SME
Organic Chemistry II
Amines
Use this for “Rank aniline, dimethylamine and pyridine from the strongest base to the weakest.”
Put in order
Order from the strongest base to the weakest.
1
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2
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3
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4
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5
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Assumptions
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A base is stronger when its conjugate acid is weaker: the larger the pKₐ of R₃NH⁺, the stronger the amine.
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A lone pair shared with a ring or a C=O is less free to take a proton.
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Alkyl groups give electrons to the nitrogen, so an alkyl amine is a stronger base than ammonia.
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Each conjugate acid’s pKₐ in water shows under its base once it is placed; the values are rounded, as tables give them.
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