20

The function of pyridine is actually not so simple and not so easy to notice at first glance. There is a fundamental reason why pyridine is used to promote the acylation reaction, which is that it can act as a catalyst. Despite its basicity and the subsequent formation of its chlorhydrate salt after the tosylation reaction, pyridine is also an excellent ...


15

Well, sulfur in general, and thiolates in particular, are known for bonding very strongly to gold, lead and mercury. In the particular case of mercury, which was known very early in the history of chemistry (indeed since the times of alchemy), this is the reason thiols are often called "mercaptans", from the Latin mercurium captans (capturing mercury). In ...


11

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)sulfurane (CSD-YAFNOI). Color code: $\color{#EEEEEE}{\Large\bullet}~\ce{H}$; $\color{#909090}{\Large\bullet}~\ce{C}$; $\color{#FFFF30}{\Large\bullet}~\ce{S}$. ...


10

According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), the trigonal pyramidal centre of the sulfinate group is converted to a tetrahedral centre using a phantom atom of low priority. P-93.3.3.2 Trigonal pyramid The configuration of molecules containing a trigonal pyramidal center (...


10

Here is the reaction scheme for the Mozingo reaction (or Mozingo reduction) taken from this Wikipedia link. The reduction works for both aldehydes and ketones and involves two steps. First, the carbonyl compound is converted into a thioketal (or thioacetal). The mechanism for this step is analogous to the mechanism for ketal or acetal formation (see here) ...


10

In the presence of $\ce{AgBF4}$, diphenylsulfide is alkylated to 3-chloropropyl diphenylsulfonium tetrafluoroborate. The sulfonium salt is stable and can be isolated as a crystalline product. This sufonium salt can be deprotonated (e.g. with $\ce{NaH}$ in $\ce{THF}$) to the corresponding sulfonium ylide. In the latter, intramolecular displacement of $\ce{...


10

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-Si} & 226\\ \ce{N-N} & 163 & \ce{P-P} & 201\\ \ce{O-O} & 146 & \ce{S-S} & 226\\ \ce{F-F} & 155 & \ce{Cl-Cl} & 240 \\ \...


9

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 go away if someone keeps on scrubbing the area until a new surface is exposed. The good news is that dirt, soil, and water will slowly remove and even scrub ...


8

There are many complexes of d-elements, that can reversibly lose/gain one electron, changing their color in process. They are known as Redox Indicators. Some of them are stable enough to be used in vivo.


7

Has the structure of trifluoromethanesulfonic acid or a structurally strongly related acid been studied in the gas phase? (Please provide a reference) Yes. See Gas Phase Structure of Methyl Trifluoromethanesulfonate, CH3OSO2CF3, and Conformational Properties of Covalent Sulfonates Inorg. Chem., 1999, 38 (13), pp 3051–3055 and references cited therein, ...


6

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 dissolves better in less polar organic solvents than the former. Methanesulfonate even may be used to dissolve some metal salts. If used to generate a better leaving ...


5

As Ben Norris already pointed out, these processes are typical a bit complex. It is however conceivable that the direct oxidation of the thioether 1 is among the first steps involved. While the oxidative cleavage of PMB (= 4-methoxybenzyl) ethers, often applied as protecting groups, is assumed to take place in the methoxy-substituted arene, here the ...


5

Electrochemistry; using microelectrodes. So, basically, place one microelectrode inside the cell, and another (the reference electrode) just outside the cell, and then use a potentiostat to measure the potential between them. Reference.


5

Is a dithioic acid. For example, a benzene with two -CSSH hubstituents in 1, 2 positions is a benzene-1,2-dicarbodithioic acid.


5

When undergoing an SN rxn, does the other atom to which the nucleophile is ionically bonded matter? It can matter. If the counterion shifts the covalent-ionic nature of the bond connecting it to the nucleophile, then the nucleophilicity of the nucleophile can change (increase or decrease). However in your example, the counterions don't make a ...


4

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 desulfurization by itself under reflux.


4

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 simple prediction rules, but there is a lot of intrinsic balance and experience associated with applying them that they may often seem unintuitive. Comparing DMSO ...


4

Why would one want to replace it? The choice of ethanethiol is a reasonable compromise between its toxicity and the extremely low detection limit around 1 ppb (1mg/1000 kg).


4

As discussed above, the pathway shown on the left is incorrect because it essentially shows insertion into a $\ce{C-H}$ bond by an anion with loss of $\ce{X^-}$, which is not the easiest path for this reaction to take by a long shot. The actual mechanism for this reaction is as shown below. First, the non-halogenated alpha-carbon is deprotonated. The ...


4

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 found to have a very small secondary kinetic isotope effect for $\mathrm{pH}<6.7$, indicating no bond breakage to the isotopically labelled hydrogen and ...


4

In asking this question - Why do chalcogens (Group VI) stink so badly? - I received a couple answers and comments along the lines of "it's not quite so simple". The same would generally apply here; there isn't one change in behavior, or even a finite set of behavioral changes, that could be predicted by an oxygen-to-sulfur exchange. Just as a basic example, ...


4

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 thoughts already pointed out in the comments: The resonance stabilization energy of benzene is greater than that of these heteroaromatic compounds. The ...


4

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 details from the IUPAC Blue Book: Mercapto- is mostly abandoned, and only used as a prefix for -SH groups. This quote is from the older edition of the Blue Book. ...


4

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 the acidic conditions. For the epoxide opening in base; as you know sterics wins, and in acid the stability of the reactive transition state is our reasoning ...


3

The byproduct of the reaction is hydrochloric acid, and with pyridine forms the water soluble pyridinium chloride, which is readily removed in work-up. Other preparations might use triethylamine instead of pyridine.


3

To get started, here are the structures of some compounds that are relevant. Thiamine Sulbutiamine Allithiamine Looking at these structures we see that you are of course correct, sulbutiamine does not contain a 5-membered thiazole ring like thiamine. Thiamine (vitamin B1) was an early focus of interest because sailors at sea for long periods of time ...


3

You could react 4-(methylthio)benzaldehyde with $\ce{HBr}$ to form a thiol, and then react the thiol with acetyl chloride in triethylamine to form 4-(thioacetate)benzaldehyde.


3

What actually happens in sulfur-gold bonding is not very well known. There have been many proposals and studies done, well-summarized here. There is some evidence, including computational studies, that suggest that dissociation into two thiolates is energetically favourable. Bridging across protruding bits of gold (we often draw gold surfaces as straight ...


3

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 structures is the oxidation state of sulphur that rises from $\mathrm{-II}$ to $\pm0$ to $\mathrm{+II}$. The higher an element’s oxidation state, the stronger it draws ...


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