Bowknot-like Zr/La bimetallic organic frameworks for enhanced arsenate and phosphate removal: combined experimental and DFT studies

2022 ◽  
Author(s):  
Lingchao Kong ◽  
Jun Zhang ◽  
Yi Wang ◽  
Qinlin Yan ◽  
Jiayu Xu ◽  
...  
Keyword(s):  
Phosphate Removal ◽  
Dft Studies

Stereodivergent Alkyne Hydrofluorination Using a Simple Practical Reagent

2020 ◽  
Author(s):  
Rui Guo ◽  
Xiaotian Qi ◽  
Hengye Xiang ◽  
Paul Geaneoates ◽  
Ruihan Wang ◽  
...  
Keyword(s):  
Bond Formation ◽  
Biologically Active ◽  
Dft Studies ◽  
Thermodynamic Control ◽  
Important Goal ◽  
Peptide Bonds ◽  
Metal Free ◽  
Vinyl Cation ◽  
E And Z Isomers ◽  
Vinyl Fluorides

Vinyl fluorides play an important role in drug development as they serve as bioisosteres for peptide bonds and are found in a range of biologically active molecules. The discovery of safe, general and practical procedures to prepare vinyl fluorides remains an important goal and challenge for synthetic chemistry. Here we introduce an inexpensive and easily-handled reagent and report simple, scalable, and metal-free protocols for the regioselective and stereodivergent hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These conditions were suitable for a diverse collection of alkynes, including several highly-functionalized pharmaceutical derivatives. Mechanistic and DFT studies support C–F bond formation through a vinyl cation intermediate, with the (E)- and (Z)-hydrofluorination products forming under kinetic and thermodynamic control, respectively.<br>

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

Radical Capture at Ni(II) Complexes: C-C, C-N, and C-O Bond Formation

2019 ◽  
Author(s):  
Abolghasem (Gus) Bakhoda ◽  
Stefan Wiese ◽  
Christine Greene ◽  
Bryan C. Figula ◽  
Jeffery A. Bertke ◽  
...  
Keyword(s):  
Functional Groups ◽  
Bond Formation ◽  
Dft Studies ◽  
Bond Forming ◽  
Aryl Amines ◽  
Shed Light ◽  
Competing Pathways

<p>The dinuclear b-diketiminato Ni<sup>II</sup><i>tert</i>-butoxide {[Me<sub>3</sub>NN]Ni}<sub>2</sub>(<i>μ</i>-O<i><sup>t</sup></i>Bu)<sub>2 </sub>(<b>2</b>), synthesized from [Me<sub>3</sub>NN]Ni(2,4-lutidine) (<b>1</b>) and di-<i>tert</i>-butylperoxide, is a versatile precursor for the synthesis of a series of Ni<sup>II</sup>complexes [Me<sub>3</sub>NN]Ni-FG to illustrate C-C, C-N, and C-O bond formation at Ni<sup>II </sup>via radicals. {[Me<sub>3</sub>NN]Ni}<sub>2</sub>(<i>μ</i>-O<i><sup>t</sup></i>Bu)<sub>2 </sub>reacts with nitromethane, alkyl and aryl amines, acetophenone, benzamide, ammonia and phenols to deliver corresponding mono- or dinuclear [Me<sub>3</sub>NN]Ni-FG species (FG = O<sub>2</sub>NCH<sub>2</sub>, R-NH, ArNH, PhC(O)NH, PhC(O)CH<sub>2</sub>, NH<sub>2</sub>and OAr). Many of these Ni<sup>II </sup>complexes are capable of capturing the benzylic radical PhCH(•)CH<sub>3 </sub>to deliver corresponding PhCH(FG)CH<sub>3 </sub>products featuring C-C, C-N or C-O bonds. DFT studies shed light on the mechanism of these transformations and suggest two competing pathways that depend on the nature of the functional groups. These radical capture reactions at [Ni<sup>II</sup>]-FG complexes outline key C-C, C-N, and C-O bond forming steps and suggest new families of nickel radical relay catalysts.</p>

OPTIMIZATION OF PHOSPHATE REMOVAL FROM SYNTHETIC WASTEWATER BY BACTERIAL CONSORTIUM USING BOX-BEHNKEN DESIGN

2013 ◽  
Vol 12 (12) ◽  
pp. 2371-2383
Author(s):  
Krishnaswamy Usharani ◽  
Perumalsamy Lakshmanaperumalsamy ◽  
Muthusamy Muthukumar
Keyword(s):  
Bacterial Consortium ◽  
Phosphate Removal ◽  
Synthetic Wastewater ◽  
Box Behnken Design

Electrolysis of Wastewater - A Laboratory Study

1975 ◽  
Vol 10 (1) ◽  
pp. 214-223
Author(s):  
N.S. Wei ◽  
G.W. Heinke
Keyword(s):  
Energy Source ◽  
Mathematical Model ◽  
Stainless Steel ◽  
Charge Density ◽  
Energy Requirement ◽  
Phosphate Removal ◽  
Septic Tank ◽  
Metallic Ions ◽  
Treatment Unit ◽  
Consumable Electrodes

Abstract This paper presents bench scale experimental results on the electrolysis of raw domestic wastewater. Studies carried out with consumable electrodes are discussed. A mathematical model of a small electrolytic sewage treatment unit for individual household application is developed. The energy consumption and cost of such a device are discussed. Electrolysis can be described as a process in which chemical reactions are induced at each electro-liquid interface by applying an external electrical energy source to a system of electrodes immersed in a liquid. This paper deals only with electrolysis where a direct current power supply is used as the energy source. The process is governed by Faraday' s two laws on electrochemistry. The fundamental process parameter is the electrical charge density, measured as coulombs per litre (c/1) of wastewater treated. There are two basic types of electrolysis depending on the choice of anode material. When the anode is made of dissolvable metallic material such as iron, stainless steel and aluminum, the metal dissolves and goes into the sewage as metallic ions and forms hydrated metallic oxides which act as flocculating agents. The amount of metal dissolved is proportional to the quantity of electrical charges supplied to the system. Results from a series of batch experiments showed that electrolysis with consumable electrodes is capable of removing significant amounts of organic pollutants. Total organic carbon (TOC) removal was found to be a function of charge density. Phosphate removal efficiency of 90 percent or higher was achieved at a relatively low charge density of 240 coulombs per litre with either iron or stainless steel anodes. A mathematical model was derived in the conceptual design of a household electrolytic treatment unit. The model incorporates variables such as decomposition voltage of the electrodes and electrical conductivity of the wastewater as well as the physical configuration of the electrolytic cell. The energy requirement of such a unit can be calculated from the model. It is suggested in this paper that an electrolytic waste treatment unit could be an alternative to the septic tank and tile bed system in areas where the latter is not applicable due to poor soil and terrain conditions.

A Promising Combination of Two Phosphate Removal Techniques: Biological P-Removal and the Crystalactor

1991 ◽  
Vol 24 (10) ◽  
pp. 329-332
Author(s):  
P. M. J. Janssen ◽  
J. H. Rensink ◽  
E. Eggers
Keyword(s):  
Phosphate Removal ◽  
P Removal

Dynamics of phosphorus and organic substrates in anaerobic and aerobic phases of a sequencing batch reactor

1994 ◽  
Vol 30 (6) ◽  
pp. 237-246 ◽  
Author(s):  
A. Carucci ◽  
M. Majone ◽  
R. Ramadori ◽  
S. Rossetti
Keyword(s):  
Sequencing Batch Reactor ◽  
Municipal Wastewater ◽  
Batch Reactor ◽  
General Assumption ◽  
Organic Substrate ◽  
Operating Conditions ◽  
Phosphate Removal ◽  
Substrate Uptake ◽  
Organic Substrates ◽  
Polyphosphate Metabolism

This paper describes a lab-scale experimentation carried out to study enhanced biological phosphate removal (EBPR) in a sequencing batch reactor (SBR). The synthetic feed used was based on peptone and glucose as organic substrate to simulate the readily biodegradable fraction of a municipal wastewater (Wentzel et al., 1991). The experimental work was divided into two runs, each characterized by different operating conditions. The phosphorus removal efficiency was considerably higher in the absence of competition for organic substrate between P-accumulating and denitrifying bacteria. The activated sludge consisted mainly of peculiar microorganisms recently described by Cech and Hartman (1990) and called “G bacteria”. The results obtained seem to be inconsistent with the general assumption that the G bacteria are characterized by anaerobic substrate uptake not connected with any polyphosphate metabolism. Supplementary anaerobic batch tests utilizing glucose, peptone and acetate as organic substrates show that the role of acetate in the biochemical mechanisms promoting EBPR may not be so essential as it has been assumed till now.

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