Electron-pushing arrows

Draw the mechanism of this reaction (show electron-pushing arrows). (Hint This is a common reaction throughout metabolism the mechanism is similar to that catalyzed by other dehydrogenases that use NADH, such as alcohol dehydrogenase.)... 

Each reaction matrix represents a class of chemical reactions that have in common the same type of electron redistribution, i.e, a reaction matrix is representative of an "electron pushing arrow pattern." The non-zero reaction matrices and the be-matrices of integral chemistry belong to disjoint subsets of S(n), (see Section IV,c), the additive group of all X symmetric matrices with integer entries. 

This gives the chemical length of the reaction vector R, so it represents the number of "electron pushing arrows in the synthesis L,R) of Z thus, it represents the "complexity of chemical operations."... 

Several of the compounds in Problems 25 and 28 can have resonance forms. Identify these molecules and write an additional resonance Lewis structure for each. Use electron-pushing arrows to illustrate how the resonance forms for each species are derived from one another, and in each case indicate the major contrihutor to the resonance hybrid. 

KEYS TO SUCCESS USING CURVED ELECTRON-PUSHING ARROWS TO DESCRIBE CHEMICAL REACTIONS... 

Reaction Mechanisms Using Electron-Pushing Arrows CHAPTER 6... 

The first and third examples illnstrate a characteristic property of electron movanent If an electron pair moves toward an atom, that atom must have a place to put that electron pair, so to speak. In nucleophilic substitution, the carbon atom in a haloalkane has a filled outer shell another electron pair cannot be added without displacement of the electron pair bonding carbon to halogen. The two electron pairs can be viewed as flowing in a synchronous manner As one pair arrives at the closed-shell atom, the other departs, thereby preventing violation of the octet rule at carbon. When you depict electron movement with curved arrows, it is absolutely essential to keep in mind the rules for drawing Lewis structures. Correct use of electron-pushing arrows helps in drawing such structures, because aU electrons are moved to their proper destinations. 

The bimolecular elimination mechanism consists of a single step. The bonding changes that occur in its transition state are shown here with electron-pushing arrows in Figure 7-8, they are shown with orbitals. Three changes take place ... 

The Diels-Alder reaction takes place in one step. Both new carbon-carbon single bonds and the new tt bond form simultaneously, just as the three tt bonds in the starting materials break. As mentioned earlier (Section 6-4), one-step reactions, in which bond breaking happens at the same time as bond making, are concerted. The concerted nature of this transformation can be depicted in either of two ways by a dotted circle, representing the six delocalized tt electrons, or by electron-pushing arrows. Just as six-electron cyclic overlap... 

Several of the natural amino acids are synthesized from 2-oxocarboxylic acids by an enzyme-catalyzed reaction with a special coenzyme called pyridoxamine. Use electron-pushing arrows to describe each step in the following synthesis of phenylalanine from phenylpyruvic acid. 

NEW. Improved and expanded coverage of electron-pushing arrows in Sections 2-2 and 2-3. The use of electron-pushing arrows, introduced in these sections, is reinforced in Section 6-3 and numerous margin reminders in all subsequent chapters. 

---