Question

Give an acceptable name for each of the following structures. (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right)_{3}\) (b) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CH}_{2}\) (c) \(\mathrm{CH}_{3}-\mathrm{CH}-\mathrm{CH}-\mathrm{CH}_{3}\) \(\mathrm{CH}_{2}\) (d) \(\mathrm{CH}_{3} \mathrm{C} \equiv \mathrm{CCH}\left(\mathrm{CH}_{3}\right)_{2}\) (e) \(\mathrm{CH}_{3} \mathrm{CH}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right) \mathrm{CH}\left(\mathrm{CH}_{3}\right) \mathrm{CH}_{2} \mathrm{CH}_{3}\) (f) \(\mathrm{CH}_{3} \mathrm{CH}\left(\mathrm{CH}_{3}\right) \mathrm{CH}\left(\mathrm{CH}_{3}\right) \mathrm{CCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}=\mathrm{CH}_{2}\)

Short answer

(a) 2,2,2-trimethylpropane, (b) 2-methylpropene, (c) 2-methylbutane, (d) 4,4-dimethyl-2-butyne, (e) 4-ethyl-3-methylhexane, (f) 4,4-dimethyl-3-heptene

Step-by-step solution

Identify the Longest Carbon Chain

Identify the longest chain of carbon atoms in each molecule. This will form the base name of the compound.

Number the Carbon Atoms in the Chain

Number the carbon atoms in the main chain starting from the end nearest to the branch or functional group. If there's a branch at an equal distance from both ends, start from the end that will give the lowest number to the second substituent. This numbering is used to indicate the position of the substituents.

Identify and Name the Substituents

Identify any groups other than hydrogen attached to the main chain, these are called substituents. The name of the substituent is derived from the name of the alkane by replacing the ending '-ane' with '-yl'. If there are multiple identical substituents, use prefixes (di-, tri-, tetra-, etc.) to indicate the number of substituents.

Assemble the names

Assemble the names. List the substituents in alphabetical order (ignoring any numerical prefixes), follow it by the base alkane name. Use numerical prefixes to indicate the carbons to which the substituents are attached to.

Key concepts

Organic Chemistry

Organic chemistry is the branch of chemistry that focuses on the study of carbon-based compounds and their reactions. It's dubbed "organic" because the compounds studied often come from living organisms. However, it encompasses a wide range of molecules, including those synthesized in the lab.

Carbon is unique in its ability to form stable bonds with other carbon atoms, resulting in a vast variety of molecular structures. These structures can be simple straight chains, branched, or even cyclic and ring-shaped, leading to a rich diversity of organic compounds.

• The foundation of organic chemistry is the study of hydrocarbons, which only contain carbon and hydrogen atoms.
• The naming of these compounds follows a systematic method called IUPAC nomenclature, ensuring uniformity in the identification of compounds worldwide.
• Three major families of hydrocarbons are alkanes, alkenes, and alkynes, each differing in the type of carbon-carbon bonds they contain.
• Understanding the structure and naming of these hydrocarbons is essential for delving deeper into any organic chemistry topic.

Alkanes

Alkanes are the simplest type of hydrocarbon, composed only of carbon and hydrogen atoms linked exclusively by single bonds. This feature gives them the term "saturated hydrocarbons," indicating that all carbon atoms have the maximum number of hydrogen atoms attached to them.

In terms of structure, alkanes can be either linear or branched.

• The general formula for alkanes is \(C_nH_{2n+2}\), where \(n\) is the number of carbon atoms.
• They are named based on the number of carbon atoms in the longest continuous chain, using the suffix '-ane.' Common examples include methane (\(CH_4\)), ethane (\(C_2H_6\)), and propane (\(C_3H_8\)).
• For branched alkanes, the chains or substituents attached to the main chain must be identified and named. These are known as alkyl groups.

The systematic approach in organic chemistry requires numbering the main carbon chain from the end closest to any substituent, ensuring the lowest possible numbers are given to substituent locations.

Alkenes

Alkenes are another crucial class of hydrocarbons distinguished by the presence of at least one double bond between carbon atoms. This bond not only affects the chemical reactivity of these molecules but also their physical properties.

Due to the presence of the double bond, alkenes are classified as "unsaturated hydrocarbons," since the double bond means fewer hydrogen atoms are attached compared to alkanes.

• The general formula for an alkene is \(C_nH_{2n}\).
• Alkenes are named by identifying the longest carbon chain containing the double bond and ending the name with the suffix '-ene.'
• The position of the double bond is crucial and must be indicated in the name. Number the main chain from the end nearest the double bond.
• An example is ethene, commonly known as ethylene (\(C_2H_4\)), the simplest alkene, with widespread industrial uses.
• When more than one double bond is present, the compound is referred to as a 'diene' or 'triene,' depending on the number of double bonds.

Alkenes are vital in many chemical syntheses and serve as building blocks for polymers and other larger organic compounds.

Alkynes

Alkynes are a fascinating group of hydrocarbons defined by the presence of at least one triple bond between carbon atoms. This triple bond makes alkynes distinct in their reactivity and properties compared to other hydrocarbons.

The unique nature of the triple bond in alkynes also makes them "unsaturated hydrocarbons," like alkenes, meaning they do not have the full complement of hydrogen atoms.

• The general formula for alkynes is \(C_nH_{2n-2}\).
• Naming alkynes involves finding the longest chain of carbon atoms that includes the triple bond and affixing the suffix '-yne' to the root name.
• As with alkenes, it is important to number the chain from the end closer to the triple bond to minimize position numbers.
• An example of an alkyne is ethyne, commonly called acetylene (\(C_2H_2\)), which is used in welding torches due to its high temperature flame.
• Alkynes have roles in organic synthesis processes, especially as intermediates for complex molecular constructions.

Understanding alkynes and their behavior is vital for those studying chemical reactions and the synthesis of novel compounds.