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

Previous problemNext problem

Problem 1d

Textbook Question

Given the molecular formula, calculate the index of hydrogen deficiency.
(d) C₈H₉OBr

Verified step by step guidance

Step 1: Understand the concept of the Index of Hydrogen Deficiency (IHD). The IHD, also known as the degree of unsaturation, indicates the number of rings, double bonds, or triple bonds in a molecule. Each degree of unsaturation corresponds to the loss of two hydrogens compared to a fully saturated molecule.

Step 2: Use the formula for IHD: IHD = (2C + 2 - H + N - X) / 2, where C is the number of carbons, H is the number of hydrogens, N is the number of nitrogens, and X is the number of halogens (e.g., Br, Cl, F, I). For this problem, the molecular formula is C₈H₉OBr.

Step 3: Substitute the values from the molecular formula into the IHD formula. Here, C = 8, H = 9, N = 0 (no nitrogen), and X = 1 (one bromine atom). Oxygen (O) does not affect the IHD calculation, so it is ignored.

Step 4: Simplify the formula step by step. First, calculate the numerator: (2 × 8) + 2 - 9 + 0 - 1. Then divide the result by 2 to find the IHD.

Step 5: Interpret the result. The IHD value will tell you the number of rings and/or multiple bonds in the molecule. For example, an IHD of 1 indicates one double bond or one ring, while an IHD of 2 could indicate two double bonds, one triple bond, or one ring and one double bond.

Verified video answer for a similar problem:

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

Play a video:

Was this helpful?

Key Concepts

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

Index of Hydrogen Deficiency (IHD)

The Index of Hydrogen Deficiency (IHD) is a measure of the degree of unsaturation in a molecule, indicating the number of rings and/or multiple bonds present. It is calculated using the formula IHD = (2C + 2 + N - H - X) / 2, where C is the number of carbons, N is the number of nitrogens, H is the number of hydrogens, and X is the number of halogens. A higher IHD value suggests more unsaturation, which can affect the reactivity and properties of the compound.

Molecular Formula Interpretation

A molecular formula provides the number and types of atoms in a compound, which is essential for calculating the IHD. In the formula C₈H₉OBr, there are 8 carbon atoms, 9 hydrogen atoms, 1 oxygen atom, and 1 bromine atom. Understanding how to interpret this formula allows for the correct application of the IHD formula and helps in identifying the structure and potential functional groups present in the compound.

Halogens in Organic Compounds

Halogens, such as bromine, are important in organic chemistry as they can influence the saturation of a molecule. When calculating IHD, halogens are treated similarly to hydrogens, as they can replace hydrogen atoms in a saturated hydrocarbon. In the case of C₈H₉OBr, the presence of bromine must be accounted for in the IHD calculation, as it affects the overall hydrogen count and thus the degree of unsaturation in the compound.

Watch next

Master The difference between saturated and unsaturated molecules. with a bite sized video explanation from Johnny

Start learning