Crown ether catalysis of decarboxylation: a general survey of reactivity and detailed analysis of the triphenylacetate anion

1978 ◽  
Vol 56 (1) ◽  
pp. 104-113 ◽  
Author(s):  
D. H. Hunter ◽  
M. Hamity ◽  
V. Patel ◽  
R. A. Perry
Keyword(s):  
Carboxylic Acid ◽  
Crown Ether ◽  
Water Concentration ◽  
Solvent Polarity ◽  
General Survey ◽  
Reaction Conditions ◽  
Diphenylacetic Acid ◽  
Decarboxylation Rate ◽  
Optimum Reaction ◽  
Triphenylacetic Acid

The effect of 18-crown-6 ether 3 on the decarboxylation rate in THF of sodium salts of carboxylic acids formally derived from hydrocarbons has been investigated and these acids include 9-phenylfluorene-9-carboxylic acid, fluorene-9-carboxylic acid, phenylacetylene carboxylic acid, triphenylacetic acid, and diphenylacetic acid. Addition of equimolar 3 resulted in an increase in decarboxylation rate of 13- to 500-fold and there was a correlation between the decarboxylation rate and the pKa value of the product hydrocarbon.The decarboxylation of triphenylacetate was investigated in detail. The effect on reaction rate of cation (Li+, Na+, K+), crown ether concentration, water concentration, and solvent polarity has provided information as to optimum reaction conditions and has helped to clarify the reaction mechanism.

Ketones from Nickel-Catalyzed Decarboxylative, Non-Symmetric Cross-Electrophile Coupling of Carboxylic Acid Esters

2019 ◽  
Author(s):  
Jiang Wang ◽  
Brian P. Cary ◽  
Peyton Beyer ◽  
Samuel H. Gellman ◽  
Daniel Weix
Keyword(s):  
Carboxylic Acid ◽  
Solid Support ◽  
Reaction Conditions ◽  
Decarboxylative Coupling ◽  
New Strategy ◽  
The Cross ◽  
Acyl Donors ◽  
Acid Esters

A new strategy for the synthesis of ketones is presented based upon the decarboxylative coupling of N-hydroxyphthalimide (NHP) esters with S-2-pyridyl thioesters. The reactions are selective for the cross-coupled product because NHP esters act as radical donors and the thioesters act as acyl donors. The reaction conditions are general and mild, with over 40 examples presented, including larger fragments and the 20-mer peptide Exendin(9-39) on solid support.

Study on the Synthesis of Isoamyl Acetate Catalyzed by Strong Acidic Cation Exchange Resin

2011 ◽  
Vol 396-398 ◽  
pp. 2411-2415 ◽  
Author(s):  
Ping Lan ◽  
Li Hong Lan ◽  
Tao Xie ◽  
An Ping Liao
Keyword(s):  
Acetic Acid ◽  
Reaction Time ◽  
Cation Exchanger ◽  
Cation Exchange Resin ◽  
Isoamyl Acetate ◽  
Molar Ratio ◽  
Esterification Reaction ◽  
Reaction Conditions ◽  
Optimum Reaction

Isoamyl acetate was synthesized from isoamylol and glacial acetic acid with strong acidic cation exchanger as catalyst. The effects of reaction conditions such as acid-alcohol ratio, reaction time, catalyst dosage to esterification reaction have been investigated and the optimum reaction conditions can be concluded as: the molar ratio of acetic acid to isoamylol 0.8:1, reaction time 2h, 25 % of catalyst (quality of acetic acid as benchmark). The conversion rate can reach up to 75.46%. The catalytic ability didn’t reduce significantly after reusing 10 times and the results showed that the catalyst exhibited preferably catalytic activity and reusability.

scholarly journals Evaluation of wet air oxidation variables for removal of organophosphorus pesticide malathion using Box-Behnken design

2016 ◽  
Vol 75 (3) ◽  
pp. 619-628 ◽  
Author(s):  
Melike Isgoren ◽  
Erhan Gengec ◽  
Sevil Veli
Keyword(s):  
Removal Efficiency ◽  
Applied Pressure ◽  
Organophosphorus Pesticide ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
Reaction Conditions ◽  
Efficient Treatment ◽  
Optimum Reaction

This paper deals with finding optimum reaction conditions for wet air oxidation (WAO) of malathion aqueous solution, by Response Surface Methodology. Reaction conditions, which affect the removal efficiencies most during the non-catalytic WAO system, are: temperature (60–120 °C), applied pressure (20–40 bar), the pH value (3–7), and reaction time (0–120 min). Those were chosen as independent parameters of the model. The interactions between parameters were evaluated by Box-Behnken and the quadratic model fitted very well with the experimental data (29 runs). A higher value of R2 and adjusted R2 (>0.91) demonstrated that the model could explain the results successfully. As a result, optimum removal efficiency (97.8%) was obtained at pH 5, 20 bars of pressure, 116 °C, and 96 min. These results showed that Box–Behnken is a suitable design to optimize operating conditions and removal efficiency for non-catalytic WAO process. The EC20 value of raw wastewater was measured as 35.40% for malathion (20 mg/L). After the treatment, no toxicity was observed at the optimum reaction conditions. The results show that the WAO is an efficient treatment system for malathion degradation and has the ability of converting malathion to the non-toxic forms.

Preparation and Water Absorbency of Superabsorbent Kaolin/PAA-AM Composite

2013 ◽  
Vol 634-638 ◽  
pp. 1968-1976 ◽  
Author(s):  
Shi Han Shen ◽  
Yu Yu Zhang ◽  
Tian Bin Li ◽  
Qing Le Zeng
Keyword(s):  
Composite Material ◽  
Complex Structure ◽  
Water Absorbency ◽  
Solution Polymerization ◽  
Mass Ratio ◽  
Reaction Conditions ◽  
Superabsorbent Composite ◽  
Optimum Reaction ◽  
The Fourier Transform ◽  
Composite Variables

In this paper, a novel superabsorbent composite material based on acrylic acid (AA), acrylic amide (AM) and inorganic kaolin was synthesized via solution polymerization in aqueous medium with N,N’-methylene bisacrylamide (MBA) as crosslinker and potassium persulfate (KPS) as initiator. The effects of water absorbency of the composite variables, such as neutralization, kaolin concentration and MBA concentration, on the water absorbency were systematically optimized. Evidence of compositing was obtained by a comparison of the Fourier transform infrared spectra of the initial reactants with that of the superabsorbent composites, and its complex structure was confirmed with scanning electron microscope. The water absorbing mechanism was also discussed. The results indicated that the superabsorbent composite material was successfully synthesized and the optimum reaction conditions were as follows: the neutralization degree was 80%, the dosage of kaolin, crosslinker and initiator were 4%, 0.11%, and 0.9% respectively and the mass ratio of AA and AM was 3∶2. The optimum absorbency of the superabsorbent composite material in distilled water could reach 815.6g/g.

Synthesis of Optically Active Hydroxyalkyl Cycloheptatrienes: A Key Step in the Total Synthesis of 6,11-Methylene-LXB4

Synlett ◽  
2020 ◽  
Vol 32 (01) ◽  
pp. 45-50
Author(s):  
Udo Nubbemeyer ◽  
Analuisa Nava ◽  
Lukas Trippe ◽  
Andrea Frank ◽  
Lars Andernach ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Total Synthesis ◽  
Structure Elucidation ◽  
Butyl Ester ◽  
Optically Active ◽  
Chiral Hplc ◽  
Reaction Conditions ◽  
Acid Product ◽  
Tert Butyl ◽  
Nabh4 Reduction

AbstractStarting from methyl cycloheptatrienyl-1-carboxylate, 6-acylation was successfully achieved employing glutaryl chloride in the presence of AlCl3 under controlled reaction conditions to furnish keto carboxylic acid product. After protection of this keto carboxylic acid as tert-butyl ester, reagent-controlled enantioselective reductions delivered configuration-defined methyl-6-hydroxylalkyl cycloheptatriene-1-carboxylates with up to 80% ee. Whereas simple NaBH4 reduction of the keto carboxylic acid and subsequent lactonization afforded a methyl-6-tetrahydropyranonyl cycloheptatriene-1-carboxylate. Resolution using chiral HPLC delivered the product enantiomers with up to >99% ee Finally, ECD analyses enabled structure elucidation. The products are used as key intermediates in enantioselective 6,11-methylene-lipoxin B4 syntheses.

scholarly journals Indirect spectrophotometric determination of gentamicin and vancomycin antibiotics based on their oxidation by potassium permanganate

2006 ◽  
Vol 4 (4) ◽  
pp. 708-722 ◽  
Author(s):  
Akram El-Didamony ◽  
Alaa Amin ◽  
Ahmed Ghoneim ◽  
Ayman Telebany
Keyword(s):  
Acid Medium ◽  
Potassium Permanganate ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Reaction Conditions ◽  
Subsequent Determination ◽  
Optimum Reaction ◽  
Acid Orange Ii ◽  
Sulphuric Acid Medium

AbstractFour simple, accurate, sensitive and economical procedures (A–D) for the estimation of gentamicin sulphate and vancomycin hydrochloride, both in pure form and in pharmaceutical formulations have been developed. The methods are based on the oxidation of the studied drugs by a known excess of potassium permanganate in sulphuric acid medium and subsequent determination of unreacted oxidant by reacting it with amaranth dye (method A), acid orange II (method B), indigocarmine (method C) and methylene blue (method D), in the same acid medium at a suitable λmax=521, 485, 610 and 664 nm, respectively. The reacted oxidant corresponds to the drug content. Regression analysis of Beer-Lambert plots showed good correlations in the concentration ranges 4–8, 3–8, 4–9 and 5–9 µg ml−1 with gentamicin and 4–8, 1.5–4, 1.5–4 and 3.5–5.5 µg ml−1 with vancomycin for methods A, B, C, and D, respectively. The molar absorptivity, sandell sensitivity, detection and quantification limits were calculated. The stoichiometric ratios for the cited drugs were studied. The optimum reaction conditions and other analytical parameters were evaluated. The influence of the substance commonly employed as excipients with these drugs were studied. The proposed methods were applied to the determination of these drugs in pharmaceutical formulations. The results have demonstrated that the methods are equally accurate and reproducible as the official methods.

scholarly journals Determination of Nickel in End-Fitting of Spoolable Reinforced Plastic Line Pipe

2018 ◽  
Vol 142 ◽  
pp. 01002
Author(s):  
Xiaodong Shao
Keyword(s):  
Ammonium Persulfate ◽  
Reaction Conditions ◽  
Line Pipe ◽  
Acid Gas ◽  
Determination Of Nickel ◽  
Reinforced Plastic ◽  
Relative Standard ◽  
Optimum Reaction ◽  
Fitting In

Spoolable reinforced plastic line pipe will be widely used in the exploitation of acid gas and oil wells. End-fitting is a mechanical device that forms the transition from the spoolable reinforced plastic line pipe to the connector. It was well known that nickel was an important element in the end-fitting. In this paper, a novel spectrophotometric method was described for determination of nickel in the end-fitting of spoolable reinforced plastic line pipe. The method was based on the color reaction between nickel and dimethylglyoxime, which was favored in an alkaline medium, producing a red compound in the presence of ammonium persulfate as an oxidant. Under the optimum reaction conditions the absorption value was proportional to the concentration of nickel in the range of 0.080~0.50% (R2 = 0.9999), and the relative standard deviation was less than 3.0% (n=5). The proposed method was applied successfully to determine nickel in end-fitting of spoolable reinforced plastic line pipe.

scholarly journals Simplified Method to Optimize Enzymatic Esters Syntheses in Solvent-Free Systems: Validation Using Literature and Experimental Data

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1357
Author(s):  
Ronaldo Rodrigues de Sousa ◽  
Ayla Sant’Ana da Silva ◽  
Roberto Fernandez-Lafuente ◽  
Viridiana Santana Ferreira-Leitão
Keyword(s):  
Immobilized Lipase ◽  
Solvent Free ◽  
Molar Ratio ◽  
Mathematical Tool ◽  
Enzymatic Esterification ◽  
Reaction Conditions ◽  
Reaction Behavior ◽  
Optimum Reaction ◽  
Interesting Correlation ◽  
Using Data

The adoption of biocatalysis in solvent-free systems is an alternative to establish a greener esters production. An interesting correlation between the acid:alcohol molar ratio and biocatalyst (immobilized lipase) loading in the optimization of ester syntheses in solvent-free systems had been observed and explored. A simple mathematical tool named Substrate-Enzyme Relation (SER) has been developed, indicating a range of reaction conditions that resulted in high conversions. Here, SER utility has been validated using data from the literature and experimental assays, totalizing 39 different examples of solvent-free enzymatic esterifications. We found a good correlation between the SER trends and reaction conditions that promoted high conversions on the syntheses of short, mid, or long-chain esters. Moreover, the predictions obtained with SER are coherent with thermodynamic and kinetics aspects of enzymatic esterification in solvent-free systems. SER is an easy-to-handle tool to predict the reaction behavior, allowing obtaining optimum reaction conditions with a reduced number of experiments, including the adoption of reduced biocatalysts loadings.

Study on Synthesis of Cyclotriphosphazene Containing Aminopropylsilicone Functional Group as Flame Retardant

2013 ◽  
Vol 683 ◽  
pp. 25-29 ◽  
Author(s):  
Lan Lan He ◽  
Yi Zhang ◽  
Zhao Lu Qin ◽  
Yan Hua Lan ◽  
Ding Hua Li ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Chemical Structure ◽  
Gel Permeation Chromatography ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Element Analysis ◽  
Fourier Transformed Infrared Spectroscopy ◽  
Industrial Grade ◽  
Distribution Calculation ◽  
Optimum Reaction

A novel non-halogen flame retardant APESP, cyclotriphosphazene containing six aminopropyltriethoxysilicone functional groups N3P3[NH(CH2)3Si(OCH2CH3)3]6, was synthesized by menas of SN2 nucleophilic substitution reaction, using hexachlorocyclotriphosphazene(HCCP) and 3-aminopropyltriethoxy-silane (KH550) as material. Firstly the industrial grade HCCP was purified through recrystallization and sublimation. Then the reaction process was investigated to prompt the yield, and the optimum reaction conditions were as follows: triethylamine as acid-binding agent, tetrahydrofuran as solvent, HCCP/KH550/triethylamine molar ratio 1:7.2:7.2, dripping time: 1 hour, temperature: 67°C and reaction time: 20h. Maximum APESP yield reached 94.3%. The chemical structure and purity was characterized by element analysis, Fourier-transformed infrared spectroscopy (FTIR), mass spectrum, gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) analysis. The results showed that the structure of synthesized product is consistent with the theoretical structure, in which the chlorine atoms were completely substituted. The charge distribution calculation of HCCP and KH550 confirmed the reaction mechanism.

Kinetic Studies of Adsorption Process of Zambian Kapiri Mposhi Zeolites

2021 ◽  
Vol 37 (2) ◽  
pp. 467-475
Author(s):  
Marina G. Xavier
Keyword(s):  
Adsorption Process ◽  
Kinetic Studies ◽  
Solute Concentration ◽  
Exchange Property ◽  
Batch Adsorption ◽  
Reaction Conditions ◽  
Kinetics Of Adsorption ◽  
Calcination Temperatures ◽  
Optimum Reaction ◽  
Kinetics Of

Batch adsorption studies were done on aqueous solutions of Pb(NO3)2 at varying solute concentration, adsorbent dose, contact time, temperature, calcination temperatures and pH. Residual concentrations of the solute were found out using AAS and optimum conditions were studied. Adsorbent used in this study is locally available silicate rich mineral which closely resembles zeolites. The net negative charge on the framework of hydrated aluminosilicates is responsible for ion exchange property. Freundlich model was used to validate the results obtained from batch experiments plotting lnCe vs lnqe. Objective of this work is to study the kinetics of adsorption considering the interplay of particle diffusion in addition to proving the effectiveness as an adsorbent. A diffusion model also was also applied apart from kinetic model to analyze the experimental results more specifically. For maximizing the efficiency of the adsorption process and minimizing the time involved, variables like temperature, reactants and pH were manipulated using kinetic studies. It establishes the optimum reaction conditions for various experimental parameters in the process of adsorption.

Sign in / Sign up

Export Citation Format

Share Document