Obtención de monómeros asimétricos bifuncionales a partir de productos naturales abundantes : su uso para la síntesis de poliamidas quirales

• Autores: Orgueira, Hernan Antonio
• Año de publicación: 1998
• Idioma: español castellano
• Tipo de recurso: tesis doctoral
• Colaborador/a o director/a de tesis: Varela, Oscar José
• Materia: POLIAMIDAS ESTEREOREGULARES; NYLONS FUNCIONALIZADOS QUIRALES; MONOMEROS BIFUNCIONALES QUIRALES; POLIMEROS SINTETICOS; STEREOREGULAR POLAYMIDES; CHIRAL FUNCTIONAL NYLONS; CHIRAL BIFUNCTIONAL MONOMERS; SYNTHETIC POLYMERS
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

,y (Gli-AMP-AMP)n. Por otra parte, se sintetizaron poliamidas quirales estereoregulares del tipo AABB (nylons-n,n). Se utilizó como molde quiral la 4-(S)-carboxil-1,4-butirolactona derivada delácido L-glutámico. El grupo carboxilo se activó por preparación de un éster lábil y seestudió la policondensación al azar con l,6-diaminohexano obteniéndose una poliamida noestereoregular (arrégica). Por control de la estereoquímica de la polimerización, sesintetizaron una poliamida sindiorégica y otra isorrégica. También se sintetizó un análogoquiral estereoregular del nylon-2,5; con centros quirales tanto en la porción diácido comodiamina. Finalmente se prepararon polimanaramidas. Los polímeros obtenidos en este trabajo se caracterizaron fisica yespectroscópicamente. Se estudió la distribución de pesos moleculares y elcomportamiento térmico de estos materiales. A efectos de analizar su cristalinidad seefectuaron estudios de rayos X de polvo y de microscopía óptica de luz polarizada. Sedeterminaron también la higroscopicidad, solubilidad y actividad óptica de las poliamidassintéticas.
The need for conservation of petroleum feedstocks and the increased awarness ofthe environmental impact of petroleum-based polymers, has drawn attention to theutilization of natural regrowing resources for polymer synthesis. The new materials areexpected to display improved properties, such as biocompatibility and biodegradability. The introduction of new functionalities and stereocenters in a polyamide chain stronelymodifies its properties, which become similar to those of biopolymers. For this reason, themain goal of this Thesis was the synthesis and characterization of stereoregular polyamidesbased on common natural products. Stereoregular polyamides of the AB type (nylons-n) were obtained from chiral,bifunctional monomers such as the (S)-5-amino—4—methoxypentanoic acid (AMP), whichwas synthesized employing D-ribonolactone or L-glutamic acid as starting material. Polycondensation of AMP, by the active ester method, yielded the homopolymer [AMP],. Polymerization of derivatives of AMP with the natural amino acids glycine (Gly) and L-alanine (Ala) afforded stereoregular polyamides, such as [AMP-Gly]n, [AMP-Ala]n and [Gly-AMP-AMP]n. On the other hand, chiral polyamides of the AABB type (nylons-n,n) weresynthesized, employing 4-(S)-carboxyl-l,4-butyrolactone, as chiral template. Thecarboxyl group was activated by preparation of a labile ester and the resulting compoundwas subjected to random polymerization with l,6-diaminohexane. A non-stereoregular (aregic) polyamide was obtained. However, the polymerization performed understereocontrol led to a syndioregic and an isoregic polyamides. A polyhydroxy analog ofnylon-2,5, having stereocenters in the diacid as well as in the diamine co-monomers, wasalso synthesized. Finally, stereoregular polymannaramides were prepared. The polymers obtained in this work were physical and spectroscopicallycharacterized. The molecular weight distribution and thermal behavior of these materials,were studied. The crystallinity was established by means of X ray diffraction analysis andby polarized optical microspcopy. The moisture sorption, solubility and optical activity ofthe synthetic polyamides were determined.
Fil: Orgueira, Hernan Antonio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.