Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

3. Acids and Bases

Acid Base Equilibrium

Organic Chemistry

3. Acids and Bases

Acid Base Equilibrium

Previous problemNext problem

7:02 minutes

Problem 5a,b,c

Textbook Question

Predict the products of the following acid–base reactions, or indicate if no significant reaction would take place.
a. H—C≡C—H + NaNH₂
b. H—C≡C—H + CH₃Li
c. H—C≡C—H + NaOCH₃

Verified step by step guidance

Step 1: Identify the nature of the reactants in each reaction. In these reactions, H—C≡C—H is acetylene, a terminal alkyne, which can act as an acid due to the acidic hydrogen attached to the sp-hybridized carbon. The other reactants are bases: NaNH2 (sodium amide), CH3Li (methyl lithium), and NaOCH3 (sodium methoxide).

Step 2: Consider the acidity of the terminal alkyne hydrogen. Terminal alkynes have a pKa around 25, making them more acidic than alkanes and alkenes but less acidic than water or alcohols. This means they can react with strong bases.

Step 3: Evaluate the strength of the bases. NaNH2 and CH3Li are strong bases capable of deprotonating the terminal alkyne, while NaOCH3 is a weaker base compared to the other two.

Step 4: Predict the products for each reaction. For reactions with strong bases like NaNH2 and CH3Li, the terminal hydrogen of acetylene will be removed, forming the acetylide ion (C≡C⁻) and the corresponding conjugate acid of the base (NH3 for NaNH2 and CH4 for CH3Li).

Step 5: Determine if a significant reaction occurs with NaOCH3. Given that NaOCH3 is a weaker base, it is less likely to deprotonate the terminal alkyne, suggesting that no significant reaction would take place.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Base Reactions

Acid-base reactions involve the transfer of protons (H+) between reactants. In organic chemistry, these reactions often involve the deprotonation of an acidic hydrogen by a strong base. The strength of the acid and base determines the direction and extent of the reaction, with stronger acids and bases driving the reaction to completion.

Acetylide Ion Formation

The acetylide ion (C≡C−) is formed when a terminal alkyne, such as H—C≡C—H, is deprotonated by a strong base. This ion is a useful nucleophile in organic synthesis. Strong bases like NaNH2 and CH3Li can deprotonate terminal alkynes to form acetylide ions, which can then participate in further reactions, such as nucleophilic substitutions.

Base Strength and Reaction Feasibility

The feasibility of an acid-base reaction depends on the relative strengths of the acids and bases involved. Strong bases like NaNH2 and CH3Li can deprotonate terminal alkynes, while weaker bases like NaOCH3 may not significantly react with them. The pKa values of the acids and conjugate acids of the bases help predict whether a reaction will occur.

Watch next

Master The 3 steps for determining the direction of acid and base equilibrium. with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Given the K_eq values for the following acid–base reactions, identify the strongest acid and the strongest base.

(c)

Textbook Question

Given the following K_eq values, how much stronger of an acid is methanol (CH₃OH) than acetylene (HC≡CH)?

Textbook Question

Given the following K_eq values, how much stronger of a base is acetate (CH₃CO₂^-) than chloride (Cl⁻)?

Textbook Question

Explain why an amide ion cannot be used to form a carbanion from an alkane in a reaction that favors products.

Textbook Question

Complete the following acid–base reactions. In each case, indicate whether the equilibrium favors the reactants or the products, and explain your reasoning.

(e) (CH₃)₃C–O^– + CH₃CH₂OH ⇌

Textbook Question

Complete the following acid–base reactions. In each case, indicate whether the equilibrium favors the reactants or the products, and explain your reasoning.

(d)

Textbook Question

Would amide or acetate most easily deprotonate an alcohol to make the alkoxide anion? Calculate K_eq for each possibility.

Textbook Question

Which of the following reactions favor formation of the products? Recall that the equilibrium favors formation of the weaker acid.

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap

Predict the products of the following acid–base reactions, or indicate if no significant reaction would take place.a. H—C≡C—H + NaNH2 b. H—C≡C—H + CH3Li c. H—C≡C—H + NaOCH3

Key Concepts

Acid-Base Reactions

Acetylide Ion Formation

Base Strength and Reaction Feasibility

Watch next

Predict the products of the following acid–base reactions, or indicate if no significant reaction would take place.
a. H—C≡C—H + NaNH₂
b. H—C≡C—H + CH₃Li
c. H—C≡C—H + NaOCH₃