Question

Give the structure for each of the following. a. 4 -methyl- 1 -pentyne b. 2,3,3 -trimethyl- 1 -hexene c. 3 -ethyl- 4 -decene

Short answer

a. H-C≡C-C-C-CH3 | CH3 b. H2C=CH-CH(CH3)-CH(CH3)-CH2-CH3 | CH3 c. CH3-CH2-CH-CH=CH-CH2-CH2-CH2-CH2-CH3 | CH2-CH3

Step-by-step solution

Understanding the nomenclature of organic compounds

In organic chemistry, we name compounds based on the number of carbons in the longest chain and the type of functional groups present in the molecule. In this exercise, we will analyze the names of the compounds to find information about the main chain, branches, and functional groups.

Drawing the structure of 4-methyl-1-pentyne

First, we need to recognize the main chain in the compound. "Pentyne" indicates that our main chain will consist of 5 carbon atoms with a triple bond (yne). The triple bond is located in the first carbon since there is the number 1 before the "-pentyne." Secondly, there's a methyl group at the 4th carbon atom in the chain, as indicated by "4-methyl." Now, we can draw the structure for 4-methyl-1-pentyne as follows: 1. Draw a 5-carbon atom linear chain. 2. Add a triple bond between the first and second carbon. 3. Add a methyl group to the 4th carbon in the chain. The resulting structure is: H-C≡C-C-C-CH3 | CH3

Drawing the structure of 2,3,3-trimethyl-1-hexene

The name "hexene" indicates that our main chain will consist of 6 carbon atoms with a double bond (ene). The double bond is located in the first carbon, which is indicated by the number 1 before the "-hexene." We also have three methyl groups at carbons 2 and 3. Now, we can draw the structure for 2,3,3-trimethyl-1-hexene as follows: 1. Draw a 6-carbon atom linear chain. 2. Add a double bond between the first and second carbon. 3. Add three methyl groups, one at the 2nd carbon and two at the 3rd carbon in the chain. The resulting structure is: H2C=CH-CH(CH3)-CH(CH3)-CH2-CH3 | CH3

Drawing the structure of 3-ethyl-4-decene

The name "decene" indicates that our main chain will consist of 10 carbon atoms with a double bond (ene). The double bond is located in the fourth carbon, which is indicated by the number 4 before the "-decene." We also have an ethyl group at the 3rd carbon in the chain, as indicated by "3-ethyl." Now, we can draw the structure for 3-ethyl-4-decene as follows: 1. Draw a 10-carbon atom linear chain. 2. Add a double bond between the 4th and 5th carbon. 3. Add an ethyl group (CH2-CH3) to the 3rd carbon in the chain. The resulting structure is: CH3-CH2-CH-CH=CH-CH2-CH2-CH2-CH2-CH3 | CH2-CH3

Key concepts

Chemical Structure

Chemical structures are the visual representation of molecules, showing how atoms are arranged and bonded in a compound. These structures are crucial for understanding how molecules behave and react in various conditions.
In the realm of organic chemistry, chemical structures are typically illustrated using lines to represent carbon-carbon bonds and letters for different atoms, such as H for hydrogen or O for oxygen.
Each line depicts a bond between two atoms, and at the ends or junctions of lines, we find the carbon atoms. Observing the way these lines are arranged helps determine the particular effects or characteristics a molecule may exhibit. Understanding chemical structures enables chemists to predict reactivity, stability, and properties of materials.

Naming Conventions

Naming conventions in organic chemistry are methodology-based systems that establish a systematic way to name chemical structures. This globally accepted system, known as IUPAC (International Union of Pure and Applied Chemistry) nomenclature, ensures consistency in how compounds are identified.
Names usually reflect the structure of the compound, comprising several parts: the root name, which indicates the length of the carbon chain; the suffix, which often reveals the type of functional group(s); and prefixes or infixes that describe attachments or substitutions on the main chain. For example, in "4-methyl-1-pentyne," "pent" indicates five carbon atoms, "yne" signifies a triple bond, and "4-methyl" signifies a methyl group at carbon four. Grasping these conventions allows for easier communication among chemists and a better understanding of organic structures.

Functional Groups

Functional groups are specific groupings of atoms within molecules that are key determinants of a compound's chemical behavior. They define the class of the compound and influence its reactions and properties.
Some common functional groups include:

• Alkenes: Characterized by carbon-carbon double bonds (-C=C-).
• Alkynes: Defined by carbon-carbon triple bonds (-C≡C-).
• Alcohols: Contain hydroxyl groups (-OH).
• Carboxylic Acids: Feature carboxyl groups (-COOH).

In "4-methyl-1-pentyne," the alkyne functional group is indicated by "yne," showing a triple bond's presence in the chemical structure. Recognizing these groups helps predict the compound's behavior in chemical reactions.

Carbon Chains

Carbon chains form the backbone of organic compounds, consisting of sequences of carbon atoms bonded together.
These chains may be straight, branched, or even cyclic. The nature and length of a carbon chain are fundamental to the compound's identity, affecting its physical and chemical characteristics.
For example, in "2,3,3-trimethyl-1-hexene," the main carbon chain contains six carbon atoms, which is shown by the root word "hex-" and gives the compound its base name. Additional carbon atoms or groups branching from the main chain, such as methyl or ethyl groups, alter the chain's attributes, influencing properties like boiling point, solubility, and reactivity. Understanding carbon chains is essential for grasping organic chemistry's complexity and diversity.