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yonos
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How strong a long chain of carbon carbon double bonds will be compared to nano tubes?
H>c=c=c=c=c=c=c=c=...=c=c=c=c=c=c=c=c=c=c=c=c<H
H>c=c=c=c=c=c=c=c=...=c=c=c=c=c=c=c=c=c=c=c=c<H
I think this is more a consequence of the Peierls instability of long chains with equidistant bonds.TeethWhitener said:Cumulenes are actually less stable than conjugated alkenes (C-C=C...) where a single and double bond alternate. This occurs because the valence π orbitals in a cumulene are at right angles to one another and so do not allow much delocalization. For conjugated species, however, the π orbitals are oriented such that an electron can delocalize over a large distance, lowering the energy of the system and stabilizing it.
In the long-chain limit, cumulenes buckling to polyalkynes is due to Peierls distortion, but you don’t see the same strong bifurcation in CC bond lengths in polyalkenes like you do with polyalkynes. I couldn’t say for certain why that’s the case off the top of my head. (It’s also interesting that you see isomerization in short chain cumulenes as well. I have an idea for why this occurs, but no hard evidence.)DrDu said:I think this is more a consequence of the Peierls instability of long chains with equidistant bonds.
I don’t have access to the full paper right now, but I doubt it. For One, I imagine the nanotube (already a very strong material) would swamp any effect you’d see from the carbyne. Also, as far as actually using the material in bulk for its mechanical properties, the limiting factor is always going to be the weakness of the noncovalent intertube interaction. It’s the same reason the whole “elephant on a pencil” argument for graphene’s strength is so misleading.mfb said:@TeethWhitener: What about a combination of these chains plus nanotubes, as discussed in the reference I posted? Could it contribute enough to the strength to make it interesting?
The strength of a long chain of c=c double bonds is directly proportional to its length. This means that the longer the chain, the stronger it will be. This is because longer chains have more double bonds, which means more electrons are shared between atoms, making the bond stronger.
Yes, the strength of a long chain of c=c double bonds can be increased by increasing the number of double bonds in the chain. This can be achieved by adding more carbon atoms to the chain, as each carbon can form a double bond with another carbon.
The strength of a long chain of c=c double bonds can be affected by several factors, including the length of the chain, the number of double bonds, the type of atoms involved, and the presence of any functional groups. Additionally, temperature and pressure can also affect the strength of these bonds.
The strength of a long chain of c=c double bonds is generally stronger than single bonds. This is because double bonds have a higher bond energy than single bonds, meaning more energy is required to break them. However, the strength of a double bond can vary depending on the factors mentioned above.
Yes, the strength of a long chain of c=c double bonds can be measured using techniques such as spectroscopy or X-ray crystallography. These methods allow scientists to determine the bond length and energy of the double bonds, which can then be used to calculate the strength of the bond.