What is the basicity trend of organic compounds?

In summary, the conversation discusses the correct order of basic strength for compounds with nitrogen atoms. The correct order is C > D > A > B, with C having the highest basic strength due to its sp3 hybridization and low electronegativity. The conversation also acknowledges the possibility of errors in textbooks and confirms the reasoning for the order of basic strength. It is also mentioned that the basicity of these compounds can be rationalized.
  • #1
SpectraPhy09
25
3
Homework Statement
the increasing order of the basicity of the following
compounds : (Please check the image I have attached for the options )
Relevant Equations
I don't know any
I think the correct ans should be c (i.e C>D>A>B ) but its given d in my textbook( There can be a error also but I'm sure)
I think C should have the highest basic strength since Hybridisation of N in this is Sp3 so it has the least electronegativity so it can donate its lone pair easily
Then it should be D since there are two N atoms of which one's lone pair is in conjugation and one has a lone pair not in conjugation so it can donate that lone pair
Then A because it has only One N atom of whose lone pair is not in the conjugation. So it can donate it. And B last because the lone of N atom here is involved in the Aromaticity of the compound so it would be very difficult for it to donate that lone pair

Plz, can someone tell me if my reasoning is correct?

Amines_Tatva-ex-2(Q.23).png
 
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  • #2
I agree with your reasoning, and having looked it up I think you're right. Textbooks can make mistakes sometimes!
 
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  • #3
Yes I think you could say that the neutral form of D (Imidazole) Is resonance stabilised, and the protonated form not. The pKa of its conjugate acid is 6.95 whereas that of C (Pyrrolidine, you could call it cyclic butylamine) is 11.3.

It's just a secondary amine, which made me think of comparing with diethylamine. pKa of c.a. 10.54. Then I thought, assuming the difference of that with pyrrolidine is significant enough to compare, how rationalise?At first I thought solvent accessibility but predicted the wrong way round, but then I thought no, the cyclic structure can't so easily form a hydrocarbon ball as the diethyl. These amine basicities have the property that you can always rationalise them.
 

FAQ: What is the basicity trend of organic compounds?

What is basicity?

Basicity refers to the ability of a compound to accept protons or donate electrons in a chemical reaction. In organic compounds, basicity is determined by the presence of a lone pair of electrons on the molecule.

How is basicity measured?

Basicity is measured using a scale called the pKa scale, which indicates the strength of an acid or base. The lower the pKa value, the stronger the acid and the higher the basicity. A higher pKa value indicates a weaker acid and lower basicity.

What factors affect the basicity of organic compounds?

The basicity of organic compounds is affected by the electronegativity of the atoms in the molecule, the size and distribution of the lone pair of electrons, and the stability of the conjugate acid formed after protonation. Basicity also increases with the presence of electron-donating groups and decreases with the presence of electron-withdrawing groups.

What are some common examples of basic organic compounds?

Some common examples of basic organic compounds include amines, amides, and alcohols. These compounds have a lone pair of electrons on the nitrogen or oxygen atom, making them capable of accepting protons and acting as bases in chemical reactions.

How does basicity affect the reactivity of organic compounds?

The basicity of organic compounds can affect their reactivity in various ways. Compounds with higher basicity are more likely to undergo nucleophilic reactions, while those with lower basicity may undergo electrophilic reactions. Basicity also plays a role in the acidity of a compound, which can impact its reactivity in acid-base reactions.

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