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1500 questions
22
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Why does the image of cyclo[18]carbon look like a nonagon?
The $\ce{C18}$ allotrope cyclocarbon has been synthesized and imaged.[1] Science has most details behind a paywall, but this discussion includes an image:
In this octakaidecagonal molecule, each $\ce{\color{blue}{C}}$ is bonded viz.…
J.G.
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Why has the mole been redefined for 2019?
The mole is still defined as an SI unit representing the number of constituent particles (whether they be atoms, molecules etc.) in 12 grams of carbon isotope 12 (carbon-12).
Effective from May 20 this year the definition of the mole will change to…
Zebrafish
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Migratory aptitude in pinacol-pinacolone rearrangement
I am confused about the migratory aptitude of various groups, as there are many different orders for the same given in different places, especially about -Ph and -H. I would like to know if someone could reliably tell the order.
RE60K
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How can I clean my lab coat?
Over the course of my studies, my lab coat has absorbed a non-negligible amount of different chemicals, some of them nasty organic polymers, some are more insoluble inorganic compounds like $\ce{Cr2O3}$.
Even after washing the lab coat some stains…
tschoppi
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22
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2 answers
Is there a simple way to get the circular dichroism of a molecule from its structure?
Are there any heuristics to get the relative absorbtion of left and right circularly polarized light by a molecule from its molecular structure? Is it even possible to predict which polarization is selectively absorbed?
Dan
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Hottest region of Bunsen flame
Since region 1 is closer to the source, I presume it to be the hottest as complete combustion takes place there. Also, this is the part where the gas mixture(responsible for flame) reacts with oxygen first(as soon as valve is open). So, the…
MollyCooL
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21
votes
2 answers
Why do alkanes have higher boiling point than their ether counterparts?
Based on my understanding of inter-molecular forces, I expect dipole-dipole interactions to be significantly stronger than van der Waal's interactions. Hence, I expect ethers (which obviously have dipole-dipole interactions) to have higher boiling…
Sarthak123
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1 answer
Ipso substitution and its rules
I was taught that the following reaction happens:
It is called the "ipso-substitution". My professor had told me that it occurs in the case of $\ce{-SO3H}$ and $\ce{-COOH}$. But he had ended the topic there. My textbook doesn't detail any more…
Gaurang Tandon
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What is the mechanism of the reaction between hexane-2,5-dione and nitrous acid?
I don't understand the mechanism of the first reaction; I tried different ways but I can usually find how to make the ring without the double bonds, but it's obviously not the right thing; I think HNO2 reacts as the nitrosonium ion, bonding with one…
Jake Q
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What is occuring on the quantum level when a molecule rotates plane polarized light?
What is occuring on the quantum level when a molecule rotates plane polarized light?
Also, why do enantiomers then rotate light in opposite directions? I would think that the electromagnetic waves would interact with the transient electric and…
Joe
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Correlation between 1H and 13C shifts - coincidence or not?
A quick glance at any table of typical chemical shifts will reveal that the chemical shifts of protons $(\delta_\mathrm H)$ tend to correlate pretty well with the chemical shifts of the carbons to which they are attached $(\delta_\mathrm C)$. This…
orthocresol
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21
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2 answers
Some materials emit more photoelectrons than others - why?
I've been experimenting with some materials by changing the wavelength of the incident light on the material and detecting photoelectrons, like in the diagram below:
I might get a response that looks like this
Both materials have the same HOMO…
Tomi
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1 answer
How to think of solvated electrons?
This excellent answer explains at length what's happening in this fascinating video entitled Liquid Electrons - Periodic Table of Videos. In the screenshot below, the metallic-looking solvated electron layer (middle) has a bronze color.
I am trying…
uhoh
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What determines how much water of crystallisation a salt has?
Is there any reason behind the number of water of crystallisation?
For example, $\ce{LiCl.2H2O}$ has two waters of crystallisation, and $\ce{MgCl2.8H2O}$ has 8 waters of crystallisation. Why does $\ce{LiCl}$ have only 2 waters of crystallisation and…
Ruchit Vithani
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21
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4 answers
Group theoretical condition for an integral to be zero
In many aspects of chemistry it is of interest to find out whether a given integral $\int \psi \,\mathrm{d}\tau$ vanishes, i.e. becomes zero. Group theory provides us with a handy condition:
If $\Gamma_\psi$ does not include the totally symmetric…
orthocresol
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