Question

Choose the correct statement from the following:
(P) Anthraquinone derivatives are generally detected by Borntrager’s test
(Q) Anthrone is yellow colored and soluble in alkali
(R) Anthranol is insoluble in alkali and shows strong red fluorescence
(S) Borntrager’s test gives negative result with Anthranol (Reduced form)

• A. $ \text{P and S Only} $
• B. $ \text{R Only} $
• C. $ \text{Q and R Only} $
• D. $ \text{P Only} $

Hint:

Borntrager’s test is positive for free anthraquinone glycosides, not their reduced forms like anthranol.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
Anthraquinone, anthrone and anthranol are three different oxidation states of the same tricyclic system, and this question checks which statements about their colour, solubility and behaviour in Borntrager's test are true.

Step 2: Key Formula or Approach:
The oxidation ladder runs from anthranol or anthrone, the reduced, pale forms, up to anthraquinone, the oxidised, coloured form, and Borntrager's test only turns positive once a free anthraquinone nucleus is present in alkaline solution.

Step 3: Detailed Explanation:
Statement P: Borntrager's test is specific for free anthraquinone derivatives, which give a pink to red colour when shaken with dilute ammonia or alkali, so P is true.
Statement Q: anthrone is not yellow; it is a pale, largely colourless reagent widely used for detecting carbohydrates, so Q is false.
Statement R: anthranol readily dissolves in alkali because of its phenolic hydroxyl group, so calling it insoluble in alkali is wrong, and R is false.
Statement S: anthranol is the reduced form of anthraquinone, and Borntrager's test needs the oxidised quinone form to develop colour, so the test stays negative with anthranol, making S true.
Putting these together, only P and S are correct statements.

Step 4: Final Answer:
The correct combination is P and S Only.