671. The carboxylation of resorcinol and the separation of β-and γ-resorcylic acid by ion-exchange chromatography

Hale, D. K.; Hawdon, Audrey R.; Jones, J. I. M.; Packham, D. I.

doi:10.1039/jr9520003503

Cited by 17 publications

(23 citation statements)

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“…Whereas a strong increase of yield with rising temperature for very short residence times is observed, this rise decreases for longer residence times, reaches a maximum and then decreases with rising temperature. This might be due to the preferred formation of the byproduct 2,6-DHBA or c-resorcylic acid at higher temperatures and longer residence times as reported in the literature [44,45] (Scheme 2).…”

Section: Temperature Dependence Of Yield and Stymentioning

confidence: 90%

“…Hale et al [44] observed the formation of considerable amounts of 2,6-DHBA and resorcinol from the monopotassium salt of 2,4-DHBA and the liberation of carbon dioxide when it was heated in an aqueous solution at 200°C. In contrast to 2,4-DHBA, the decarboxylation of 2,6-DHBA starts already above 80°C, i.e., at still higher temperatures, it will be in significant parts decomposed to resorcinol, which could not be distinguished from the starting material by HPLC analysis.…”

Section: Temperature Dependence Of Yield and Stymentioning

confidence: 98%

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Flow Chemistry of the Kolbe‐Schmitt Synthesis from Resorcinol: Process Intensification by Alternative Solvents, New Reagents and Advanced Reactor Engineering

et al. 2009

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The Kolbe-Schmitt synthesis from resorcinol was exemplarily investigated to figure out the process intensification potential of continuous processing in the milli and micro scale, alone and combined with additional intensification means like alternative solvents, new reagents and an advanced reactor design. The oil bathheated synthesis was investigated for capillary reactors of different dimensions, using aqueous solutions of KHCO 3 and reactive ionic liquids. Already the first case led to space-time yields (STY) of 15,500 kg/(m 3 h) at 37 % yield. Synthesis with different CO 2 -donating salts showed that KHCO 3 has the highest activity and that hydrogen carbonates are better than carbonates. The replacement of KHCO 3 by reactive ionic liquids led to a substantial increase, both in yield (58 %) and STY (69,900 kg/(m 3 h)). The application of scCO 2 did not significantly increase the yield despite an even more substantial change of the reaction medium. Using an electrically heated microstructured reactor resulted in a tenfold higher productivity (0.75 t/a) compared to the capillary reactor and does much better ensure scalability of the reaction.

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Section: Temperature Dependence Of Yield and Stymentioning

confidence: 90%

Section: Temperature Dependence Of Yield and Stymentioning

confidence: 98%

Flow Chemistry of the Kolbe‐Schmitt Synthesis from Resorcinol: Process Intensification by Alternative Solvents, New Reagents and Advanced Reactor Engineering

et al. 2009

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“…25 %), which was not obtained in any other of the Kolbe-Schmitt reactions carried out in this study. It is known that decarboxylation takes place at elevated temperature, which proceeds via 2,6-dihydroxybenzoic acid [39]. The nature of this side product was ascertained by comparison of the retention time with a commercially obtained sample of 2,6-dihydroxybenzoic acid.…”

Section: Kolbe-schmitt Synthesis Using Ionic Liquidsmentioning

confidence: 99%

Microwave‐Assisted Kolbe‐Schmitt Synthesis Using Ionic Liquids or Dimcarb as Reactive Solvents

et al. 2009

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The activation of relatively inert carbon dioxide as a building block for organic products is of interest from both ecological and chemical points of view. One of the few industrially relevant processes using CO 2 is the Kolbe-Schmitt synthesis. Two strategies to obtain the carboxylated product 2,4-dihydroxybenzoic acid from resorcinol are presented: both Dimcarb and hydrogencarbonate-or methylcarbonate-based ionic liquids are employed as reactive solvents in a microwaveassisted reaction. Reaction optimization shows that the ionic liquids are more reactive than Dimcarb. However, Dimcarb offers advantages with regard to ecological aspects, such as the Global Warming and Human Toxicity Potential and the Cumulative Energy Demand, which were assessed as part of the process development.

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“…A byproduct 2,6-dihydroxy benzoic acid is formed, 63 which is favoured at high temperatures and long residence times. 64 Due to continuous processing and to its small dimensions the experimental set up offers the capability to improve selectivity. The process variant of the Kolbe-Schmitt synthesis used here is different from that used for the synthesis of monohydroxycarboxylic acids like acetylsalicylic acid which is a gassolid reaction performed in pressurised vessels (autoclaves) at high temperatures.…”

Section: Current Implementation Of Novel Process Windows Into Chemica...mentioning

confidence: 99%

Sustainability through green processing – novel process windows intensify micro and milli process technologies

Hessel

Kralisch

Krtschil

2008

Energy Environ. Sci.

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671. The carboxylation of resorcinol and the separation of β-and γ-resorcylic acid by ion-exchange chromatography

Cited by 17 publications

References 0 publications

Flow Chemistry of the Kolbe‐Schmitt Synthesis from Resorcinol: Process Intensification by Alternative Solvents, New Reagents and Advanced Reactor Engineering

Flow Chemistry of the Kolbe‐Schmitt Synthesis from Resorcinol: Process Intensification by Alternative Solvents, New Reagents and Advanced Reactor Engineering

Microwave‐Assisted Kolbe‐Schmitt Synthesis Using Ionic Liquids or Dimcarb as Reactive Solvents

Sustainability through green processing – novel process windows intensify micro and milli process technologies

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