Iodine → 2-Iodo-4-nitro-l-phenylalanine

Participants

Reaction Steps

A 250 mL round bottomed flask equipped with a magnetic stirrer was charged with 60 mL of fuming sulfuric acid (Aldrich) and 12.1 g of iodine (Aldrich). To the resulting dark red solution was added 10.0 g of 4-nitro-L-phenylalanine by slow addition. The flask was fitted with a CaCl2 drying tube and the reaction mixture was stirred at RT for 18 h. The mixture was then poured onto 300 g of crushed ice. A yellow-brown emulsion resulted which was treated with 7.4 g of sodium thiosulfate and stirred. The resulting light brown suspension was basified to pH=9 by addition of solid NaCO3. This was followed by acidification to pH=5.5 by addition of conc. H3SO4. A brown solid precipitated which was collected by filtration and dried in vacuo. This afforded 6.54 g (41%) of 2-iodo-4-nitro-L-phenylalanine as a brown powder, m.p.>200° C.

Provenance & Evidence