Investigation of the Stability of Quaternary Ammonium Methyl Carbonates

Weisshaar, Duane E.; Earl, Gary W.; Amolins, Michael W.; Mickalowski, Kyle L.; Norberg, Justin G.; Rekken, Brian D.; Burgess, Angela M.; Kaemingk, Bethany D.; Behrens, Katherine C.

doi:10.1007/s11743-011-1292-1

Cited by 5 publications

(7 citation statements)

References 18 publications

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“…However, in the process of alkali washing, if the concentration of NaOH is too high, TOMAC may be transformed into R 4 NOH, with poor stability. If the concentration of NaOH is too low, the number of alkali washings may need to increase, which affects the transformation efficiency (Weisshaar et al, 2012 ). Therefore, the effects of NaOH concentration and the number of alkali washings on the further conversion of

-type quaternary ammonium salt and the extraction rate of As III were investigated, respectively, and the experimental results are shown in Figure 4 .…”

Section: Resultsmentioning

confidence: 99%

Study on Extraction Separation of Thioarsenite Acid in Alkaline Solution by CO32--Type Tri-n-Octylmethyl-Ammonium Chloride

et al. 2021

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To overcome the problem of arsenic separation and enrichment from an alkaline leaching solution in arsenic-containing dust, a CO32--type tri-n-octylmethyl-ammonium chloride (TOMAC) method for extracting thioarsenite is proposed in this paper. Considering an alkaline leaching solution as the research object, after vulcanization pretreatment, TOMAC transformation and organic phase saturated extraction capacity were measured, and the extraction mechanism was preliminarily studied. First, Cl−-type quaternary ammonium salt was effectively transformed to HCO3--type by treating organic phase with saturated NaHCO3five times. TOMAC was effectively transformed from HCO3- to CO32- type by alkaline washing with 1.0 mol/l NaOH solution; this washing was repeated thrice. Thereafter, the effects of organic phase composition, phase ratio, extraction time, and temperature on the extraction and separation of arsenic were investigated. The results show that under the conditions of 30% CO32--type TOMAC + 15% sec-octanol + 55% sulfonated kerosene, VO/VA = 1/1, and 5 min extraction at room temperature, the single-stage extraction rate of AsIII is 85.2%. The AsIII concentration in raffinate can be reduced to less than 1.33 × 10−3 mol/l by four-stage countercurrent extraction, and the extraction rate of AsIII can exceed 98.4%.

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-type quaternary ammonium salt and the extraction rate of As III were investigated, respectively, and the experimental results are shown in Figure 4 .…”

Section: Resultsmentioning

confidence: 99%

Study on Extraction Separation of Thioarsenite Acid in Alkaline Solution by CO32--Type Tri-n-Octylmethyl-Ammonium Chloride

et al. 2021

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“…Besides the methyl acetate formation, there are several side products formed. Tetrabutylammonium acetate can react with DMC and participate in Hoffman elimination reactions Figure shows the GC–MS of the compounds formed during the different experiments at 100 °C.…”

Section: Resultsmentioning

confidence: 99%

“…The stability of the methylcarbonate anion determines if hydrolysis (Figure , R.5) or a second methylation reaction (R.4) will occur. Alkylammonium methylcarbonate salts are stable at temperatures below 170–180 °C, but they hydrolyze promptly in the presence of water (R.5). − An option for avoiding this hydrolysis step is to have an excess of methanol to push the equilibrium in the direction of the methylcarbonate anion. , …”

Section: Introductionmentioning

confidence: 99%

Separation and Catalysis of Carboxylates: Byproduct Reduction during the Alkylation with Dimethyl Carbonate

Cabrera-Rodríguez

Wielen

Straathof

2015

Ind. Eng. Chem. Res.

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Quaternary ammonium carboxylates (both ionic liquids and resins) can be used for formation of methyl carboxylate esters in an alkylation reaction with dimethyl carbonate (DMC). This reaction is pursued in the context of a low-waste process for recovery and upgrading of fermentative carboxylates. Byproducts, such as methanol, are produced during the alkylation reaction with DMC. A molar yield of methyl acetate on acetate of 0.84 and modest selectivity (0.54–0.95 mol of methyl acetate/mol of methanol) are obtained with an anion exchanger fully in the acetate form. Water and DMC concentrations have a strong effect on the yield and selectivity of the reaction. Model calculations indicate that an excess of 50 mol of DMCin/mol of acetatein in DMC is needed to achieve yields above 0.98 mol of methyl acetate/mol of acetatein, and water concentrations in the resin below 0.04 g of water/g of resin to achieve a selectivity above 1.1 mol of methyl acetate/mol of methanol. The explanation for the modest selectivity is the hydrolysis and absence of methylating activity of the methylcarbonate anion. This indicates that 1 mol of DMC is consumed for the alkylation of 1 mol of a monocarboxylate salt. The utilization of a low amount of DMC is critical, especially for low value products such as methyl acetate.

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“…The Hofmann elimination has been well known since 1958 and is considered to be the main reaction pathway. 19,20 With hydroxide present, different elimination and substitution mechanisms are possible. 21 The Hofmann elimination proceeds via a nucleophilic attack of the anion on the 𝛽-hydrogen, relative to the nitrogen atom.…”

Section: Degradation Mechanismsmentioning

confidence: 99%

“…Other studies have shown that methyl carbonate can react with water to form methanol and bicarbonate. 20,30 This change in anion could result in a more stable QAS, which would explain the profound stabilizing effect that water facilitates.…”

Section: Degradation Kineticsmentioning

confidence: 99%

Degradation kinetics and solvent effects of various long‐chain quaternary ammonium salts

Kleijwegt

Winkenwerder

Baan³

et al. 2021

Int J of Chemical Kinetics

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Surfactants such as quaternary ammonium salts (QAS) have been in increasing demand, for emerging new applications. Recent attempts at process intensification of their production have disclosed the need for a better understanding of QAS thermal stability. This work aims to determine the degradation kinetics of various QASs and the associated solvent effects. The degradation kinetics of four methyl carbonate QASs were determined in various polar solvents in stainless steel batch autoclaves. 1 H NMR spectrometry was employed for offline analysis of the reaction mixtures. The kinetic parameters were then used to compare the thermal stability of the four compounds in the polar solvents. Water showed no degradation, and methanol (MeOH) was the solvent that provided the secondbest stability. Water-MeOH mixtures may provide an overall optimum. Moreover, and longer long-chain substituents increased the degradation rate. Thermogravimetric analysis was used to obtain the thermal stability in a solid state, that is, solventless environment. Isoconversional analysis showed that no reliable kinetic parameters could be determined. Nevertheless, the data did allow for a comparison of the thermal stability of 14 different QASs. Furthermore, the relative instability of the compounds in the solid state demonstrated the challenges of solventless QAS production.

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Investigation of the Stability of Quaternary Ammonium Methyl Carbonates

Cited by 5 publications

References 18 publications

Study on Extraction Separation of Thioarsenite Acid in Alkaline Solution by CO32--Type Tri-n-Octylmethyl-Ammonium Chloride

Study on Extraction Separation of Thioarsenite Acid in Alkaline Solution by CO32--Type Tri-n-Octylmethyl-Ammonium Chloride

Separation and Catalysis of Carboxylates: Byproduct Reduction during the Alkylation with Dimethyl Carbonate

Degradation kinetics and solvent effects of various long‐chain quaternary ammonium salts

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