Lipase catalysed conversion of triglycerides to amides in liquid ammonia

John H. Atherton, Michael I. Page, Nicholas T. Powles

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

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.

LanguageEnglish
Pages768-772
Number of pages5
JournalJournal of Physical Organic Chemistry
Volume29
Issue number12
Early online date25 May 2016
DOIs
Publication statusPublished - 1 Dec 2016

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liquid ammonia
ammonolysis
Lipase
Ammonia
Amides
amides
glycerols
Triglycerides
Glycerol
Liquids
enzymes
Antarctic regions
Chain length
esters
Esters
Enzymes
selectivity
Triolein
solvolysis
Catalyst selectivity

Cite this

Atherton, John H. ; Page, Michael I. ; Powles, Nicholas T. / Lipase catalysed conversion of triglycerides to amides in liquid ammonia. In: Journal of Physical Organic Chemistry. 2016 ; Vol. 29, No. 12. pp. 768-772.
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Lipase catalysed conversion of triglycerides to amides in liquid ammonia. / Atherton, John H.; Page, Michael I.; Powles, Nicholas T.

In: Journal of Physical Organic Chemistry, Vol. 29, No. 12, 01.12.2016, p. 768-772.

Research output: Contribution to journalArticle

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