Textbook Question
What is the molecular formula for each of the following?
a. a 4-carbon hydrocarbon with two bonds and no rings
1. A Review of General Chemistry
Degrees of Unsaturation
2:31 minutesProblem 44c
Textbook Question
Cholesterol, C27H46O, has only one pi bond. With no additional information, what else can you say about its structure?
Verified step by step guidance1
Begin by understanding the molecular formula of cholesterol, which is C27H46O. This indicates that cholesterol is composed of 27 carbon atoms, 46 hydrogen atoms, and one oxygen atom.
Recognize that cholesterol has only one pi bond. Pi bonds are typically found in double or triple bonds, which are unsaturated bonds. The presence of only one pi bond suggests that cholesterol is largely saturated, meaning most of its carbon atoms are involved in single bonds.
Consider the implications of having a single pi bond in a molecule with 27 carbon atoms. This suggests that the majority of the carbon atoms are likely arranged in a saturated hydrocarbon chain or rings, with only one unsaturated site.
Recall that cholesterol is a steroid, which is a type of organic molecule characterized by a specific arrangement of four fused carbon rings. The presence of one pi bond could be part of a double bond within one of these rings or in a side chain.
Conclude that the structure of cholesterol is predominantly saturated, with a complex ring system typical of steroids, and the single pi bond contributes to a specific structural feature, such as a double bond in one of the rings or a functional group.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Pi Bonds
Pi bonds are a type of covalent bond that results from the sideways overlap of p orbitals. They are typically found in double and triple bonds, contributing to the molecule's rigidity and affecting its geometry. In cholesterol, the presence of only one pi bond suggests limited unsaturation, indicating that most of the carbon atoms are likely involved in single (sigma) bonds, contributing to a more saturated structure.
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Saturation in Organic Molecules
Saturation refers to the presence of single bonds between carbon atoms in a molecule, with no double or triple bonds. A saturated molecule, like cholesterol with only one pi bond, implies that it is mostly composed of single bonds, which affects its chemical reactivity and physical properties. This suggests that cholesterol is largely a saturated compound, with a stable and less reactive structure.
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Steroid Structure
Cholesterol is a type of steroid, characterized by a core structure of four fused carbon rings. This rigid ring system is a hallmark of steroids, contributing to their distinct shape and biological function. The presence of only one pi bond in cholesterol suggests that the rest of the structure is composed of these saturated rings, which are crucial for its role in cell membranes and as a precursor for other steroids.
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