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

1. A Review of General Chemistry

Degrees of Unsaturation

Organic Chemistry

1. A Review of General Chemistry

Degrees of Unsaturation

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Problem 6a

Textbook Question

Several studies have shown that β-carotene, a precursor of vitamin A, may play a role in preventing cancer. β-Carotene has a molecular formula of C₄₀H₅₆, and it contains two rings and no triple bonds. How many double bonds does it have?

Verified step by step guidance

Determine the degree of unsaturation (also known as the index of hydrogen deficiency, IHD) for the molecule using the molecular formula C₄₀H₅₆. The formula for IHD is: IHD = (2C + 2 - H)/2, where C is the number of carbons and H is the number of hydrogens.

Substitute the values for C and H into the IHD formula: IHD = (2(40) + 2 - 56)/2. Simplify the expression to calculate the degree of unsaturation.

Interpret the IHD value. Each unit of IHD corresponds to either a double bond, a ring, or a triple bond. Since the problem states that the molecule contains two rings and no triple bonds, subtract 2 (for the rings) from the IHD value to determine the number of double bonds.

Verify the molecular structure of β-carotene. Ensure that the calculated number of double bonds aligns with the molecular formula and the structural constraints (e.g., no triple bonds, two rings).

Conclude the number of double bonds in β-carotene based on the IHD calculation and the structural information provided in the problem.

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Key Concepts

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

Molecular Formula Interpretation

The molecular formula of a compound provides information about the number and types of atoms present. In the case of b-carotene, C40H56 indicates that there are 40 carbon atoms and 56 hydrogen atoms. Understanding how to interpret this formula is essential for deducing structural features, such as the presence of double bonds.

Unsaturation and Double Bonds

Unsaturation in organic compounds refers to the presence of double or triple bonds between carbon atoms. Each double bond reduces the number of hydrogen atoms that can be attached to the carbon skeleton. The degree of unsaturation can be calculated using the formula: (2C + 2 - H)/2, where C is the number of carbons and H is the number of hydrogens, helping to determine the number of double bonds in b-carotene.

Structure of b-Carotene

b-Carotene is a carotenoid with a specific structure that includes two conjugated double bond systems within its rings. The arrangement of these double bonds contributes to its color and biological activity. Recognizing the structural features of b-carotene is crucial for understanding its chemical properties and potential health benefits.

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Related Practice

Textbook Question

What is the index of hydrogen deficiency for each of the following molecular formulas?

(b) C₁₂H₁₁NO₃

Textbook Question

Calculate the index of hydrogen deficiency for the following molecules.

(c)

Textbook Question

For each molecular formula, represent all constitutional isomers using line-angle drawings.

Textbook Question

Determine the degree of unsaturation for hydrocarbons with the following molecular formulas:

c. C₁₂H₂₀

d. C₄₀H₅₆

Textbook Question

Give five examples of structures with this formula (C₆H₁₂). At least one should contain a ring, and at least one should contain a double bond.

Hint: If you prefer to use a formula, elements of unsaturation = 1/2(2C + 2 - H)

C = number of carbons

H = number of hydrogens

Textbook Question

For each of the following molecular formulas, determine the number of elements of unsaturation, and draw three examples.

a. C₄H₄Cl₂

b. C₄H₈O

c. C₆H₈O₂

Textbook Question

For each of the following molecular formulas, determine the number of elements of unsaturation, and draw three examples.

d. C₅H₅NO₂

e. C₆H₃NClBr

Textbook Question

Calculate the index of hydrogen deficiency for curacin A, which has a molecular formula of C₂₃H₃₅NOS .

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Several studies have shown that β-carotene, a precursor of vitamin A, may play a role in preventing cancer. β-Carotene has a molecular formula of C40H56, and it contains two rings and no triple bonds. How many double bonds does it have?

Key Concepts

Molecular Formula Interpretation

Unsaturation and Double Bonds

Structure of b-Carotene

Watch next

Several studies have shown that β-carotene, a precursor of vitamin A, may play a role in preventing cancer. β-Carotene has a molecular formula of C₄₀H₅₆, and it contains two rings and no triple bonds. How many double bonds does it have?