| Author(s): |
Telma Rie Doi
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. , ilustrações. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Química |
| Defense date: | 2005-10-06 |
| Examining board members: |
Roberto Rittner Neto;
Matheus Puggina de Freitas;
Carlos Roland Kaiser;
Yuji Takahata;
Rogério Custodio
|
| Advisor: | Roberto Rittner Neto |
| Field of knowledge: | Physical Sciences and Mathematics - Chemistry |
| Indexed in: | Base Acervus-UNICAMP; Biblioteca Digital da UNICAMP |
| Location: | Universidade Estadual de Campinas. Biblioteca Central Cesar Lattes; T/UNICAMP; D684a; Universidade Estadual de Campinas. Biblioteca do Instituto de Química; T/UNICAMP; D684a |
| Abstract | |
The conformational equilibrium of 1-monosubstituted and 1,1-disubstituted acetones was studied by NMR, IR, and theoretical calculations. The existence of two most stable rotamers - cis and gauche - was shown to occur in all 1-halosubstituted acetones (chloro-, bromo-, and iodoacetone), as predicted by the theoretical calculations and observed experimentally. The JCH-based conformational study indicated that the rotamer population changed according to the solvent polarity: gauche predominates in less polar solvents, and cis predominates in more polar solvents. For the haloacetones, there was good correlation between the calculated and experimental rotamer energy differences. The study of the rotational isomerism of the other acetones showed that a similar behaviour of the JCH coupling constant only happened for methoxyacetone and 1,1-dichloroacetone. That constant, therefore, could only be used in the conformational study of those two acetones. Cis and trans rotamers are the most stable forms for methoxyacetone, and the JCH variation is due to the trans sub-rotamers. For 1,1-dichloroacetone, cis predominates in less polar solvents, and gauche in more polar solvents. In this case, there is also a good correlation between calculated and experimental results. For the other compounds (hydroxyacetone, 1,1-dibromoacetone, and N,N-dimethylaminoacetone), the use of solvent effect calculations based on Onsager's theory helped understand their rotational isomerism (AU) | |