Chemical Shift

Which of the following deuterated solvents is able to show anisotropic shift over the protons of a given molecule?

• CDCl₃

• C₆D₆

• D₂O

• Deuterated methylene chloride

The chemical shift of an active NMR nucleus depends on the following properties:

• Only inductive effects

• Only mesomeric effects

• Only anisotropic effects

• All the mentioned effects

The chemical shift of an active NMR nucleous is higher...

• When using a 300 MHz instrument

• When using a 500 MHz instrument

• When using a 100 MHz instrument

• Chemical shift does not depend on the magnetic field of the instrument

When running a ¹HNMR experiment, the most used reference is...

• Water

• Tetramethylsilane

• Trimethylsilane

• Chlorotrimethylsilane

In a ¹HNMR spectrum, a peak with a chemical shift of 10 ppm is said to be...

• Deshielded

• All the two proposed answers

• At Downfield

• Non of the two proposed answers

In a ¹HNMR spectrum, a peak at low frequency is said to be...

• Deshielded

• All the two proposed answers

• Shielded

• Non of the two proposed answers

The chemical shift (300 MHz, CDCl₃) of the ¹Hs of MeCl is lower (3.05 ppm) than for methylene chloride (5.30 ppm) due to anisotropic effects

• False

• True

The chemical shift (300 MHz, CDCl₃) of the ¹Hs of benzene is 7.26 ppm. This is only due to the inductive effect of the sp² C hybridization of the ring.

• False

• True

Ortho ¹Hs of anisole (300 MHz, CDCl₃) are more shielded (6.30 ppm) than meta ones (7.26 ppm) mainly due to...

• Anisotropic effects

• Resonance effects

• The use of CDCl₃ as solvent

• Inductive effects

The chemical shift of the ortho ¹Hs of aniline (300 MHz, CDCl₃) appear at lower frequencies than those in anisole.

• True

• False