23Mar 2014 by Vincent Summers No Comments

The Quintessential Aromatic Hydrocarbon Benzene (Pt.3)

Chemistry
[caption id="attachment_18860" align="alignright" width="440"] Figure 1.[/caption] The aromatic hydrocarbon benzene, chemical formula C6H6, is the single most-often discussed of the aromatic hydrocarbons. It possesses the quintessential aromatic structure. How is that? It possesses the Hückel Rule correct number of 4n + 2 number π-electrons, for n = 1, and is flat. In addition, it meets all the other requirements for aromatic compounds. As an aromatic compound, its chemistry is considerably different than it would be if it existed as a mere cyclohexatriene isomer. We will discuss those differences in this, the third installment of our three-part article. Behavior of Hypothetical Cyclohexatriene Since cyclohexatriene would behave as if it were merely three conjugated1 double bonds, we would expect the compound to behave as any other alkene—rich in available electrons—only more so.…
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23Mar 2014 by Vincent Summers No Comments

The Quintessential Aromatic Hydrocarbon Benzene (Pt.2)

Chemistry
[caption id="attachment_6069" align="alignright" width="440"] Benzene De-localized Pi-system - CCA Share Alike 3.0 Unported by Vladsinger[/caption] In Part One of The Quintessential Aromatic Hydrocarbon Benzene, we saw that the so-called 1,3,5-cyclohexatriene was really not completely described by the structure that that name implies. It is equivalent to 2,4,6-cyclohexatriene (if you flip the 1,3,5- structure over, and you get the 2,4,6- structure), and includes a variety of other contributing factors. Although we did not list them, they may include ionic contributors.1 In general, these are discounted. Visualizing Benzene's Structure The conclusion is that the compound actually has six equivalent bonds between adjacent carbon atoms, forming six internal angles angle each equal to 60°. The bonds are each, then, “single-and-one-half” bonds between each carbon pair. The molecule is flat, even as a collection…
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23Mar 2014 by Vincent Summers No Comments

The Quintessential Aromatic Hydrocarbon Benzene (Pt.1)

Chemistry
[caption id="attachment_14959" align="alignright" width="440"] Cyclohexane - Chair Form[/caption] Benzene? What's that? Living creatures universally share an important characteristic: they all are constructed of carbon-containing compounds. For that reason, chemists call such compounds organic. Now the term organic has taken on additional meaning. Compounds that are similar, but not found in nature, are also called organic compounds. One group of organic compounds, whether found in nature or not, possess special properties—chemical and physical—that put them into a category apart. Once it was thought such compounds were distinguishable by smell or aroma. Each was labeled an aromatic, and—the property itself—aromaticity. Simple Hydrocarbons The simplest hydrocarbon1 is methane (CH4)—a gas. It possesses a tetrahedral structure, with a carbon atom at its center and four hydrogen atoms at the corners (See Figure 1). Since…
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