16 votes

When 2-pentene reacts with HBr, what will be the major product?

This sort of reaction isn't investigated seriously anymore. But 80 years ago, Kharasch et al. (J. Am. Chem. Soc. 1939, 61 (6), 1559–1564) wrote that Both results agreed within the limit of error (3%...
  • 69.5k
9 votes
Accepted

Why hydrogen bonding in some acids make them a stronger acid when it is present even before deprotonation?

Some of the conformers of salicylic acid are given below, all of which are planar in configuration.$\mathrm{^{[1]}}$ Although the compound can adopt several conformations the first conformer(in the ...
  • 447
9 votes
Accepted

Acidic strength of nitrophenols

I have recently answer a question about some $\mathrm{p}K_\mathrm{a}$ value discrepancies on different hydroxytetralone derivatives. As Oscar Lanzi pointed out in his answer that the major reason why ...
7 votes

Why don't we consider the attached hydrogens in inductive effect?

I will show you how I understand this effect. I like to think that partial positive charge on $\ce{C1}$ attracts the electrons from $\ce{C2}$ because of the electrostatic force. With this model your ...
  • 477
7 votes

Acidic strength of nitrophenols

There may be hydrogen bonding between the hydroxyl hydrogen and a nitro group oxygen in the ortho isomer, which would stabilize the proton. But 0.09 $\pu{pK_a}$ unit could be within experimental error....
  • 46.7k
6 votes
Accepted

How do steric effects affect inductive effect in compounds with tetravalent nitrogen?

Since you are asking for a theoretical explanation, I believe a theoretical calculation might be helpful. It is possible to calculate the partial charges on atoms using electronic structure programs. ...
  • 5,507
6 votes

Why hydrogen bonding in some acids make them a stronger acid when it is present even before deprotonation?

The other answer has given the major conformer of the protonated form of the o-hydroxybenzoic acid, but I believe there is a part of your question that still remains to be answered. You asked why the ...
  • 5,507
5 votes

When 2-pentene reacts with HBr, what will be the major product?

Your argument of inductive effect and hyperconjugation, made me to tell you a story about theory behind these two effects. I think after reading that you may able to understand how far we have come ...
4 votes

Inductive effect of hydrogen isotopes

A $\ce{C-D}$ bond has a shorter distance, thus can be in a more favorable position to donate electron density towards an electron deficient center. The $\ce{D}$ has a greater mass, and would show a ...
4 votes
Accepted

Effect of phenyl and vinyl substituents on Acidity of carboxylic

When the cases of carboxilic acids are considered, we must note that the conjugation of $\ce{COO-}$ group is so strong in itself, that it's conjugation with the rest of the compound is rendered ...
4 votes
Accepted

Confusion in comparing the contribution of resonating structures to resonance hybrid

For $b$, you have equivalent resonating structures as the structures are identical. The structures $a'$ and $b'$ are not correct as nitrogen cannot expand it's octet. For $a''$ and $b''$, the first ...
  • 1,221
4 votes
Accepted

Effect of distance on the mesomeric effect

According to the IUPAC goldbook, the definition of the mesomeric effect is as follows, The effect (on reaction rates, ionization equilibria, etc.) attributed to a substituent due to overlap of its p- ...
4 votes
Accepted

Why is ethanol more acidic than acetone?

Taking the data from this answer by ron, the equilibrium constant for the keto-enol tautomerism seen in acetone is $$K_\mathrm{eq} = \frac{\text{[enol]}}{\text{[carbonyl]}}$$ $$ \begin{array}{lc} \...
4 votes

Why is the inductive effect possible?

That's an interesting reasoning you give here. The point is, the inductive effect is not the major factor explaining the acidity of a compound. Electronegativity will give insights on the position of ...
4 votes

Acidic strength order among hydroxytetralones

Let's look at some experimental $\mathrm{p}K_\mathrm{a}$ values of known hydroxytetralones and related compounds (Ref.1): $$ \begin{array}{l|c|c|r} \text{Entry} & \text{Compound} & \text{Ionic ...
3 votes
Accepted

What does acidity of para-alkyl substituted phenols depend on?

The reason provided by ML cannot explain the difference in acidities since the +I effect doesn't come into play normally for the para positions. A more likely reason is hyperconjugation (or no bond ...
3 votes

Does Cl- Have more -I effect or +M effect ( Resonance effect)?

Chloro group is considered a deactivating group according to Hammett plots of each possible reaction. The $\sigma_\mathrm{para}$ of $\ce{Cl}$-substituent is listed as $+0.227$ while $\sigma_\mathrm{...
3 votes

What is the stability order of the carbocation and carboanion?

Alkanes or $\mathrm{sp^3}$ hybridized carbons show +I effect. Alkenes contain $\mathrm{sp^2}$ hybridized carbons. Due to greater $\mathrm{s}$ character they have higher electron withdrawing tendency....
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3 votes

Which of the two structures is more stable?

The explanation can[1] be given by analysing their respective resonance[2] structures which is as follows: (Credits: ChemWriter) Now, inductive effects would work. In case of first (c's resonance),...
  • 2,975
3 votes

Stability of meta ethyl and meta methyl benzene carbocations respectively

We know that effect of neither hyperconjugation nor resonance is observed if the groups are attached in meta position. Hence, stability of structures I and IV will be decided on the basis of inductive ...
3 votes
Accepted

Effect of electron-donating and electron-withdrawing groups on the C=O bond

This is easiest to see when a mesomerically electron-donating group is attached to the carbonyl, as in the case of carboxylate: The O atom attached to the carbonyl donates a lone pair of electrons ...
  • 352
3 votes

Is NH2 electron donating or electron withdrawing?

You did not specify it in your question, but this topic is usually taught in the context of electrophilic aromatic substitution reactions, and I will use them as an example. Let's say you go to the ...
  • 125
2 votes

Which Carbocation is most stable among the three?

You are correct as resonance is most powerful factor for stabilisation of carbonation So C is most stable and after that due to hyperconjugation B would be more stable than A. Order for governing ...
  • 1,633
2 votes

Comparing relative negative inductive effect of substituents (dialkyl amine, amine, alkoxide, fluoride)

The inductive effect is the polarization of σ (sigma) bonds within a chemical species caused usually by differences in electronegativity between the neighboring atoms. The higher the polarization it ...
  • 1,311
2 votes

Odd looking carbocation stability order

How to decide whether +M effect or -I effect will operate in this case? The extent of stabilizing effect follows the order: $\ce{\text{Mesomeric} > \text{Hyperconjugation} > \text{Inductive}}$. ...
  • 2,975
2 votes

Change in inductive effect of a susbstituent when -R group replaces -H atom

There are several examples where the negative inductive effect of a substituent gets increased when a hydrogen atom on that substituent is replaced by an alkyl group. Some particular examples: \begin{...
2 votes

Ortho-para directing and meta directing groups: Activating or deactivating the aromatic ring?

I'm not sure if G is an activating or deactivating compound. You may want to look at the relative order of activation/deactivation of some substituents, (source: www.chem.ucalgary.ca) As per the ...
  • 2,975
2 votes
Accepted

Relative acidity of acetic acid derivatives with strongly withdrawing substituents

Some cheminformatic descriptors for the puzzling compounds can be found on the PubChem website: SMILES N+(=O)O ; Nitroacetic acid; 625-75-2; alfa-Nitro acetic acid; 2-nitroacetic acid; ALFA-...
  • 20.1k
2 votes

Acidic nature comparison; benzoic acid and phenylacetic acid

The acidity of benzoic acid $(\ce{C6H5-COOH})$ and its substituted derivatives, $\ce{R-C6H4-COOH}$ $(e.g., \ \ce{4-NO2-C6H4-COOH})$ have been studied extensively using the Hammett Equation. Similarly, ...
2 votes

Carbocation formation and stability from bromo compounds

Yes, both your answers and reasoning are correct. For the second compound a slight ambiguity might arise, because the $\mathrm{sp^2}$-hybridized carbons show $\text{-I}$ effect which would destabilize ...

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