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Habilitation Thesis
DOI
10.11606/T.46.2008.tde-06062008-143916
Document
Author
Full name
Hans Viertler
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1978
Committee
Petragnani, Nicola (President)
Alves, Herbert Magalhães
Gottlieb, Otto Richard
Mano, Eloisa Biasotto
Rúveda, Edmundo Alfredo
Title in Portuguese
Espectroscopia no ultravioleta de cicloalcanonas 'ALFA' - alquiltio substituídas.
Keywords in Portuguese
Conformações moleculares
Estereoisômeros
Interações eletrônicas entre S/C=O
Abstract in Portuguese
No presente trabalho são apresentados os espectros de absorção no ultravioleta, em n-hexano e metanol absolutos, das 2-mercapto-(XLI) e 2-etiltiociclopentanonas (XL), 2-metiltio-(XXXIX), 2-etiltio-(XXX)), 2-t-butiltio-(XXXI) e 2-etiltio-2-metitilciclohexanonas (XXXII). A fim de melhor compreender a importância das conformações moleculares nas modificações observadas nas bandas de absorção correspondentes às transições n→π* do grupo carbonila e n→σ* do átomo de enxofre, foram sintetizadas várias cetonas α-alquiltio-substituídas conformacionalmente definidas: 2-metiltio-(XXXIII) e 2-etiltio-4-t-butilciclohexanonas (XXXIV), os 3-metiltio-(XXXVII) e 3-etiltio-(XXXVIII) derivados da trans-octahidro-4a-metil-2(1H)-naftalenona e a 3-metiltio-1, 7, 7-trimetil-biciclo2.2.1 heptanona-2(XLII). As propriedades espectroscópicas dos compostos estudados são discutidas considerando as possíveis interações eletrônicas entre o átomo de enxofre e o grupo carbonila. Conclui-se que as interações dependem das conformações moleculares e que serão maiores quando: (a) – A ligação C-S ocupar uma posição axial ou quase-axial; (b) – A conformação do grupo alquiltio permitir a máxima superposição do par solitário de elétrons do enxofre com a ligação CC=0–Cα.
Title in English
Ultraviolet spectroscopy of alpha-alkyltrio substituted cycloalkanones.
Keywords in English
Electronic interactions between S/C=0
Molecular conformations
Stereoisomers
Abstract in English
The ultraviolet absorption spectra in absolute n-hexane and methanol of 2-mercapto-(XLI) and 2-ethylthiocyclopentanones (XL), 2-methylthio-(XXIX), 2-ethylthio – (XXX), 2-t-butylthio-(XXXI) and 2-ethylthio-2-methylcyclohexanones (XXXII) are presented. In order to evaluate the importance of the molecular conformations upon observed modifications of the absorption bands due the n→π* transition of the carbonyl group and n→σ* transition of the sulphur atom, several conformationally defined α-alkythio-ketones were synthesized: 2-methylthio-(XXXIII) and 2-ethylthio-4-t-butylcyclohexanones (XXXIV), the 3-methylhio-(XXXVII) and 3-ethylthio (XXXVIII) derivatives of trans-octahydro-4a-methyl-2(1H)-naphtalenone and 3-methylthio-1,7,7 trimethyl-bicyclo  2.2.1 heptan-2-one (XLII). The spectroscopic properities of the studied compounds are discussed, considering the possible orbital interactions between the sulphur atom and the carbonyl group. It is concluded that such interactions are conformation dependent and are more important when: (a) – The C-S bond is axial or quasi-axial; (b) – The conformation of the alkylthio group allows the maximum overlap of the sulphur lone-pair and the CC=0 – Cα bond.
 
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Publishing Date
2008-06-10
 
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