Abdul Majeed Seayad
@a-star.edu.sg
Principal Scientist II, Catalysis and Green Process Engineering
Institute of Sustainability for Chemicals, Energy and Environment
RESEARCH, TEACHING, or OTHER INTERESTS
Chemistry, General Chemistry, Organic Chemistry
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Ping Sen Choong, Wendy Rusli, Abdul Majeed Seayad, Jayasree Seayad, and Satyasankar Jana
Elsevier BV
Mohammadreza Kosari, Kyungho Lee, Chao Wang, Sajjad Rimaz, Shenghui Zhou, Emmerson Hondo, Shibo Xi, Abdul Majeed Seayad, Hua Chun Zeng, and Armando Borgna
Elsevier BV
Ping Sen Choong, Kwok Wai Eric Tam, Ning Xi Chong, Abdul Majeed Seayad, Jayasree Seayad, and Satyasankar Jana
American Chemical Society (ACS)
Eric Kwok Wai Tam, Ning Xi Chong, Ping Sen Choong, Barindra Sana, Abdul Majeed Seayad, Satyasankar Jana, and Jayasree Seayad
Royal Society of Chemistry (RSC)
Water-soluble/dispersible, bio-derived, non-toxic and biodegradable nonisocyanate polyurethane (NIPU) phosphate monoesters were synthesized by applying green chemistry principles. Potential applications include personal care and cosmetic products.
Mohammadreza Kosari, Alvin M. H. Lim, Yu Shao, Bowen Li, Kelvin M. Kwok, Abdul Majeed Seayad, Armando Borgna, and Hua Chun Zeng
Royal Society of Chemistry (RSC)
Silica/silicate-based nanocatalysts have shown great potential for catalytic hydrogenation of CO2 to various value-added chemicals. This review presents the recent development of siliceous matter in this important field of heterogeneous catalysis.
Mohammadreza Kosari, Saeed Askari, Abdul Majeed Seayad, Shibo Xi, Sibudjing Kawi, Armando Borgna, and Hua Chun Zeng
Elsevier BV
Mohammadreza Kosari, Uzma Anjum, Shibo Xi, Alvin M. H. Lim, Abdul Majeed Seayad, Emmanuel A. J. Raj, Sergey M. Kozlov, Armando Borgna, and Hua Chun Zeng
Wiley
Beyond the catalytic activity of nanocatalysts, the support with architectural design and explicit boundary could also promote the overall performance through improving the diffusion process, highlighting additional support for the morphology‐dependent activity. To delineate this, herein, a novel mazelike‐reactor framework, namely multi‐voids mesoporous silica sphere (MVmSiO2), is carved through a top‐down approach by endowing core‐shell porosity premade Stöber SiO2 spheres. The precisely‐engineered MVmSiO2 with peripheral one‐dimensional pores in the shell and interconnecting compartmented voids in the core region is simulated to prove combined hierarchical and structural superiority over its analogous counterparts. Supported with CuZn‐based alloys, mazelike MVmSiO2 nanoreactor experimentally demonstrated its expected workability in model gas‐phase CO2 hydrogenation reaction where enhanced CO2 activity, good methanol yield, and more importantly, a prolonged stable performance are realized. While tuning the nanoreactor composition besides morphology optimization could further increase the catalytic performance, it is accentuated that the morphological architecture of support further boosts the reaction performance apart from comprehensive compositional optimization. In addition to the found morphological restraints and size‐confinement effects imposed by MVmSiO2, active sites of catalysts are also investigated by exploring the size difference of the confined CuZn alloy nanoparticles in CO2 hydrogenation employing both in‐situ experimental characterizations and density functional theory calculations.
Ping Sen Choong, Ning Xi Chong, Eric Kwok Wai Tam, Abdul Majeed Seayad, Jayasree Seayad, and Satyasankar Jana
American Chemical Society (ACS)
Polymer coatings having high amounts of renewable carbon and self-healing properties are highly sought after in a sustainability perspective. We report here the development of bio-/CO2-derived nonisocyanate polyurethane (NIPU) coatings which are recyclable and healable via three different types of healing mechanisms. These NIPUs contain furan rings in their main chain which after cross-linking with bismaleimides form organogels having a thermo-reversible sol-gel transition and solvent-borne coatings with improved properties. Judicial selection of the bismaleimide cross-linker structure enabled us to produce recyclable and intrinsic healable coatings mediated by heat (thermo-healing), moisture (moisture-healing), and, more interestingly, dry conditions at room temperature (self-healing). The intrinsic moisture-healing property of NIPU-based coatings is unprecedented and is mainly due to the presence of hydroxyl functionalities in the NIPU structure. The uniqueness of these cross-linked biobased NIPU as recyclable coatings having triple healing sites present in their structure gives these materials potential for sustainable and functional applications.
Mohammadreza Kosari, Abdul Majeed Seayad, Shibo Xi, Sergey M. Kozlov, Armando Borgna, and Hua Chun Zeng
American Chemical Society (ACS)
Hollow functional metal silicate materials have received the most interest due to their large inner space, permeable and functional shell, lighter density, and better use of material compared to their solid counterparts. While tremendous success has been made in the synthesis of individual metal silicates with uniform morphology, the synthesis of multi-phase hollow silicates has not been explored yet, although their direct applica-tions could be promising. In this study, mesoporous aluminosilicate spheres (MASS) are transformed to submicrometer copper aluminosilicate hollow spheres (CASHS) via one-pot hydrothermal process. CASHS has a hollow interior with Cu-Al-Si thorn-like moieties in a lamellar struc-ture on its outer shell. The structure and morphology of CASHS are unique and different from the previously reported tubular copper silicates that are emanated from Stöber silica spheres. Herein, we also demonstrate that extent of hollowing in CASHS can be attained by controlling the aluminum content of pristine MASS. The application of CASHS as a potential heterogeneous catalyst has been directed to important oxidation processes such as olefin oxidation and advanced oxidation process (AOP). In cyclohexene oxidation, for instance, high selectivity to cyclohex-2-en-1-one is achieved under moderate conditions using tert-butyl hydroperoxide (TBHP) as the oxidant. CASHS is a robust heterogeneous cata-lyst and is recyclable for this reaction. CASHS-derived catalysts also favor AOP and enhance the removal of cationic dyes together with H2O2 through an adsorption-degradation process.
Tuan Thanh Dang and Abdul Majeed Seayad
Wiley
Efficient [Cu(NHC)]-catalyzed syntheses of pyrroles via two and three-component coupling methods are described. Various 1,2-, 1,2,3-, 1,2,3,5- and fully substituted pyrroles were readily accessible through a suitable choice of ketone, primary amine and diol in a three-component reaction. The N-unsubstituted pyrrole formation is also feasible through a two-component reaction involving a β-amino alcohol and a ketone.
Tuan Thanh Dang and Abdul Majeed Seayad
Wiley
An efficient ruthenium catalyst is reported, for the first time, to catalyse the α-methylation of ketones and esters using methanol as a green methylating agent. The in situ generated catalyst from the complexes [RuCp*Cl2]2 or [RuCp*Cl2]n with dpePhos provided up to quantitative yields in the presence of only 20 mol% of lithium tert-butoxide (LiO-t-Bu) as a base. Regioselective mono- or multi-methylation could be effectively controlled by temperature. This catalyst system was also effective for the one-pot sequential α-alkylation–α-methylation of methyl ketones and conjugate reduction–α-methylation of α,β-unsaturated ketones to synthesise α-branched ketones. An application of the α-methylation of esters using the ruthenium catalyst was demonstrated for an alternative catalytic synthesis of Ketoprofen.
Tuan Thanh Dang, Balamurugan Ramalingam, and Abdul Majeed Seayad
American Chemical Society (ACS)
An in situ-generated complex from [RuCp*Cl2]2 and dpePhos ligand is reported as an efficient catalyst in the presence of 5 mol % of LiOtBu for the N-methylation of amines using methanol as the methylating agent at moderate conditions, following hydrogen borrowing strategy. This simple catalyst system provides selective N-monomethylation of substituted primary anilines and sulfonamides as well as N,N-dimethylation of primary aliphatic amines in excellent yields at 40–100 °C with good tolerance to reducible functional groups. The catalytic intermediate Cp*Ru(dpePhos)H was isolated and was shown to be active for methylation in the absence of base.
Tuan Thanh Dang, Siah Pei Shan, Balamurugan Ramalingam, and Abdul Majeed Seayad
Royal Society of Chemistry (RSC)
Silica supported palladium–NiXantphos complex is an efficient and high turnover heterogeneous catalyst for N-alkylation of amines and α-alkylation of ketones using alcohols under neat conditions at 120–140 °C following hydrogen borrowing strategy.
Siah Pei Shan, Xie Xiaoke, Boopathy Gnanaprakasam, Tuan Thanh Dang, Balamurugan Ramalingam, Han Vinh Huynh, and Abdul Majeed Seayad
Royal Society of Chemistry (RSC)
Simple non-chelating ruthenium benzimidazolin-2-ylidene complexes as efficient N-alkylation catalysts using alcohols and diols following a hydrogen borrowing strategy.
Yi Yang See, Tuan Thanh Dang, Anqi Chen, and Abdul Majeed Seayad
Wiley
This is the peer reviewed version of the following article: See, Y. Y.; Dang, T. T.; Chen, A. Q.; Seayad, A. M., Concise synthesis of vesnarinone and its analogues by using Pd-catalyzed C–N bond-forming reactions. European Journal of Organic Chemistry 2014, 2014, (33), p 7405–7412, which has been published in final form at https://dx.doi.org/10.1002/ejoc.201403054. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Siah Pei Shan, Tuan Thanh Dang, Abdul Majeed Seayad, and Balamurugan Ramalingam
Wiley
Efficient and recyclable ruthenium catalysts were synthesized from readily available polystyrene‐ or silica‐supported phosphine ligands. Catalysts bound to the polymer support through an ether linkage showed good to excellent activity towards the N‐alkylation of primary and secondary amines to afford the alkylated products in 62–99 % yield at 120–140 °C. The supported phosphine ligand/ruthenium ratio was found to be crucial for higher catalytic activity and lower ruthenium leaching. The continuous flow N‐alkylation of amines was demonstrated by using the supported catalyst in a column reactor. By adopting the hydrogen‐borrowing strategy, the synthesis of the anti‐Parkinson agent Piribedil was established in 98 % yield at 140 °C.
Subhash Chandra Ghosh, Cheng Chao Li, Hua Chun Zeng, Joyce S. Y. Ngiam, Abdul M. Seayad, and Anqi Chen
Wiley
This work was supported by GlaxoSmithKline (GSK), Singapore Economic Development Board (EDB) under GSK-Singapore Partnership for Green and Sustainable Manufacture, and the Institute of Chemical and Engineering Sciences (ICES), Agency for Science, Technology and Research (A*STAR), Singapore. We thank Mr. Jeffery Ng (ICES) for carrying out the NH 3 -TPD analysis.
Tuan Thanh Dang, Anqi Chen, and Abdul Majeed Seayad
Royal Society of Chemistry (RSC)
Palladium nanoparticles on ZIF-8 as a robust and recyclable catalyst for Weinreb amide and ketone synthesis through carbonylative coupling.
Tuan Thanh Dang, Balamurugan Ramalingam, Siah Pei Shan, and Abdul Majeed Seayad
American Chemical Society (ACS)
PdCl2 in the presence of dppe or Xantphos(t-Bu) as the ligand is found to be an efficient catalyst for the N-alkylation of various primary and cyclic secondary amines using primary alcohols at 90–130 °C under neat conditions. Interestingly, good to excellent yields were achieved when more challenging secondary alcohols were used as alkylating agents at 130–150 °C. The reaction could be easily scaled up, as demonstrated for a 10 mmol scale achieving yields up to 90% with a TON of 900.
Subhash Chandra Ghosh, Joyce S.Y. Ngiam, Abdul M. Seayad, Dang Thanh Tuan, Charles W. Johannes, and Anqi Chen
Elsevier BV
Tuan T. Dang, Yinghuai Zhu, Joyce S. Y. Ngiam, Subhash C. Ghosh, Anqi Chen, and Abdul M. Seayad
American Chemical Society (ACS)
Pd nanoparticles supported on ZIF-8 (PdNPs/ZIF-8) are described as an efficient heterogeneous catalyst for the aminocarbonylation of bromoarenes in the presence of phosphines and iodoarenes under phosphine-free conditions. The catalyst can be readily prepared and is air-stable. The palladium loading can be as low as 1 wt %, and the catalyst was recycled four times with negligible change in catalytic performance. A variety of pharmaceutically important amides was readily synthesized. A TON of 2540 was easily achieved in a batch reaction by scaling up to a gram scale. The catalyst reported can also be applied to the synthesis of cyclic and primary amides as well as an alkoxycarbonylation reaction to form an ester.
Subhash Chandra Ghosh, Joyce S. Y. Ngiam, Abdul M. Seayad, Dang Thanh Tuan, Christina L. L. Chai, and Anqi Chen
American Chemical Society (ACS)
A practical method for the amidation of aldehydes with economic ammonium chloride or amine hydrochloride salts has been developed for the synthesis of a wide variety of amides by using inexpensive copper sulfate or copper(I) oxide as a catalyst and aqueous tert-butyl hydroperoxide as an oxidant. This amidation reaction is operationally straightforward and provides primary, secondary, and tertiary amides in good to excellent yields for most cases utilizing inexpensive and readily available reagents under mild conditions. In situ formation of amine salts from free amines extends the substrate scope of the reaction. Chiral amides are also synthesized from their corresponding chiral amines without detectable racemization. The practicality of this amide formation reaction has been demonstrated in an efficient synthesis of the antiarrhythmic drug N-acetylprocainamide.
Jayasree Seayad, Abdul Majeed Seayad, Joseph Kok Peng Ng, and Christina Li Lin Chai
Wiley
In view of the world’s diminishing natural resources, the search for sustainable and renewable alternatives for chemicals, fuels, and materials is an ongoing challenge. In synthesis, the building blocks are carbon containing compounds that are derived either from nature or from petroleum feedstock. Thus, alternative, sustainable sources of carbon building blocks are highly coveted in chemical industries. One such possible alternative is the use of carbon dioxide as a one carbon source in synthesis. Carbon dioxide is abundantly available, renewable and is considered an environmentally friendly building block. Oxazolidinones are important heterocyclic compounds that are widely used as chiral auxiliaries and the oxazolidinone motif is present in many pharmaceutical, as well as fine chemical intermediates. In particular, 5-substituted oxazolidin-2-ones are frequently employed as biologically active compounds for pharmaceutical and agricultural uses. The cycloaddition of CO2 to aziridines (Scheme 1) or to aminoalcohols [6] is among the most attractive routes to oxazolidin-2-ones as compared to alternative processes that use the toxic and corrosive phosgene or CO .
Subhash Chandra Ghosh, Joyce S. Y. Ngiam, Christina L. L. Chai, Abdul M. Seayad, Tuan Thanh Dang, and Anqi Chen
Wiley
A practical and efficient method for the synthesis of amides has been developed by iron-cat- alysed oxidative amidation of aldehydes with amine hydrochloride salts. A wide range of amides have been obtained in good to excellent yields under mild conditions. The application of this novel amide formation reaction to the synthesis of pharmaceuti- cal compounds has been successfully demonstrated.
Abdul M. Seayad, Balamurugan Ramalingam, Christina L. L. Chai, Chuanzhao Li, Marc V. Garland, and Kazuhiko Yoshinaga
Wiley
A robust heterogeneous self-supported chiral titanium cluster (SCTC) catalyst and its application in the enantioselective imine-cyanation/Strecker reaction is described under batch and continuous processes. One of the major hurdles in the asymmetric Strecker reaction is the lack of availability of efficient and reusable heterogeneous catalysts that work at room temperature. We exploited the readily hydrolyzable nature of titanium alkoxide to synthesize a self-supported chiral titanium cluster (SCTC) catalyst by the controlled hydrolysis of a preformed chiral titanium-alkoxide complex. The isolated SCTC catalysts were remarkably stable and showed up to 98 % enantioselectivity (ee) with complete conversion of the imine within 2 h for a wide variety of imines at room temperature. The heterogeneous catalysts were recyclable more than 10 times without any loss in activity or selectivity. The robustness, high performance, and recyclability of the catalyst enabled it to be used in a packed-bed reactor to carry out the cyanation under continuous flow. Up to 97 % ee and quantitative conversion with a throughput of 45 mg h(-1) were achieved under optimized flow conditions at room temperature in the case of benzhydryl imine. Furthermore, a three-component Strecker reaction was performed under continuous flow by using the corresponding aldehydes and amines instead of the preformed imines. A good product distribution was obtained for the formation of amino nitriles with ee values of up to 98 %. Synthetically useful ee values were also obtained for challenging α-branched aliphatic aldehyde by using the three-component continuous Strecker reaction.