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9
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0answers
465 views

multielectron spin-orbit coupling and energy level

For multi-electron atoms for which the Hamiltonian (including the spin-orbit coupling) reads $$H=\sum_i T_i-Z\sum_i V_i+\sum_i V_i^{\text{s.o.}}+\sum_{i>j}V_{ij}$$ The $T_i$ are the kinetic ...
9
votes
1answer
3k views

Why does iron have an abnormally high ionization energy?

Along a period the ionization energy should increase because the atomic number is increasing, but there is negligible increase in shielding. However, $\mathrm{IE}_\ce{Mn} < \mathrm{IE}_\ce{Fe} > ...
9
votes
1answer
210 views

The Krieger-Li-Iafrate Approximation

I am having trouble understanding what KLI approximation is. Could someone explain it to me in an intuitive/simple way?
8
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1answer
184 views

Frontier orbital analysis of zinc-catalysed carbonyl-ene reaction

Q1. Is the $\sigma_\ce{C-H}$ bond a donor in this reaction? If not, then can we take the alternate combination (HOMO of alkene, LUMO of the $\ce{C-H}$ bond and, HOMO of the carbonyl)? Q2. We can also ...
8
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0answers
62 views

Mechanism of Hypervalent Iodine Phenolic Coupling

I need some help understanding the hypervalent iodine phenolic coupling reaction taking place in this synthesis of morphine, the reaction uses $\ce{PhI(OAc)2}$ as the hypervalent reagent and ...
8
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0answers
560 views

Does heating potato starch destroy its resistant starch?

Resistant starch, as found in potato starch, is supposed to have health benefits. There are differing opinions on whether or not heating potato starch destroys the resistant starch in it and thereby ...
8
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0answers
240 views

Why does a sealed plastic bag of dish soap, water and air expand when shaken?

I've noticed that when I put dish soap, water and a little air into a sealed plastic bag, and then shake the mixture, it forms soap suds and the bag expands significantly in volume. Why does it expand?...
8
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0answers
269 views

Why does 1,4-diiodobenzene have a non-zero dipole moment?

From this answer, I came to know that 1,4-diiodobenzene has a dipole moment of $0.19~\rm D$ in benzene at $20\ ^\circ\rm C$. On the basis of symmetry, I'd expect the bond moments due to the difference ...
8
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0answers
279 views

DIY hand sanitiser solution forms spongy substance

I am trying to make my own hand sanitiser since it’s sold out everywhere. The formula I use is 1 part aloe vera gel in 2 parts 100% isopropyl alcohol. The problem is when mixing the two, the solution ...
8
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0answers
174 views

Have IH₃ and IH₅ already been synthesized?

I've seen a paper by Sikalov [1] that says that $\ce{IH3}$ and $\ce{IH5}$ should be observable. Has anyone actually tried to synthesize such molecules? References Sikalov, A. A. Hypervalent Halogen ...
8
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0answers
174 views

Why are IUPAC's definitions of exo- and endothermic disconnected from the direction of heat flow?

I'm wondering if anyone can provide a rationale for IUPAC's definitions of exothermic and endothermic, since they disconnect these terms from the direction of heat flow. Specifically, here are IUPAC'...
8
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0answers
110 views

Are primitive GTOs normalised before contraction, or is the resultant basis function normalised afterwards?

I'm quite curious about this: In a basis set (I'll just use minimal-basis STO-nG basis sets for convenience), the basis functions are written as a linear combination of primitive GTOs. Are the GTOs ...
8
votes
1answer
459 views

Can I make a mirror on PET plastic using Tollen's reaction?

I want to make a very shiny surface, like a mirror. I tried to use chrome paint but it's barely shiny. It's more like gray even though I bought one of the most expensive chrome looking paint. I know ...
8
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0answers
913 views

Role of pH in azo C-coupling reaction, continued

In the question, "What is the role of pH in azo coupling reaction of diazonium with phenol and aniline?" asked by @DhrubaBanerjee and answered by @Klaus-DieterWarzecha, I find several ends ...
8
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0answers
1k views

Why does reduction using sodium borohydride require a protic solvent?

Recently, I was looking at the chapter on chemoselectivity in Clayden et al.'s Organic Chemistry (2nd ed.). On p. 530, it is mentioned that sodium borohydride reduction only occurs in protic solvents ...
8
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0answers
428 views

Bond orders in the 3c-4e bond and 3c-2e bond

According to D. P. M. Mingos, in his book Essential Trends in Inorganic Chemistry, the bond order of the three-centre four-electron bond is approximately 0.717, which is one divided by the square root ...
8
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0answers
510 views

Why are lithium (Z)-enolates more stereoselective than (E)-enolates in aldol reactions?

In aldol reactions, it is apparently a general rule of thumb that (Z)-enolates give higher stereoselectivity (for the syn aldol product) than (E)-enolates do for the anti product. Quoting Carey & ...
8
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0answers
915 views

What is the fabric in heating mantles made of?

An ordinary lab heating mantle often has a white fabric coating for the flask compartment, which looks like an inorganic fiber: Image source I'm pretty sure that for some time in the past ...
8
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0answers
387 views

Sulfonyl azides: diazo or azide transfer?

Sulfonyl azides, $\ce{RSO2N3}$, are capable of acting as sources of electrophilic azide ("$\ce{N+3}$"), but are also capable of effecting diazo transfer, as shown in the scheme below, taken from ref 1:...
8
votes
1answer
591 views

How would you measure the rate of this SN1 reaction?

I am performing the following $\mathrm{S_N1}$ reaction: $$\ce{t-BuOH + HCl -> t-BuCl + H2O}$$ I would also like to measure the rate of this reaction, but I cannot seem to find a way. I initially ...
8
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0answers
8k views

At what temperature does charcoal burn?

According to an old Wikipedia revision, charcoal burns at temperatures as high as 2600 °C. Other sources which seem less reliable give a figure around 1000 °C. The Wikipedia article has since been ...
8
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0answers
189 views

Where is bifurcation situated on cyclohexane isomerisation PES?

I am wondering what does PES for cyclohexane isomerisation looks like. I have two possibilities in mind but each has some kind of vagueness. 1) Starting from boat conformation minimum, followed by ...
8
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0answers
2k views

What does Molecular Orbital Theory get wrong?

I am learning about MO theory in my advanced inorganic chemistry course and am starting to realize that it is truly the most accurate representation of how molecular orbitals look like, where they are ...
8
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0answers
336 views

Why do chlorinated silanes have lower boiling points than their methane analogs?

The boiling points of the chlorinated silanes and methanes are given below: $$\begin{array}{ccc} \hline \text{Species} & \text{Boiling point (X = Si) / }\mathrm{^\circ C} & \text{Boiling ...
8
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0answers
92 views

Stereoselectivity of 1,3-dipolar cycloadditions

How do the 1,3-dipolar cycloadditions follow the endo rule as in the reaction below, where the anti diastereoisomer is formed predominantly?
8
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0answers
193 views

New finding in cobalt compound that absorbs oxygen - is it really a breakthrough?

Very recently Chemical Sciences published results of the discovery of a new cobalt compound that can absorb oxygen at presumably a higher capacity than what has been achievable before. The paper is ...
8
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0answers
537 views

Identifying Alkyl Ligands as Pi Donors or Pi Acceptors in Transition Metal Complexes

Just wondering if there was a systematic way to identify an alkyl ligand as a $\pi$ acceptor or $\pi$ donor in a transition metal complex? Although various sources indicate that weak field ligands ...
8
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0answers
333 views

Grubbs, Wittig & hydroboration reactions and Woodward-Hoffmann rules

Several organic mechanisms I know involve [2+2] cycloadditions and retro-[2+2] cycloadditions, namely: The Wittig reaction Hydroboration of an alkene Olefin metathesis (using Grubbs' catalyst) How ...
8
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1answer
102 views

Will the sulfur-iodine cycle and Haber Method work at lower pressures and temperatures?

I have a year-long research project next year in my senior year of high school, in which we have to make some product or prototype to solve some issue. My interest was in the Liquid Fluoride ...
7
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0answers
91 views

Why do poisoned catalysts (Lindlar, nickel borate) result in partial hydrogenation of alkynes?

I read that alkene is more reactive than alkyne, so in hydrogenation of alkynes, it's difficult to isolate the alkenes. But with poisoned catalysts like Lindlar's catalyst or Nickel-Boron (Ni2B), they ...
7
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0answers
99 views

Changing the level of theory for organometallic compounds

I'm finishing my Ph.D. in Inorganic Chemistry and having a debate with my supervisor. The work in question have two organometallic compounds A and B. The structures are based on X-Ray Diffraction, so ...
7
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0answers
42 views

How does (E)CA glue ("super glue", "crazy glue", etc.) cure?

I use CA glue† very frequently in my shop, but I'm not entirely sure how it works. I've noticed three main modes of curing, I've emphasized the key observations: When dispensed, it will remain fluid ...
7
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0answers
81 views

Why does entropy increase in reactions that make more molecules?

I used to understand this (more molecules ⇒ more degrees of freedom), but do no longer, because the total number of atoms is conserved, so translational d.o.f. should just be turned into internal d.o....
7
votes
1answer
155 views

Is the correct zeroth-order wave function $\phi^{(0)}$ an eigenfunction of the perturbation Hamiltonian $H'$?

Consider the perturbation treatment of He $1s2s$ excited state configuration. The quantum mechanical Hamiltonian for the He-atom is: \begin{aligned} \hat{H} = \sum_{i=1}^2 h_i + \frac 1 {r_{1 2}} \\ ...
7
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0answers
74 views

Why does diethylmethylamine have such a low melting point?

According to PubChem, diethylmethylamine has a remarkably low melting point of $-196.0\ \mathrm{^\circ C}$. This is substantially lower than the melting points of dimethylethylamine ($-140.0\ \mathrm{^...
7
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0answers
143 views

Distilling milligram quantities of oil like it's late 1970s

In a currently retracted* manuscript by Tomas Hudlicky [1, Retraction Watch] the following has been noted: Fifty years ago professors took an active part in all laboratory instructions and they ...
7
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0answers
1k views

What are the limitations of the Born-Lande' equation?

The Born-Lande' equation is used to theoretically calculate the lattice energy, $\Delta U$, of ionic compounds. It is often cited as such in literature, $$\Delta U = -\frac{k_Az_1z_2Me^2}{4 \pi \...
7
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0answers
168 views

Relativistic contraction of orbitals

I am confused about what seems to me two very different explanations for the relativistic contraction of orbitals for heavy elements. My teacher told me that since 1s electrons in heavy elements ...
7
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0answers
370 views

Cloud-based molecular modeling software

I’m an IT Acquisitions and Licensing specialist researching well-supported cloud software alternatives to Fujitsu’s molecular modeling SCiGRESS. I am coming in with a tech background, but little to ...
7
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0answers
43 views

Identifying Name/Purpose of piece of ellipsoid glassware with internal tube?

I recently went to a market in Southern France and found this little piece of equipment for sale along with a whole bunch of other chemistry things. the guy had no idea what it was for or where he'd ...
7
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0answers
97 views

Additional example determining Marcus parameters searched

Background / theory: The electron transfer in organic materials was formalized by the Marcus theory, introducing $|H_{ab}|$ to describe the how molecules (or more generally: sites) are coupled with ...
7
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0answers
152 views

Is there a reliable chemical theory that predicts pKa based on structure?

Obviously, there are general stability arguments that can be made to estimate relative pKas, such as evaluating the stability of the conjugate base of an acid, or thinking about how polarized the bond ...
7
votes
0answers
752 views

About Smoke Grenades and Sugar Rockets

The most common formula for smoke grenades and sugar rocket fuel is $60\%\ \ce{KNO3}$ (potassium nitrate) and $40\%\ \ce{C12H22O11}$ (sugar). This is a 3:2 ratio, but I've also seen 2:1 and 5:3 with ...
7
votes
0answers
293 views

What is the hybridization state of the carbon atoms in [10]annulene?

I know that one of the more stable structures of [10]annulene or cyclodecapentaene is planar boat-shaped. But that means the hybridization state of the carbons must have changed to suit the geometry. ...
7
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0answers
221 views

The Action of Nitrogen Iodide on Methyl Ketones

I recently encountered two old publications on action of nitrogen iodide on various compounds (Ref.1 and Ref.2). Between them, Ref.1 described the idoform formation by methyl ketones upon treatment of ...
7
votes
0answers
80 views

Effect of spontaneous transmutation of atom in crystal

What happens to a compound when one of its atoms changes via spontaneous nuclear reaction to an atom with very different bonding? For example, beryllium-7 turns into lithium-7 with a half-life of 53 ...
7
votes
0answers
123 views

Is the 9H-fluoren-9-ylium cation aromatic?

In this cation, there are two individual benzene rings which are aromatic. But in the entire π system, there are 12 π-electrons which should make it antiromatic. Which is correct?
7
votes
0answers
139 views

Why does lithium aluminium hydride appear grey?

Commercial lithium aluminium hydride is a grey compound, which loses a lot of reactivity the darker it is. Luckily you can clean it up to get the reactive white compound and the separated grey ...
7
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0answers
287 views

Electron promotion in hybridisation: A misconception

Recently, I read through a short article on Nature Chemistry, written by Michelle Francl, titled "Talking to Pauling's ghost". The article talks about how electron promotion was never something that ...
7
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0answers
119 views

Does this cycle of reactions appear in nature?

Does anyone know a real-world example of a cycle exactly like this: or in other words, this: $$\begin{array}{ccc} \ce{A + C1 -> C2}\\ \ce{X + C2 -> C3}\\ \ce{C3 -> B + C4}\\ \ce{C4 -> Y +...

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