Textbook Question
The structure of the amino acid lysine (in its uncharged form) is shown below.
a. Which amine groups would be able to participate in hydrogen bonding?
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17. Amines
Amine Reactions
2:23 minutesProblem 12a
Textbook Question
Write an equation for the acid-base equilibrium of:
a.Pyrrolidine and water
Label each species in the equilibrium as either an acid or a base.
Verified step by step guidance1
Identify the chemical nature of pyrrolidine. Pyrrolidine is a cyclic amine, which means it acts as a weak base because it has a lone pair of electrons on the nitrogen atom that can accept a proton (H⁺).
Write the general reaction for a base reacting with water. A base reacts with water by accepting a proton from water, forming its conjugate acid and hydroxide ions (OH⁻).
Set up the equilibrium equation for pyrrolidine and water. Pyrrolidine (C₄H₉NH) reacts with water (H₂O) to form its conjugate acid (C₄H₉NH₂⁺) and hydroxide ions (OH⁻). The equation is:
Label each species in the equilibrium. Pyrrolidine (C₄H₉NH) is the base because it accepts a proton. Water (H₂O) acts as the acid because it donates a proton. The conjugate acid is C₄H₉NH₂⁺, and the conjugate base is OH⁻.
Verify the reaction follows the Brønsted-Lowry acid-base theory. In this theory, acids are proton donors, and bases are proton acceptors. Pyrrolidine accepts a proton, and water donates a proton, confirming the reaction aligns with this theory.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Acid-Base Theory
Acid-base theory explains the behavior of acids and bases in chemical reactions. According to the Brønsted-Lowry theory, an acid is a proton donor, while a base is a proton acceptor. This framework helps in understanding how substances interact in equilibrium, particularly in aqueous solutions.
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Equilibrium Constant
The equilibrium constant (K) quantifies the ratio of concentrations of products to reactants at equilibrium for a given reaction. In acid-base equilibria, it helps determine the strength of acids and bases. A larger K value indicates a stronger acid or base, as it favors the formation of products.
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Pyrrolidine as a Base
Pyrrolidine is a cyclic amine that acts as a weak base due to the presence of a lone pair of electrons on the nitrogen atom. In the context of acid-base equilibrium with water, pyrrolidine can accept a proton from water, forming its conjugate acid and hydroxide ions. Understanding its role is crucial for labeling species in the equilibrium.
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