Document Detail

Superelectrophilic activation of 4-heterocyclohexanones. Implications for polymer synthesis. A theoretical study.
MedLine Citation:
PMID:  18052258     Owner:  NLM     Status:  PubMed-not-MEDLINE    
The stability and the reactivity of mono- and diprotonated 4-heterocyclohexanones as well as cyclohexanone in triflic acid have been studied at the PBE0/aug-cc-pvtz//PBE0/6-31+G** level of theory. In all cases the first protonation is an exergonic process occurring at a carbonyl oxygen except for 4-piperidone where a nitrogen atom is protonated fist. Second protonation is only slightly endergonic for all studied molecules except for cyclohexanone where the second protonation is very unfavorable thermodynamically. According to calculations, diprotonated 4-heterocyclohexanones are much more active in the reactions of triflic acid mediated polyalkoxyalkylation with aromatic hydrocarbons compared to monoprotonated ones. The increase of the reactivity of diprotonated 4-heterocyclohexanones is due to inductive effect rather than through space electrostatic influence as follows from the electronic structure analysis of dications. Moreover, the second protonation reduces the possibility of an aldol condensation side reaction, reducing the enol electrophilicity rendering heterocyclohexanones as promising monomers for superacid mediated polyhydroxyalkylation.
Alfredo Lopez Lira; Mikhail Zolotukhin; Lioudmila Fomina; Serguei Fomine
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Publication Detail:
Type:  Journal Article     Date:  2007-12-05
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  111     ISSN:  1089-5639     ISO Abbreviation:  J Phys Chem A     Publication Date:  2007 Dec 
Date Detail:
Created Date:  2007-12-20     Completed Date:  2008-03-06     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  13606-10     Citation Subset:  -    
Instituto de Investigaciones en Materiales Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, CU, Coyoacan, Mexico DF 04510, México.
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