08Jul 2019 by Vincent Summers 1 Comment

Alkene Isomers and Nomenclature: 1,3,5-Hexatriene

Chemistry
Many moons ago, chemistry was divided into two large groups, organic chemistry and inorganic chemistry. Organic chemistry was thought to be the 'chemistry of life'. This was because a mysterious "vital force" associated with life was thought essential to produce organic compounds. Most organic compounds consist of carbon and hydrogen atoms, with or without nitrogen, oxygen, phosphorous, or other atoms. We will discuss a simple hydrocarbon. A hydrocarbon consists solely of carbon and hydrogen. Hydrocarbon Bonds Carbon and hydrogen usually bonds in one of three ways: single bonds (-), double bonds (=), and triple bonds (≡). In this article, we will feature only single and double carbon-to-carbon bonds... two single and three double. The compound is 1,3,5-hexatriene. Notice the featured image (above) that illustrates the most common way it is…
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10May 2019 by Vincent Summers No Comments

Motor Oil Degradation in Automotive Engines

Chemistry, Technology
Why is it so important to change the motor oil in your car? The answer is due to motor oil degradation. Unrecycled motor oils originate from naturally occurring crude oil. As such, motor oils are necessarily a complex combination of organic compounds: Molecules made simply of carbon and hydrogen. A percentage of these hydrocarbons include ring structures—whether saturated aliphatic rings or aromatic rings (benzene or polycyclic). However, the largest percentage of motor engine oil consists of straight and branched chain hydrocarbons of varying lengths. Motor oils are high-quality lubricants, but even the best of these products will degrade with use. Why is Oil a Lubricant? A good lubricant must readily flow and have sufficient viscosity. It should not freeze in even cold environments. It should possess a high level of…
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18Apr 2019 by Vincent Summers 3 Comments

Where Does Crude Oil Come From? Biotic or Abiotic Processes?

Chemistry, Education
Crude oil is used in the production of gasoline, diesel fuel, and other important substances, including plastics. The crude oil comes from the ground beneath our feet. But the question arises, how did it get there? Where Does Crude Oil Come From? There are two basic theories for the origin of crude oil: biotic and abiotic. The biotic theory predominates. It attributes oil’s formation to the decay of animal and plant matter. The less widely accepted – even controversial – abiotic theory denies the involvement of living organisms in the production of crude oil. These two theories are finding most of their adherents in two camps – the Western camp (biotic) and the Russian-Ukrainian camp (abiotic) – although there are western scientists in the R-U camp. This division is especially…
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17Jan 2018 by Vincent Summers 3 Comments

What Went Wrong? Preparing an Alkyl Halide

Chemistry, Entertainment
[caption id="attachment_18523" align="alignright" width="440"] Reflux and distillation apparatus.[/caption] Preparing an alkyl halide was one of the earliest of my home lab experiences. First, allow me to give you a little background. In the 8th grade, we were instructed by our English teacher, Mrs. Best, to write a career report about our intended future employment. My guess is most of us had not thought about that. At least I hadn't. So I chose astronomy. I mentioned this to Mom. "No," she said, "you will not become an astronomer. Astronomers don't make any money." I tried to talk her out of it, but eventually I gave up. "Chemistry," I said. Mom agreed that was acceptable. One of her friends had a chemistry background. So in the '70s I obtained my BS in…
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09May 2016 by Vincent Summers 1 Comment

Ethane Sigma Bond Rotation Conformers

Chemistry
[caption id="attachment_14316" align="alignright" width="440"] Methane Ball & Stick Model[/caption] Methane is the smallest molecule consisting of just carbon and hydrogen, CH₄. The second smallest hydrocarbon is ethane, C₂H₆. It is sometimes written H₃C–CH₃. The “dash” between the two carbon atoms represents a single bond. It is also a sigma bond. What is a sigma bond? And what are ethane sigma bond rotation conformers? What is a Sigma Bond? The carbon to carbon single bond is a covalent bond. That is, bonding electrons lying between the two carbon atoms are shared equally. A sigma bond is the strongest variety of covalent bond. The two atoms overlap head-on. One could view such a bond as being of cylindrical symmetry or like a straight line between the two atoms. Hence, the dash notation.…
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21Aug 2014 by Vincent Summers No Comments

Cubane: The Chemist’s Toy?

Chemistry
Cubane is an organic hydrocarbon. It consists of carbon and hydrogen and is cubic in shape. It is a very curious substance, indeed. With no practical purpose in view, it was first prepared in 1964. There is an endless number of theoretical molecular possibilities in the world of organic chemistry. Some chemicals are simple. Others are complex. Some are of practical use to mankind. Some are mere toys of the intellect. Yes, adults must have their toys! Cubism "We do the difficult immediately. The impossible takes a little time." Chemists enjoy challenges. One challenge was to synthesize cubane (C8H8). It is a cut with a carbon atom at each corner. Attached to each of them is one hydrogen atom (see the image). Now carbon "prefers" to form angles of 109.5…
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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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21Mar 2014 by Vincent Summers 2 Comments

The Aromatic Cyclopentadienyl Anion

Chemistry, Education
[caption id="attachment_16480" align="alignright" width="440"] Cyclopentadienyl Anion[/caption] Is it possible that for an ion to be aromatic? Yes. Consider the aromatic cyclopentadienyl anion. Hückel’s Rule dictates a flat ring with 4n + 2 π (pi) conjugated electrons. The smallest neutral ring with these qualifications has n = 1. It is benzene (C₆H₆). But Hückel’s law does not require an electronically neutral structure. The smallest aromatic ion is the cyclopropenyl cation¹ (C₃H₃⁺). Is there a negative ion that has 6 π electrons and is aromatic? The answer is yes. The aromatic cyclopentadienyl anion (C₅H₅⁻). Neutral Cyclopentadiene Neutral cyclopentadiene is flat. It is pentagon shaped. Three of the carbon-carbon bonds are single bonds. The other two are double bonds. At each of the four ends of the two double bonds there is one…
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