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Author: Subject: Resonance between reagents?
Fulmen
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[*] posted on 21-7-2020 at 13:41
Resonance between reagents?


Wikipedia: Chemical equilibrium

Reactions can either be reversible or non-reversible. A reversible reaction can be described through this general reaction: A + B <=> AB
This reaction will form an equilibrium where the components continuously react back and forth in a random pattern.




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[*] posted on 21-7-2020 at 16:16


Let me rephrase my question.

In compounds such as benzene that demonstrate stronger and shorter bonds because of the resonance between the carbon atoms, do other nearby benzene molecules combine their orbitals so that they share resonance amongst themselves as a whole? Can you find two electrons in the same orbital if the molecules are mixed together in a solution? Does the electron that makes up the resonance structure trade electrons with compounds of the same molecular formula? Does a mixture of benzene molecules share their pi bonds amongst each other or are the electrons locked in orbit around one particular molecule?

I deleted my original post as it was misinformative. Let me know if there's still confusion




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[*] posted on 21-7-2020 at 17:39


No, not unless they are chemically reacting with each other.



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[*] posted on 21-7-2020 at 18:53


This question comes across as a bit of a muddle.
On the issue of bonding, it is sometimes helpful (and historic) to visualise some situations as resonance – an oscillation between two extremes. But it is more accurate and generally more helpful to consider molecular orbitals.



On the matter of equilibrium, I don't think that oscillation back and forth over an equilibrium point is possible – at least not without some other complex multiple step process being in place (such as with the Briggs-Rauscher reaction.)

Oscillation occurs in systems where there is a feedback loop of a particular kind – such as happens in pendulums, springs, capaciteance-induction circuits and so forth. In each of these cases the "force" driving the system back towards equilibrium is second order: proportional to the square of the displacement from equilibrium point. so, for a spring, a=-kx² (where a= accelration and x, distance.) The system is modelled by a quadratic differentail equation. When this equation has complex roots then oscillation (damped or otherwise) occurs.

In the case of chemical equilibria, I think the equations are first order: the driving force is proportional to the distance from equilibrium and not the square of this. (I might be wrong and am more than happy to be corrected.) Therefore the approach to equilibrium is exponential decay and not sinusoidal.
In saying this I know that the equilibrium constant can be quadratic or cubic or even higher. But this quantifies the position of the equilibrium and not the forces driving the forwards and backwards reactions.
And even if sinusoidal oscillations existed, my intuition suggests these would tend to be dampened by kinetic considerations. Again, I am more than happy to have some expert insight on this.

[edit]
And now the original question is gone. <sigh>
This does not make the thread clearer.

[Edited on 22-7-2020 by j_sum1]
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[*] posted on 21-7-2020 at 20:22


Quote: Originally posted by ThoughtsIControl  
Let me rephrase my question.

In compounds such as benzene that demonstrate stronger and shorter bonds because of the resonance between the carbon atoms, do other nearby benzene molecules combine their orbitals so that they share resonance amongst themselves as a whole?


There is some interaction. Benzene is widely used for modeling pi-pi stacking system - this is the way that it makes dimers. You may want to read those papers and I'm sure you will find much more.


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[*] posted on 21-7-2020 at 21:34


Thank you all for the feedback. It was helpful to my visualization of the molecules. Also, those were quite interesting paper. It seems as if there's orbital interaction in benzene molecules but not to the extent of exchanging electrons. Instead, the pi orbitals align themselves in a way that puts them in their lowest energy state as a unit. Molecules of the same identity interact in a closer proximity compared to molecules of varying counterparts.

So.... on the topic of electrons.. how about that double slit experiment ? haha keep the thread alive:)




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[*] posted on 22-7-2020 at 05:56


Well DNA is somewhat conductive due to orbital overlap of delocalised electrons in the stacked rings of the bases. (referred to in review in https://www.tandfonline.com/doi/pdf/10.1080/23746149.2016.12...)
Quite a bit of work is being done to improve this with metal doping, in terms of increasing the stability and also improving the conductivity.

Chlorophyll too works in plant cells as a harvester of light-released electrons that travel through the porphyrin rings of the chlorophyll and jump from ring to ring until they reach some active site.

Note that in each of these cases, the biological molecules have a constrained and "controlled" structure - a bit of an overlap of biophysics, biochemistry and chemistry.

In the case of scintillants used for beta emitters and beta counting, such as tritium and c14, the solvent is always aromatic so as to facilitate transfer of electrons from molecule to molecule until they meet a fluor and "flash". Substances that interfere with this process are called quenchers, and I remember a zillion and a half years ago having to make up standard curves of these when I moved to one of the safer new scintillants from the old toluene based ones that my (then) uni had bought standards for.

So yeah, good question.
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[*] posted on 22-7-2020 at 09:35


"Well DNA is somewhat conductive due to orbital overlap of delocalized electrons in the stacked rings of the bases"

Absolutely fascinating! Lifes best work apparently utilizes this idea to accomplish some of the most important functions. To elaborate on the article posted above, Richard Feynman is the one who originally came up with the idea of nanocircuits. Of course, we are still in the infancy of this technology but the basis of it relies on the physical properties of the electron as I mentioned in the original post. The potential applications of this technology are mentioned in this source. The article here states "A complete nanoscaled circuit is then accomplished by metallising the patterned
DNA origami templates to make conductive wires and is integrated with semiconducting materials to provide multiple transistor functionalities. However, correct
DNA patterning, DNA metallisation, and the integration between DNA origami
and semiconductor materials are challenges that determine the success of this
DNA-based nanoscaled electronic circuitry"
(https://www.tandfonline.com/doi/pdf/10.1080/23746149.2016.12...)

At this point in time, we're trying to make a DNA based circuits running of the principle of exchanging electrons. The challenge we're at currently is efficiently connecting the microscopic circuit to a macroscopic one. It's interesting to think about. Perhaps when I graduate in eight years then I will be able to modify a chloroplast to capture energy from the sun for my needs rather than a solar panel. Haha! A kid can dream





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