (2.6mM). Specificity constants (kcat/KM) of 5900 and 450 s-1.mM-1 were obtained for the double mutant on benzonitrile and acrylonitrile respectively. The amino acid residues lining the substrate channel were identified and the geometric dimensions measured. Cavity calculations revealed a 29% increase in volume and a 13% increase in inner surface area for the substrate channel of the double mutant when compared to the wild type. Surface representation of the wild type structure revealed two extended, curved channels, which are accessible to the bulk solvent from two locations in the heterodimer. The removal of the βF52may have contributed to the presence of a single channel with two opposing openings across the dimers with no internal blockage. Normal Mode Analysis calculations also indicate a higher intrinsic flexibility of the mutant relative tothe wild type enzyme. The increased flexibility within the mutant NHase could have introduced a functionally relevant aromatic substrate recognition conformation. / South Africa

Magister Scientiae - MSc / In this study G. pallidus RAPc8 NHase mutants were screened for reduced substrate inhibition compared to the wild type enzyme. Wild type and mutant enzymes were expressed and purified using hydrophobic interaction chromatography. Amidase coupled enzyme stop assays were conducted using 3-cyanopyridine as a substrate, whereas continuous enzyme kinetics were conducted using acrylonitrile as a substrate. / South Africa

This thesis describes the total synthesis of (±)-stephalic acid (96), the development of methodology for the conversion of ketones into α,β-unsaturated nitriles and exploratory studies aimed at developing a synthetic approach to cis-clerodane diterpenoids. In the total synthesis of (±)-stephalic acid (96), the ketone 94 (previously synthesized from 3-methyl-2-cyclohexen-1-one (105)) was converted into the enol trifluoromethanesulfonate (triflate) 108. The enol triflate 108 was coupled with lithium cyanide in the presence of a Pd(0) catalyst to provide the α,β-unsaturated nitrile 102. The latter substance was transformed into the α,β-unsaturated aldehyde 104, which was stereoselectively converted into the enol silyl ether 111. A novel triisobutylaluminum-promoted Claisen rearrangement-reduction process converted the enol allyl ether 103, obtained from the enol silyl ether 111, into the diene alcohol 118. The diene alcohol 118 was transformed via a series of reactions into (±)-stephalic acid (96). Conversion of the ketone 94 into the α,β-unsaturated nitrile 102 required the development of new methodology for the conversion of ketones into the corresponding α,β-unsaturated nitrites. Reaction of the enol triflates 158 and 162-167 with lithium cyanide in benzene (room temperature) in the presence of catalytic amounts of 12-crown-4 and tetrakistriphenylphosphinepalladium(0) provided the α,β-unsaturated nitriles 168 and 170-175, respectively. Conversion of the ketone 92 (previously synthesized from 2-methyl-2-cyclohexen-1-one (191)) into the enol silyl ether 204 was accomplished via an eight step sequence. Several features of this sequence should prove useful in the development of synthetic routes to the cw-clerodane family of diterpenoids. [diagrams omitted] / Science, Faculty of / Chemistry, Department of / Graduate

The structures of four inorganic compounds have been determined by single-crystal X-ray diffraction methods. Three of the structures investigated were phosphonitrilic derivatives: octamethylcyclotetra-phosphonitrilium trichlorocopper(II), [NPMe₂]₄H.CuCl₃, bis-(octa-methylcyclotetraphosphonitrilium) tetrachlorocobaltate(II), [(NPMe₂)₄H⁺] ₂ CoCl₄²ˉ , and hexadecamethoxycyclo-octaphosphonitrile, [NP(OMe)₂]₈. The fourth analysis was a study of the ionic compound caesium difluorophosphate. For each structure determination the intensity measurements were collected on a diffractometer using a scintillation counter and Mo-K̲⍺ radiation. The structure of [NPMe₂]₄H.CuCl₃ was determined from Patterson and Fourier summations. Refinement of positional and thermal parameters of the atoms was by least squares. The structure consists of discrete molecules in which the eight-member phosphonitrilic ring approximates the "tub" conformation with pairs of adjacent phosphorus and nitrogen atoms displaced alternately above and below the ring plane. A ring nitrogen atom is bonded to the copper atom (N-Cu = 2.04 Å) which has three chlorines arranged about it in a distorted square planar configuration. Across the ring from the N-Cu bond, there is a protonated nitrogen atom which is hydrogen-bonded to a neighbouring chlorine. The phosphorus-nitrogen bond lengths are not equal around the ring, but occur instead in four distinct pairs having lengths 1.63 Å, 1.60 Å, 1.56 Å, and 1.67 Å. These varying bond distances are explainable in terms of π-bonding systems. The structure of [ (NPMe₂)₄H⁺] ₂CoCl₄²ˉ has been determined by Patterson and Fourier methods and refined by least-squares. Most of the methyl hydrogen atoms were located in a final difference Fourier summation. The structure consists of tetrahedral CoCl₄²ˉ ions hydrogen-bonded to two protonated phosphonitrilic rings. The N-H...C1 distance in each case is 3.21 Å. The two independent rings have slightly different conformations. One approaches the "tub" shape and the other tends towards the "saddle" conformation. Protonation of the phosphonitrilic rings again results in non-equivalent P-N bond lengths. Averaged values for the two rings are 1.69 Å, 1.54 Å, 1.61 Å and 1.58 Å. Parameters which are unaffected by the addition of the proton agree with those found in related compounds when averaged values are considered. [NP(OMe)₂]₈ is a centrosymmetric sixteen-member phosphonitrile. Its structure was determined by Patterson, electron density, and least squares techniques. The phosphonitrilic ring consists of two approximately planar and parallel six-atom segments joined by a step. The P-N bond lengths are all equal within experimental error, their mean being 1.561 Å. The average P-0 and 0-C bond distances are 1.576 Å and 1.440 Å respectively. The methoxy groups cover the ring evenly, their arrangement being such that there is little conflict between steric and π- bonding requirements. The structure of caesium difluorophosphate was determined by comparison with KPO₂F₂ and refined by least square methods. Caesium and rubidium difluorophosphate are isomorphous with the potassium salt; all have the barium sulfate structure. The mean P-F distance in CsP0₂F₂ is 1.58 Å, the P-0 bond length, 1.48 Å. The lattice parameters and interionic distances increase with increasing radius of the alkali-metal cation. / Science, Faculty of / Chemistry, Department of / Graduate