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The tetramethylammonium ion (TMA + ) versus the hydronium ion (H 3 O + ) as internal reference for 1 H NMR measurements in superacid media. Solute–solvent interactions
Author(s) -
Rimmelin Paul,
Schwartz Sylvie,
Sommer Jean
Publication year - 1981
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270160220
Subject(s) - tetramethylammonium , superacid , hydronium , counterion , chemistry , bromide , solvent , ion , inorganic chemistry , organic chemistry , catalysis
It is shown that the chemical shift of the generally utilized internal reference for 1 H NMR measurements in superacid media, namely, tetramethylammonium bromide, which is normally fixed at 3.10 ppm from external TMS, changes with the composition of the acid mixture (HF or HSO 3 F:SbF 5 ). This is attributed to solute–solvent interactions. The use of both the tetramethylammonium ion or the hydronium ion as internal references is discussed, as the hydronium ion appears to be only slightly influenced by these interactions.