Unanswered Questions

38
votes
0answers
914 views

Is there a general consensus on the causes of the alpha-effect?

There have been various explanations posited for the $\alpha$-effect. The $\alpha$-effect refers to a phenomenon wherein nucleophiles with lone pairs on atoms adjacent (i.e., in the $\alpha$- ...
14
votes
0answers
52 views

Manuals for a Cahn TG-171 Thermogravimetric Analyzer

Recently a Cahn TG-171 Thermogravimetric Analyzer was donated to my school. We did not get a service or user's manual with it, and some of it still needs to be put back together. I have tried to ...
13
votes
0answers
193 views

How can I update a map/mesh and coordinates in a PyMol session file?

I have a PyMol session file I was using to create my figures. It contains a protein and ligand broken into several groups of atoms with a fair bit of overlap. There are also a few meshes built from ...
12
votes
0answers
439 views

Deliquescence/efflorescence: How can I convert between salt concentration and RH?

I am looking at two phase diagrams, one has axes of $T$ and $\%\ce{MgClO4}$ in a $\ce{H2O-MgClO4}$ mix, and the other has axes of $T$ and relative humidity. The authors of the second phase diagram say ...
10
votes
0answers
96 views

What is the justification for Hückel's Rule?

I know that experimentally, the rule has been verified but I am having trouble understanding why it works. I see no reason why equivalent cyclic structures can undergo resonance and be just as stable. ...
10
votes
0answers
185 views

Finding the number of cyclic isomers algorithmically

Is there an algorithm for finding the number of cyclic isomers a given compound might have? I've found a general algorithm for all isomers: link, but I'm not sure how to apply it for cyclic isomers ...
10
votes
0answers
155 views

Molecular Imaging - Any surprises to be had?

Molecular imaging, using STM and AFM technologies, appear so far to visually prove most of what we already know about chemical structures, such as VSEPR theory. For instance, here are the ideal ...
9
votes
0answers
75 views

Hosoya Z Index and Correlation with Boiling Point

I have recently read about the Z topological index found by Hosoya. The papers/sources The Z index is the sum of the coefficients of the matching polynomials (no. of ways to choose an independent edge ...
9
votes
0answers
83 views

When measuring avidity should you use the ligand concentration or the nanoparticle concentration?

Looking at avidity between a ligand-receptor, you're looking at an enhancement of the $K_d$ compared to a lone ligand. Is it more appropriate to compare the $K_d$ using the concentration of the ...
8
votes
0answers
99 views

How to calculate the pH of a saturated solution from its solubility constant Ksp and acidity constant Ka?

Given that $K_{\mathrm{sp}}(\ce{CaF2})=3.2\cdot 10^{-11}$, $K_{\mathrm{a}}(\ce{HF})=10^{-5}$, and $K_{\mathrm{w}}=10^{-14}$. Calculate $\mathrm{pH}$ of saturated $\ce{CaF2}$. Here is my ...
8
votes
0answers
39 views

Alkylation conjugated nitrile

Why does the enolate of the nitrile attack the alkyl chloride from the bond shown in the picture and not from the far end pi bond?
8
votes
0answers
71 views

Bandgap of a semiconductor for photocatalytic water splitting

I'm reading a review article on photocatalytic water splitting (using semiconductors) and I came across the following: "To achieve photocatalytic water splitting using a single photocatalyst, the ...
8
votes
1answer
129 views

Carbocation stability order

I was wondering whether the following order (from here) is correct: In the first inequality, why did 9 hyperconjugations dominated resonance effect of benzene ring? In the last inequality ...
8
votes
0answers
151 views

Mechanism of dehydrogenation with Nosylate

What is the mechanism of the attached reaction? How could nosylate do the dehydrogenation? The reaction is from this synthesis (46th IChO preparatory problem 26):
8
votes
0answers
162 views

Is hybridization used in ab-initio valance bond calculation?

Many general chemistry textbooks introduced the concept "hybridization" to construct a symmetry-adapted VB-type wavefunction. In the textbooks, usually the minimal basis is used and without optimizing ...

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