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In the mid-nineteenth century, European textile dyeing relied overwhelmingly on natural alizarin extracted from the roots of the madder plant (*Rubia tinctorum*). The commercial viability of synthetic alternatives shifted dramatically in 1868 when chemists Carl Graebe and Carl Liebermann synthesized alizarin from anthracene, a hydrocarbon derived from coal tar waste. However, Graebe and Liebermann’s initial laboratory method required expensive bromine reagents, rendering large-scale industrial synthesis financially impractical for textile manufacturers.

To overcome this economic bottleneck, industrial chemist Heinrich Caro, working at the Badische Anilin- und Soda-Fabrik (BASF), devised an alternative chemical route in 1869 using sulfuric acid to sulfonate anthraquinone rather than brominating anthracene. This modification eliminated the need for costly bromine, drastically lowering raw material expenditures. Concurrently, English chemist William Henry Perkin independently discovered the identical sulfonation pathway and filed a patent application in London just one day after BASF filed its patent in Berlin. Rather than engaging in costly transatlantic patent litigation, BASF and Perkin reached a cross-licensing compromise: Perkin retained exclusive manufacturing and distribution rights within the British market, whereas BASF controlled production across continental Europe. Consequently, within a decade of the 1869 sulfonation breakthrough, global cultivation of madder collapsed, marking one of the earliest instances of a synthetic chemical compound completely supplanting an agricultural commodity in international commerce.

According to the passage, Graebe and Liebermann’s initial 1868 method for synthesizing alizarin was commercially unviable primarily because of which of the following factors?

  1. It relied on chemical reactions that required expensive bromine reagents.Cevap
  2. B
    It depended on anthracene, an organic compound that could not be derived from industrial waste products.
  3. C
    It precipitated immediate transatlantic patent disputes between European chemical manufacturers.
  4. D
    It introduced a sulfonation reaction using sulfuric acid that caused substantial raw material waste.
  5. E
    It required supplementary extracts from madder roots to stabilize the synthetic dye.

Cevap

The initial 1868 method was commercially unviable because it relied on chemical reactions requiring expensive bromine reagents.
The passage explicitly states in the first paragraph that Graebe and Liebermann’s initial laboratory method required expensive bromine reagents, which rendered large-scale industrial synthesis financially impractical for textile manufacturers. The correct choice accurately paraphrases this detail.

Adım Adım Çözüm

1
Locate the explicit discussion of Graebe and Liebermann's 1868 method in the passage.
Identified the first paragraph, which discusses the 1868 synthesis of alizarin from anthracene.
Direct factual retrieval requires finding the exact sentence detailing the targeted entity.
2
Analyze the stated reason for the method's financial/commercial impracticality.
Found the explicit statement: 'Graebe and Liebermann’s initial laboratory method required expensive bromine reagents, rendering large-scale industrial synthesis financially impractical.'
Matches the stem's question regarding why the method was commercially unviable.
3
Select the choice that accurately paraphrases this explicit detail without introducing external extrapolations or misattributions.
The statement specifying reliance on expensive bromine reagents matches the passage evidence directly.
Ensures factual precision and adherence to strict passage evidence.

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