Draw structures for molecules that fit the following descriptions: (a) C 3 H 6 O containing an aldehyde functional group

Hi, everyone. Let's look at our next problem. Pitt says, what is the possible structure of a compound of the chemical formula of C five H 10 0 that contains an aldehyde functional group. We have four different structures labeled A through D and we need to figure out which one of these could possibly be the structure given the formula we have. Well, first, let's look and see if they all have aldehyde groups. So what is our aldehyde functional group? You recall it is attached to an R group. We have a carbon double bot to an oxygen and another bond just to a hydrogen. So let's check all of these. I'll use a blue highlighting sharks A has an aldehyde group. Structure B, structure C, but structure D instead of having a bond to a hydrogen over here has a methyl group instead. So structure D does not have an aldehyde group. So we'll go ahead and cross that out. Now, we see that structure B has a cyclops ring. However, it's a cyclopedic ring attached to an aldehyde group, which means we have five carbons in our ring plus 1/6 carbon on the aldehyde group. So structure B is impossible because our structure should only have five carbons. Now, let's look at A and C both have single bond alkyl chains. Structure C, it's a straight chain with 1234 carbons attached to the fifth Carmen. On the aldehyde structure A has two methyl groups attached two branches. But if we look at how many carbons there are, that gives us too many carbons. We have 1234 in a straight chain, but then five and six carbons on the two methyl groups that are attached. So structure A also has too many carbons. So we've just got one left choice C it has 12345 carbons. We already know it's correct just by elimination. But to be thorough, let's double check that we've got the right amount of hydrogens present. So I'll label them in black. So we know that each of the central carbons in the, in the chain have two hydrogens attached. So I'm gonna label each of those carbons with a number two for two hydrogens and the terminal carbon will have three hydrogens. So we have two plus two plus two plus three equals nine hydrogens. So we have the correct number of hydrogens because we have the one hydrogen from the alky aldehyde group, excuse me. So 10 hydrogens total, we have five carbons and we have the one oxygen. So structure C is indeed a possible structure for our molecule. This straight chain of five carbons terminating in an aldehyde group. See you in the next video.

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12. Introduction to Organic Chemistry

Functional Groups in Chemistry

GOB Chemistry

12. Introduction to Organic Chemistry

Functional Groups in Chemistry

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Problem 2a

Textbook Question

Draw structures for molecules that fit the following descriptions:
(a) C₃H₆O containing an aldehyde functional group

Verified step by step guidance

Step 1: Understand the molecular formula C3H6O. This indicates the molecule contains 3 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom.

Step 2: Recall the structure of an aldehyde functional group. An aldehyde contains a carbonyl group (C=O) bonded to at least one hydrogen atom. The general formula for an aldehyde is R-CHO, where R is a hydrocarbon group.

Step 3: Arrange the 3 carbon atoms in a chain. Since the aldehyde group must be at the end of the chain, place the carbonyl group (C=O) on one of the terminal carbons, and attach a hydrogen atom to the same carbon to complete the aldehyde group.

Step 4: Distribute the remaining hydrogen atoms to the other two carbons in the chain to satisfy the octet rule for each carbon atom. Ensure that each carbon has four bonds in total.

Step 5: Verify the structure by counting the total number of carbon, hydrogen, and oxygen atoms to ensure it matches the molecular formula C3H6O, and confirm the presence of the aldehyde functional group.

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Key Concepts

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

Aldehyde Functional Group

An aldehyde is a type of organic compound characterized by the presence of a carbonyl group (C=O) bonded to a terminal carbon atom. This means that the carbonyl group is located at the end of the carbon chain, which distinguishes aldehydes from ketones, where the carbonyl group is found within the chain. Aldehydes typically have the general formula RCHO, where R represents a hydrocarbon group.

Molecular Formula Interpretation

The molecular formula C3H6O indicates that the molecule contains three carbon atoms, six hydrogen atoms, and one oxygen atom. Understanding how to interpret this formula is crucial for constructing the molecular structure, as it provides insight into the number of bonds and the arrangement of atoms. The presence of fewer hydrogen atoms relative to carbon suggests the potential for functional groups, such as the aldehyde in this case.

Structural Representation of Organic Molecules

Drawing structures for organic molecules involves representing the arrangement of atoms and the types of bonds between them. This can be done using various methods, such as Lewis structures or skeletal formulas. For the given molecular formula C3H6O with an aldehyde group, one must ensure that the carbonyl group is positioned at the end of the carbon chain while satisfying the tetravalency of carbon and the valency of other atoms involved.

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