Answer: The 6-step process involved stoichiometric inorganic reagents (e.g., AlCl₃ as reagent, not catalyst) that became waste by-products not incorporated in ibuprofen, so most atom mass from reactants did not appear in the final product.
- A It used expensive platinum catalysts that had to be discarded after each batch, adding large non-product masses to the calculation under usual circumstances according to most studies in the majority of documented cases as widely reported
- B The 6-step process involved stoichiometric inorganic reagents (e.g., AlCl₃ as reagent, not catalyst) that became waste by-products not incorporated in ibuprofen, so most atom mass from reactants did not appear in the final product
- C The Boots synthesis had a low percentage yield at each individual step, which by definition reduces the atom economy calculation in standard reference material under most conditions studied in most observed cases under typical physiological conditions
- D The 6-step synthesis operated at high temperatures, causing thermal decomposition of ibuprofen, reducing the mass of product collected according to standard texts in general clinical practice as frequently documented in most reference accounts
Correct answer: B. The 6-step process involved stoichiometric inorganic reagents (e.g., AlCl₃ as reagent, not catalyst) that became waste by-products not incorporated in ibuprofen, so most atom mass from reactants did not appear in the final product
Explanation: Atom economy = MW(desired product) / Σ MW(all products) × 100%. The Boots process used stoichiometric AlCl₃ as a Lewis acid (consumed, not recycled), and stoichiometric oxidants and reagents at multiple steps, each generating large amounts of inorganic waste salts that were not ibuprofen. This gave ~40% atom economy. The BHC process uses catalytic HF (recycled), three steps, and incorporates most atoms into the product - achieving ~99% atom economy. Atom economy is independent of yield.
Classical smog is a reducing mixture of SO₂ and fog, while photochemical smog is an oxidising mixture generated by UV-driven reactions of NOx and hydrocarbons.
Concept context
Understand how human activities alter the atmosphere, water, and soil. Covers air pollutants, smog types, ozone depletion, acid rain, greenhouse effect, water and soil pollution, and the principles of green chemistry.