The ammonolysis of esters in liquid ammonia

Griffin, Joseph M.; Atherton, John H.; Page, Michael I.

doi:10.1002/poc.3148

Cited by 8 publications

(9 citation statements)

References 30 publications

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“…The observed rate constants are of the order expected for the direct ammonolysis in liquid ammonia of an ester with an aqueous pK a of the leaving alcohol of 14–15. It is thought that the mechanism of ammonolysis of esters in liquid ammonia involves the rate‐limiting formation of the neutral tetrahedral intermediate by a ‘proton switch’ . Similarly, the reduced rate with longer alkyl chain length in the carboxyl residue is compatible with a small steric effect.…”

Section: Resultsmentioning

confidence: 69%

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Lipase catalysed conversion of triglycerides to amides in liquid ammonia

Griffin

Atherton

Page

et al. 2016

J of Physical Organic Chem

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Immobilised lipase B (Candida antarctica lipase B) is, perhaps unexpectedly, catalytically active in liquid ammonia and exhibits chain length selectivity in the ammonolysis of triglycerides. Using glycerol triacetate as the substrate, the ammonolysis of only the first ester linkage is catalysed by the enzyme, whereas for glycerol tributyrate, the cleavage of all three ester groups is catalysed and converted to the corresponding amide. These observations represent the first example of the use of enzymes in pure liquid ammonia, exemplifying both catalysis and selectivity. Glycerol trioleate is relatively stable in liquid ammonia but, with Candida antarctica lipase B present, readily undergoes ammonolysis to give oleamide and glycerol even at 25°C. There is no enzyme-catalysed ammonolysis with the native lipase as it is insoluble in liquid ammonia. The solvolysis of triglycerides in liquid ammonia occurs by a stepwise conversion of the triester to diester to monoester to glycerol with one equivalent of carboxylic acid amide produced at each stage. The pseudo first-order rate constants for each of the three steps of the uncatalysed ammonolysis of triglycerides in liquid ammonia decrease with increasing alkyl chain length in the carboxyl residue as expected from a small steric effect.

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Section: Resultsmentioning

confidence: 69%

“…Preparation of liquid ammonia reaction solutions . The equipment and methodology for charging the vessel with liquid ammonia were as described previously …”

Section: Methodsmentioning

confidence: 99%

Lipase catalysed conversion of triglycerides to amides in liquid ammonia

Griffin

Atherton

Page

et al. 2016

J of Physical Organic Chem

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“…Chemisorbed ammonia will be less nucleophilic than free ammonia in solution. We have shown elsewhere 7 that the rate-determining step in the homogeneous reaction of esters with ammonia is attack of ammonia on the ester, rather than leaving group departure.…”

Section: Resultsmentioning

confidence: 91%

“…In the solvolysis of benzoate esters by liquid ammonia, the Bronsted β lg is −1.18, corresponding to a rate increase of >4 × 10 5 when the leaving group is changed from ethoxy to vinyloxy (a pK a change in the leaving group alcohol of −4.8). 7 There is therefore a problem of directly converting unactivated esters into amides without using drastic conditions. The half-life for conversion of ethyl benzoate to benzamide in liquid ammonia at 25 °C is around 7 months.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of the conversion of methyl benzoate to benzamide by the alumina catalysed reaction with liquid ammonia at 120 °C

Sun

Page

Atherton

et al. 2014

Catal. Sci. Technol.

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“…Proses aminasi dibagi dua yaitu aminasi secara reduksi dan aminasi dengan menggunakan amonia. Aminasi secara reduksi dilakukan pada senyawa yang sudah mengandung gugus amina (Santoro et al 2012) sedangkan proses aminasi dengan amonia yang dikenal dengan amonolisis (Griffin, Atherton, dan Page 2013). Amonolisis adalah proses aminasi senyawa lain seperti alkohol, eter dan keton dengan amonia.…”

Section: Hasil Dan Pembahasanunclassified

Aminasi Hyperbranched Polyglycerol (HPG) Dengan Gas Amonia

Rahmi¹

2018

J. Kimia Kemasan

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AMINASI HYPERBRANCHED POLYGLYCEROL (HPG) DENGAN GAS AMONIA. Hyperbranched polyglycerol amine (HPG-amina) adalah salah satu senyawa amin yang berpotensi diterapkan pada berbagai industri. Saat ini HPG-amina disintesis dari proses aminasi HPG dengan diethylamine melalui reaksi tosilasi. Metoda ini sulit bila ditingkatkan menjadi skala industri dan juga kurang ramah lingkungan. Penelitian ini bertujuan melakukan proses aminasi dengan menggunakan gas amonia dalam reaktor tertutup. Penambahan katalis logam Fe dan Ni, suhu reaksi dan waktu proses berpengaruh signifikan terhadap produk yang dihasilkan. Dari hasil uji gugus fungsi HPG-amina yang diproses dengan penambahan katalis Ni pada suhu 100 o C selama 8 jam menunjukkan adanya kandungan amina primer-CONH2 dan amina sekunder R-NH dengan kandungan N total sebesar 6,7 ppm dan amonia bebas sebesar 3,4 ppm. Aminasi yang dilakukan tanpa penambahan katalis dan penambahan katalis Fe menghasilkan HPG-amina dengan sedikit gugus R-NH dan C=O yang belum bereaksi dengan amonia. Suhu proses di atas 100 o C menjadikan HPG-amina berwarna lebih gelap dan bahkan terlihat keruh. Proses yang dilakukan lebih dari 8 jam menurunkan kandungan N total menjadi 5,8 ppm.

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The ammonolysis of esters in liquid ammonia

Cited by 8 publications

References 30 publications

Lipase catalysed conversion of triglycerides to amides in liquid ammonia

Lipase catalysed conversion of triglycerides to amides in liquid ammonia

Kinetics of the conversion of methyl benzoate to benzamide by the alumina catalysed reaction with liquid ammonia at 120 °C

Aminasi Hyperbranched Polyglycerol (HPG) Dengan Gas Amonia

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