Jannis Andreska
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Hardness and softness are terms used to describe which aspect of acidic behaviour?
24 votes

The terms softness and hardness are used in HSAB theory to distinguish Lewis acids and bases by charge density, polarizability, electronegativity, and, in the case of molecular compounds, HOMO and ...

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HI/P reduction mechanism
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23 votes

According to the source mentioned in the comments to your question, the first step is indeed nucleophilic substitution of the OH group by $\ce{I-}$, faciliated by protonation of the alcohol. For the ...

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Difference in the functioning of alkaline and acidified KMnO4
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15 votes

Permanganate as oxidizing agent works most efficiently in acidic solution, because it is reduced to the greatest extent in this medium, from oxidation state +VII in $\ce{MnO4-}$ to +II in $\ce{Mn^2+}$....

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Mercury assisted deprotection of dithiane
12 votes

$\ce{Hg^2+}$ has a high affintity to thiols and other sulfur functional groups, and therefore $\ce{HgCl2}$ forms a Lewis acid-base adduct with the dithiane. The cyclic sulfonium cation undergoes ring ...

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Are all amides also amines?
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12 votes

An R group is used in structural formulae as a placeholder for a range of possible subtituents, e.g. hydrogen, alkyl chains or aryl groups etc. It can also be used as an abbreviation when R is a ...

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Why does phosphoric acid mask the colour of iron(III) complex in water?
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11 votes

When phosphoric acid is added to an aqueous solution of iron (III), the ligands in the yellow complexes $\ce{[Fe(OH)(H2O)5]^2+}$ and $\ce{[Fe(OH)2(H2O)4]+}$ ( $\ce{[Fe(H2O)6]^3+}$ are weakly colored ...

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Synthetic route for the conversion of ethanol to but-1-yne
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11 votes

The first reaction is the conversion of the alcohol to an alkyl chloride using thionyl chloride. The mechanism of the reaction starts with nucleophilic attack of the alcohol oxygen on sulphur, ...

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How do you determine a chemical formula given the molecule's crystal structure?
11 votes

Knowledge of the crystal structure implies that you are also able to describe the unit cell of the compound. To determine its formula, count all sorts of atoms inside the unit cell, also considering ...

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Where is the acid in DNA/RNA?
10 votes

The phosphate ester groups which connect the nucleotides contain one acidic proton at their OH group, and two at the end of each strand. As you can see here, here and in the picture below (with the ...

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Condition For NaHCO3 to react to form CO2 with organic acids
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10 votes

$\ce{NaHCO3}$ is the basic sodium salt of carbonic acid, a diprotic acid which exists only in small amounts in aqueous solution, because the equilibrium $$\ce{CO2 + H2O <=> H2CO3}$$ lies ...

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How to identify an emerald green solution with possibly two anions?
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9 votes

You can have two different anions if your solution is a mixture of two different metal salts, a chloride and a sulfate. The color change from green to blue upon dilution with water fits well with $\ce{...

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2-methylpropene to tert-butyl alcohol Reaction Mechanism
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7 votes

It is an acid-catalyzed hydration of the double bond. First, the double bond is protonated to yield the tert-butyl cation which is most stabilized by hyperconjugation (protonation at C2 would form a ...

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Reaction of perchloric acid with cyclopropenol
7 votes

The first step is indeed 1,2-addition of the Grignard reagent to the keto group, and product A is the alcohol: Treatment of the alcohol with the strong acid $\ce{HClO4}$ cannot yield the usual ...

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Meaning of "mono-N-demethylation"
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7 votes

Mono-N-demethylation means the removal of a single (mono) methyl group from a nitrogen(N)-containing functional group. For example, a reaction which transforms the alkylated amine group $\ce{-NHCH3}$ ...

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Semipinacol-type rearrangement leading to ring expansion
7 votes

Three-membered rings are not exceptionally stable, on the contrary, they suffer a lot of ring strain and readily take part in ring-opening reactions. Exceptions include the Hückel-aromatic ...

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What is the correct Lewis structure of diazomethane?
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7 votes

The image above depicts three mesomeric structures of diazomethane ($\ce{CH2N2}$). When you count the valence electrons for every atom, you will find that only the left and middle structure satisfy ...

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The Acidity of the Hydrated Iron (III) Ion
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7 votes

When a water molecule coordinates to $\ce{Fe^3+}$, one non-bonded $sp^3$ hybrid orbital (with one of the 2 lone pairs) of oxygen overlaps with an empty $d$ or $p$ orbital of $\ce{Fe^3+}$. Electron ...

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What's the difference between graphite, nanotubes, and fullerenes?
7 votes

All three carbon modifications indeed contain covalently bond carbon atoms. The $sp^2$-hybridized C atoms are connected by $\sigma$ and delocalized $\pi$ bonds in all cases. It is the geometric ...

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What's the mechanism of the reaction of (E)-methyl 3-(furan-2-yl)acrylate in acidic methanol?
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6 votes

As Uncle Al already pointed out, the mechanism starts with protonation of the ester carbonyl oxygen. This yields a resonance-stabilized cation whose charge can be delocalized into the furan ring, ...

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What type of intermolecular forces will dominate Diethyl ether?
6 votes

As you have already figured out, diethyl ether is a small dipole due to the electronegativity difference between carbon and oxygen, which can also be seen in this electron density plot. As both dipole ...

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Why do they use graphite electrodes in the Hall–Héroult process?
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6 votes

According to this source, graphite is used as anode material because carbon is easier to oxidize than $\ce{O^2-}$. The anodic oxidation of carbon $$\ce{C + 2O^2- \rightarrow CO2 + 4e-}$$ proceeds ...

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Why Fe(CO)5 exists, but Fe(NH3)5 doesn't?
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6 votes

While we cannot be sure that $\ce{Fe(NH3)5}$ does not exist, the bonding between ligand and metal offers a good explanation for why it is expected to be less stable than $\ce{Fe(CO)5}$. In metal ...

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Boron trihalides acidity
5 votes

The following order is experimentally found: $$\ce{BF3}<\ce{BCl3}<\ce{BBr3}<\ce{BI3}$$ This stands in contrast to what is expected when the electronegativity of the halides is considered. A ...

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Convert benzene to isopropylbenzene
5 votes

You are right, both abstracting $\ce{Cl-}$ from the alkyl chloride with Lewis acid as well as dehydration of isopropanol with $\ce{H2SO4}$ are suitable ways to generate the 2-propyl carbocation, your ...

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Reactions of tin (IV) iodide with potassium iodide and water
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5 votes

If iodide is oxidized to iodine (the cause of the yellow color), then something needs to be reduced in turn. Potassium is already in its most stable oxidation state (+I), so tin will be reduced, from $...

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What is the purpose of ammonium chloride in anti hydrogenation of alkynes?
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5 votes

Products from reaction step (1) are the trans-alkene and 2 equivalents of the amide $\ce{LiNHEt}$, a strong base. Step (2) is the workup of the reaction mixture with aqueous $\ce{NH4Cl}$ solution, ...

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Can you synthesize phenol from salicyladehyde?
5 votes

It is possible to convert salicylaldehyde into phenol in a two-step process. Firstly, salicylaldehyde is oxidized to salicylic acid with a standard reagent like $\ce{KMnO4}$ (see the answers to this ...

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Formation of carbonic acid from breath?
5 votes

It is possible that carbonic acid will form; however, only in small amounts because the equilibrium of the hydration of $\ce{CO2}$ to $\ce{H2CO3}$ lies mainly on the educt side. As more $\ce{CO2}$ is ...

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What is the oxidation number of the oxygen in BaO2
5 votes

"oxygen always -2 except in peroxides" This exception is in effect here, because $\ce{BaO2}$ is a peroxide consisting of $\ce{Ba^{2+}}$ and $\ce{O2^{2-}}$ ions. The oxidation number of Ba is +II, and ...

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Can we prepare aryl halides by heating with halogen acids?
5 votes

The partial double bond character of the C-O bond in phenol becomes obvious from the resonance structures. Contributions from the structures with $\ce{C=O}$ double bond explain why the character of ...

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