Research and Development

@article{Guidote2014Electronic,

title = {Electronic Effects in Oxidation Reactions Utilizing Dinuclear Copper Complexes with the Bis[3-(2-hydroxybenzylideneamino)phenyl] Sulfone Ligand},

author = {Armando M. Guidote Jr. and Ronald L. Reyes and Riyo Kashihara and Yasuhiko Kurusu and Yoshiro Masuyama},

url = {https://kimika.pfcs.org.ph/index.php/kimika/article/view/180},

doi = {10.26534/kimika.v25i2.11-22},

issn = {2508-0911},

year  = {2014},

date = {2014-10-20},

journal = {KIMIKA},

volume = {25},

number = {2},

pages = {11-22},

abstract = {Copper acetate and the ligands bis[3-(3-tert-butyl-2-hydroxy-5-methoxybenzylidene-amino)phenyl] sulfone and bis[3-(3,5-di-tert-butyl-2-hydroxybenzylideneamino)phenyl] sulfone were reacted to form the complexes with 2:1 copper:ligand ratio, Cu2[B(t-Bu) (OMe)BAPS](µ-OCH3)2 (4) and with 2:2 copper:ligand ratio, Cu2[B(t-Bu)2BAPS]2 (5),  respectively.  Structures of 4 and 5 were determined based on IR, UV-Vis, and FAB-MS data in comparison with previously characterized related copper complexes. The two complexes 4 and 5 were utilized in the oxidation of the substrates 2,4- and 2,6-di-tert-butylphenol (dtbp) at -50C with H2O2 in CH2Cl2.  The coupling products are preferred in both cases. For 2,4-dtbp, yields of 4,600% and 7,200% of 3,3’,5,5’-tetra-tert-butyl-2,2’-biphenol were achieved with the use of 4 and 5, respectively. For 2,6-dtbp, yields of 1,900% and 400% of 3,3’,5,5’-tetra-tert-butyl-4,4’-biphenol were realized utilizing 4 and 5, respectively. These show that the methoxy groups activated the complex. Based on low temperature UV-vis results, a µ-η2:η2-peroxo or a µ-hydroperoxo intermediate was possibly formed by the reaction of 4 with the H2O2. This effected the oxidation of the 2,4- and 2,6-dtbp substrates but also resulted in the attack of other complexes which acted as substrates.  A proposed oxidation mechanism using complex 4 and related complexes is presented.},

keywords = {catalysis, copper complex, dinuclear, hydrogen peroxide, oxidation},

pubstate = {published},

tppubtype = {article}

}

@article{Dimzon2011,

title = {Physico-Chemical and Microbiological Parameters in the Deterioration of Virgin Coconut Oil},

author = {Ian Ken D. Dimzon and Melodina F. Valde and Jaclyn Elizabeth R. Santos and Mark Joseph Garrovillas and Henson M. Dejarme and Jo Margarette W. Remollo and Fabian M. Dayrit},

url = {https://philjournalsci.dost.gov.ph/home-1/33-vol-140-no-1-june-2011/439-physico-chemical-and-microbiological-parameters-in-the-deterioration-of-virgin-coconut-oil},

issn = {0031-7683},

year  = {2011},

date = {2011-06-01},

journal = {Philippine Journal of Science},

volume = {140},

number = {1},

pages = {89-103},

abstract = {The deterioration of virgin coconut oil (VCO) due to physico-chemical oxidation and hydrolysis and microbiological processes was studied. The physico-chemical oxidation of VCO in the air at room temperature was negligible. Oxidation of VCO was observed only in the presence of air, UV radiation, ferric ion (Fe3+), and high free fatty acid (FFA) content. Chemical hydrolysis was performed at varying moisture levels and temperatures. The rate of hydrolysis to produce FFAs was measured using 31P NMR under conditions of saturated water (0.22%) and 80°C was found to be 0.066 µmol/g-hr (expressed as lauric acid). At 0.084% moisture and 80°C, the rate of FFA formation was found to be 0.008 µmol/g-hr. The microbial decomposition of VCO was determined after four days of incubation at 37°C. At low moisture levels (<0.06%), VCO was stable to microbial decomposition. However, at higher moisture levels, there was an increase in the formation of organic acids, in particular, lactic acid, dodecanoic acid, succinic acid, acetic acid, and fumaric acid, indicating that microbial action had occurred. The most important conditions that influence the physico-chemical and microbial degradation of VCO are moisture, temperature, and the presence of microorganisms. These degradation processes can be minimized if the moisture level is maintained below 0.06%.},

keywords = {hydrolysis, microbial deterioration, oxidation, virgin coconut oil},

pubstate = {published},

tppubtype = {article}

}

@article{Guidote2001,

title = {Synthesis, characterization and reactivity of a series of dinuclear copper complexes bearing the ligand bis[3-(2-hydroxybenzylideneamino)phenyl] sulfone and derivatives},

author = {Armando M. Guidote Jr. and Ken-ichi Ando and Kazunori Terada and Yasuhiko Kurusu and Hirotaka Nagao and Yoshiro Masuyama},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0020169301005898},

doi = {10.1016/S0020-1693(01)00589-8},

year  = {2001},

date = {2001-11-15},

journal = {Inorganica Chimica Acta},

volume = {324},

pages = {203-211},

abstract = {The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS] (μ-OH)2 (2), and Cu2[BCl2BAPS] (μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2. The results show that (1) the coupling products are preferred when CH2Cl2 is used; and (2) the quinone yield increases when THF is utilized. In CH2Cl2 with 2,4-dtbp, the yield of the coupling product based on the complex amount, is in the order 2, 1, and 3 with yields of 6300, 4700 and 200%, respectively. Low temperature UV–Vis results of the reaction of 1 with H2O2 showed the growth of peaks at 390 and 580 nm indicative of a μ-η2:η2-peroxo or μ-η1:η1-hydroperoxo intermediate. At −50 °C, this spectrum does not change. But when warmed to 0 °C, a spectrum similar to the original spectrum was obtained. This probably indicates hydrogen radical abstractions of the peroxo intermediate from solvents, and if excess H2O2 is present, the peroxo intermediate may again be formed. This reusability of the complex explains the high yield using 1 and 2.



The ligands bis[3-(X-2-hydroxybenzylideneamino)phenyl] sulfones (X=none: BHBAPS, X=3-tert-butyl: BH(t-Bu)BAPS and X=3,5-dichloro: BHCl2BAPS) were prepared. These, together with Cu(OAc)2 were used in the syntheses of the dinuclear copper complexes Cu2(BBAPS)(μ-OMe)2 (1), Cu2[B(t-Bu)BAPS](μ-OH)2 (2), and Cu2[BCl2BAPS](μ-OMe)2 (3). Complex 1 was crystallographically characterized. The structures of 2 and 3 are similar to 1 by comparison of IR, UV–Vis, FAB-MS and elemental analyses results. Complexes 1–3 (1 mol%) were used in the oxidation of 2,4- and 2,6-di-t-butylphenol (dtbp) at −50 °C with H2O2.},

keywords = {catalysis, copper complex, dinuclear, oxidation, schiff base type ligand},

pubstate = {published},

tppubtype = {article}

}