Question

Question: Sodium hypochlorite (NaOCl, the oxidant in household bleach) in aqueous CH₃COOH is also touted as a “green” oxidizing agent. For example, oxidation of (CH₃)₂CHOH with NaOCl forms along with NaCl and H₂O. (a) What advantages and/or disadvantages does this method have over oxidation with HCrO₄––Amberlyst A-26 resin? (b) What advantages and/or disadvantages does this method have over oxidation with CrO₃, H₂SO_4,H₂O.

Short answer

Answer

a. NaOCl in acetic acid forms a by-product, which is NaCl, and water. Amberlyst A-26 resin forms a by-product, which is a polymer-based by-product, and it is known to be carcinogenic.

Thus, the by-product of the former is less toxic to nature than that of Amberlyst A-26 resin.

b.Oxidation with CrO₃, H₂SO_4,H₂O creates a by-product. The reagents also contain corrosive acids.

Step-by-step solution

Green chemistry

The use of harmful chemicals as reagents poses a threat to nature and humankind, creating toxic by-products.

Green chemistry aims to replace these reagents with the ones that are eco-friendly, require lesser solvents, and create by-products that are easier to dispose of.

For oxidation, the green oxidizing agents are Amberlyst A-26 reagent, NaOCl in aqueousCH₃COOH .

Oxidation with NaOCl in acetic acid

When (CH₃)₂CHOH is treated with NaOCl in acetic acid, the product that is obtained is shown below:

Oxidation using NaOCl

Advantages of sodium hypochlorite over Amberlyst A-26 resin

Oxidation with sodium hypochlorite produces NaCl and water as the by-products. On the other hand, with HCrO₄^- - Amberlyst A-26 resin, the by-product is a polymer-supported Cr3+ by-product.

Though the by-product formed in the latter can be filtrated out without added solvent, it still poses to be carcinogenic. In contrast, the by-product formed in the case of NaOCl poses no harm to nature and can easily be separated out.

Thus, sodium hypochlorite is advantageous over the resin reagent.

Advantages/disadvantages of sodium hypochlorite over CrO3,H2SO4,H2O

The oxidizing reagent CrO₃,H₂SO_4,H₂O contains highly corrosive sulphuric acid. The by-products formed are also harmful to nature and need proper disposal, which is not the case for sodium hypochlorite.

Hence, as a green oxidizing reagent, sodium hypochlorite is advantageous over CrO₃,H₂SO_4,H₂O .