Questions tagged [reference-request]

This tag is for questions looking for a single specific, or a small number of (citable) references.

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39
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4answers
1k views

Do symmetric hydrogen bonds in neutral molecules exist?

As far as I know, there have only few truly symmetric hydrogen bonds been observed. Unquestionable is the existence of it in the bifluoride ion, $\ce{[F-H-F]-}$, see also here. There are a couple of ...
38
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3answers
2k views

Is Hexafluorocyclohexane the “Most Polar” Small Molecule?

Earlier this year, there was a lot of attention when all-cis 1,2,3,4,5,6-hexafluorocyclohexane was synthesized*: Notably, C&E News quoted the lead author: This compound is remarkable for being ...
32
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1answer
3k views

What would follow in the series sigma, pi and delta bonds?

I realise, that this question is a stretch, but I was wondering, how would a bonding orbital be called if it was formed from two $f_{x(x^2−3y^2)}$ or $f_{y(3x^2−y^2)}$ orbitals. Have there been any ...
30
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1answer
500 views

Imaginary Bonding Interactions

Usually in chemistry, we deal with bonding interactions. That is, if I have the diatomic A-A molecule or A-B molecule, there's a favorable interaction (i.e., a bond) and a prototypical MO diagram like ...
24
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1answer
2k views

Theoretical basis behind orbital correlation diagram for pericyclic reactions

When discussing pericyclic reactions, the Woodward-Hoffman rules allow one to predict whether a reaction will be thermally/photochemically allowed. This has been discussed in many questions on chem.SE,...
22
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2answers
4k views

Storing hydrofluoric acid before the invention of plastics

The first person to synthesize hydrofluoric acid in large quantities was Carl Wilhelm Scheele in 1771. This acid is known for its ability to corrode glass and metals. What materials were the ...
22
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3answers
711 views

What is the isomer distribution in monosubstituted fluorobullvalene?

Bullvalene (tricyclo[3.3.2.02,8]deca-3,6,9-triene) is a fluxional molecule able to interconvert any two carbon atoms through a series of degenerate Cope rearrangements (for more information, see the ...
22
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2answers
1k views

Which is the currently accepted mechanism of a Wittig reaction?

The Wittig reaction is one of the most significant advances in synthetic organic chemistry in the 20th century and rightfully won its discoverer, Georg Wittig, the Nobel Prize in Chemistry. A Wittig ...
22
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1answer
877 views

DFT Code for Atoms : Sources

Some time ago I implemented the restricted and unrestricted Hartree-Fock methods. I had a lot of fun and I learned a lot. It goes without saying that Szabo and Ostlund's book "Modern Quantum Chemistry"...
20
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1answer
520 views

What are modern approaches to describe and/or quantify aromaticity?

I know that Schleyer described an approach for evaluating aromaticity using nucleus-independent chemical shifts (NICS, see e.g. Chem. Rev. 2005, 105 (10), 3842–3888) quite some time back. I also ...
20
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1answer
3k views

What is the nature of the bonding in cyclotriphosphazene?

The bonding in $\ce{(NPCl2)3}$ (and other compounds of the form $\ce{(NPR2)3}$) has historically been described using the ‘Dewar island model’. By analogy to benzene, $\ce{(NPCl2)3}$ is π-electron ...
19
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5answers
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Where can I find a downloadable spreadsheet of element properties?

Sorry for the FAQ, but I really don't know where to find a full spreadsheet for element properties. I mean a table that has one row for each element, and the columns are its properties, such as name, ...
19
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3answers
2k views

Modern open-source tools for simulation of NMR spectra

I am interested in predicting the NMR spectrum of small organic compounds. It doesn't matter to me if the prediction is very accurate. I'll eventually be comparing the prediction to experimental ...
19
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3answers
532 views

Do modern dispersion-corrected DFT methods give more accurate molecular geometries?

I was discussing with a colleague the use of modern dispersion-corrected density functionals. I take it almost as a given that the methods generally produce "better" (for some definition) geometries, ...
19
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3answers
3k views

Conductivity as a function of acid concentration

I have conducted an experiment measuring the conductivity of both hydrochloric acid and sulfuric acid in solution respectively, with varying concentration. Wikipedia as well as a question on the site ...
19
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1answer
318 views

What did actually happen when Staudinger tried to synthesise diamond?

It is a famous reaction that used to be a teaching lab experiment, but is now banned in Germany, because it is too dangerous. To quote-translate quite liberally from the German www.seilnacht.com: ...
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5answers
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Which substance has the highest temperature range between melting and boiling point

Which substances exist that are normally liquid and that will not freeze nor boil even at relatively low/high temperatures as compared to the freezing and boiling points of water? Or how can I ...
18
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1answer
1k views

Is there any experimental evidence for OClF5?

On page 88 and 89 of this document, the author laments that $\ce{OClF5}$ has still not been discovered. He says it would be "just about the ultimate possible storable oxidizer" (for rockets). (Note: ...
17
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3answers
1k views

What is the formally correct notation of t-Bu, i-Pr, p-NO2, n-Bu, a-HCl, etc.?

In chemical notation, can I safely assume that the notation of a single lower-case latin character followed by a hyphen followed by an Element upper-case latin character (and possibly more characters)...
17
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2answers
3k views

What is the least dense liquid under normal conditions?

What is the least dense liquid under normal conditions, room temperature, one atmosphere of pressure, doesn't combust upon contact with air, also wouldn't kill a human just for being in the same room ...
16
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2answers
73k views

EZ-Water - Fraud or breakthrough?

Recently the quack medicine folks online have been promoting the research of a certain Dr. Gerald Pollack who claims to have discovered a "forth phase of water", and who has recently published a book ...
16
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1answer
1k views

How can benzaldehyde have a pKa of 14.9?

There are numerous websites out there which claim that the pKa of benzaldehyde – C6H5CHO – is 14.90. (Just do a Google search for benzaldehyde pka to see what I ...
16
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0answers
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f-electrons in chemistry of heavy transition metals

In one lecture on recent MCR-X conference I was puzzled by a side-note "f-hole is critical to describe DoS of $\ce{IrO2}$ correctly." The context was DFT periodic plane-wave calculations with ...
14
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2answers
447 views

Serious introduction to the chemistry of explosives recommendation

I'm looking for a serious introduction to the chemistry (and perhaps to a lesser extend the physics) of explosives. Presupposition of basic university courses in Organic Chemistry and Thermodynamics ...
13
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2answers
2k views

Melting point of aspirin, contradicting sources

Querying wolfram alpha for the melting point of aspirin (link) returns $\pu{140 °C}$. The Wikipedia page for Aspirin lists $\pu{136 °C}$ instead, citing this book. How am I supposed to know which ...
13
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2answers
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Is there an iron–iron bond in diiron nonacarbonyl?

Diiron nonacarbonyl, $\ce{[Fe2(CO)9]}$, is often depicted with an Fe–Fe bond as shown at the left-hand side: The Fe—Fe bond is usually invoked in order to (1) explain the observed diamagnetism and (2)...
13
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2answers
2k views

What is “chemical pressure”?

While reading some publications on solid superconductors, I encountered a term "chemical pressure" a few times, which is usually attributed to the changes of superconducting transition ...
13
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3answers
449 views

Concise description of primary organic reaction types mechanisms

Long story short, I'm mostly doing calculations in the past 5 years of my scientific carrier and every year I get less and less confident in my knowledge of organic chemistry which besides was never ...
13
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2answers
171 views

What function is used to graph the potential curve of two hydrogens with parallel spins?

TL; DR I am asking for an analytic potential curve function for the triplet state of $\ce{H2}$ (preferred) with experimental parameters, or experimental data (enough points to realise a smooth-...
13
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1answer
776 views

Why does bond length decrease with increased basis set quality for SCF methods?

From Reviews in Computational Chemistry Vol. 5, for $\ce{H2O}$ using HF, MP2, CCSD, and CCSD(T), all lengths in angstroms: $$ \small \begin{array}{rcccc} \text{Basis} & \text{HF} & \text{MP2}...
12
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3answers
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Does milk drinking prevent long-term chemical poisoning?

I have heard some rumors that drinking milk prevents chemical poisoning. I have done a bit research and some sources confirm that. Corrosive Poisons The best first aid is to dilute the poison as ...
12
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2answers
343 views

Proper dash to use for negative charge

What type of dash does one use when indicating something like F$^{-}$? I assumed it was a minus, since you indicate positive charge with a +, but there is one professor I know who insists that it ...
12
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4answers
2k views

Public API for physical properties

Is there a publicly available API that serves physical property data for organic molecules? Pubchem does not serve properties, ChemSpider closes property access to API calls, and Toxnet only serves ...
12
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1answer
304 views

What is the structure of trifluoromethanesulfonic acid in the gas phase?

During an interesting discussion in our group’s seminar, the question arose what actually causes trifluoroacetic acid to be a much better nucleophile than trifluoromethanesulfonic acid. Part of the ...
12
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1answer
870 views

Introductory chemistry book with calculus prerequisite

I understand that the policy here is that book requests are allowed, as long there is an effort to narrow it down. This question is similar to Can someone recommend me a book ( preferably written long ...
11
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3answers
1k views

List of functional groups in a molecule

Does anyone know if there's a tool for listing the functional groups present in a molecule?
11
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1answer
669 views

What are the most extreme chemicals?

Some chemicals certainly have extraordinary properties. One can consider them extreme in a sense, that they are the prime example for a concept, or they achieve the highest or lowest values in a ...
11
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1answer
973 views

Is Linus Pauling's General Chemistry still readable and up-to-date today?

I've found a Dover edition copy of Pauling's General Chemistry in the bookstore near me. I'd like to know if it's still readable today, I mean, is it still up-to-date? I have no background in ...
11
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1answer
194 views

Models for diastereoselectivity in nitronate additions

In the scheme below (taken from the referenced Chem. Eur. J. paper on the synthesis of Tamiflu), there is a step in which a nitronate anion (the anion derived from 5) is added into an electrophile 6, ...
11
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1answer
4k views

Why is electronegativity increasing with oxidation state increase?

I may be a rudimentary fact or something really "not-that-hard-to-figure-out", but In inorganic chemistry it is common to consider a single value of the electronegativity to be valid for most "...
11
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1answer
1k views

Does sulfoxide H₂SO exist?

The question Does H2SO or H2CO have a higher dipole moment? left me wondering whether $\ce{H2SO}$ has already been synthesized. There are experimental evidences that both hydrogen thioperoxide $\ce{...
11
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3answers
523 views

Free chemical database to search for physical properties?

I am looking for an Open-access tool that can search "backwards", eg. give me all the structures corresponding to a given heat of formation, critical pressure, etc. It would be even better if the ...
11
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1answer
256 views

Which electronic effects are responsible for the reduction of nucleophilicity of a hydroxy group orthogonal to an ester?

I am facing a similar synthetic problem as Boekman Jr. et al noted in their synthesis of Tetronolide.[1] I will quote their’s rather than disclosing my actual synthetic problem, but note that the key ...
11
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1answer
379 views

Database for molecular dipole transition moments?

I'm looking for the dipole transition matrix elements for electronic transitions between the ground and excited states of the carbon dioxide cation, $\text{CO}_2^+$, that is, objects like $$\langle\...
11
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1answer
238 views

Possibility of π–π stacking in non-aromatic systems

Is it possible to have π–π stacking for non-conjugated double bond systems? For example, can the carbonyl groups of two urea molecules participate in π–π stacking? Although urea prefers to stay in ...
10
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2answers
292 views

Data repository of organic compounds

Does there exist any data repository of chemical compound that gives the structure of the compounds with the help of coordinate geometry. It would be like each atom has a coordinate and the list of ...
10
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1answer
1k views

What substance has the lowest solubility product?

What substance has the lowest $K_\mathrm{sp}$ and what is its value? The lowest I could find is $2.6\cdot 10^{-124}$ for cobalt(III) sulfide $\ce{Co2S3}$.
10
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1answer
422 views

What general uses do beta-lactam functional groups have?

I am currently working on a mechanistic study that deals with stereoselective $\beta$-lactam formation. I am well aware that there is a class of antibiotics, that involve this particular functional ...
10
votes
1answer
437 views

Is isobutyl chloride or ethyl chloride more reactive in an SN1 reaction?

Compare the rate of $\mathrm{S_N1}$ reaction in the following compounds: We see that both compounds form primary carbocations. However, there is more hyperconjugation in the second compound as ...
10
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1answer
213 views

Finding large databases of sphere packings

Part of my research is investigating sphere packings and their properties.I really would like a large database of sphere packings that I could investigate using a program I have written that tells me ...

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