The Effect of Solvent Accessible Surface on Hammett-Type Dependencies of Infinite Dilution 29Si and 13C NMR Shifts in Ring Substituted Silylated Phenols Dissolved in Chloroform and Acetone

0375412 - ÚCHP 2013 RIV GB eng J - Journal Article
Blechta, Vratislav - Šabata, Stanislav - Sýkora, Jan - Hetflejš, Jiří - Soukupová, Ludmila - Schraml, Jan
The Effect of Solvent Accessible Surface on Hammett-Type Dependencies of Infinite Dilution 29Si and 13C NMR Shifts in Ring Substituted Silylated Phenols Dissolved in Chloroform and Acetone.
Magnetic Resonance in Chemistry. Roč. 50, č. 2 (2012), s. 128-134. ISSN 0749-1581. E-ISSN 1097-458X
R&D Projects: GA AV ČR IAA400720706; GA ČR GA203/06/0738
Institutional research plan: CEZ:AV0Z40720504
Keywords : 1H NMR * 13C NMR * 29Si NMR
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 1.528, year: 2012

Infinite dilution 29Si and 13C NMR chemical shifts were determined from concentration dependences in dilute chloroform and acetone solutions of para substituted silylated phenols, 4 R C6H4 O –SiR'2R'' (R = Me, MeO, H, F, Cl, NMe2, NH2, and CF3) where the silyl part included groups of different sizes: dimethylsilyl (DMS, R' = Me, R'' = H), trimethylsilyl (TMS, R' = R'' = Me), tert. butyldimethylsilyl (TBDMS, R' = Me, R'' = CMe3) and tert. butyldiphenylsilyl (TBDPS, R' = C6H5, R'' = CMe3). Dependences of the silicon and C-1 carbon chemical shifts on Hammett substituent constants are discussed. It is shown that substituent sensitivity of these chemical shifts is reduced by association with chloroform, the reduction being proportional to solvent accessible surface of the oxygen atom in the Si-O-C link.
Permanent Link: http://hdl.handle.net/11104/0208073