Layered metal laurates as active catalysts in the methyl/ethyl esterification reactions of lauric acid

Abstract

No presente trabalho são reportadas as sínteses, caracterizações e investigações das atividades catalíticas de lauratos lamelares de cobre(II), manganês(II), lantânio(III) e níquel(II) nas reações de esterificação metílica e etílica do ácido láurico. Nas reações de esterificação metílica, conversões entre 80 e 90% foram observadas para todos os catalisadores, ao passo que, para a esterificação etílica, somente o laurato de manganês mostrou atividade catalítica razoável, com conversões próximas de 75%. Reações de reuso dos lauratos de cobre e lantânio em três ciclos de reação foram investigadas; nelas, ambos os catalisadores preservaram a sua estrutura e mantiveram a atividade catalítica próxima daquela observada para o primeiro ciclo de reação. In this work we report the synthesis, characterization and investigation of the catalytic activity of layered copper(II), manganese(II), lanthanum(III) and nickel(II) laurates in the methyl and ethyl esterification reactions of lauric acid. In the methyl esterification, conversions between 80 and 90% were observed for all catalysts, while for the ethyl esterification only manganese laurate showed reasonable catalytic activity, with conversions close to 75%. Reuse of copper and lanthanum laurates in three cycles of reaction was also investigated and both catalysts preserved the structure and retained catalytic activity close to that observed for the first reaction cycle.

Marine-friendly antifouling coating based on the use of a fatty acid derivative as a pigment

“…For dodecanoic acid (Figure 1a), absorption bands at 2918 and 2853 cm -1 were attributed to C-H stretching vibrations while the bands at 1702 and 940 cm -1 were assigned to the C=O stretching and OH-deformation of the carboxyl moiety, respectively 36,37 . The CH 2 bending deformation at 721 cm -1 , which is characteristic of the saturated chain in fatty acids 27 , appears in the two spectra. Figure 1b shows two new absorption bands at 1445 and 1586 cm -1 (symmetric and asymmetric COO -, respectively), which reflect the interaction between copper ions and carboxylate groups 36 .…”

“…The synthetic procedure reported by Lisboa et al 27 was used for the synthesis of copper dodecanoate, with some modifications. A quantity of 20 g of dodecanoic acid was dissolved in 120 mL of ethanol and then neutralized with 4 g of NaOH (previously dissolved in 100 mL of ethanol).…”

Isopropyl Octanoate Synthesis Catalyzed by Layered Zinc n-Octanoate

“…11,24,25 After cooling the system, the catalyst is restructured and separated after the removal of isopropanol in excess, which was used during the reaction. This catalyst melting/dispersion occurs inside the reactor, even under the influence of pressure generated internally by the vapor from the more volatile component in the media, in this case the alcohol used in the reaction.…”

“…Although the catalyst was recovered after each catalytic cycle, it is important to emphasize that the catalytic activity experiments were carried out at temperatures higher to the phase transitions observed in Figure 5, so the zinc octanoate is "melted" in the reaction media, acting approximately in a hydrophobic homogeneous way, just like what occurs for other layered carboxylates. 11,25,32 Figures 6A and 6B show the 13 C NMR spectra of synthesized zinc octanoate, as well as the compound which was recovered from esterification reactions and submitted to heat treatment at 140 °C.…”

“…Laurates of transition metals and benzoates of alkaline earth metals have been employed successfully for the production of methyl laurate and methyl benzoate, respectively. 11,12 Research into new catalytic systems is facilitated by the use of alternative experimental designs, such as the Box-Behnken design (BBD), which is a factorial planning with three levels consisting of three interlocked 2 2 designs and a central point, in order to reduce the number of experiments that are required during the investigation of complex matrices. 13 BBD has mainly been applied to optimize extraction of several analytes, synthesis/ derivatization reactions, chromatographic separation and electrochemical processes, but has not yet been applied for esterification of octanoic acid with isopropanol.…”