We explain in Chapter 24 that bisphenols can be oxidized to quinones.
(a) Calculate the oxidation numbers of C1 and C₂ in going from reactant to product.
(b) Provide a mechanism for this transformation. [The reaction begins like the alcohol oxidations of Section 13.9.]

Verified step by step guidance

1. Identify the structure of the reactant and product. The reactant is a bisphenol with hydroxyl groups on C1 and C2, and the product is a quinone with carbonyl groups on C1 and C2.
2. Calculate the oxidation number of C1 and C2 in the reactant. In the bisphenol, each carbon (C1 and C2) is bonded to an -OH group and two other carbons. Assign oxidation numbers based on these bonds.
3. Calculate the oxidation number of C1 and C2 in the product. In the quinone, each carbon (C1 and C2) is bonded to an oxygen (double bond) and two other carbons. Assign oxidation numbers based on these bonds.
4. Compare the oxidation numbers of C1 and C2 in the reactant and product to determine the change in oxidation state, indicating oxidation.
5. Outline the mechanism for the transformation. The reaction begins with the formation of a chromate ester intermediate, followed by elimination to form the carbonyl groups, similar to alcohol oxidation mechanisms.

Key Concepts

Oxidation Numbers

Oxidation numbers are a way to keep track of electron transfer in chemical reactions. They indicate the degree of oxidation of an atom in a compound, helping to identify how many electrons are lost or gained. In the context of the transformation from bisphenols to quinones, calculating the oxidation numbers of specific carbon atoms (C1 and C2) allows us to understand the changes in electron density and the overall oxidation state during the reaction.

Mechanism of Oxidation

The mechanism of oxidation describes the step-by-step process by which a reactant is converted into a product through the breaking and forming of bonds. In the case of bisphenols oxidizing to quinones, the mechanism typically involves the removal of hydrogen atoms and the formation of double bonds, which can be illustrated using curved arrows to show electron movement. Understanding this mechanism is crucial for predicting the behavior of similar organic reactions.

Alcohol Oxidation

Alcohol oxidation refers to the chemical process where alcohols are converted into carbonyl compounds, such as aldehydes or ketones, often involving the loss of hydrogen. This process is fundamental in organic chemistry and serves as a basis for understanding more complex transformations, such as the oxidation of bisphenols to quinones. Familiarity with the principles of alcohol oxidation helps in grasping the underlying reactions and mechanisms involved in the transformation discussed in the question.