Phase transfer catalysis: Chemistry and engineering

Naik, Sanjeev D.; Doraiswamy, L. K.

doi:10.1002/aic.690440312

Cited by 166 publications

(109 citation statements)

References 230 publications

(181 reference statements)

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“…Therefore, the phase transfer catalyst should be cationic and have sufficient organic character to be lipophilic, but remain small enough to avoid steric hindrance (López-Fonseca et al 2009;Polk et al 1999). The most common types of phase transfer catalysts are quaternary ammonium or phosphonium salts with lipophilic side chains (Naik and Doraiswamy 1998). López-Fonseca et al tested the difference between these two types and found only minor differences between phase transfer catalysts based on ammonium or phosphonium ions (López-Fonseca et al 2009).…”

Section: Introductionmentioning

confidence: 99%

“…The effect of the phase transfer catalyst is, thus, to carry the hydroxide ions to the surface of the PET to facilitate the reaction (Naik and Doraiswamy 1998). Therefore, the phase transfer catalyst should be cationic and have sufficient organic character to be lipophilic, but remain small enough to avoid steric hindrance (López-Fonseca et al 2009;Polk et al 1999).…”

Section: Introductionmentioning

confidence: 99%

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Development of an efficient route for combined recycling of PET and cotton from mixed fabrics

et al. 2017

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Most textile waste is either incinerated or landfilled today, yet, the material could instead be recycled through chemical recycling to new high-quality textiles. A first important step is separation since chemical recycling of textiles requires pure streams. The focus of this paper is on the separation of cotton and PET (poly(ethylene terephthalate), polyester) from mixed textiles, so called polycotton. Polycotton is one of the most common materials in service textiles used in sheets and towels at hospitals and hotels. A straightforward process using 5-15 wt% NaOH in water and temperature in the range between 70 and 90°C for the hydrolysis of PET was evaluated on the lab-scale. In the process, the PET was degraded to terephthalic acid (TPA) and ethylene glycol (EG). Three product streams were generated from the process. First is the cotton; second, the TPA; and, third, the filtrate containing EG and the process chemicals. The end products and the extent of PET degradation were characterized using light microscopy, UV-spectroscopy, and ATR FT-IR spectroscopy, as well as solution and solid-state NMR spectroscopy. Furthermore, the cotton cellulose degradation was evaluated by analyzing the intrinsic viscosity of the cotton cellulose. The findings show that with the addition of a phase transfer catalyst (benzyltributylammonium chloride (BTBAC)), PET hydrolysis in 10% NaOH solution at 90°C can be completed within 40 min. Analysis of the degraded PET with NMR spectroscopy showed that no contaminants remained in the recovered TPA, and that the filtrate mainly contained EG and BTBAC (when added). The yield of the cotton cellulose was high, up to 97%, depending on how long the samples were treated. The findings also showed that the separation can be performed without the phase transfer catalyst; however, this requires longer treatment times, which results in more cellulose degradation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development of an efficient route for combined recycling of PET and cotton from mixed fabrics

et al. 2017

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“…Hence, the sufficient organic structure (large alkyl groups) was responsible for a substantial partition of the cation-anion pair into the organic phase [15]. In sum, these two PTCs fulfilled the requirements of having enough organic character in order to be lipophilic while small enough in order to avoid sterically hindering the reaction (to a larger extent for 4OPB compared with 3Bu6DPB).…”

Section: Alkaline Hydrolysis Of Pet Assisted By Phase Transfer Catalystsmentioning

confidence: 88%

Chemical recycling of PET by alkaline hydrolysis in the presence of quaternary phosphonium and ammonium salts as phase transfer catalysts

López‐Fonseca

González-Marcos

González‐Velasco

et al. 2008

WIT Transactions on Ecology and the Environment

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Chemical or tertiary recycling of waste polymers including PET, poly(ethylene terephthalate), is the only method according to the principles of Sustainable Development, since it leads to the formation of the raw materials (monomers) from which the polymer is made of. This work has been focused on the determination of the kinetics of the depolymerisation of PET by means of alkaline hydrolysis and on the identification of the catalytic behaviour, if any, of a series of phosphonium and ammonium salts as phase transfer catalysts (9 salts with varying alkyl groups, central cation (N or P) and anion (Cl -, Br -, I -, OH -)). Among the catalysts tested tributylhexadecylphosphonium bromide (3Bu6DPB) is found to be the most effective catalyst. Complete conversion of PET with considerably low catalyst concentration and temperature can be achieved. The selected phase transfer catalyst fulfils the requirements of having enough character in order to be lipophilic, while small enough in order to avoid steric hindrance. The time for complete hydrolysis (>90% conversion) of solid PET under alkaline conditions with 3Bu6DPB at 80 ºC is 1.5 hours and 10 hours without 3Bu6DPB.

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“…All 1 H and 13 C NMR spectra were recorded on a JEOI JNM-EX 400 FT-NMR system using CDCl3 as a solvent at room temperature. Chemical shifts are given in ppm and J-values in Hz.…”

Section: Methodsmentioning

confidence: 99%

Phase transfer catalyzed conjugate addition-initiated ring-closure (CAIRC) reactions with 2-bromo-2-cyclopentenones

Yirsaw¹,

Carlson²

2017

Arkivoc

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When 2-bromo-2-cyclopentenone is treated with various carbon nucleophiles containing active methylenes, it undergoes a conjugate addition initiated-ring closure (CAIRC) reaction. This leads to the formation of carboand heterocyclic compounds in a regioselective fashion with good to high yield. Several bases and phase transfer catalysts were investigated. CsF-Si(OEt)4 as base together with benzyldimethyl (2-hydroxyethyl)-ammonium chloride, C6H5CH2N(Cl)(CH3)2CH2CH2OH, as phase transfer catalyst, were found to be mild and efficient reagents for carrying out the synthetic transformation

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Phase transfer catalysis: Chemistry and engineering

Cited by 166 publications

References 230 publications

Development of an efficient route for combined recycling of PET and cotton from mixed fabrics

Development of an efficient route for combined recycling of PET and cotton from mixed fabrics

Chemical recycling of PET by alkaline hydrolysis in the presence of quaternary phosphonium and ammonium salts as phase transfer catalysts

Phase transfer catalyzed conjugate addition-initiated ring-closure (CAIRC) reactions with 2-bromo-2-cyclopentenones

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