Subsupercritical Water Generated by Inductive Heating Inside Flow Reactors Facilitates the Claisen Rearrangement

Synlett ◽  
2020 ◽  
Vol 31 (19) ◽  
pp. 1942-1946
Author(s):  
Andreas Kirschning ◽  
Mona Oltmanns
Keyword(s):  
Organic Solvents ◽  
High Temperatures ◽  
Claisen Rearrangement ◽  
Flow System ◽  
Aqueous Media ◽  
Inductive Heating ◽  
Flow Conditions ◽  
Flow Reactors

AbstractClaisen rearrangement of electron-deficient O-allylated phenols, including fluorine-modified phenols, is facilitated in aqueous media at high temperatures and pressures under flow conditions, as opposed to organic solvents. The O-allylation of phenols can be coupled with the Claisen rearrangement in an integrated flow system.

Transition-Metal-Free Synthetic Strategies for the Cross-Coupling Reactions in Water: A Green Approach

2020 ◽  
Vol 07 ◽  
Author(s):  
Tanmay Chatterjee ◽  
Nilanjana Mukherjee
Keyword(s):  
Transition Metal ◽  
Organic Solvents ◽  
Aqueous Media ◽  
Cross Coupling ◽  
Transition Metal Catalysts ◽  
Synthetic Methods ◽  
Coupling Reactions ◽  
Organic Transformations ◽  
Green Approach ◽  
Dehydrogenative Coupling

Abstract: A natural driving force is always working behind the synthetic organic chemists towards the development of ‘green’ synthetic methodologies for the synthesis of useful classes of organic molecules having potential applications. The majority of the essential classes of organic transformations, including C-C and C-X (X = heteroatom) bond-forming crosscoupling reactions, cross dehydrogenative-coupling (CDC) mostly rely on the requirement of transition-metal catalysts and hazardous organic solvents. Hence, the scope in developing green synthetic strategies by avoiding the use of transitionmetal catalysts and hazardous organic solvents for those important and useful classes of organic transformations is very high. Hence, several attempts are made so far. Water being the most abundant, cheap, and green solvent in the world; numerous synthetic methods have been developed in an aqueous medium. In this review, the development of transitionmetal- free green synthetic strategies for various important classes of organic transformations such as C-C and C-X bondforming cross-coupling, cross dehydrogenative-coupling, and oxidative-coupling in an aqueous media is discussed.

scholarly journals Nitrile Synthesis with Aldoxime Dehydratases: A Biocatalytic Platform with Applications in Asymmetric Synthesis, Bulk Chemicals, and Biorefineries

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4466
Author(s):  
Pablo Domínguez de María
Keyword(s):  
Asymmetric Synthesis ◽  
Organic Solvents ◽  
Raw Materials ◽  
Aqueous Media ◽  
Industrial Processes ◽  
Polymer Chemistry ◽  
Fine Chemicals ◽  
Mild Conditions ◽  
Bulk Chemicals ◽  
Recent Developments

Nitriles comprise a broad group of chemicals that are currently being industrially produced and used in fine chemicals and pharmaceuticals, as well as in bulk applications, polymer chemistry, solvents, etc. Aldoxime dehydratases catalyze the cyanide-free synthesis of nitriles starting from aldoximes under mild conditions, holding potential to become sustainable alternatives for industrial processes. Different aldoxime dehydratases accept a broad range of aldoximes with impressive high substrate loadings of up to >1 Kg L−1 and can efficiently catalyze the reaction in aqueous media as well as in non-aqueous systems, such as organic solvents and solvent-free (neat substrates). This paper provides an overview of the recent developments in this field with emphasis on strategies that may be of relevance for industry and sustainability. When possible, potential links to biorefineries and to the use of biogenic raw materials are discussed.

scholarly journals Iodination of insulin in aqueous and organic solvents

1969 ◽  
Vol 115 (1) ◽  
pp. 11-18 ◽  
Author(s):  
A. Massaglia ◽  
U. Rosa ◽  
G. Rialdi ◽  
C. A. Rossi
Keyword(s):  
Ethylene Glycol ◽  
Organic Solvents ◽  
Molecular Conformation ◽  
Aqueous Media ◽  
Native Structure ◽  
Experimental Conditions ◽  
Polar Environment ◽  
Polar Area ◽  
The Difference ◽  
A Chain

1. The iodination of insulin was studied under various experimental conditions in aqueous media and in some organic solvents, by measuring separately the uptake of iodine by the four tyrosyl groups and the relative amounts of monoiodotyrosine and di-iodotyrosine that are formed. In aqueous media from pH1 to pH9 the iodination occurs predominantly on the tyrosyl groups of the A chain. Some organic solvents increase the iodine uptake of the B-chain tyrosyl groups. Their efficacy in promoting iodination of Tyr-B-16 and Tyr-B-26 is in the order: ethylene glycol and propylene glycol≃methanol and ethanol>dioxan>8m-urea. 2. It is suggested that each of the four tyrosyl groups in insulin has a different environment: Tyr-A-14 is fully exposed to the solvent; Tyr-A-19 is sterically influenced by the environmental structure, possibly by the vicinity of a disulphide interchain bond; Tyr-B-16 is embedded into a non-polar area whose stability is virtually independent of the molecular conformation; Tyr-B-26 is probably in a situation similar to Tyr-B-16 with the difference that its non-polar environment depends on the preservation of the native structure.

Study on the synthesis of thioamides from aldehyde N-tert-butylsulfinyl amide and sulfur in aqueous media

2021 ◽  
pp. 54-60
Author(s):  
Pham Xuan Thao
Keyword(s):  
Organic Chemistry ◽  
Metal Complex ◽  
Organic Synthesis ◽  
Noble Metal ◽  
High Temperatures ◽  
Bioactive Compounds ◽  
Plant Protection ◽  
Aqueous Media ◽  
Environmentally Friendly ◽  
Straightforward Method

Thioamides have been widely used in the fields of medicine and organic chemistry, some of which are essential bioactive compounds, plant protection agents, and drugs. It could also be used as a vulcanizing agent, an additive to lubricants and greases, and a ligand in organic synthesis. Usually, thioamide is synthesized at high temperatures or in the microwave using an expensive noble metal complex as catalysts. This paper presented a straightforward method for synthesizing thioamides by using N-tert-butylsulfinyl amide, aldehyde, and sulfur. The reaction was carried out in water, which is an environmentally friendly solvent. The reaction selectivity and yield were up to 89%.

scholarly journals A multi-functional and multi-compartment constructed wetland to support urban waterway restoration

2018 ◽  
Vol 13 (4) ◽  
pp. 764-770 ◽  
Author(s):  
T. M. Adyel ◽  
M. R. Hipsey ◽  
C. Oldham
Keyword(s):  
Constructed Wetland ◽  
Flow System ◽  
Surface Flow ◽  
Base Flow ◽  
Low Flow ◽  
Nutrient Loads ◽  
Storm Events ◽  
Flow Conditions ◽  
Storm Flow ◽  
Diverse Area

Abstract This study assessed the significance of a multi-functional and multi-compartment constructed wetland (CW) implemented to restore a degraded urban waterway in Western Australia. The wetland was initially constructed as a surface flow system, then modified through the incorporation of the additional laterite-based subsurface flow system, with the potential for operation of a recirculation scheme and groundwater top-up during low water flows in summer. The CW performance was assessed by comparing nitrogen (N) and phosphorus (P) attenuation during base flow, high flow and episodic storm flow conditions. The performance varied from approximately 41% total nitrogen (TN) and 66% total phosphorus (TP) loads reduction during storm events, increasing up to 62% TN and 99% TP during low flow and summer recirculation periods. In overall, the CW attenuated about 45% TN and 65% TP loads from being delivered to the downstream sensitive river between 2009 and 2015. The CW design proved to be not only highly effective at reducing nutrient loads, but also improved the ecological services of the urban waterway by providing a diverse area for habitat and recreational activities.

scholarly journals Cloning, Expression, and Characterization of a Novel Thermostable and Alkaline-stable Esterase from Stenotrophomonas maltophilia OUC_Est10 Catalytically Active in Organic Solvents

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 401 ◽  
Author(s):  
Xinwei Gao ◽  
Xiangzhao Mao ◽  
Ping Lu ◽  
Francesco Secundo ◽  
Changhu Xue ◽  
...  
Keyword(s):  
Organic Solvents ◽  
Stenotrophomonas Maltophilia ◽  
Aqueous Media ◽  
Residual Activity ◽  
Catalytic Triad ◽  
Multiple Sequence ◽  
Medium Temperature ◽  
Reading Frame ◽  
Conserved Sequence ◽  
Catalytically Active

A thermostable and alkaline-stable novel esterase (Est7) was identified through the whole genome sequencing of Stenotrophomonas maltophilia OUC_Est10. The open reading frame of this gene encoded 617 amino acid residues. After heterologous expression in Escherichia coli BL21 (DE3), the purified Est7 was separated as a single protein and presented a molecular mass of 70.6 kDa. Multiple sequence alignment indicated that Est7 had a typical catalytic triad (Ser-Asp-His) and the conserved sequence (GDSL) typical of the family II lipid hydrolase proteins. Est7 showed good stability in alkaline buffers, especially in Tris-HCl buffer at pH 9.0 (residual activity 93.8% after 96 h at 4 °C) and in the medium temperature conditions (residual activity 70.2% after 96 h at 45 °C and pH 8.0). The enzyme also retained higher stability toward several hydrophilic and hydrophobic organic solvents (e.g., after incubation in 100% acetonitrile or in n-hexane the enzyme retained about 97% and 84% of the activity in the absence of organic solvent, respectively). Furthermore, Est7 could catalyze the transesterification reaction of vinylacetate with 2-phenylethanol and cis-3-hexen-1-ol to their corresponding acetate esters in petroleum ether or tert-butyl methyl ether. These results indicate Est7 as a promising biocatalyst for applications of Est7 in non-aqueous media.

Reaction of lead ions with hydroxylapatite granules

2008 ◽  
Vol 62 (5) ◽  
Author(s):  
Madjid Hadioui ◽  
Patrick Sharrock ◽  
Mohamed-Oimar Mecherri ◽  
Véronique Brumas ◽  
Marina Fiallo
Keyword(s):  
Heavy Metal ◽  
Lead Concentration ◽  
Aqueous Media ◽  
Absorption Capacity ◽  
Lead Ions ◽  
Flow Conditions ◽  
Lead Phosphate ◽  
Surface Areas ◽  
Heavy Metal Sorption ◽  
Phosphate Source

AbstractIn the effort to improve the performance of hydroxylapatite (HA) in removing lead ions from aqueous solutions, millimeter-sized granules with 50 % porosity were synthesized. Such HA particles, after drying at 100°C, or heating at 800°C or 1100°C, exhibited the specific surface areas of 50 m2 g−1, 25 m2 g−1, and 5 m2 g−1, respectively. It was found that heavy metal sorption capacity of HAs can be related to their surface area. Non-calcined granules were difficult to handle and easy to crush. Hardened granules showed heavy metal absorption on their outer surfaces. Absorption capacity of sintered HA particles towards lead was lower but adsorbed lead ions were spread inside the porous structure of HA granules more evenly. Under flow conditions, lead ions were captured by HA at a rate of 0.5 mg g−1 min−1. Small lead phosphate aggregates were released from the HA sorbent together with calcium ions. Size of the aggregates depended on the lead concentration and ranged from 1–50 μm in diameter; the aggregates could be removed by ultrafiltration. Results show that porous hardened HA granules can be used as an efficient phosphate source for the immobilization of lead ions from aqueous media. Organic ligands tend to interfere with the water purification procedure.

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