10/25/2023 0 Comments Formal charge of carbon in benzene![]() ![]() Watch for violations of the octet rule - always specifically draw in all of the atoms (including hydrogens and lone pairs) at any atom undergoing a transformation.ĭraw arrows in the right direction (from donor to acceptor). Note that the last arrow in a chain must be either a bond making arrow terminating at a sextet atom, or a bond breaking arrow. Again, all of the central carbons have no change in their charges or number of bonds, the first and last atoms change as for Bond Making and Bond Breaking processes. In this way a series of electron movements can be strung together. If this cannot be done in an electronically reasonable fashion, then the process is not feasible. When a Bond Making or Bond Movement arrow ends at an octet atom, then a Bond Breaking or a second Bond Movement processes has to "clear out" the extra pair of electron. It is really shorthand for consecutive or simultaneous bond breaking and bond making processes: A Bond Movement arrow starts at a σ or π bond, and ends at a sextet atom, forming a new σ or π bond: In each case, the formal charge becomes one unit more positive at the starting atom and one unit more negative at the terminal atom.Ī third very commonly used type, Bond Movement, is used to depict synchronous processes. There are two fundamental types of electron pushing processes: Used properly, they have tremendous value not just for understanding reactions, but also for for predicting chemical reactivity Electron pushing arrows are used as a "bookkeeping" device to easily keep track of bonding and formal charges when interconverting resonance structures or depicting reactions. This handout deals with electron pushing arrows: the movement of a pair of electrons from an electron rich site (a lone pair of electrons or a bond) to an electron poor site. ![]()
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