Question

Draw a structural formula for each of the following compounds. a. 2 -methylpropane b. 2 -methylbutane c. 2 -methylpentane d. 2 -methylhexane

Short answer

The structural formulas for the given compounds are: a. 2-methylpropane: \( CH_3-CH(CH_3)-CH_3 \) b. 2-methylbutane: \( CH_3-CH(CH_3)-CH_2-CH_3 \) c. 2-methylpentane: \( CH_3-CH(CH_3)-CH_2-CH_2-CH_3 \) d. 2-methylhexane: \( CH_3-CH(CH_3)-CH_2-CH_2-CH_2-CH_3 \)

Step-by-step solution

Identify the number of carbon atoms and the position of the methyl group in each compound

In IUPAC nomenclature, the prefix 'meth-', 'eth-', 'prop-', 'but-', 'pent-', and 'hex-' indicates the number of carbon atoms in the parent chain. The number attached to the 'methyl' word represents the position of the methyl group attached to the carbon chain. a. 2-methylpropane: Here, 'prop-' is used, so there are 3 carbon atoms in the parent chain, and the methyl group will be attached to the 2nd carbon atom. b. 2-methylbutane: There are 4 carbon atoms in the parent chain, and the methyl group will be attached to the 2nd carbon atom. c. 2-methylpentane: There are 5 carbon atoms in the parent chain, and the methyl group will be attached to the 2nd carbon atom. d. 2-methylhexane: There are 6 carbon atoms in the parent chain, and the methyl group will be attached to the 2nd carbon atom.

Draw the structural formulas for each compound

Based on the identified carbon atoms and the position of methyl groups, we can draw the structural formulas as follows: a. 2-methylpropane: \( CH_3-CH(CH_3)-CH_3 \) b. 2-methylbutane: \( CH_3-CH(CH_3)-CH_2-CH_3 \) c. 2-methylpentane: \( CH_3-CH(CH_3)-CH_2-CH_2-CH_3 \) d. 2-methylhexane: \( CH_3-CH(CH_3)-CH_2-CH_2-CH_2-CH_3 \)

Key concepts

IUPAC Nomenclature

Understanding IUPAC Nomenclature is a fundamental part of organic chemistry. IUPAC stands for the International Union of Pure and Applied Chemistry, and the system created by this organization is universally used for naming chemical substances. The nomenclature makes it possible to write a unique name for every distinct compound, which reflects its structure and can also help deduce the structure from the name.

Functional groups, prefixes, infixes, and suffixes are the building blocks of this system. In our exercises with the methyl group, we start by identifying the longest continuous carbon chain to define the base name. Numbers are used to indicate the positions of substituents like methyl groups on the chain. For example, in the term '2-methylpropane', '2-' indicates the position, 'methyl' specifies the substituent, and 'propane' defines the three-carbon chain. The correct application of IUPAC rules enables consistent communication and avoids ambiguity in the chemical literature.

Methyl Group

A methyl group (—CH₃) is among the simplest of alkyl substituents in organic chemistry. It consists of one central carbon atom bonded to three hydrogen atoms. This structure is tetrahedral, following the general shape created by four atoms bonded to a central carbon atom.

In our textbook solutions, we've encountered the methyl group as a side chain, demonstrating its role as a substituent that can modify the properties and reactivity of molecules. It's important to note that the methyl group can be added to different carbon atoms within a chain, altering the compound's name and potential chemical behavior. Despite its simplicity, the presence of a methyl group can significantly impact a compound's solubility, boiling point, and reactivity, which is pivotal in fields like pharmaceuticals and materials science.

Carbon Chain Structure

The carbon chain of an organic molecule provides the backbone from which all other functional groups and atoms extend. The length and shape of this chain play a crucial role in determining the compound's properties. The simplest carbon chains are straight chains, where each carbon atom is connected to at most two others. Branched chains have at least one carbon atom attached to three or more other carbons.

In the provided exercises, the carbon chain structure varies in length but shares a common feature: they all contain a methyl group branching off from the second carbon atom. The prefix 'meth-', 'eth-', 'prop-', up to 'hex-' correspond to the number of carbon atoms in the main chain. Understanding this concept is key to deciphering the structures behind the names. The chain length affects physical properties such as the melting point and boiling point, and also influences how the molecule may interact with other substances.