Arrow pushing application

Scheme 1.8 Application of arrow pushing to homolytic cleavage using single-barbed arrows.

Scheme 1.9 Application of arrow pushing to heterolytic cleavage using double-barbed arrows.

The answer to this question depends on information presented in Chapter 7. However, through an understanding of the nature of various nucleophiles coupled with application of arrow-pushing techniques, the answer can be derived from information presented thus far. 

The two arrows show (1) movement of a pair of electrons from oxygen to carbon to form the new C—O bond and (2) movement of a pair of electrons from the C—Cl bond to chlorine to form the chloride ion. Mechanism arrows depict the movement of pairs of electrons, not the movement of atoms. This is a logical result of the fact that chemical reactions are due to changes in bonds, and bonds are made out of electrons. Practice using electron pushing in mechanisms as frequently as you can so that you can get used to the technique. Note that proper use of electron-pair arrows automatically results in the correct Lewis structures for the products of a reaction, including charges, if any. An example of its application to an even simpler reaction, the reaction of an acid and a base, is shown below. 

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