Textbook Question
Butane, the fuel used in disposable lighters, has the formula C4H10. The carbon atoms are connected in the sequence C-C-C-C, and each carbon has four covalent bonds. Draw the structural formula of butane.
Ch.23 - Organic and Biological Chemistry
Chapter 23, Problem 6
How many dienes (compounds with two double bonds) are there with the formula C5H8? Draw as many structures as you can.
Verified step by step guidance1
Step 1: Understand the molecular formula C5H8, which indicates a hydrocarbon with 5 carbon atoms and 8 hydrogen atoms. The presence of two double bonds classifies it as a diene.
Step 2: Calculate the degree of unsaturation using the formula: Degree of Unsaturation = (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. For C5H8, this simplifies to (2*5 + 2 - 8) / 2.
Step 3: Recognize that the degree of unsaturation indicates the number of rings and/or multiple bonds. For C5H8, the degree of unsaturation is 2, which can be satisfied by two double bonds.
Step 4: Begin drawing possible structures by arranging the carbon atoms in a linear or branched chain and adding double bonds. Ensure that each carbon atom forms four bonds in total.
Step 5: Verify each structure by counting the total number of carbon and hydrogen atoms to ensure they match the molecular formula C5H8, and confirm that each structure contains exactly two double bonds.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Dienes
Dienes are organic compounds that contain two double bonds between carbon atoms. They can be classified into two main types: conjugated dienes, where the double bonds are separated by a single bond, and isolated dienes, where the double bonds are separated by more than one single bond. Understanding the structure and reactivity of dienes is crucial for predicting their chemical behavior and potential reactions.
Structural Isomers
Structural isomers are compounds that have the same molecular formula but differ in the arrangement of atoms. For C5H8, various structural isomers can be formed by altering the position of the double bonds or the carbon skeleton. Recognizing and drawing these isomers is essential for determining the total number of distinct diene structures that can exist for a given formula.
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Isomers
Degree of Unsaturation
The degree of unsaturation indicates the total number of rings and multiple bonds in a compound. For a hydrocarbon, it can be calculated using the formula (2C + 2 - H)/2, where C is the number of carbons and H is the number of hydrogens. For C5H8, the degree of unsaturation is 3, suggesting the presence of multiple double bonds or rings, which is key to understanding the possible diene structures.
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