25Aug 2019 by Vincent Summers No Comments

Odor Chemistry: Lady Beetle Vs. Marmorated Stink Bug

Chemistry, Nature
It was the ol' one-two. First we were attacked by Asian Lady Bird Beetles, Harmonia axyridis, then the brown marmorated stink bug, Halyomorpha halys. The Lady Bird Beetles were detected first in Louisiana in 1988. Close on its heels, the Stink bugs were detected in Pennsylvania in 1996. Both exude horrible odors when provoked or crushed, though the constituent chemicals are entirely different. Stink Bug Chemistry The stench of the Stink Bug is actually rather simple, as far as stenches go. Two organic compounds, each a "first cousin" of the other, are the culprits: trans-2-octenal and trans-2-decenal (see image). These two compounds are classified as both aldehydes (-CHO) and alkenes (-C=C-). Let's first examine how they are named. Notice both compounds have a straight chain or backbone of carbon atoms…
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30Jan 2017 by Vincent Summers No Comments

The Difference Between Alkanes, Alkenes, and Alkynes

Chemistry, Education
[caption id="attachment_16044" align="alignright" width="440"] An acetylene (ethyne) torch.[/caption] Alkanes, alkenes, and alkynes are made up of carbon and hydrogen. The carbon atoms in each exhibit a valency of four.  Though these three hydrocarbon varieties are similar, there is a difference in bonding. We illustrate this with the simplest example: ethane vs. ethene vs. ethyne. Common and Scientific Names Common names are names given to many compounds, but they may mislead the uninitiated. For instance, the scientific names of alkenes contain the suffix –en(e) as part of their name. But acetylene is not an alkene. It is an alkyne. The scientific names of alkynes contains the suffix –yne. Acetylene is scientifically named ethyne. Yet, it nomenclature is not the only difference between alkanes, alkenes, and alkynes. Alkanes Alkanes are completely saturated…
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22Aug 2014 by Vincent Summers No Comments

Explaining Saturation and Unsaturation

Chemistry
What is Saturation? What is Unsaturation? Even those scientifically uninclined use the words. Saturation, unsaturation, and polyunsaturation are dietary terms closely associated with health. Most know they are also chemical terms. But they don't understand what they mean. This is a shame, since "saturation" can be easily understood by any bright student. Saturated Hydrocarbon Linkage Living matter (plant or animal) is made of of organic compounds. These include (but are not limited to) fats, carbohydrates, and proteins. All these substances contain a kind of backbone or chain, of atoms of carbon (C) bonded to atoms of hydrogen (H). Each carbon is capable of bonding with four hydrogens. [sc name="MidArticleAdsense"] For purposes of illustration, we'll assume we have before us a chain of four carbon atoms, with every available bond possibility…
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04Feb 2013 by Vincent Summers 2 Comments

Epoxide Ring Preparation by Oxidation of Alkenes

Chemistry
How many have purchased a 2-tube pack of epoxy at their local hardware or grocery store? It’s a routine item we use to repair a variety of objects. But what is it that makes epoxy glue so strong? Its name gives it away. Epoxy glues use epoxy compounds. Epoxides. What is an epoxide? It’s Simple? Yes An epoxide is a molecule with a tiny 3-member ring in its structure. One atom is oxygen. Two are carbon. The epoxy link is illustrated in Figure 1. R₁, R₂, R₃, and R₄ are pendant groups. How is such a 3-member ring created? Often by the oxidation of an alkene. The reader may appreciate an example.1 Propene Let's try the oxidation of propene, CH3CH=CH2.2 What would be a suitable oxidizing agent for the reaction?…
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