Advanced Pharmaceutical Analysis IR spectroscopy Examples Lecture 3 17 Advanced Pharmaceutical Analysis IR spectroscopy Examples P 105 Dr. Baraa Ramzi

Approach this as a puzzle - it can be fun!

Example 1 Ants emit tiny amounts of chemicals called alarm pheromones to warn other ants (of the same species) of the presence of an enemy. Several of the components of the pheromone in one species have been identified, and two of their structures follow. Which compound has the infrared spectrum shown? Conjugation of CJO with phenyl; 1700—1660 cm−1

Example 1

Example 1

Example 2 The main constituent of cinnamon oil has the formula C9H8O. From the following infrared spectrum, deduce the structure of this component?

Index of Hydrogen Deficiency

Example 2 IHD=6 C9H8O Ar : above 3000 , 1600 , 700 Ald : c-h 2700 , 2800 C=o : 1677 , low wavenum cuz conj C9H8O IHD=6

Example 3 B

Example 4 E

Example 5 D

Example 6 C

Example 7 Assign a structure to each of the following three spectra. The structures are shown here.

Example 7 (1)

Example 7 (2)

Example 7 (3)

Example 8 Choose the structure that best fits the infrared spectrum shown

Example 8

Example 8

Example 9 In each of the following parts, a molecular formula is given. Deduce the structure that is consistent with the infrared spectrum.

Example 9 Strong band N-H when attached to aromatic IHD=4

Example 10 C3H6O2 IHD=1

Example 11 Choose the structure that best fits the infrared spectrum shown

Example 11

Example 11

Example 12 C7H6O2 IHD=5

Example 13 Choose the structure that best fits the infrared spectrum shown

Example 13

Example 13

Di-methyl Gem Doublet at 1390-1380 and 1370-1360.

Di-methyl Gem

Example 14 C7H6O IHD=5