Electrostatic potential plot

When comparing two maps, the comparison is useful only if they are plotted using the same scale of color gradation. For this reason, whenever we compare two plots in this text, they will be drawn side by side using the same scale. It will be difficult to compare two plots in different parts of the book, because the scale may be different. Despite this limitation, an electrostatic potential plot is a useful tool for visually evaluating the distribution of electron density in a molecule, and with care, comparing the electron density in two different molecules. 

Electrostatic potential plots for H2O and CO2 appear in Figure 1.18. Additional examples of polar and nonpolar molecules are given in Figure 1.19. 

Electrostatic potential plots are color-coded maps of electron density, indicating electron-rich and electron-deficient regions (Section 1.11). 

Electrostatic potential plots in Figure 2.2 compare the electron density around the oxygen atoms in these conjugate bases. The darker red around the O atom of CH3CH2O indicates a higher concentration of electron density compared to the O atom of CF3CH2O . 

Electrostatic potential plots of these carbanions appear in Figure 2.4. 

Dark blue areas in electrostatic potential plots indicate regions low in electron density. As alkyl substitution increases, the region of positive charge is less concentrated on carbon. 

Alkenes are electron rich, as seen in the electrostatic potential plot in Figure 10.7. The electron density of the n bond is concentrated above and below the plane of the molecule, making the n bond more exposed than the o bond. 

The red electron-rich region of the n bond is located above and below the plane of the molecule. Because the plane of the alkene depicted in this electrostatic potential plot is tipped, only the red region above the molecule is visible. 

Electrostatic potential plots for a conjugated and an isolated diene... 

Because oxygen is more electronegative than either carbon or hydrogen, the C—O and O—H bonds are polar. The electrostatic potential plot of acetic acid in Figure 19.1 shows that the carbon and hydrogen atoms are electron poor and the oxygen atoms are electron rich. 

Electrostatic potential plot of acetic acid (CH3COOH)... 

The electrostatic potential plots in Figure 23.1 compare the electron density of the acetone enolate, which is resonance stabilized and delocalized, with that of (CH3)2CHO , an alkoxide that is not resonance stabilized. 

The NH2 group gets more electron rich as the para substituent changes from NO2 H CH3. This is indicated by the color change around NH2 (from green to yellow to red) in the electrostatic potential plot. 

Electrostatic potential plots of vitamins A and E (Figure 29.6) show that the electron density is virtually uniform in these compounds. The large regions of nonpolar C-C and C-H bonds tend to obscure small dipoles that occur in the one or two polar bonds, making these vitamins nonpolar and hydrophobic. 

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