14
votes
Accepted
Do quaternary sulfur dications exist?
Ogawa et al. [1] were first to report a crystal structure (CSD-YAFNOI) of a compound with quaternary sulfur, bis(2,2′-biphenylylene)sulfurane:
Figure 1. Molecular structure of bis(2,2'-biphenylene)...
- 38.5k
10
votes
How to remove stain from pavement after having dropped sulfuric acid on it?
You did the right thing by neutralizing with a base.
The best solution is to let time heal the stain. The surface is obviously damaged, but there is no way to reverse that damage. The stain will only ...
- 42.6k
10
votes
Why are peroxides unstable but disulfide bridges considered stable? Why are esters stable but thiolesters are unstable?
Some hard data: bond enthalpies (in $\pu{kJ mol-1}$)
$$\begin{array}{c|c|c|c} \text{Bond} & \text{Enthalpy} &
\text{Bond} & \text{Enthalpy} \\ \hline
\ce{C-C} & 350 & \ce{Si-...
- 21.9k
8
votes
Accepted
which is more acidic thiols or carboxylic acid?
Some $pK_a$ values:
$\ce{H3C–SH}$: 10.4
$\ce{H3C–C(O)–OH}$: 4.8
This comparison clearly indicates that the carboxylic acid group imparts stronger acidity than the thiol group.
The determinimg factor ...
- 62.6k
7
votes
Accepted
Why do DMSO and acetone have such radically different melting temperatures?
The first thing to remember is that boiling and melting points, while seemingly simple, are incredibly hard to predict. Yes, many teachers and professors give their pupils and students a number of ...
- 68.7k
6
votes
Toluenesulfonate vs. methylsulfonate
From the point of atom efficiency, methylsulfonate is advantageous compared to the p-toluenesulfonate.
On the reagent itself, the methanesulfonate is more polar than the p-TsOH; so the later ...
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6
votes
Accepted
Retrosynthesis of (2E)-1-(2,4-dimethylphenyl)-3-(thiophen-2-yl)prop-2-en-1-one
There are several approaches to this molecule, but I think the key disconnection is the E-double bond. This looks like it can be formed by a Horner-Emmons-Wadsworth reaction between the widely ...
- 23k
6
votes
Accepted
Identify the more acidic hydrogen in 1-(methylsulfanyl)propane-2-thione
The +M effect is as you describe if it is there. But it can come only through sulfur taking up a positive formal charge, which is most favored when you have a cation to begin with. Here you have an ...
- 62.6k
5
votes
Thiol prefixes for nomenclature
Mercapto- and sulfanyl- are both prefixes for use with the $\ce{-SH}$ group (known as a thiol), while thio- is used to denote the "sulfur" equivalent of an oxygen-containing functional group.
More ...
- 979
5
votes
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Attack on cyclic intermediate during NGP
Inductive reasoning in organic chemistry can be somewhat hard at times, given all of the exceptions that can pop up, for example the SN2-like mechanism of opening an epoxide in basic conditions versus ...
- 86
5
votes
Why do tosylation and mesylation of alcohols follow different mechanisms?
The only real difference between an alkanesulfonyl chlorides and arylsulfonyl chlorides is the $\alpha$-hydrogen. In a mechanistic study of the hydrolysis of methanesulfonyl chloride, the reaction was ...
- 24.1k
5
votes
Accepted
Mechanism of Grignard reaction with 2-(thiiran-2-yl)oxirane
Sulfur attacking the less-hindered end of the epoxide would generate a [4] ring. This is more strained than a [3] ring and thus energetically less favourable. The attack is reversible, so the more ...
- 23k
5
votes
Does sulfuric acid in snow damage fabric?
That is a wrong question.
A better question would be:
"Does snow contain enough sulfuric acid to be concerned about it?"
And the answer would be:
"No, it does not, unless you live near ...
- 45.1k
4
votes
Accepted
Removing sulfur in Barton-Kellogg reaction without triphenylphosphine
After contacting the authors of the paper, one author, Prof. Wezenberg said that a conclusive mechanism is not yet available for this case but he believes that the unstable episulfide undergoes ...
- 531
4
votes
Accepted
Can thiols be created using a Grignard reagent?
I've done this with aromatic Grignards, but I have no reference and no database access any longer.
I think when I did it, I was relying on an older colleague's instructions. It was pretty much ...
- 23k
4
votes
Difference between tendency of benzene and thiophene to undergo sulfonation
In the chapter Aromatic five-membered ring heterocycles with one heteroatom in Organic Chemistry by J. William Suggs (2002) the following explanation can be found (pp. 403-404) which summarizes the ...
- 4,402
4
votes
Accepted
Why does acidity increase going from sulfide to sulfoxide to sulfone?
The oxidation state of sulphur and its therefore increased inductive effect should be enough to explain this effect.
Besides the number of oxygens, the principle difference between the three ...
- 68.7k
4
votes
Absolute configuration of sulfur in phenyl styryl sulfoxide
Phenyl gets the second highest priority. To break the tie, check the level of substitution at the carbon bonded to sulfur. Duplicate the doubly bonded carbon. Hence in phenyl it is bonded to three ...
4
votes
What is the density of sodium trimethylsilylpropanesulfonate (DSS)?
The reported crystallographic density for sodium 3-(trimethylsilyl)-1-propane-sulfonic acid monohydrate is $\pu{1.32 g cm^-3}$ [1].
The title compound which is used as reference for some NMR spectra ...
- 38.5k
3
votes
Accepted
A question about thiamine
Thiamine (Vitamin B1) has a positive charge on the nitrogen of thiazole ring, because that nitrogen is tetravalent. Thus, it should be neutralized by a counter ion. Usually, the counter ion is ...
- 42.1k
3
votes
Does cinnabar react with iodine?
I did a cursory search and found some information particularly from books of late 19th century(1,2):
Cinnabar and iodine
On heating, it (cinnabar) is readily decomposed with formation of small ...
- 26.8k
3
votes
Accepted
At what acid concentration does potassium metabisulfite react?
Potassium metabisulfite ($\ce{K2S2O5}$) is a white crystalline powder, which also known as potassium pyrosulfite. It is mainly used as an antiseptic for winemaking, process engraving, and as a source ...
- 42.1k
3
votes
Is there a single or double bond between S and O in propanethial S-oxide?
The $\ce{S-O}$ bond in sulfoxides is best considered as a single covalent bond with positive charge on $\ce{S}$ and negative on oxygen. The oxygen is significantly nucleophilic (see for example the ...
- 23k
3
votes
Mechanism of Grignard reaction with 2-(thiiran-2-yl)oxirane
One other aspect is after the initial opening of the sulfur-bearing ring, the sulfur ends up closer to the bridgehead carbon than to any other part of the oxirane ring. (You can see this in a ...
- 62.6k
3
votes
Detection of Nitrogen and Sulfur in Lassaigne's Test
Please note that nobody uses Lassaigne's test of the 18th century to test $\ce{S}$, $\ce{N}$ and halogens in organic compounds. It is unsafe and really obsolete method of qualitative analysis. I know ...
- 42.6k
3
votes
Accepted
Why doesn’t the reaction between 3-mercaptopropionic acid and methyl iodide yield a methyl ester?
You don't really have an alcohol. With the carbonyl group also there you have a carboxylic acid instead. The combination of a carbonyl group directly bonded to hydroxyl is in fact considered a ...
- 62.6k
2
votes
Release of sulfur dioxide from odored fuel gases
According to this North American Energy standards board publication , the total concentration of sulfur in natural gas, both natural and from oderant additives, must not exceed $\pu{70 ppbv}$. ...
- 17.7k
2
votes
Accepted
Why might PM2.5 concentration increase or stay the same when SO2 is reduced?
Your research is correct: increasing $\ce{SO2}$ concentration increases $\mathrm{PM_{2.5}}$ concentration. Gaseous $\ce{SO2}$ is photochemically oxidized to $\ce{SO3}$ which becomes sulfuric acid on ...
- 17.7k
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