Clean, reusable and low cost heterogeneous catalyst for amide synthesis

Comerford, James W.; Clark, James H.; Macquarrie, Duncan J.; Breeden, Simon W.

doi:10.1039/b901581g

Cited by 110 publications

(73 citation statements)

References 17 publications

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“…A catalytic protocol based on activated amorphous K60 silica was developed by Comerford et al 148 In refluxing toluene, 12 different amides were synthesized in isolated yields of 20-81%, 45 using 20 mol% catalyst. Higher yields were often observed with an increased catalyst loading, and the thermal reaction was generally low (0-10%).…”

Section: Luque and Clark (2009)mentioning

confidence: 99%

Catalytic amide formation from non-activated carboxylic acids and amines

et al. 2014

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The amide functionality is found in a wide variety of biological and synthetic structures such as proteins, polymers, pesticides and pharmaceuticals. Due to the fact that synthetic amides are still mainly produced by the aid of coupling reagents with poor atom-economy, the direct catalytic formation of amides from carboxylic acids and amines has become a field of emerging importance. A general, efficient and selective catalytic method for this transformation would meet well with the increasing criterias for green 10 chemistry. This review covers catalytic and synthetically relevant methods for direct condensation of carboxylic acids and amines. A comprehensive overview of homogeneous and heterogeneous catalytic methods is presented, covering biocatalysis, Lewis acid catalysts based on boron and metals as well an assortment of other types of catalysts.

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Section: Luque and Clark (2009)mentioning

confidence: 99%

Catalytic amide formation from non-activated carboxylic acids and amines

et al. 2014

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“…for the first example, this can be calculated to be 0.08 g h -1 ). 7 Secondly, the effect of increasing catalyst quantity in the batch reaction (so that is approaches that of the continuous system) was minimal. Little or no benefit in conversion or rate of reaction was seen, and both systems were operating at their optimum.…”

Section: Application To a Continuous Flow Reactormentioning

confidence: 99%

“…[5][6] We recently published research on a new route to amides using thermally-treated chromatographic silica as a clean and reusable catalyst, giving excellent yields (>70%) for a range of amides. 7 More recently, Akamanchi et al have demonstrated that sulfated tungstate is also an effective catalyst for this reaction. 8 While both of these systems have clear benefits over existing routes, both require significant amounts of catalyst (typically 20%wt silica, and 18%wt sulfated tungstate).…”

Section: Introductionmentioning

confidence: 99%

“…8 While both of these systems have clear benefits over existing routes, both require significant amounts of catalyst (typically 20%wt silica, and 18%wt sulfated tungstate). [7][8] Additionally, it was deemed desirable to develop a continuous process for the synthesis of amides, as the selectivity to product is excellent and therefore recycling of the unreacted fraction would be very advantageous. Other benefits associated with the use of continuous flow processing include improved safety due to smaller quantity of solvent/reaction mixture being heated at any one time as well as control of reagent concentration, higher catalyst to reagent ratio, and easier scale-up.…”

Section: Introductionmentioning

confidence: 99%

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Mesoporous structured silica – An improved catalyst for direct amide synthesis and its application to continuous flow processing

Comerford¹,

Farmer²,

Macquarrie³

et al. 2012

Arkivoc

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We recently published details of an effective, reusable and benign heterogeneous amidation catalyst based on thermal treatment of amorphous K60 silica, however the loading of catalyst required was high for some reactions. We report herein our further development of a series of heterogeneous catalysts based on structured silica (SBA) that retain all the green credentials of the previously described amorphous silica, but with increased efficiency. These catalysts were then utilised in continuous flow systems, achieving excellent conversions with dramatically reduced reaction times.

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“…However, the complexity of the system required may be a limitation of the approach. Comerford et al 13 showed the feasibility of the direct amide synthesis from 4-phenylbutyric acid and aniline in continuous flow over an acidic silica catalyst.…”

Section: Introductionmentioning

confidence: 99%

Direct amide synthesis over core–shell TiO₂@NiFe₂O₄ catalysts in a continuous flow radiofrequency-heated reactor

et al. 2016

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A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription. AbstractCore-shell composite magnetic catalysts TiO2@NiFe2O4 with a titania loading of 9-32 wt. % have been synthesised by sol-gel method for direct amide synthesis in a radiofrequency (RF)-heated continuous flow reactor. The catalyst calcination temperature was optimised in the range of 350-500 ºC and the highest activity was observed for the catalyst calcined at 500 ºC due to conversion of titania into catalytically active anatase phase. No reaction between the magnetic core and the titania shell was observed up to the calcination temperature of 1000 ºC and no sintering of titania shell was observed after calcination at 500 ºC. The comparison of direct amide synthesis in a continuous flow fixed bed reactor under conventional and RF heating demonstrated that the RF heating mode increased the apparent reaction rate by 60 % and decreased the deactivation rate due to a better temperature uniformity. The titania weight normalised reaction rate in the RF-heated reactor was constant for titania loadings above 17 wt. %, while it decreased by a factor of 3 at lower titania loadings because of interactions between the ferrite core on the thin layer of the catalyst. The catalyst deactivation study showed that the deactivation rate could be accurately described by a first order kinetics and that the main reason of deactivation was coking. The catalyst regeneration via calcination at 400 ºC resulted in the catalyst sintering, while a treatment with a hydrogen peroxide solution at 90 ºC fully recovered catalytic activity.

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Clean, reusable and low cost heterogeneous catalyst for amide synthesis

Abstract: We have developed a heterogeneous silica catalyst that can effectively catalyse amide synthesis from acid and amine, without production of toxic by-products and with the advantage of being readily available, low cost, environmentally benign and reusable.

Cited by 110 publications

References 17 publications

Catalytic amide formation from non-activated carboxylic acids and amines

Catalytic amide formation from non-activated carboxylic acids and amines

Mesoporous structured silica – An improved catalyst for direct amide synthesis and its application to continuous flow processing

Direct amide synthesis over core–shell TiO₂@NiFe₂O₄ catalysts in a continuous flow radiofrequency-heated reactor

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Clean, reusable and low cost heterogeneous catalyst for amide synthesis

Abstract: We have developed a heterogeneous silica catalyst that can effectively catalyse amide synthesis from acid and amine, without production of toxic by-products and with the advantage of being readily available, low cost, environmentally benign and reusable.

Cited by 110 publications

References 17 publications

Catalytic amide formation from non-activated carboxylic acids and amines

Catalytic amide formation from non-activated carboxylic acids and amines

Mesoporous structured silica – An improved catalyst for direct amide synthesis and its application to continuous flow processing

Direct amide synthesis over core–shell TiO2@NiFe2O4 catalysts in a continuous flow radiofrequency-heated reactor

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Direct amide synthesis over core–shell TiO₂@NiFe₂O₄ catalysts in a continuous flow radiofrequency-heated reactor