[webassignbuddy]

The answer key says structure A is X and structure B is Y. Since Y is MUCH lower in energy, it's conjugate base is a STRONGER BASE.
I don't understand this one because both nitrogens are sp3 hybridized and possess the same amount of electron density no??
Except structure B has a longer carbon chain...but what does that indicate???

For example, N-methylbenzylamine is said to be more basic than N-ethylaniline .
According to my teacher at least. She never explained why though and my reasoning was that the electron density at the Nitrogen in N-methylbenzylamine is MORE because Nitrogen has a SHORTER carbon cain, whereas in N-ethyaniline's structure, the nitrogen has less electron density because it has to smear it's electron density more due to the longer carbon chain. And then I realized that alkyl groups are supposed to be electron DONATING. SO MY question is, why isn't N-ethylaniline MORE BASIC than N-methylbenzylamine?!
And how can I apply THIS concept to the diagram above?

I'm so utterly confused.

[opsomath]

The nitrile group is electron withdrawing, which makes the conjugate base a weaker base. The farther you get it away from the basic nitrogen, the stronger the base is.

Your other question is inconsistent. Do you mean N-methylbenzylamine, or N-methylaniline? One of these has the N directly bonded to the phenyl ring, another has a CH2 group between the N and ring. Big difference there.

[webassignbuddy]

The nitrile group is electron withdrawing, which makes the conjugate base a weaker base. The farther you get it away from the basic nitrogen, the stronger the base is.

Your other question is inconsistent. Do you mean N-methylbenzylamine, or N-methylaniline? One of these has the N directly bonded to the phenyl ring, another has a CH2 group between the N and ring. Big difference there.

I...don't think I follow.

I know that nitrogen is electron withdrawing in the energy diagram. It's the same for both structure A and B.
But Structure B's carbon chain in the middle is longer than Structure A's. My question was, how does that effect the basicity of N?

What confuses me even more is the basicity differnece between N-methylbenzylamine and N-ethylaniline. N-ethylaniline has a LONGER carbon chain on Nitrogen but the structure is LESS basic...

So essentially my question is, how do alkyl groups/carbon chains on a nitrogen effect the nitrogens basicity??

[kriggy]

...
I...don't think I follow.
...

You were asking question about N-methylbenzylamine but the structure you drew is actualy N-methylaniline not methylbenzylamine


N-methylbenzylamine is this.
So if we are talking about compounds you did draw then N-ethylaniline should be more basic than N-methylaniline. If about those you named then I dont know.

[webassignbuddy]

...
I...don't think I follow.
...

You were asking question about N-methylbenzylamine but the structure you drew is actualy N-methylaniline not methylbenzylamine


N-methylbenzylamine is this.
So if we are talking about compounds you did draw then N-ethylaniline should be more basic than N-methylaniline. If about those you named then I dont know.

Hmm...maybe google didnt give me the right structure...if that IS the structure, than how is the answer to this question N-methylbenzylamine

"(b) Select the amine whose equilibrium solution will contain the largest concentration of hydroxide ions when the amine is placed in water: N-methylbenzylamine or N-ethylaniline"

EDIT: oh ok nvm I see how N-methylbenzylamine is more basic than N-ethylaniline because N is further away from the pi system and it's electron density is greater because the p orbital doesn't overlap with the rings pi system like N-ethylaniline's does. 

Ok so that's resolved!

But back to the diagram...

How would I explain the the basicity differnece between Structure A and Structure B?
CN, which is a really strong electron withdrawing R group is FURTHER away from the Nitrogen on the right compared to Structure B, thus Structure B's nitrogen has MORE electron density at the Nitrogen, making it MORE basic.
Would that be a good explanation?