Question

Write structural formulas for the following compounds. (a) 2-methylbutane (b) 3,3 -diethyl-2-methylhexane (c) 3,5 -dimethylnonane (d) 3 -ethyl-2,2-dimethylhexane

Short answer

The structural formulas for the described compounds have been drawn, considering the number of carbon atoms in the parent chain denoted by the suffix -ane and the substituents (methyl or ethyl groups) denoted by their prefixes. Each substituent is positioned on the carbon atom number specified before its prefix.

Step-by-step solution

Draw the structural formula for 2-methylbutane

Butane implies a carbon chain of four atoms. The prefix '2-methyl' means that a methyl (\(\mathrm{CH_3}\)) group is attached to the second carbon atom from either end. Therefore, start by drawing a straight chain of four carbons, and then add the methyl group to the second carbon.

Draw the structural formula for 3,3-diethyl-2-methylhexane

Hexane means a carbon chain of six atoms. Three groups are attached to this chain: two ethyl groups (\(\mathrm{C_2H_5}\)) at the third carbon from either end (because of the prefix 3,3-diethyl), and a methyl group at the second carbon (because of the prefix 2-methyl). Draw the parent chain of six carbon atoms, and then add the ethyl groups at the third carbon and the methyl group at the second.

Draw the structural formula for 3,5-dimethylnonane

Nonane implies a carbon chain of nine atoms. The prefix '3,5-dimethyl' means that methyl groups are attached to the third and fifth carbons from either end. Start by drawing a straight chain of nine carbons, and then add the methyl groups to the third and fifth carbons.

Draw the structural formula for 3-ethyl-2,2-dimethylhexane

Hexane implies a carbon chain of six atoms. The prefix '3-ethyl' denotes an ethyl group at the third carbon, and '2,2-dimethyl' denoted two methyl groups at the second carbon. Draw a six carbon parent chain, and then add the relevant substituents at the indicated positions.

Key concepts

Understanding Organic Chemistry

Organic chemistry focuses on the study of carbon-containing compounds. These molecules are fascinating because carbon atoms can easily bond with each other and with other elements, leading to an enormous variety of compounds. Organic chemistry is crucial as it forms the basis for life, being involved in creating biological molecules like DNA and proteins.
A huge portion of organic chemistry involves understanding the structure and behavior of hydrocarbons, which are compounds composed solely of carbon and hydrogen atoms.
These hydrocarbons can have different structures, such as chains or rings, making the study both diverse and rich. Mastering organic chemistry helps you grasp the chemical properties of biological systems, synthetic drugs, and materials.

Basics of Alkane Nomenclature

Alkane nomenclature is key in organic chemistry, as it provides a standardized way to name compounds. This system was developed by IUPAC (International Union of Pure and Applied Chemistry) and is used worldwide.
Alkanes are the simplest type of hydrocarbons consisting entirely of single bonds.

• First, determine the longest continuous chain of carbon atoms; this becomes the parent name, derived from the number of carbons, like methane, ethane, propane, etc.
• If the molecule contains branches or substituents, their position should be indicated by numbers.
• Substituents like methyl (\(\mathrm{CH_3}\)) or ethyl (\(\mathrm{C_2H_5}\)) are named by using prefixes such as di- for two, tri- for three, to indicate the multiple identical groups.
• In nomenclature, the lowest possible numbers are used to indicate the positions of the substituents.

Understanding alkane nomenclature allows chemists to deduce the structure of a compound from its name easily.

Identifying Substituent Groups

Substituent groups are secondary groups of atoms that replace hydrogen atoms on the carbon chain of an alkane. They are crucial in creating the vast diversity of organic molecules.
Methyl (\(\mathrm{-CH_3}\)), ethyl (\(\mathrm{-C_2H_5}\)), propyl (\(\mathrm{-C_3H_7}\)), and others are common alkyl groups that act as substituents.

• The position of the substituents on the carbon chain is vital as it affects the compound's properties and name.
• When a molecule has more than one substituent group, the position of each group is crucial and must be precisely noted using numbers.
• Substituent names are listed in alphabetical order in the full name of the compound, ignoring any di-, tri-, tetra- prefixes when alphabetizing.

By mastering substituent groups, you can efficiently construct and recognize the structure of complex organic molecules based on their names.