The lab’s purpose was to carry out iodination of salicylamide and characterize the product using its melting point range and IR spectrum to determine the major product’s substitution pattern. The major product was hypothesized to be 5-iodosalicylamide (A) and not 4-iodosalicylamide (B), since activating groups (ortho/para (o-/p-) directors) tend to dominate deactivating groups (meta directors) when both are on the same benzene ring. As such, it was predicted that the hydroxyl group would dominate the nitro group, and the major product would have iodine substituted p- to the hydroxyl group, i.e. A. The crude product was a dense, white, powdery paste, while the isolated product was a beige, crystalline powder. No literature appearances of A and B were found, so those of 4- and 5-iodosalicylic acid were used. However, these doe not help determine the major product since both appearances were given as “white powder.” , The melting point range obtained was 232.0℃-235.5℃, while the literature values were 206℃ for B and 228℃ for A. The percent recovery was 59.1%, and the percent yield was 43.8%. The obtained melting point range was closer to the literature value of A, supporting A as the major product. Notably, the measured range was fairly small, indicating a …show more content…
Based on resonance, donating groups tend to shift o-hydrogens upfield, while withdrawing groups do the opposite. Curphy-Morrison additivity constants were used to predict aryl hydrogen shifts of A and B, and the prediction for A matched the spectrum far more than B, supporting A as the major product. As a qualitative example, it is predicted that A would have Hf shifted downfield due to the o-hydroxyl group, while the same hydrogen in B would not be shifted far from that of a phenyl hydrogen due the o-hydroxyl and o-iodine effects cancelling; the shift for Hf at 6.95 ppm supports