Decanedioic Acid (C10H18O4)/Dodecanedioic Acid (C12H22O4) System: Polymorphism of the Components and Experimental Phase Diagram

Autor: Raül Benages, Teresa Calvet, Denise Mondieig, Laura Bayés, Francisco Javier Novegil-Anleo, L. Ventolà, Miquel Àngel Cuevas-Diarte
Rok vydání: 2008
Předmět:
Zdroj: Dipòsit Digital de la UB
Universidad de Barcelona
ISSN: 1522-2675
0018-019X
DOI: 10.1002/hlca.200890140
Popis: The experimental temperature/composition phase diagram of the binary system decanedioic acid (C10H18O4)/dodecanedioic acid (C12H22O4) was established by combining X-ray powder diffraction (XRD), differential-scanning calorimetry (DSC), infrared spectroscopy (IR), scanning electron microscopy (SEM), and thermo-optical microscopy (TOM). Both compounds crystallize in the same ordered form, C (P21/c), which is the phase that melts in both cases. The C form melts in C12H22O4 earlier than in C10H18O4 , in contrast to other unbranched-chain compounds (alkanes, alkanols, and alkanoic acids) in which the melting temperatures increase as the C-atom number rises. Contrary to what might be expected, total solid-state miscibility is not observed. The C10H18O4/C12H22O4 binary system shows a complex phase diagram. At low temperatures, a new monoclinic form, Ci (P21/c), stabilizes as a result of the disorder of composition in the mixed samples; two [C þ Ci] domains appear. Upon heating, four solid - solid and seven solid - liquid domains appear related by eutectic and peritectic invariants. All the crystallographic forms observed are isostructural.
Databáze: OpenAIRE
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