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- Modelling and optimization of ethyl butyrate production catalysed by Rhizopus oryzae lipasePublication . Grosso, Carla; Ferreira Dias, S.; Cabral, Paula PiresResponse surface methodology was used to model and optimise the production of ethyl butyrate, catalysed by Rhizopus oryzae lipase immobilised in a hydrophilic polyurethane foam. Experiments were carried out following a central composite rotatable design, as a function of reaction temperature (T: 22-38 degrees C) initial butyric acid concentration (A: 0.031-0.619 M) and initial molar ratio ethanol/acid (MR; 0.257-2.443). After 48 h reaction time, the production of ethyl butyrate could be fitted to a surface described by a second-order polynomial model. A maximum ethyl butyrate concentration of 0.106 M, corresponding to 47% conversion into ester and a productivity of 2.21 mu mole/mL h, is expected at initial reaction conditions of T, A and MR of 33 degrees C, 0.225 M and 1.637, respectively. This maximum was experimentally confirmed. (c) 2012 Elsevier Ltd. All rights reserved.
- Comparison of liquid-phase olefin epoxidation catalysed by dichlorobis-(dimethylformamide)dioxomolybdenum(VI) in homogeneous phase and grafted onto MCM-41Publication . Monteiro, Bernardo; Balula, Salete S.; Gago, Sandra; Grosso, Carla; Figueiredo, Sónia; Lopes, Andre D.; Valente, Anabela A.; Pillinger, Martyn; Lourenço, J. P.; Gonçalves, Isabel S.A mesoporous silica-supported molybdenum oxide catalyst with a loading of 0.17Mo/nm2 was prepared by liquid phase deposition ofMoO2Cl2(dmf)2 (1) onto MCM-41 (dmf = dimethylformamide). Powder X-ray diffraction and N2 adsorption studies of Mo-MCM-41 indicate that the texture properties of the support were preserved during the grafting experiment. On the basis of evidence from FTIR spectroscopy, 13C and 29Si MAS NMR, and Mo K-edge EXAFS, the Mo atoms in this catalyst are mainly present as isolated {MoO2[(–O)3SiO]2(dmf)2} species, with a small contribution from oxo-bridged dimers. Catalysis tests show that complex 1 and Mo-MCM-41 are highly active oxidation catalysts for liquid-phase epoxidation of unfunctionalised olefins using tert-butylhydroperoxide as oxidant, from ambient to 55 ◦C. The high stability and recyclability of the heterogeneous Mo-MCM-41 catalyst is attributed to the strong metal oxide–support interaction. With cyclooctene, 1-octene, trans-2-octene and norbornene substrates, the corresponding epoxides were the only observed reaction products. The reactions of the other substrates gave by-products such as 8,9-p-menthen-1,2-diol from (R)-(+)-limonene, campholenic aldehyde from -pinene, and benzaldehyde from styrene. The addition of dichloromethane as a co-solvent had a beneficial effect on catalytic performance, and in the case of (R)-(+)-limonene allowed the epoxide to be formed as the only reaction product.
- Produção de butirato de etilo catalisada por lipases imobilizadasPublication . Grosso, Carla; Cabral, Paula; Dias, Suzana FerreiraEste trabalho de dissertação, teve como objectivo seleccionar o biocatalisador que melhor se adaptasse às condições reaccionais pretendidas, a partir de um screening de lipases comerciais de Aspergilus níger e Rhizopus oryzae, imobilizadas em espuma hidrofílica de poliuretano Hypol FHP 2002TM e de lipases não comerciais de Yarrowia lipolytica imobilizadas em diferentes suportes: Lewatit VP OC 1065, HPL, Amberlite 96, Lewatit K 2629, Lewatit VO OC 1026 e Lewatit MP TP 214 e de Rhizopos oryzae imobilizada em espuma de poliuretano Hypol FHP 2002TM, de modo a modelar e optimizar a reacção de esterificação de etanol com ácido butírico en n-hexano, para produção de butirato de etilo. A lipase comercial de Rhizopus oryzae imobilizada em Hypol FHP 2002TM foi o biocatalisador que conduziu a valores mais elevados de produtividade volumétrica (2,12 μmol/mL.h), velocidade inicial de esterificação (148 μmol/min.gbiocatalisador), concentração (0,102 M) e conversão (31,9 %) em butirato de etilo, quando testada nas condições do ponto central do delineamento experimental realizado. A Metodologia das Superfícies de Resposta foi utilizada para modelar a reacção de esterificação acima referida, como função da temperatura, T (21,6 ºC - 38,4 ºC), da concentração inicial de ácido butírico, A (0,031 M - 0,619 M) e da razão molar inicial etanol/ácido butírico, RM (0,257 M - 2,443 M). Os ensaios foram realizados de acordo com um delineamento experimental central rotativo compósito, tendo-se verificado que a produção e conversão em butirato de etilo podem ser descritas por equações polonomiais de segunda ordem. A concentração máxima de butirato de etilo (0,106 M) e a taxa conversão máxima em éster (32,6 %), previstas pelos modelos, verificam-se quando as condições reaccionais iniciais de T, A e RM são 31,5 ºC, 0,225 M e 1,637 e 18,9 ºC, 0,27M e 1,687, respectivamente. Verificou-se que o aumento da concentração de ácido butírico, na presença de excesso de etanol provoca um aumento na concentração de etanol no microambiente do biocatalisador. A temperatura tem uma influência significativa no aumento da concentração de etanol no microambiente do biocatalisador.
- Hetero-Diels-Alder approach to Bis(indolyl)methanesPublication . Grosso, Carla; Cardoso, Ana L.; Rodrigues, Maria Joao; Marques, Catia; Barreira, Luísa; Lemos, Americo; Pinho e Melo, Teresa M. D. V.A novel synthetic approach to bis(indolyl)methanes has been established. Our one-pot synthetic strategy based on two consecutive hetero-Diels-Alder cycloaddition reactions of electrophilic conjugated nitrosoalkenes with indoles was extended to a range of new 1-hydroxyiminomethyl-bis(indolyl) methanes. Furthermore, a similar and broad range approach was applied to the synthesis of previously unknown 1-hydrazonomethyl-bis(indolyl)methanes. The biological evaluation of the new bis(indolyl) methanes as anti-cancer agents was investigated. (C) 2016 Elsevier Ltd. All rights reserved.