Question

Why is sodium thiosulfate used in this experiment?

slow fa st + H-Y H aromaticity destroyed H aromaticity restore A variety of electrophiles (Ey will react with benzene, and derivatives of benzene, to yield substitution products. Halogenation of benzene rings is an important reaction Br Pentab PBDE Br have important uses, e.g, pentabromodiphenyl ether CH PBDE; flame retardant) and Vancomycin (naturally because H, occurring antibiotic). However, halogens are not very CH, reactive toward benzene rings. and for this reason, they typically must be activated in some way to make them more electrophilic. For Cl, and Br this is accomplished through coordination to a Lewis acid, Fea, or FeBr, which polarizes the halogen and makes it more reactive. lodine (I) usually requires oxidation to I', or a species that acts like before it will react with a benzene ring. In this experiment, you will use EAS to iodinate salicylamide, a component of some analgesics. When salicylamide is monoiodinated, four different products may be formed. You will be asked to predict the major product of this reaction and explain how your prediction was made. You will then use IR spectroscopy to determine whether or not your prediction was correct NH2 NH2 Nal, NaOci NH2 EtOH NH2 possible products of monolodination of salicylamide possible products of monoiodination of sa UNDERSTANDING THE EXPERIMENT The "I" clectrophile that is required to iodinate a benzene ring is often generated by the of I, with various oxidizing agents (eg, hydrogen peroxide or a copper salt like CuClL.). In this experiment, " (possibly ICI or IOCH,CH) is generated by the oxidation of Nal with sodium hypochlorite, NaOCI, aka, common household bleach. Use of Nal is preferred to use of I, which is o iodinate a benzene ring is often generated by the oxidation Uise of Nal is preferred to uwe of I, which is ·Fionne is an exception. It is too reactive and usually does not allow for isolation of monofluorinated products. Floorine i an exception I s too reactive and usuly does nor allou for isolation of 39

Answer 1

sodium thiosulfate is used to remove exsess of Iodine.

2Na₂S₂O₃ + I₂ → Na₂S₄O₆ + 2NaI