Knowledge of the interfacial reactions between CO/CO2 and transition metal oxide containing slags is more important to understand various metallurgical processes. The present research studied the kinetics of reaction between CO/CO2 and MnOx/TiOx containing Slags. Measurements of the rate of interfacial reaction between CO/CO2 and MnOx/TiOx -CaO-SiO2 Slags were made using 13CO2-CO isotope exchange technique. The dependence of rate constant with respect to the effects of oxygen activity, MnOx/TiOx content, slag basicity and temperature was discussed. It is found that the apparent rate constant increases with increasing MnOx/TiOx content, slag basicity and temperature and decreases while increasing oxygen activity. The apparent rate constants obtained for MnOx/TiOx containing slags show similar behavior to that of FeOx containing slags and the rates gradually increase for TiOx, FeOx and MnOx containing slags at same experimental conditions. The rate constant expressions for MnOx/TiOx containing slags are obtained by using a single charge transfer model. Comparison of calculated and measured rate constants shows that there is a good fit between the two, which implies that the single charge transfer model may be generally applicable. / Thesis / Master of Science (MSc)

This project examined the feasibility of using flux modification to reduce the as-deposited hydrogen content of basic-type shielded metal arc welds. Additions of oxidizing ingredients (micaceous iron oxides) to the reference flux formulation lowered the diffusible weld hydrogen content by up to 70%. Increasing amounts of silica caused a slight reduction in hydrogen content, probably as a result of the reaction between SiO2 and CaF2, which produces SiF4 and CaO as reaction products. Flux formulations containing additions of fluorine-containing compounds and calcite displayed lower hydrogen levels, with the diffusible weld metal hydrogen content reaching a minimum with increasing additions. Higher levels caused an increase in the weld hydrogen content. Thermodynamic slag modelling attributes the existence of these minima to a decrease in slag water capacity with an increase in slag fluorine content (at constant basicity), brought about by higher concentrations of fluorine-containing compounds in the flux formulation. The effect of flux additions on the weld mechanical properties and the electrode operating characteristics was not evaluated during the course of this investigation. / Dissertation (MSc (Metallurgy))--University of Pretoria, 2007. / Materials Science and Metallurgical Engineering / unrestricted

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Dois estudos consecutivos foram realizados para reavaliar a faixa ideal de pH e a tolerÃncia de juvenis de tilÃpia do Nilo, Oreochromis niloticus, à acidez elevada da Ãgua de cultivo, em condiÃÃes eutrÃficas de cultivo. Os pesos iniciais dos animais eram semelhantes em ambas as fases. No primeiro trabalho, foram adotadas quatro condiÃÃes distintas de pH da Ãgua de cultivo: pH = 5,56  1,21 (pH 5); pH = 6,59  0,77 (pH 6); pH = 8,25  0,39 (pH 8); pH = 9,21  0,37 (pH 9), obtidas pelas aplicaÃÃes de soluÃÃes Ãcidas ou alcalinas à Ãgua. Os animais foram mantidos em tanques externos de 250 L por oito semanas. NÃo houve renovaÃÃo da Ãgua de cultivo ao longo de todo o trabalho. Neste trabalho, foram observadas variÃveis de qualidade de Ãgua, solo, zootÃcnicas e metabÃlicas. As maiores concentraÃÃes de nitrogÃnio amoniacal total da Ãgua foram encontradas nos tanques pH 5 e as menores nos tanques pH 8. A concentraÃÃo de gÃs sulfÃdrico na Ãgua foi maior nos tanques pH 5. O peso corporal final, a taxa de crescimento especÃfico e a produtividade do pescado nos tanques pH 5 foram maiores do que o observado nos tanques pH 9. Observou-se maior consumo de oxigÃnio nos respirÃmetros de pH 9. Concluiu-se que a faixa ideal de pH da Ãgua para o cultivo de juvenis de tilÃpia do Nilo, em Ãguas eutrofizadas, vai de 5 a 8. O delineamento experimental do segundo trabalho foi constituÃdo por quatro tratamentos, a saber: Ãguas de cultivo com diferentes valores de pH (pH 4: 4,12  0,84; pH 5: 5,13  0,74; pH 6: 6,14  0,64 e pH 8: 8,06  0,48), com cinco repetiÃÃes cada. NÃo houve troca da Ãgua de cultivo, apenas reposiÃÃo para manter o nÃvel inicial. Durante oito semanas, foram observadas variÃveis de qualidade de Ãgua, solo, zootÃcnicas, metabÃlicas e qualidade de efluentes. Embora a concentraÃÃo de nitrogÃnio amoniacal total (NAT) na Ãgua tenha sido menor nos tanques pH 8, sua concentraÃÃo de amÃnia nÃo-ionizada (NH3) foi maior que nos demais. Ao final, o menor peso corporal dos peixes foi observado nos tanques pH 8. Houve significativa melhora nos resultados de conversÃo alimentar e na taxa de eficiÃncia proteica com a acidificaÃÃo da Ãgua. As concentraÃÃes de NH3 nos efluentes dos tanques acidificados foram reduzidas. Concluiu-se que a acidificaÃÃo gradual da Ãgua de cultivo de juvenis da tilÃpia do Nilo atà pH 4 à benÃfica ao crescimento corporal dos peixes. A avaliaÃÃo de todos os resultados permite inferir que a faixa de pH da Ãgua para cultivo de O. niloticus seja de 4 a 8. / The first experiment aimed to reassess the Nile tilapiaâs optimum range of water pH for culture in eutrophic conditions. The initial weights of the animals were similar in both phases. There were four different conditions of water pH: pH = 5,56  1,21 (pH 5); pH = 6,59  0,77 (pH 6); pH = 8,25  0,39 (pH 8); pH = 9,21  0,37 (pH 9), that were obtained by acidic or alkaline applications upon the rearing waters. The fishes were maintained in twenty outdoor 250-L tanks for eight weeks. No water exchange was performed over the entire study. Variables of water and soil quality, growth performance and metabolism were monitored in the 1st work. The highest concentration of total ammonia nitrogen was observed in the pH 5 tanks and the lowest ones in the pH 8 ones. The hydrogen sulfide concentrations were higher in the pH 5 tanks. Fish final body weight, specific growth rate and yield were higher in the pH 5 tanks than in the pH 9 ones. There was a higher consumption of dissolved oxygen in the pH 9 respirometers than in the other ones. It was concluded that the optimum water pH range for Nile tilapia culture in eutrophic waters is 5 â 8. The second experiment aimed to determine the tolerance of Nile tilapia juveniles to high acidic culture waters and the effects of the culture water acidification upon the tanksâ effluents quality. The experimental design had four treatments, e.g., waters with different pH values (pH 4: 4,12  0,84; pH 5: 5,13  0,74; pH 6: 6,14  0,64 e pH 8: 8,06  0,48), with five replicates each. No water exchange was carried out over the entire study, just water replenishment to maintain the initial level. Variables of water quality, soil, growth performance, metabolism and effluents were observed over eight weeks. In spite of the lower total ammonia nitrogen (TAN) concentration in the pH 8 tanks, their levels of non-ionized ammonia (NH3) were the highest. At the end, the lowest fish body weight was observed in the pH 8 tanks. There was a significant improvement in the feeding conversion ratio and protein efficiency rate by the water acidification. The concentrations of NH3 were reduced in the acidic tank effluents. It was concluded that the gradual water acidification up to pH 4 is good to Nile tilapia juvenilesâ growth performance. The evaluation of all the results shows that the water pH range for cultivation of O. niloticus is 4-8.

<p>In this thesis, the improved synthesis and investigations into the properties of some 3,7-diazabicyclo[3.3.1]nonane (bispidine) derivatives are described. These compounds are structurally related to the naturally occurring lupanine alkaloids, they are of interest because of their cardiac antiarrhythmic function as well as their use as bases or ligands in organic chemical reactions. Their chemical properties are related to the presence of a rigid molecular scaffold with two nitrogen atoms that can be utilized for binding interactions with a variety of Lewis acids.</p><p>An improved synthesis has been developed, providing access to bispidines <i>via</i> bispidinones while avoiding the use of highly toxic hydrazine, which is required as reducing agent in alternative methods.</p><p>A series of bispidine derivatives with a variety of substituents were characterized regarding their basicity, which spans thirteen orders of magnitude. Correlations between structure and basicity are discussed and computational methods have been used to propose further derivatives with even higher basicity.</p><p>The structures of several bispidine derivatives and their protonated forms have been characterized in the solid state by X-ray crystallography and in solution using NMR spectroscopy. Structure and solution dynamics in a sterically congested (π-allyl)palladium complex with a bispidine ligand have been investigated, revealing mechanistic insight into the dynamic process. Using a bulky bispidine as a temporary ligand for a (η³-propenyl) palladium complex, the novel adamantanoid [{(η³-propenyl)Pd}₆(μ₃-OH)₄] cluster was prepared.</p>

In this thesis, the improved synthesis and investigations into the properties of some 3,7-diazabicyclo[3.3.1]nonane (bispidine) derivatives are described. These compounds are structurally related to the naturally occurring lupanine alkaloids, they are of interest because of their cardiac antiarrhythmic function as well as their use as bases or ligands in organic chemical reactions. Their chemical properties are related to the presence of a rigid molecular scaffold with two nitrogen atoms that can be utilized for binding interactions with a variety of Lewis acids. An improved synthesis has been developed, providing access to bispidines via bispidinones while avoiding the use of highly toxic hydrazine, which is required as reducing agent in alternative methods. A series of bispidine derivatives with a variety of substituents were characterized regarding their basicity, which spans thirteen orders of magnitude. Correlations between structure and basicity are discussed and computational methods have been used to propose further derivatives with even higher basicity. The structures of several bispidine derivatives and their protonated forms have been characterized in the solid state by X-ray crystallography and in solution using NMR spectroscopy. Structure and solution dynamics in a sterically congested (π-allyl)palladium complex with a bispidine ligand have been investigated, revealing mechanistic insight into the dynamic process. Using a bulky bispidine as a temporary ligand for a (η3-propenyl) palladium complex, the novel adamantanoid [{(η3-propenyl)Pd}6(μ3-OH)4] cluster was prepared.

abstract: The field of Ionic Liquid (IL) research has received considerable attention during the past decade. Unique physicochemical properties of these low melting salts have made them very promising for applications in a many areas of science and technology such as electrolyte research, green chemistry and electrodeposition. One of the most important parameters dictating their physicochemical behavior is the basicity of their anion. Using four sets of Protic Ionic Liquids (PILs) and spectroscopic characterization of them, a qualitative order for anion basicity of ILs is obtained. Protic Ionic Liquids are made by proton transfer form a Brønsted acid to a base. The extent of this transfer is determined by the free energy change of the proton transfer process. For the cases with large enough free energy change during the process, the result is a fully ionic material whereas if the proton transfer is not complete, a mixture of ions, neutral molecules and aggregates is resulted. NMR and IR spectroscopies along with electrochemical and mechanical characterization of four sets of PILs are used to study the degree of ionicity. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2016

Due to the high efficiency and productivity of continuous casting process, this method has been the most employed process to produce steel in past decades. The need to improve and optimize the finished product made it essential to gain more knowledge about the process, types of defects that may occur and the reasons for them. Moreover, the solutions for reducing the shortcomings in continuous casting process have been an intriguing subject to study. Many attempts have been done in order to reach this goal. Understanding, determining and optimizing the mould flux slag properties is especially important, since it plays an important and significant role in this process. For this, it is of outmost importance to acquire more knowledge about different properties of mould flux powders. Hence, there has been a world wide effort to measure and model the properties of mould flux properties, such as liquidus and solidus temperatures, heat capacity, enthalpy, thermal expansion, density, viscosity, electrical conductivity, surface tension and thermal conductivity. This thesis presents a brief review on continuous casting process, mould flux powder and its properties and characteristics. Furthermore, it focuses on the thermo-physical properties of mould fluxes. In present work, different industrial mould flux powders have been analyzed to measure their viscosity, break temperature, physical properties such as density, flowablity of powder, slag structure and chemical composition. The experimental data have been compared to some of the most commonly used models such as Riboud model, Urbain model, Iida model and KTH model.

Plusieurs aminoglycosides font partie d’une famille d’antibiotiques à large spectre d’action. Les aminoglycosides ayant une activité antibiotique viennent interférer dans la synthèse protéique effectuée par les bactéries. Les protéines mal codées entraineront la mort cellulaire. Au fil des années, de nombreux cas de résistance ont émergé après une utilisation soutenue des aminoglycosides. De nombreux aminoglycosides semi-synthétiques ont été synthétisés avec comme objectif de restaurer leur activité antimicrobienne. Parmi les modifications ayant connu du succès, notons la didésoxygénation d’un diol et l’introduction de la chaine latérale HABA. Des études précédentes ont montré l’efficacité de ces modifications sur les aminoglycosides. Les présents travaux portent sur l’installation de la chaine latérale HABA et la didésoxygénation d’un diol sur la paromomycine et la néomycine. La didésoxygénation sélective des diols a été effectuée en utilisant la méthodologie développée par Garegg et Samuelsson, une variation de la réaction de Tipson-Cohen. Cette méthode a permis l’obtention du motif didésoxygéné sur les cycles A et D dans des rendements jamais égalés pour ce motif synthétique. La chaîne latérale a été introduite en tirant profit de la réactivité et de la sélectivité d’un carbamate cyclique. Ces méthodes combinées ont permis la synthèse efficace de nombreux analogues semi-synthétiques nouveaux. La 3',4'-didéhydro-N-1-HABA-néomycine et la 3',4',3''',4'''-tétradésoxy-N-1-HABA-néomycine montrent une activité impressionnante contre des souches de bactéries résistantes aux aminoglycosides. Des tests de toxicité effectués en collaboration avec Achaogen Inc. ont démontré que ces composés sont relativement toxiques sur les cellules rénales de type H2K, ce qui réduit de façon importante leur index thérapeutique. Afin d’abaisser la toxicité des composés, la relation entre toxicité et basicité a été explorée. Des substitutions de l’amine en 6''' ont été effectuées afin d’abaisser la basicité de l’amine. Les résultats de toxicité et d’activité antimicrobienne démontrent une corrélation importante entre la basicité des amines et la toxicité/activité des aminoglycosides antibiotiques. L’effet d’une modulation du pKa a aussi été exploré en installant des chaines fluorées sur l’amine en 6''' de la paromomycine et de la néomycine. Une séquence synthtétique pour isoler l’amine en 6''' de la néomycine a aussi été développée. / Some aminoglycosides are part of a broad-spectrum family of antibiotics used in the clinic. They interfere in protein synthesis in bacterium cell by interfering with the transcription of proteins leading to cellular death. After an intense usage of aminoglycosides in the clinic, numerous cases of resistance have been encountered which render aminoglycosides less effective. Semi-synthetic aminoglycosides have been synthesized with the objective of restoring their original antimicrobial activity. Deoxygenation of the diol on ring A and introduction of the lateral chain HABA at N-1 had a significant impact on their antimicrobial activity against resistant strains. The present work will focus on deoxygenation of the diol at 3', 4' and on the introduction of the lateral HABA chain on aminoglycoside, more specificaly on paromomycin and neomycin. The selective dideoxygenation of the A ring diol was done using a methodology developed by Garegg and Samuelsson, which is a modification of the original Tipson-Cohen reaction. This method allows the dideoxygenation on ring A and D with unprecedented yields. The lateral HABA chain was introduced via the ring opening of a cyclic carbamate. These methods were combined to produce very potent analogs such as 3',4'-didehydro-N-1-HABA-neomycin and 3',4',3''',4'''-tetradeoxy-N-1-HABA-neomycin. Toxicity tests done in collaboration with Achaogen Inc. showed that these analogs were toxic to H2K renal cells, which reduced significantly their therapeutic index. In order to lower the toxicity of those compounds, the relation between toxicity and basicity was explored. Substitution of the amine at 6''' was done in order to lower the basicity of this amine. The results showed a strong correlation beetween the basicity of this amine and toxicity/activity. The pKa of this amine was modulated by installing fluorinated alkyl chain on the amine at 6''' in order to see the effect of the pKa on the activity/toxicity on paromomycin and neomycin. A synthetic sequence was also developed to allow the 6''' amine on neomycin to be modified selectively.

Plusieurs aminoglycosides font partie d’une famille d’antibiotiques à large spectre d’action. Les aminoglycosides ayant une activité antibiotique viennent interférer dans la synthèse protéique effectuée par les bactéries. Les protéines mal codées entraineront la mort cellulaire. Au fil des années, de nombreux cas de résistance ont émergé après une utilisation soutenue des aminoglycosides. De nombreux aminoglycosides semi-synthétiques ont été synthétisés avec comme objectif de restaurer leur activité antimicrobienne. Parmi les modifications ayant connu du succès, notons la didésoxygénation d’un diol et l’introduction de la chaine latérale HABA. Des études précédentes ont montré l’efficacité de ces modifications sur les aminoglycosides. Les présents travaux portent sur l’installation de la chaine latérale HABA et la didésoxygénation d’un diol sur la paromomycine et la néomycine. La didésoxygénation sélective des diols a été effectuée en utilisant la méthodologie développée par Garegg et Samuelsson, une variation de la réaction de Tipson-Cohen. Cette méthode a permis l’obtention du motif didésoxygéné sur les cycles A et D dans des rendements jamais égalés pour ce motif synthétique. La chaîne latérale a été introduite en tirant profit de la réactivité et de la sélectivité d’un carbamate cyclique. Ces méthodes combinées ont permis la synthèse efficace de nombreux analogues semi-synthétiques nouveaux. La 3',4'-didéhydro-N-1-HABA-néomycine et la 3',4',3''',4'''-tétradésoxy-N-1-HABA-néomycine montrent une activité impressionnante contre des souches de bactéries résistantes aux aminoglycosides. Des tests de toxicité effectués en collaboration avec Achaogen Inc. ont démontré que ces composés sont relativement toxiques sur les cellules rénales de type H2K, ce qui réduit de façon importante leur index thérapeutique. Afin d’abaisser la toxicité des composés, la relation entre toxicité et basicité a été explorée. Des substitutions de l’amine en 6''' ont été effectuées afin d’abaisser la basicité de l’amine. Les résultats de toxicité et d’activité antimicrobienne démontrent une corrélation importante entre la basicité des amines et la toxicité/activité des aminoglycosides antibiotiques. L’effet d’une modulation du pKa a aussi été exploré en installant des chaines fluorées sur l’amine en 6''' de la paromomycine et de la néomycine. Une séquence synthtétique pour isoler l’amine en 6''' de la néomycine a aussi été développée. / Some aminoglycosides are part of a broad-spectrum family of antibiotics used in the clinic. They interfere in protein synthesis in bacterium cell by interfering with the transcription of proteins leading to cellular death. After an intense usage of aminoglycosides in the clinic, numerous cases of resistance have been encountered which render aminoglycosides less effective. Semi-synthetic aminoglycosides have been synthesized with the objective of restoring their original antimicrobial activity. Deoxygenation of the diol on ring A and introduction of the lateral chain HABA at N-1 had a significant impact on their antimicrobial activity against resistant strains. The present work will focus on deoxygenation of the diol at 3', 4' and on the introduction of the lateral HABA chain on aminoglycoside, more specificaly on paromomycin and neomycin. The selective dideoxygenation of the A ring diol was done using a methodology developed by Garegg and Samuelsson, which is a modification of the original Tipson-Cohen reaction. This method allows the dideoxygenation on ring A and D with unprecedented yields. The lateral HABA chain was introduced via the ring opening of a cyclic carbamate. These methods were combined to produce very potent analogs such as 3',4'-didehydro-N-1-HABA-neomycin and 3',4',3''',4'''-tetradeoxy-N-1-HABA-neomycin. Toxicity tests done in collaboration with Achaogen Inc. showed that these analogs were toxic to H2K renal cells, which reduced significantly their therapeutic index. In order to lower the toxicity of those compounds, the relation between toxicity and basicity was explored. Substitution of the amine at 6''' was done in order to lower the basicity of this amine. The results showed a strong correlation beetween the basicity of this amine and toxicity/activity. The pKa of this amine was modulated by installing fluorinated alkyl chain on the amine at 6''' in order to see the effect of the pKa on the activity/toxicity on paromomycin and neomycin. A synthetic sequence was also developed to allow the 6''' amine on neomycin to be modified selectively.

Neste trabalho investigamos a influência de alquiltio grupos sobre a basicidade e frequência de estiramento do ciano grupo de nitrilas alifáticas. Com esta finalidade foi estudada uma grande série de nitrilas alquiltio-substituidas em posição &#945;, &#946; &#947;, e &#948;, além de nitrilas não substituídas, incluídas para efeito de comparação. A série completa compõe-se dos seguintes compostos: acetonitrila, propionitrila, butironitrila, valeronitrila, hexanonitrila, heptanonitrila, octanonitrila, isobutironitrila, 2-metilvaleronitrila, pivalonitrila, 2,2\'-dimetilvaleronitrila, metiltioacetonitrila, &#945;-metiltiopropionitrila, etiltioacetonitrila, &#945;-etiltiopropionitrila, &#945;-etiltioisobutironitrila, &#945;-terc-butiltioacetonitrila, &#946;-etiltiopropionitrila, &#946;-etiltiobutironitrila, &#947;-etiltiobutironitrila e &#948;-etiltiovaleronitrila. É apresentada uma revisão bibliográfica na qual são abordados aspectos de estrutura, características espectrais e habilidade de formação de ponte de hidrogênio do ciano grupo de nitrilas, além de serem relatados trabalhos concernentes à auto-associação e momento dipolar de tais compostos. São fornecidos os dados de medidas de deslocamentos da frequência do grupo hidroxila do fenol e p-clorofenol (&#916;vo(OH)) em complexo 1:1 com as nitrilas estudadas, em tetracloreto de carbono, pelo emprego da espectroscopia no infravermelho. São apresentadas as frequências de estiramento do ciano grupo (vo (CN)) das mesmas nitrilas, em tetracloreto de carbono. São descritas as sínteses de algumas das nitrilas da série estudada, a saber: hexanonitrila, heptanonitrila, 2-metilvaleronitrila, 2,2\'-dimetilvaleronitrila, etiltioacetonitrila, &#945;-etiltioisobutironitrila e &#947;-etiltiobutironitrila. Feita uma análise dos resultados das medidas realizadas, conclue-se que: 1) as nitrilas &#945;-alquiltio-substituídas apresentam uma diminuição da basicidade e uma diminuição da frequência de estiramento do ciano grupo, com relação aos compostos análogos não substituídos; 2) as nitrilas &#946-etiltio-substituídas apresentam uma ligeira diminuição de basicidade em comparação com os compostos não substituídos correspondentes; 3) a introdução de um etiltio grupo nas posições &#947; e &#948; não produz qualquer alteração na basicidade do ciano grupo. Urna discussão é apresentada, focalizando-se a validade dos resultados de basicidade obtidos, assim como a sua atribuição. É eliminada a possibilidade da competição do átomo de enxofre na medida de basicidade do ciano grupo. São excluídas, também, as hipóteses de o impedimento estérico e o efeito indutivo do enxofre serem os únicos efeitos responsáveis pela diminuição de basicidade do ciano grupo, observada em &#946;-alquiltio-nitrilas. Os resultados relatados para as &#945;-, &#946;-, &#947;-e &#948;-alquiltio-nitrilas, investigadas pelo emprego de sistema ternário, são comparados com os anteriormente obtidos por B.Wladislaw e col, em sistema ternário. Observa-se concordância no caso de nitrilas &#945;-alquiltio-substituídas, mas não no de nitrilas com enxofre em posições mais afastadas, para as quais, em sistema binário, foi relatado um aumento de basicidade. Discutem-se as divergências observadas, sugerindo-se a possibilidade da ocorrência, no caso de sistema binário, de uma associação intra ou intermolecular envolvendo o enxofre e o ciano-grupo. Finalmente, é sugerida a interação entre enxofre e ciano grupo como provável causa da diminuição de basicidade em &#945;-alquiltio-nitrilas. É aventada a hipótese de que a ligeira diminuição de basicidade em &#946;-etiltio-nitrilas, observada em sistema ternário, seja proveniente do efeito indutivo do enxofre. / This thesis investigates the influence of alkylthio-groups on the basicities and stretching frequencies of the cyano-group of aliphatic nitriles. A large series of alkylthio- and unsubstituted nitriles was studied, including the following compounds: acetonitrile, propionitrile, butyronitrile, valeronitrile, capronitrile, heptanenitrile, octanenitrile, isobutyronitrile, 2-methylvaleronitrile, trimethylacetonitrile, 2,2\'-dimethylvaleronitrile, methylthioacetonitrile, &#945;-methylthiopropionitrile, ethylthioacetonitrile, &#945;-ethyl-thiopropionitrile, &#945;-ethylthioisobutyronitrile, &#945;-tert-butylthioacetonitrile, &#946;.ethylthiopropionitrile, &#946;-ethylthiobutyronitrile, &#947;-ethylthiobutyronitrile and &#948-ethylthiovaleronitrile. The thesis contains: A literature review on the structure, polarity and hydrogen bonding ability of the cyano-group of aliphatic nitriles, as well as self-association and dipolar moments of the same compounds. The data of relative basicities (&#916;vo(OH)) of the cyano-group as measured by i.r. shifts of OH stretching vibration of phenol and p-chlorophenol associated to the above mentioned nitriles (1:1), in carbon tetrachloride. The stretching frequencies (vo (CN)) of the cyano-group for the same nitriles, in carbon tetrachloride. The syntheses of the following compounds: capronitrile, heptanenitrile, 2-methylvaleronitrile, 2,2\'-dimethylvaleronitrile, ethylthioacetonitrile, &#945;-ethlthioisobutyronitrile and &#947;-ethylthiobutyronitrile. The &#916;vo(OH) measurements show that: 1) the &#945;-alkylthio-nitriles are less basic than the corresponding unsubstituted nitriles; 2) there is a slight decrease of the cyano-group basicity when the &#946;-methylene-group is replaced by a sulphur atom; 3) the nitriles, in which sulphur atom and cyano-group are apart by three or four methylene-groups, do not undergo any change in the basicity. Several aspects are discussed in the light of the obtained data. Thus, evidences are provided that the decrease of basicity observed is a measure of the cyano-group basicity, without any competition of the sulphur atom. The hypotheses of steric hindrance and inductive effect as responsible for the decrease of the cyano-group basicity in the &#945;-alkylthio-nitriles are excluded. The basicity data obtained for &#945;-, &#946;-, &#947;- and &#948;-alkylthio-nitriles, in ternary system, are compared with those reported, previously, by B.Wladislaw et al., for binary system. While our results for the &#945-derivatives are in accord with the previous ones, those for the nitriles with sulphur further removed from the cyano-group are contrasting. The increase of basicity for the latter compounds, observed previously, is tentatively explained by intra- or intermolecular association involving the cyano-group and sulphur atom. Finally, an interaction between cyano-group and sulphur is suggested as responsible for the decrease of basicity in the &#945;-alkylthio-nitriles. The slight decrease of basicity, observed for the &#946;-derivatives, is suggested to be best explained as due to the inductive effect of sulphur atom.