Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde
Autor(a) principal: | |
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Data de Publicação: | 1999 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Journal of the Brazilian Chemical Society (Online) |
Texto Completo: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000500008 |
Resumo: | The reaction of methylamine with acetaldehyde in pentane at 230 K leads to formation of both E- and Z- aldimines, the Z-isomer being the main product and generated upon kinetic control. The E- form is more stable than the Z- form by 3.3 kcal/mol (deltaG*). Ab initio calculations have indicated that a tetrahedral zwitterion intermediate is not formed, and the bimolecular process, forming the aminoalcohol intermediate, occurs through a four center transition state, with concerted formation of C-N bond and proton transfer. However, the predicted deltaG*<FONT FACE="Symbol">¹</FONT> is very high, indicating that the true mechanism for this step is not bimolecular. A catalyzed pathway must be actuating. The following step, unimolecular elimination of water, also presents a very high activation free energy. Similarly, a catalyzed mechanism is needed. The isomerization from the Z- form to the E- form through inversion of the nitrogen atom has a predicted deltaG*<FONT FACE="Symbol">¹</FONT> of 27.0 kcal/mol at 298.15 K, resulting in a lifetime of four months for the Z-isomer. |
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Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehydereaction mechanismE- and Z-Aldimines equilibriumab initio calculationsThe reaction of methylamine with acetaldehyde in pentane at 230 K leads to formation of both E- and Z- aldimines, the Z-isomer being the main product and generated upon kinetic control. The E- form is more stable than the Z- form by 3.3 kcal/mol (deltaG*). Ab initio calculations have indicated that a tetrahedral zwitterion intermediate is not formed, and the bimolecular process, forming the aminoalcohol intermediate, occurs through a four center transition state, with concerted formation of C-N bond and proton transfer. However, the predicted deltaG*<FONT FACE="Symbol">¹</FONT> is very high, indicating that the true mechanism for this step is not bimolecular. A catalyzed pathway must be actuating. The following step, unimolecular elimination of water, also presents a very high activation free energy. Similarly, a catalyzed mechanism is needed. The isomerization from the Z- form to the E- form through inversion of the nitrogen atom has a predicted deltaG*<FONT FACE="Symbol">¹</FONT> of 27.0 kcal/mol at 298.15 K, resulting in a lifetime of four months for the Z-isomer.Sociedade Brasileira de Química1999-10-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000500008Journal of the Brazilian Chemical Society v.10 n.5 1999reponame:Journal of the Brazilian Chemical Society (Online)instname:Sociedade Brasileira de Química (SBQ)instacron:SBQ10.1590/S0103-50531999000500008info:eu-repo/semantics/openAccessPliego Jr.,Josefredo R.Alcântara,Antônio Flávio de C.Veloso,Dorila PilóAlmeida,Wagner B. deeng2001-06-07T00:00:00Zoai:scielo:S0103-50531999000500008Revistahttp://jbcs.sbq.org.brONGhttps://old.scielo.br/oai/scielo-oai.php||office@jbcs.sbq.org.br1678-47900103-5053opendoar:2001-06-07T00:00Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ)false |
dc.title.none.fl_str_mv |
Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde |
title |
Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde |
spellingShingle |
Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde Pliego Jr.,Josefredo R. reaction mechanism E- and Z-Aldimines equilibrium ab initio calculations |
title_short |
Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde |
title_full |
Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde |
title_fullStr |
Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde |
title_full_unstemmed |
Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde |
title_sort |
Theoretical and experimental investigation of the formation of E- and Z-Aldimines from the reaction of methylamine with acetaldehyde |
author |
Pliego Jr.,Josefredo R. |
author_facet |
Pliego Jr.,Josefredo R. Alcântara,Antônio Flávio de C. Veloso,Dorila Piló Almeida,Wagner B. de |
author_role |
author |
author2 |
Alcântara,Antônio Flávio de C. Veloso,Dorila Piló Almeida,Wagner B. de |
author2_role |
author author author |
dc.contributor.author.fl_str_mv |
Pliego Jr.,Josefredo R. Alcântara,Antônio Flávio de C. Veloso,Dorila Piló Almeida,Wagner B. de |
dc.subject.por.fl_str_mv |
reaction mechanism E- and Z-Aldimines equilibrium ab initio calculations |
topic |
reaction mechanism E- and Z-Aldimines equilibrium ab initio calculations |
description |
The reaction of methylamine with acetaldehyde in pentane at 230 K leads to formation of both E- and Z- aldimines, the Z-isomer being the main product and generated upon kinetic control. The E- form is more stable than the Z- form by 3.3 kcal/mol (deltaG*). Ab initio calculations have indicated that a tetrahedral zwitterion intermediate is not formed, and the bimolecular process, forming the aminoalcohol intermediate, occurs through a four center transition state, with concerted formation of C-N bond and proton transfer. However, the predicted deltaG*<FONT FACE="Symbol">¹</FONT> is very high, indicating that the true mechanism for this step is not bimolecular. A catalyzed pathway must be actuating. The following step, unimolecular elimination of water, also presents a very high activation free energy. Similarly, a catalyzed mechanism is needed. The isomerization from the Z- form to the E- form through inversion of the nitrogen atom has a predicted deltaG*<FONT FACE="Symbol">¹</FONT> of 27.0 kcal/mol at 298.15 K, resulting in a lifetime of four months for the Z-isomer. |
publishDate |
1999 |
dc.date.none.fl_str_mv |
1999-10-01 |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000500008 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000500008 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
10.1590/S0103-50531999000500008 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
text/html |
dc.publisher.none.fl_str_mv |
Sociedade Brasileira de Química |
publisher.none.fl_str_mv |
Sociedade Brasileira de Química |
dc.source.none.fl_str_mv |
Journal of the Brazilian Chemical Society v.10 n.5 1999 reponame:Journal of the Brazilian Chemical Society (Online) instname:Sociedade Brasileira de Química (SBQ) instacron:SBQ |
instname_str |
Sociedade Brasileira de Química (SBQ) |
instacron_str |
SBQ |
institution |
SBQ |
reponame_str |
Journal of the Brazilian Chemical Society (Online) |
collection |
Journal of the Brazilian Chemical Society (Online) |
repository.name.fl_str_mv |
Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ) |
repository.mail.fl_str_mv |
||office@jbcs.sbq.org.br |
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1750318163796426752 |