Question

Draw a structural formula for each of the following compounds. a. \(2,2-\) dimethylheptane b. 2,3 -dimethylheptane c. \(3,3-\) dimethylheptane d. \(2,4-\) dimethylheptane

Short answer

a. \(CH_3-CH(CH_3)-CH_2-CH_2-CH_2-CH_2-CH_3\) b. \(CH_3-CH(CH_3)-CH(CH_3)-CH_2-CH_2-CH_2-CH_3\) c. \(CH_3-CH_2-CH(CH_3)-C(CH_3)-CH_2-CH_2-CH_3\) d. \(CH_3-CH(CH_3)-CH_2-CH(CH_3)-CH_2-CH_2-CH_3\)

Step-by-step solution

Identify the Main Carbon Chain

First, we need to identify the main carbon chain in each compound, which is heptane in this case. Heptane has 7 carbon atoms, and we should draw the main chain with the correct number of carbons.

Add the Methyl Groups

Next, we need to add the methyl groups (CH3) at the correct positions based on the numbering given in the exercise. a. 2,2-dimethylheptane: Methyl groups are present on the 2nd and 2nd carbon atoms. b. 2,3-dimethylheptane: Methyl groups are present on the 2nd and 3rd carbon atoms. c. 3,3-dimethylheptane: Methyl groups are present on the 3rd and 3rd carbon atoms. d. 2,4-dimethylheptane: Methyl groups are present on the 2nd and 4th carbon atoms.

Draw the Structural Formulas

Finally, draw the structural formulas for each of the compounds as follows: a. \(2,2-\text{dimethylheptane}\) CH3-CH(CH3)-CH2-CH2-CH2-CH2-CH3 b. \(2,3 -\text{dimethylheptane}\) CH3-CH(CH3)-CH(CH3)-CH2-CH2-CH2-CH3 c. \(3,3 -\text{dimethylheptane}\) CH3-CH2-CH(CH3)-C(CH3)-CH2-CH2-CH3 d. \(2,4 -\text{dimethylheptane}\) CH3-CH(CH3)-CH2-CH(CH3)-CH2-CH2-CH3

Key concepts

Organic Chemistry

Organic chemistry is a branch of chemistry that focuses on the study and synthesis of carbon-containing compounds. This field explores the structure, properties, composition, reactions, and preparation of substances that consist of mainly carbon and hydrogen, along with nitrogen, oxygen, halogens, phosphorus, silicon, and sulfur.

Within organic chemistry, molecules are often represented using structural formulas to show how atoms are connected. Understanding these molecular structures is key to grasping how substances will behave in chemical reactions and in various environments. Students of organic chemistry learn how to draw and interpret these formulas to better comprehend the underlying mechanisms of organic reactions.

Alkanes

Alkanes are the simplest family of hydrocarbons - compounds consisting entirely of hydrogen and carbon. They are saturated organic molecules, meaning they hold the maximum number of hydrogen atoms possible in their structure; therefore, they only contain single bonds between the carbon atoms.

Commonly referred to as paraffins, alkanes have the general chemical formula of \(C_nH_{2n+2}\). They can be straight-chain (normal) alkanes, branched alkanes, or cyclic (ring-shaped) alkanes. The simplest alkane is methane \(CH_4\), and complexity increases as carbon chains grow longer and more branches are introduced. Learning about alkanes is foundational in organic chemistry because they serve as the basis for naming and understanding more complex organic molecules.

Molecular Structure Drawing

Molecular structure drawing is a visual representation of atoms and their connectivity. These drawings are crucial for representing organic compounds in a clear and understandable way. In a structural formula, lines represent chemical bonds between atoms; the line ends or corners represent the atoms themselves, typically carbon, unless otherwise indicated.

In organic chemistry, learning to draw molecular structures helps students visualize the spatial arrangement of compounds. This can be particularly challenging when attempting to show three-dimensional geometry on a two-dimensional surface, so different types of drawings - like skeletal formulas, dash-wedge notation, and chair conformations - are used depending on the level of detail required.

IUPAC Nomenclature

The International Union of Pure and Applied Chemistry (IUPAC) nomenclature is a standardized way of naming chemical substances. In the realm of organic chemistry, this system enables chemists to give a unique name to each compound, which can then be used to derive its structure. The IUPAC nomenclature for alkanes involves identifying the longest carbon chain as the base name and using prefixes, infixes, and suffixes to indicate the presence of other functional groups, branches, or double/triple bonds.

For students, mastering IUPAC nomenclature is critical for professional communication in science and for understanding the chemical literature. It clarifies which specific substance is in question and conveys essential structural information about the molecule itself.