15. Analytical Techniques:IR, NMR, Mass Spect

Choose the bond in each pair that you expect to have the more intense stretching band

(b) C=O vs. C=N

Justify the carbonyl stretching frequencies indicated for benzaldehyde and 4-methoxybenzaldehyde.

Choose the bond in each pair that you expect to vibrate at the higher wavenumber.

(a) C―N vs. C = N

Choose the bond in each pair that you expect to vibrate at the higher wavenumber.

(b) C―H vs. C―O

Rank the following acetophenone derivatives on the basis of the carbonyl stretching frequency (1 = highest ; 4 = lowest ).

(a)

(b)

(c)

(d)

Justify the carbonyl stretching frequencies indicated for 3-chlorobenzaldehyde and 3-fluorobenzaldehyde.

There are three carbon–oxygen bonds in methyl acetate.

a. What are their relative bond lengths?

b. What are the relative infrared (IR) stretching frequencies of these bonds?