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Titolo:
1,2-CARBON TO NITROGEN MIGRATIONS .2. AB-INITIO STUDY ON THE REARRANGEMENT OF (ALPHA-METHYLAZO)ALKYL ISOCYANATES
Autore:
KROEMER RT; GSTACH H; LIEDL KR; RODE BM;
Indirizzi:
SANDOZ GMBH,FORSCHUNGSINST,BRUNNER STR 59 A-1235 VIENNA AUSTRIA INNSBRUCK UNIV,INST ALLGEMEINE ANORGAN & THEORET CHEM A-6020 INNSBRUCK AUSTRIA
Titolo Testata:
Perkin transactions. 2
fascicolo: 10, , anno: 1994,
pagine: 2129 - 2135
SICI:
0300-9580(1994):10<2129:1TNM.A>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
CURTIUS-TYPE REARRANGEMENT; POTENTIAL-ENERGY SURFACE; PINACOL REARRANGEMENT; CRYSTAL-STRUCTURE; BECKMANN REARRANGEMENT; MIGRATORY APTITUDE; SCF-MO; MECHANISM; ABINITIO; CARBOCATIONS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
63
Recensione:
Indirizzi per estratti:
Citazione:
R.T. Kroemer et al., "1,2-CARBON TO NITROGEN MIGRATIONS .2. AB-INITIO STUDY ON THE REARRANGEMENT OF (ALPHA-METHYLAZO)ALKYL ISOCYANATES", Perkin transactions. 2, (10), 1994, pp. 2129-2135

Abstract

Ab initio molecular orbital calculatons have been emp dyed to study the rearrangement of (alpha-methylazo)alkyl isocyanates to 1,2,5-trisubstituted 1,2-dihydro-1,2,4-triazol-3-ones. The migration of three different substituents (methyl, ethyl and isopropyl) has been investigated. Geometries of stationary points on the potential energy hypersurfacewere optimized at the HF/6-31G level of theory. Second order MoellerPlesset perturbation theory with the 6-31G basis set was applied in order to correct for correlation effects. Selected geometries were reoptimized at the MP2/6-31G level. HF/6-31G*, MP2/6-31G*//HF/6-31G* andMP2/6-31G energies predict migratory aptitudes in the: order isopropyl > ethyl > methyl. In the transition states, partial charges obtained from natural population analysis indicate strong electron deficiencyat the nitrogen atom being the target for migration. The transition states show partial carbocation character of the migrating group with respect to charge distribution and geometry. An alternative reaction pathway, namely 1,2-shift of a methyl group to the adjacent nitrogen of the isocyanato function leading to formation of 2,4,5-trimethyl-2,4-dihydro-1,2,4-triazol-3-one, has been investigated, but can be excluded due to the much higher activation energy required.

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Documento generato il 18/11/17 alle ore 05:52:01