http://oar.a-star.edu.sg:80/jspui/handle/123456789/110 2017-06-23T23:36:20Z 2017-06-23T23:36:20Z Shaik, Salim M. Loh, Gabriel Sharratt, Paul N. http://oar.a-star.edu.sg:80/jspui/handle/123456789/2068 2017-03-08T09:38:43Z 2016-05-24T00:00:00Z

Title: Identification of hazards and generating inherently safer process options Authors: Shaik, Salim M.; Loh, Gabriel; Sharratt, Paul N. Abstract: In the drive for better chemical processes, there is a need for close collaboration between engineers and chemists. This type of close, multidisciplinary collaboration improves the overall process development effort by identifying potential downstream issues early. However, safety assessments are usually conducted later in the process development stage once the chemistry and basic process steps have been firmed up, for example, in Hazop 1 studies. The benefits of early stage safety intervention are widely acknowledged since the degrees of freedom available to change things is significantly greater during the early stages of process development. This is especially so if we aim to incorporate inherently safer options in the design. Tools such as reaction maps, driving force tables and process definition diagrams provide an information-rich, common platform for a multidisciplinary team to communicate with each other. These tools are part of the core BRITEST suite of tools and methodologies and they work by building-up process information and understanding in stages. The different tools address different levels of a system under study. For example, reaction or transformation maps (TM) and driving force analysis (DFA) provide an analysis of the chemistry whilst the Process Definition Diagrams (PDD) offers a view at the process level. This innate structure of the BRITEST tools provides opportunities to study safety issues at various levels and introduce inherently safer design options during process development. Using these process understanding tools as a basis for safety assessment help to anchor the identification of hazards and their possible solutions within a scientific framework that takes into consideration factors such as chemical and physical transformations, material properties, physics and manipulated parameters. This is achieved using a newly developed tool called the source-pathway-receptor (SPaR) tool. This tool was designed to accept the inputs (chemistry and process information) from the core process understanding tools (i.e. TM, DFA, PDD) and organise them within the source-pathway-receptor model. This model has been commonly used to demonstrate the link between a hazard source and the ultimate impact on receptor(s). Receptors can be in the form of human exposure, physical structures (including equipment) and environmental receptors. Subsequently, inherent safety strategies could be infused into the SPaR tool to generate options for improvements.

2016-05-24T00:00:00Z Duong, Hung A. Nguyen, Tuan Minh Rosman, Nurul Zubaidah Binte Tan, Lionel Jia Liang http://oar.a-star.edu.sg:80/jspui/handle/123456789/1897 2016-11-03T10:02:51Z 2014-07-01T00:00:00Z

Title: Carboxylation of organoboronic esters with potassium methyl carbonate under copper catalysis Authors: Duong, Hung A.; Nguyen, Tuan Minh; Rosman, Nurul Zubaidah Binte; Tan, Lionel Jia Liang Abstract: In the presence of a copper catalyst, potassium methyl carbonate serves as a versatile carboxylating agent of allyl- and ­arylboronic esters for the preparation of carboxylic acids.

2014-07-01T00:00:00Z Wang, Chuan Guo, Zhen Yang, Yanhui Chang, Jie Borgna, Armando http://oar.a-star.edu.sg:80/jspui/handle/123456789/1896 2016-11-03T09:59:07Z 2014-06-20T00:00:00Z

Title: Hydrogenation of furfural as model reaction of bio-oil stabilization under mild conditions using multiwalled carbon nanotube (MWNT)-supported Pt catalysts Authors: Wang, Chuan; Guo, Zhen; Yang, Yanhui; Chang, Jie; Borgna, Armando Abstract: Pt nanoparticles supported on multiwalled carbon nanotubes (MWNT) were synthesized and applied in the catalytic hydrogenation of furfural, the model reaction of mild stabilization of reactive bio-oil. The catalytic properties of the catalysts were modified by changing the surface concentration of oxygen-containing groups (OCGs) of MWNT. Various characterization techniques, including fluorescent labeling, nitrogen physisorption, powder X-ray diffraction, transmission electron microscopy, and in situ DRIFTS analysis, were employed to study both the supports and catalysts. Pt nanoparticles supported on MWNT with high OCGs show high activity and selectivity, attributed to the formation of small Pt particles as a result of the high concentration of OCGs.

2014-06-20T00:00:00Z Fong, Jacqueline Zi Mei Choo, Simon Sze Shiong Richard, Jean-Alexandre Garland, Marc V. Guo, Liangfeng Johannes, Charles W. Nguyen, Tuan Minh http://oar.a-star.edu.sg:80/jspui/handle/123456789/1895 2016-11-03T09:54:40Z 2015-01-08T00:00:00Z

Title: Synthesis of 3-fluoro-2-hetarylindoles and 3,3-difluoro-2-hetarylindolines through Lewis acid-catalyzed formation of 3,3-difluoroindolium ions Authors: Fong, Jacqueline Zi Mei; Choo, Simon Sze Shiong; Richard, Jean-Alexandre; Garland, Marc V.; Guo, Liangfeng; Johannes, Charles W.; Nguyen, Tuan Minh Abstract: Synthesis of 3-fluoro-2-hetarylindoles through addition of hetarenes to 3,3-difluoroindolium ions generated in situ by Zn(OTf)2-catalyzed oxazolidine ring opening is described. Indoles, pyrroles and alkyl-substituted furans can be used as hetaryl nucleophiles to afford a range of 3-fluoro-2-hetarylindole products 6 in 56–95 % yields. A diverse array of 3,3-difluorinated 2-hetarylindolines 7 can also be synthesized in 43–84 % yields by a tandem sequential process that involves hetarene nucleophilic addition, HF elimination and fluorocyclization reactions. Our study by 1H NMR and UV/Vis spectroscopy reveals that 3,3-difluorinated 2-hetarylindolines possess interesting substituent-dependent acidochromic properties. UV absorption and fluorescence spectra of selected compounds 6 and 7 are also studied. Description: This is the peer reviewed version of the following article: Fong, J. Z. M.; Choo, S. S. S.; Richard, J.-A.; Garland, M. V.; Guo, L. F.; Johannes, C. W.; Nguyen, T. M., Synthesis of 3-fluoro-2-hetarylindoles and 3,3-difluoro-2-hetarylindolines through Lewis acid-catalyzed formation of 3,3-difluoroindolium ions. European Journal of Organic Chemistry 2015, 2015 (5), 995-1006, which has been published in final form at https://dx.doi.org/10.1002/ejoc.201403443. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

2015-01-08T00:00:00Z