Question

What prefixes would be used in the systematic name of an alkane to indicate that the alkane contained the following numbers of methyl branches? a. two b. four c. five d. three

Short answer

The prefixes used in the IUPAC naming system for alkanes with the specified number of methyl branches are: a. Two methyl branches - "dimethyl" b. Four methyl branches - "tetramethyl" c. Five methyl branches - "pentamethyl" d. Three methyl branches - "trimethyl"

Step-by-step solution

Introduction to Alkanes and Methyl Branches

Alkanes are a class of organic compounds that consist only of carbon (C) and hydrogen (H) atoms, with single bonds between the carbon atoms. A methyl branch is a group consisting of one carbon atom bonded to three hydrogen atoms (CH3), and is connected to another carbon atom in the main chain of an alkane molecule. The IUPAC naming system is used in chemistry to create a standard nomenclature for organic compounds like alkanes. Prefixes are added to the systematic name of an alkane to indicate the presence of a certain number of methyl branches.

a. Alkane Containing Two Methyl Branches

For an alkane with two methyl branches, the appropriate prefix is "di-", which indicates the presence of two identical substituents. Therefore, the IUPAC name of the alkane will have the prefix "dimethyl".

b. Alkane Containing Four Methyl Branches

For an alkane with four methyl branches, the appropriate prefix in the IUPAC naming system is "tetra-", which indicates the presence of four identical substituents. Thus, the IUPAC name of the alkane will have the prefix "tetramethyl".

c. Alkane Containing Five Methyl Branches

For an alkane with five methyl branches, the appropriate prefix in the IUPAC naming system is "penta-", which indicates the presence of five identical substituents. The IUPAC name of the alkane will therefore have the prefix "pentamethyl".

d. Alkane Containing Three Methyl Branches

For an alkane with three methyl branches, the appropriate prefix in the IUPAC naming system is "tri-", which indicates the presence of three identical substituents. Thus, the IUPAC name of the alkane will have the prefix "trimethyl". In summary, the prefixes used in the IUPAC naming system for alkanes with the specified number of methyl branches are as follows: a. Two methyl branches - "dimethyl" b. Four methyl branches - "tetramethyl" c. Five methyl branches - "pentamethyl" d. Three methyl branches - "trimethyl"

Key concepts

alkane

An alkane is a type of hydrocarbon where all the carbon-carbon bonds are single bonds. These compounds belong to a larger class of organic compounds known as alkanes, which are saturated hydrocarbons. The simplest alkane is methane (CH4), but as the carbon chain grows longer, more complex alkanes are formed.

• Alkanes have the general formula C\(_n\)H\(_{2n+2}\).
• They are also known as paraffins or saturated hydrocarbons.
• They are characterized by their non-polarity and insolubility in water.

The systematic naming of alkanes is crucial in organic chemistry, as it ensures a clear understanding of their structure across different scientific fields. Alkanes only contain carbon (C) and hydrogen (H) atoms, connected by single covalent bonds resulting in their saturated nature.

methyl branches

Methyl branches are simple substituents attached to the main carbon chain of an alkane. A methyl group is represented as CH\(_3\) and consists of one carbon atom bound to three hydrogen atoms.

• They act as "branches" off the main carbons, often altering the overall shape and properties of the molecule.
• When more than one methyl branch is present, we use prefixes to indicate their number in the molecular name.

This branching influences aspects like molecular stability and boiling points of alkanes. In naming, the location and number of branches are pivotal for correct IUPAC nomenclature.

organic compounds

Organic compounds are molecules primarily composed of carbon and hydrogen atoms. They can also include other elements like oxygen, nitrogen, sulfur, and halogens. This class of compounds is vast, encompassing everything from simple methane to complex proteins and DNA.

• They are categorized based on their carbon backbone, which can be chains or rings.
• The diversity in organic compounds arises from the ability of carbon to form stable bonds with itself and other elements.

Alkanes are among the simplest organic compounds, serving as building blocks for more complex organic molecules. Understanding their basic structure and naming conventions is foundational in organic chemistry.

naming system

The IUPAC naming system is a standardized method used worldwide for naming chemical substances, particularly organic compounds. This ensures that each compound has a unique and universally recognized name.

• It is based on rules set by the International Union of Pure and Applied Chemistry (IUPAC).
• For naming alkanes, prefixes are used to depict the number of carbons and any branches.
• In the case of methyl branches, prefixes like "di-", "tri-", "tetra-", and "penta-" indicate two, three, four, and five methyl groups, respectively.

The consistent application of these rules helps chemists and students communicate chemical structures effectively, reducing confusion and errors in scientific dialogue.

molecular structure

The molecular structure of an organic compound describes the spatial arrangement of its atoms. For alkanes, this typically involves straight or branched chains of carbon atoms bonded to hydrogen atoms.

• Molecular structure determines the physical and chemical properties of a compound.
• The presence and position of methyl branches can significantly influence the molecule's geometry.

For instance, more methyl branches in an alkane usually lead to higher boiling points and altered reactivity compared to their straight-chain counterparts. Understanding these structural variations is crucial for predicting the behavior of organic molecules in different chemical reactions.