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Kenneth Anderson

Why is diethylamine a stronger base than ethylamine?

Dan Lazuran  Follow

You have given us NO data with regard to the [math]pK_{b}[/math] of diethylamine, [math](H_{3}CCH_{2})_{2}NH[/math], or ethylamine [math]H_{3}CCH_{2}NH_{2}[/math]… and no data with respect to [math]pK_{a}[/math] of their conjugate acids … your proposition is unsupported. It might be the EXTRA hydrocarbyl substitution on the nitrogen centre would increase its basicity, and also the stability of the conjugate base… But what do we know…? We have no data to consider…

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Brian Chilando  Follow

The reason is because the ethyl group is electron donor and it stabilises the positive charge of the primary amine CH3-CH2-NH2 when it becomes salt (CH3-CH2-NH3+). If I have 2 ethyl groups I’ve a secondary amine (CH3-CH2)2-NH and the conjugate acid (CH3-CH2)2-NH2+) will be even more stable. IGenerally speaking, secondary amines are bases stronger than primary amines and tertiary amines are bases even stronger.

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