Gas-Phase Nucleophilic Reactivity of Alkoxysilanes
Autor(a) principal: | |
---|---|
Data de Publicação: | 2013 |
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=S0103-50532013000200012 |
Resumo: | The gas-phase reactivity of the Me4-nSi(OEt)n (n = 1-3) alkoxysilanes was investigated by Fourier transform ion cyclotron resonance (FT-ICR) technique in order to characterize the fundamental mechanisms associated with nucleophilic attack on these important precursors of new materials. Typical nucleophiles such as F-, MeO- and EtO- react readily and preferentially by attack at the silicon center with formation of a pentacoordinated siliconate that undergoes elimination processes initiated by either a nascent methide ion, Me, or an ethoxide ion, EtO, that can abstract a proton -to yield either a carbanion or a siloxide-type anion. Carbanions of the type X(Me)3-nSi(OEt)nCH2 (X = F, MeO, EtO and n = 1-3) and siloxide ion of the type X(Me)4-nSi(OEt)n-1O- (X = F, MeO, EtO and n = 2-3) can be easily dissociated by infrared multiphoton excitation with a CO2 laser to give rise to a large variety of simple siloxide and silicate-type anions that are reminiscent of intermediate species in the early stages of sol-gel processes. For the higher-ethoxy containing substrates, a competing reaction is observed that is analogous to an E2 elimination reaction in which the nucleophile abstracts a β-proton from the ethoxy group leading to elimination of ethylene. The kinetics, relative product distribution and thermochemistry of these reactions are also reported for some specific cases. |
id |
SBQ-2_0ad9332b2ca676082988211e0a8539dc |
---|---|
oai_identifier_str |
oai:scielo:S0103-50532013000200012 |
network_acronym_str |
SBQ-2 |
network_name_str |
Journal of the Brazilian Chemical Society (Online) |
repository_id_str |
|
spelling |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanesalkoxysilanesnucleophilic reactivitygas-phase ion chemistrysiliconatesThe gas-phase reactivity of the Me4-nSi(OEt)n (n = 1-3) alkoxysilanes was investigated by Fourier transform ion cyclotron resonance (FT-ICR) technique in order to characterize the fundamental mechanisms associated with nucleophilic attack on these important precursors of new materials. Typical nucleophiles such as F-, MeO- and EtO- react readily and preferentially by attack at the silicon center with formation of a pentacoordinated siliconate that undergoes elimination processes initiated by either a nascent methide ion, Me, or an ethoxide ion, EtO, that can abstract a proton -to yield either a carbanion or a siloxide-type anion. Carbanions of the type X(Me)3-nSi(OEt)nCH2 (X = F, MeO, EtO and n = 1-3) and siloxide ion of the type X(Me)4-nSi(OEt)n-1O- (X = F, MeO, EtO and n = 2-3) can be easily dissociated by infrared multiphoton excitation with a CO2 laser to give rise to a large variety of simple siloxide and silicate-type anions that are reminiscent of intermediate species in the early stages of sol-gel processes. For the higher-ethoxy containing substrates, a competing reaction is observed that is analogous to an E2 elimination reaction in which the nucleophile abstracts a β-proton from the ethoxy group leading to elimination of ethylene. The kinetics, relative product distribution and thermochemistry of these reactions are also reported for some specific cases.Sociedade Brasileira de Química2013-02-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532013000200012Journal of the Brazilian Chemical Society v.24 n.2 2013reponame:Journal of the Brazilian Chemical Society (Online)instname:Sociedade Brasileira de Química (SBQ)instacron:SBQ10.5935/0103-5053.20130033info:eu-repo/semantics/openAccessCorrera,Thiago C.Xavier,Luciano A.Riveros,José M.eng2013-05-20T00:00:00Zoai:scielo:S0103-50532013000200012Revistahttp://jbcs.sbq.org.brONGhttps://old.scielo.br/oai/scielo-oai.php||office@jbcs.sbq.org.br1678-47900103-5053opendoar:2013-05-20T00:00Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ)false |
dc.title.none.fl_str_mv |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanes |
title |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanes |
spellingShingle |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanes Correra,Thiago C. alkoxysilanes nucleophilic reactivity gas-phase ion chemistry siliconates |
title_short |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanes |
title_full |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanes |
title_fullStr |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanes |
title_full_unstemmed |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanes |
title_sort |
Gas-Phase Nucleophilic Reactivity of Alkoxysilanes |
author |
Correra,Thiago C. |
author_facet |
Correra,Thiago C. Xavier,Luciano A. Riveros,José M. |
author_role |
author |
author2 |
Xavier,Luciano A. Riveros,José M. |
author2_role |
author author |
dc.contributor.author.fl_str_mv |
Correra,Thiago C. Xavier,Luciano A. Riveros,José M. |
dc.subject.por.fl_str_mv |
alkoxysilanes nucleophilic reactivity gas-phase ion chemistry siliconates |
topic |
alkoxysilanes nucleophilic reactivity gas-phase ion chemistry siliconates |
description |
The gas-phase reactivity of the Me4-nSi(OEt)n (n = 1-3) alkoxysilanes was investigated by Fourier transform ion cyclotron resonance (FT-ICR) technique in order to characterize the fundamental mechanisms associated with nucleophilic attack on these important precursors of new materials. Typical nucleophiles such as F-, MeO- and EtO- react readily and preferentially by attack at the silicon center with formation of a pentacoordinated siliconate that undergoes elimination processes initiated by either a nascent methide ion, Me, or an ethoxide ion, EtO, that can abstract a proton -to yield either a carbanion or a siloxide-type anion. Carbanions of the type X(Me)3-nSi(OEt)nCH2 (X = F, MeO, EtO and n = 1-3) and siloxide ion of the type X(Me)4-nSi(OEt)n-1O- (X = F, MeO, EtO and n = 2-3) can be easily dissociated by infrared multiphoton excitation with a CO2 laser to give rise to a large variety of simple siloxide and silicate-type anions that are reminiscent of intermediate species in the early stages of sol-gel processes. For the higher-ethoxy containing substrates, a competing reaction is observed that is analogous to an E2 elimination reaction in which the nucleophile abstracts a β-proton from the ethoxy group leading to elimination of ethylene. The kinetics, relative product distribution and thermochemistry of these reactions are also reported for some specific cases. |
publishDate |
2013 |
dc.date.none.fl_str_mv |
2013-02-01 |
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=S0103-50532013000200012 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532013000200012 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
10.5935/0103-5053.20130033 |
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.24 n.2 2013 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 |
_version_ |
1750318174470930432 |