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Oxygenated Benzene Nanotubes

Toward making smaller-diameter nanotubes
  [vote for,

An earlier Idea of mine considered using the smallest possible size of carbon nanotubes, and I talked about the 6-atom molecular ring of benzene as a model. See the first link. However, one of the annotations indicated that actual nanotubes are rather larger-circumference than six carbon atoms.

Well, then, perhaps we need a different way of making nanotubes. Thus this Idea, which is intended to start with actual benzene molecules. See the "benzene" link for a model of how the molecule is constructed, with 6 carbon atoms forming the ring, and 6 hydrogen atoms attached to the ring.

What we would LIKE to do starts with a 2nd benzene molecule, "stacked" above the first. Imagine that three of the hydrogen atoms are removed from each molecule, and the three unconnected bonds of carbon atoms in the lower benzene ring are attached to the three unconnected bonds of carbon atoms in the the upper benzene ring.

Another ring we could imagine adding by stacking another benzene molecule, and removing 3 and 3 hydrogens, and connecting the carbons as before. The middle benzene ring has now lost all its hydrogens, but connects to the upper ring with three bonds, and connects to the lower ring with three bonds.

Imagine we keep adding rings and connections, as before, to make however-long a nanotube that we might want. However, in actuality THAT idea can't be done! There is a limit to how much the natural "bond angles" of atoms can be bent, in forming complex molecules, and the above imaginings, for any middle benzene ring in the sequence, exceed that limit. Look at that linked image again, thinking about connecting stacked adjacent rings, using the bonds normally connected to hydrogens, to see what I'm talking about.

We need a different way to connect those rings together. One alternative would ignore the hydrogens, and consider the double-bonds in the ring. if they were broken, we could maybe use those bonds to connect the rings (3 connections between rings, as before).

However, that notion eliminates a prime feature of carbon nanotubes, which is the fact that double-bonds allow the tube to conduct electricity --and if we break them to create the tube, then we will lose that conductivity property.

So now we come to the reason why the first word in the title of this Idea is "oxygenated". Oxygen typically has two chemical bonds available, and here we could "simply" replace two hydrogens with one oxygen (three times), to connect an adjacent pair of benzene rings. That would distort the carbon bond-angles much less than mentioned in the first part of this Idea, likely enough for an actual oxygenated benzene nanotube to be able to exist in reality.

The exact details of accomplishing that construction still need to be worked out, of course, which is why this Idea is Half- Baked. For starters, though, we could imagine replacing all the hydrogens with "hydroxyl" groups (an oxygen connected to a hydrogen).

There is a well-known process ("dehydration synthesis") by which two separate molecules combine, each starting out with a hydroxyl group, such that afterward one oxygen then connects the two molecules, while the other oxygen and the two hydrogens depart together as a single water molecule. Here, a "hard part" would consist of getting exactly 3 hydroxyl groups on one of the benzene rings to combine with 3 hydroxyl groups on an adjacent ring.

Perhaps we should start with only 3 hydroxyl groups on one ring. We KNOW that at the end of an overall nanotube only 3 connections will exist, so we need a molecule that can be called a "cap". For that particular benzene molecule, we replace 3 hydrogens with hydroxyl groups, and the other 3 hydrogens with fluorine atoms.

Now when that molecule is reacted with a fully hydroxylated benzene ring, only 3 connections between the two rings will be possible. When THAT two-ring construction is reacted with another fully hydroxylated benzene ring, only 3 connections will be possible. And so on...for as many rings as we care to add, to create an overall oxygenated benzene nanotube. At the very end we replace the last 3 hydroxyls with 3 more fluorine atoms.

Vernon, Jun 22 2015

Old nanotube-usage Idea Nanotube_20Deuteron_20Aiming
As mentioned in the main text. [Vernon, Jun 22 2015]

Benzene molecule model http://i.ytimg.com/...aAzms/hqdefault.jpg
As mentioned in the main text. [Vernon, Jun 22 2015]

Electron clouds near a benzene ring http://www.isis.stf...-thumbnail10870.jpg
As indicated in an annotation. [Vernon, Jun 22 2015]

Benzene's unfixed double bonds https://paulingblog.../modern-benzene.jpg
This representation of the benzene molecule is intended to show that the double-bonds are not fixed in place, which leads to the electron clouds mentioned elsewhere on this page. [Vernon, Jun 22 2015]

An example of dehydration synthesis https://www.boundle...ynthesis-294-11427/
Mentioned in the main text. This example (scroll down the page far enough) shows two molecules, each having a "core" of the benzene ring, joining together at one place. We want three connections, though. [Vernon, Jun 22 2015]


       Aryl rings exhibit delocalised pi-bonds; the single-double- single- double visualisation doesn't hold good under X-ray diffraction analysis. That's why rings are conventionally represented as a hexagon with a circle inside.   

       The presence of the pi electron "cloud" militates against the sort of "stacking" proposed in the idea.
8th of 7, Jun 22 2015

       [8th of 7], while you have certainly indicated an increased-difficulty factor, I'm not sure it is enough to make this Idea impossible. IF the tube can be constructed, then the inside of the tube will be chock-full of rather-loose electrons, just waiting to assist in the conduction of an overall electric current.   

       I've added a bit at the end of the main text, showing at least part of a possible pathway to overall success, in constructing an oxygenated benzene nanotube.
Vernon, Jun 22 2015

       //The presence of the pi electron "cloud" militates against the sort of "stacking" proposed in the idea.//   

       And yet many aromatic molecules pi-stack.
MaxwellBuchanan, Jun 22 2015


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