Q85. Question: The curved arrow notat... [FREE SOLUTION]

Chapter 1: Q85. (page 60)

Question: The curved arrow notation introduced in Section 1.6 is a powerful method used by organic chemists to show the movement of electrons not only in resonance structures but also in chemical reactions. Since each curved arrow shows the movement of two electrons, following the curved arrows illustrates what bonds are broken and formed in a reaction. Consider the following three-step process: (a) Add curved arrows in Step [1] to show the movement of electrons. (b) Use the curved arrows drawn in Step [2] to identify the structure of X; X is converted in Step [3] to phenol and HCl.

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Step-by-Step SolutionStep 1: Curved arrow notation

The electron flow in almost every reaction is shown with the help of curved arrows. The mechanistic pathway of numerous reactions can be explained with the help of curved arrows.

Step 2: Movement of electrons in Step [1]

In this particular reaction, the initial reactant contains the epoxide ring. The protonation of the oxygen atom leads to the generation of a carbocation in the first step. It is formed as the ring opens.

Movement of electrons in Step [1]

Identification of structure X

In this particular structure, the lone pair of electrons on the oxygen atom moves down, leading to the formation of the C-O double bond. The migration of the hydride group happens to lead to the structure given below.

Identification of structure X

The chloride ion then attacks the hydrogen atom, and the double bond moves toward the positive charge found on the hydroxyl group's oxygen atom. It leads to the formation of phenol and HCl .