| Journal: | Journal of the Brazilian Chemical Society |
| Database: | PERIÓDICA |
| System number: | 000311060 |
| ISSN: | 0103-5053 |
| Authors: | Rezende, Marcos C1 |
| Institutions: | 1Universidad de Santiago, Facultad de Química y Biología, Santiago de Chile. Chile |
| Year: | 2001 |
| Volumen: | 12 |
| Number: | 1 |
| Pages: | 73-80 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Artículo |
| Approach: | Experimental |
| English abstract | The gas-phase acidity of nine carbon acids of the form CH3Z (nitromethane, acetophenone, dimethylsulfone, acetaldehyde, butanone, acetone, methyl acetate, acetonitrile and dimethylsulfoxide) was investigated, in the search of correlations with global and local HSAB properties, calculated at the 3-21G, 6-31G* and 6-31+G(3df,2p) levels. A reasonable correlation was obtained with the calculated ionization energies. Based on the obtained correlation, the gas-phase acidity of methyl thioacetate was estimated (deltaG°= 1476 kJ mol-1) as close to that of the most acidic member of the series, nitromethane. The nucleophilic Fukui functions of the hard and soft anionic centers in each base - CH2Z stabilized by direct conjugation were calculated, following two different approaches, and their ratios utilized to interpret the shifts in acidity when the acids are transferred from gas-phase to aqueous solution |
| Portuguese abstract | A acidez em fase gasosa de nove ácidos carbonados do tipo CH3Z (nitrometano, acetofenona, dimetilsulfona, acetaldeído, butanona, acetona, acetato de metila, acetonitrila e dimetilsulfóxido ) foi estudada, em busca de correlações com propriedades locais e globais, calculadas em níveis 3-21G, 6-31G* e 6-31+G(3df,2p), segundo a teoria de ácidos e bases duros e macios ("HSAB"). Uma correlação razoável foi obtida com as energias de deprotonação calculadas, o que permitiu estimar a acidez em fase gasosa do tioacetato de metila (deltaG° = 1476 kJ mol-1), próxima da do nitrometano, o membro mais ácido da série. As funções de Fukui para ataque nucleofílico dos centros aniônicos duros e macios em cada base -CH2Z foram usadas para interpretar as variações de acidez quando os ácidos são transferidos da fase gasosa para a fase aquosa |
| Disciplines: | Química |
| Keyword: | Química orgánica, Acidos carbonados, Acidez, Teoría duro blando ácido base, Funciones de Fukui |
| Keyword: | Chemistry, Organic chemistry, Carbon acids, Acidity, Hard soft acid base theory, Fukui functions |
| Full text: | Texto completo (Ver HTML) |
