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47 votes

Ortho-effect in substituted aromatic acids and bases

I would like to back up Klaus' answer with some Quantum Theory of Atoms in Molecules (QTAIM) results, based on a DF-BP86/def2-SVP calculation. Note that these are results, obtained without the ...
41 votes
Accepted

Why does lemon juice reduce the "fish" odor of sea food — specifically fish?

There are 2 cases, both related to the acid-base reactions. Both are also partial reasons why so many fish recipes use lemon juice. Fish, especially sea fish, naturally contain trimethylamine-N-oxide $...
  • 29.7k
34 votes

Is the ammonium substituent (-NH3+) really meta-directing in electrophilic substitution?

how is anilinium ion meta directing for electrophiles? Actually, anilinium is not meta directing (I know it is often taught that way), but rather it inductively deactivates the entire aromatic ring. ...
  • 82.5k
21 votes
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Selective nitro reduction of poly nitro compounds

Is there any way to predict which nitro group will be reduced After having gone through three pages of Google Scholar and reading several research papers looking for an answer, there is definitely no ...
21 votes

What is this fluorinated organic substance?

The name of the compound is 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (CAS #: 140681-55-6), which is commonly known as Selectfluor, a trademark of Air Products ...
20 votes
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Can an amide nitrogen be a hydrogen bond acceptor?

If I understood you correctly, you are talking about the peptide bond nitrogens ($\ce{R-C(=O)-\color{red}{N}H-R}$). This is, reduced to its significant chemical functional group an amide, more ...
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18 votes
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Does nitrogen inversion affect the basicity of amines?

Background Amine basicity correlates with, among other things, the hybridization of the nitrogen orbital that is holding the lone pair of electrons. The less s-character in this orbital, the more ...
  • 82.5k
17 votes
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Why can the lone pair not align with the phenyl moiety in 2,6-xylidine?

There is no prove for this statement, as it is most likely incorrect for 2,6-xylidene. This is based on an electronic structure theory approach. However, there are non-negligible steric interactions, ...
17 votes

Usage of ammine vs amine in nomenclature

(Will do more research into ammines come February.) Premise Ammonia is spelled with two 'm's. The more natural derivative of the word in a linguistic sense would also have the same number 'm's. Thus ...
17 votes
Accepted

Does aniline react with diazonium ions at C or N?

This is a really interesting question and the answer is that the reaction of benzenediazonium chloride with aniline is a bit different to most of the reactions of benzenediazonium salts in that the ...
  • 19.4k
17 votes

Does aniline react with diazonium ions at C or N?

In general, for anilines reaction at nitrogen is kinetically faster than reaction at carbon. However, the C-substituted product is usually more stable than the N-substituted product, so can prevail ...
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14 votes
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What is this fluorinated organic substance?

That is generally known as Selectfluor, a source of electrophilic fluorine. The zig-zag line is a 2-D representation of the third ethylene $\ce{-CH2-CH_{2} -}$ unit that links the two nitrogens. more ...
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13 votes
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Why are triamino compounds so rare?

You may be familiar with the equilibrium that exists between a gem-diol and the corresponding carbonyl compound, as shown in the figure below. The carbonyl double bond is very strong, so in most ...
  • 82.5k
13 votes
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The mechanism of demethylation of a quaternary ammonium

As you point out, the tert-butyl group wants to remain in an equatorial position, else both the tert-butyl group and the trimethylammonium group end up being axial which is disfavoured for two bulky ...
  • 16.8k
13 votes

What causes rapid nitrogen inversion?

In the second row of the periodic table, elements have relatively small differences between the size their $\mathrm s$- and $\mathrm p$-orbitals. Therefore, the orbitals of $\ce{NR3}$ can go from $\...
12 votes
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Hydrogenolysis of benzylic C-N bond

Hydrogenolysis typically involves a metal surface ($\ce{Pd, Pt}$, etc.) and hydrogen gas. In the reaction a weak bond, that is, a bond that is either strained or a bond that can generate a stabilized ...
  • 82.5k
12 votes
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Can a cyclic amine form an amide?

The heterocycle in this question is indole and is aromatic. This means that the N lone pair is delocalised and not readily available for nucleophilic attack. Think of it as similar in reactivity to a ...
  • 19.4k
11 votes
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Mechanism for formation of amide by reaction of amine with ester

Surely the negatively charged oxygen would protonate before the other oxygen would. Most of the time, but not all of the time. The amine group is more basic than the "alcohol group" that must ...
  • 82.5k
11 votes
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Why amino acids (Zwitterion) become either negative or positive at low and high pH solutions?

Firstly a note about terminology. The word "terminus" is reserved for the N- or C-termini of a polypeptide chain. For a free amino acid, you should refer to the carboxyl and amino groups as the $\...
  • 66.8k
11 votes
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Hoffman broamide degradation but with alkoxide as base instead of NaOH

This answer is wrong, the answer should be the carbamate 4. The reaction intermediate is the isocyanate which is captured by MeOH to give the carbamate (std Hofmann mechanism below from ...
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10 votes
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Reduction of α,β-unsaturated nitro compounds

I'm not aware of a $\ce{NaBH4}$-based reduction of nitroalkenes to saturated amines, such as in: It is however possible to reduce nitroalkenes to saturated hydroxylamines using $\ce{BH3*THF}$ in the ...
10 votes

Ortho-effect in substituted aromatic acids and bases

In the presence of bulky group that is methyl in this case causes steric hinderence making the plane the $\ce{NH3}$ out the plane thus preventing resonance which could have helps it in delocalising ...
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10 votes

Identify two amines

$\ce{Fc}$ stands for ferrocenyl. So the first compound is an amide of ferrocenecarboxylic acid and tetramethylene diamine, and the second compound is p-ferrocenyl aniline.
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10 votes
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Identify two amines

The proposed strucutre of these compound are, correct me if i am wrong.
  • 1,196
10 votes

Byproducts of LiAlH4 reduction of amides

Organic chemistry textbooks I flipped through usually don't focus on by-products, only noting that LAH ($\ce{LiAlH4}$) in dry solvent (THF, diethylether) is necessary for reduction, but when one ...
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10 votes
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Is steric inhibition of resonance or steric inhibition of protonation dominant in o-toluidine?

The reason for the decreased basicity is essentially the ortho-effect as outlined here: Ortho-effect in substituted aromatic acids and bases. Your question on the other hand asks about a seeming ...
10 votes
Accepted

Do amines or alcohols have stronger intermolecular hydrogen bonds?

The boiling point of non-ionic compounds are highly depend on their H-bonding abilities. For example, boiling point of water (molar mass: $\pu{18.02 g/mol}$) is $\pu{100 ^\circ C}$ at $\pu{1 atm}$ ...
10 votes

Do amines or alcohols have stronger intermolecular hydrogen bonds?

Mathew Mahindaratne has provided analysis based on experimental values of the boiling points of the two compounds. I would like to offer a different view using bonding analysis. Before I begin ...

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