Oleoquímica I: Estudios sobre la preparación y la estructura de los jabones de litio.

Lithium stéarate, palmitate, myristate, laurate, caprate and caprylate were prepared by means of fusion method. Elementary analysis and the infrared absorptions spectra of the prepared lithium soaps as well as their X-ray diffractions and the thermogravimetric analyses were carried out. The anhydrous lithium salts of fatty acids with 12 carbon atoms or less showed thermal stability up to ca. 300 ± 78 °C depending on the chain length. On other hand the salts with 14 carbon atoms or more were decomposed at 126 ± 4 °C leading to formation of lithium carbonate. The homologous lithium soaps had very similar crystal structure among them and their metal -to- oxygen bonds were similar for the acyl chains between 8 and 18 carbons. However the angle of inclination of the molecular axes to the basal plane increased with the decreasing of the number of carbon atoms of the fatty acid chain, as determined by X-ray diffraction. In addition, the ionic character of the metal -to- oxygen bond was enhanced with the decrease of the number of carbon atoms as shown by infrared spectroscopy.Se han preparado estearato, palmitato, miristato, laurato, caprato y caprilato de litio por fusión. Se ha realizado el análisis elemental, los espectros de absorción en el infrarrojo y las difracciones de rayos X de los Jabones de litio preparados, además del análisis termogravimétrico de los mismos. Las sales de litio anhidra de los ácidos con 12 átomos de carbono o menos mostraron una estabilidad térmica hasta los 300 ± 78 °C dependiendo de la longitud de la cadena. Por otro lado las sales con 14 átomos de carbono o más se descompusieron a 126 ± 4 °C formándose carbonato de litio. Los jabones homólogos de litio mostraron una estructura cristalina similar, siendo los enlaces metal-oxígeno del mismo tipo para los ácidos grasos de número de átomos de carbono entre 8 y 18. Sin embargo el ángulo de inclinación que forma la molécula con el plano basal aumentó con la disminución del número de átomos de carbono, lo que se observó por difracción de rayos X. Se comprobó por espectroscopia infrarroja la intensificación del carácter iónico del enlace metal-oxígeno al disminuir el número de átomos de carbono

Modification of Castor Oil by Isomerization, Halogenation and Application of Some Modified Products as Plasticizer in Nitrile Rubber Formulations

383-395The preparation of bromo-as well as chloro-derivatives of castor oil by addition and substitution reactions is reported. Bromine water and chlorine gas have been used to ha logenate the oil by addition while N-bromosuccinimide and PCl5 have been used in the substitution reactions. The course of the reaction has been followed using 1H-NMR and IR analyses. Positional isomerization and geometrical isomerization of the double bond in castor oil have also been considered in this investigation. Conjugation of the double bond in the bromo-castor oil has been checked by UV absorbance at 233 and 268 nm. Geometrical isomerization whereby the cis-double bond transforms into trans-isomer has been studied in case of castor oil as well as its chloro-derivative using IR analysis. The results show that greater percentage of trans-acids can be achieved by isomerization of the chlorinated derivative. The percentage of the trans-acid of this derivative has been found as 75 per cent, compared to 8 per cent in the case of castor oil. In addition, castor oil and its halogenated derivatives have been evaluated as plasticizer in NBR formulations instead of dibutylphthalate. The evaluation parameters used are the rheometric characteristics and the physicomechanical properties of rubber such as tensile strength and elongation per cent at break. In addition, the effect of the prepared plasticizers on the rubber swelling in toluene as well as in motor oil and their effect on the rubber properties after aging have also been studied. The results show that castor oil and its derivatives are advantageous over dibutylphthalate in terms of their effect on the mechanical properties as well as the rubber resistance to swelling in motor oil. The best properties could be obtained using hexachloro-castor oil and the optimum concentration has been 3 phr

Estabilidad térmica de jabones metal-palmitato con diversas aplicaciones industriales

The soaps of alkaline earth's and transition elements and closed ‘d’ orbitals were prepared by the double decomposition method by the reaction between metallic salts and sodium palmitate. The thermal stability of these soaps was studied in order to throw the light on their suitability for using as catalysts or lubricants. The soaps of alkaline earth's were found to be more stable than transition and ‘d’ closed shell soaps.Se han preparado jabones de tierras alcalinas y elementos de transición y orbitales “d” completos por el método de la descomposición doble mediante la reacción entre sales metálicas y palmitato sódico. La estabilidad térmica de estos jabones se estudio con el fin de arrojar luz sobre su idoneidad para su uso como catalizadores o lubricantes. Se encontró que los jabones de las tierras alcalinas son más estables que los de transición y que los jabones con la capa “d” completa