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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Tetra-Tert-Butyl Methane – The Acyclic Alkane That Seemingly Should Exist

Chemistry, Education
The smallest non-cyclic alkane that theoretically should exist, but to date has never successfully been prepared, is tetra-tert-butyl methane. The reason it is so elusive is crowding or steric hindrance. Introducing TTBM Tetra-tert-butyl methane is the common name of 3,3-ditert-butyl-2,2,4,4-tetramethylpentane. A glimpse at the structure reveals the overcrowding. Despite the overcrowding, according to energy calculations, the molecule (we’ll call it TTBM) should be capable of existence. Assembling the Model Even building the model from its component parts presented a measure of difficulty. The 17 carbon atoms (black spheres) and 36 hydrogen atoms (smaller white spheres) required some effort to assemble into TTBM. Still, it was accomplished with all the component atoms not touching one another. What is the problem or problems? [caption id="attachment_16028" align="alignleft" width="405"] Molecular Model TTBM[/caption] Synthesis While…
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Decarboxylation of Carboxylic Acids Useful in Synthesis

For one reason or another, it may be desirable to remove a carboxylic acid group (–COOH) from a molecule. This process is called, logically, decarboxylation. It may be the carboxylic group was previously introduced to guide some of steps in a synthesis. What? A Simple Example Consider the simple hexagonal ring, aromatic compound benzene, C6H6. From the top and clockwise, let's number the carbon atoms, one through six. If we wish to attach a group synthetically to the ring, how do we determine the ring carbon to which it will attach? It's simple. They're all identical. Whichever carbon atom it does attach to becomes the number one carbon atom! But say we want to attach another group to the No. 2 carbon atom. Well, in this situation, the carbon atoms…
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