- Computational and experimental studies on the mechanism of formation of poly(hexahydrotriazine)s and poly(hemiaminal)s from the reactions of amines with formaldehyde
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Combined experimental and computational studies have been performed on the mechanism of formation of poly(hexahydrotriazine) and hemiaminal dynamic covalent network (PHT and HDCN) thermosetting polymers from the reactions of diamines with formaldehyde (Science 2014, 344, 732-735). Results suggest that these polymers are formed by a mechanism involving the water promoted stepwise addition of amines with formaldehyde in preference to dimerization or cyclotrimerization of imine intermediates or self-catalysis by the amine reagents. The predicted mechanism also explains experimentally observed electronic effects for hexahydrotriazine formation. (Chemical Equation Presented).
- Jones, Gavin O.,Garca, Jeannette M.,Horn, Hans W.,Hedrick, James L.
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- Are Aminomethyl Thioesters Viable Intermediates in Native Chemical Ligation Type Amide Bond Forming Reactions?
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The condensation of N-mercaptomethyl amines and thioesters is a potential route to amides, via aminomethyl thioester intermediates, in a native chemical ligation type process followed by self-cleavage of the 'mercaptomethyl' auxiliary. This paper describes investigations towards the preparation of aminomethyl thioesters, and subsequent conversion into amides, from a three-component coupling of formaldehyde, a thioacid, and an amine. Our studies suggest that while such intermediates may be formed en route to amides, no advantages are offered over the direct reaction of the amine and thioacid precursors.
- Charron, Carlie L.,Cottam Jones, Jade M.,Hutton, Craig A.
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p. 697 - 701
(2018/09/11)
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- A mechanistic study of the reactions of formaldehyde with aniline in the presence of sulfite
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1H NMR results are reported for the reactions of hydroxymethanesulfonate, 1, with aniline and its derivatives to produce anilinomethanesulfonates, 3. The mechanism of the reaction involves dissociation of 1 to produce formaldehyde, as a steady state intermediate, which reacts with aniline to give a carbinolamine;? subsequent dehydration and reaction with sulfite produces the product. The kinetics of individual steps have been investigated. The release of sulfite from 1, measured by reaction with iodine, is shown to involve the ionised, dianionic form when pH >3. Rate constants, k2, and equilibrium constants, K2, are reported for carbinolamine formation; the values of k2, but not K2, are affected significantly by substituents in the aniline. It is deduced that the rate-limiting step in the overall formation of products 3 changes in the pH range 6-8 from carbinolamine formation to carbinolamine dehydration.
- Atherton, John H.,Brown, Kathryn H.,Crampton, Michael R.
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p. 941 - 946
(2007/10/03)
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