Question

Write expanded structures showing the \(\mathrm{C}-\mathrm{C}\) bonds for each of the following condensed formulas. Name each substance by an accepted system. a. \(\left(\mathrm{CH}_{2}\right)_{10}\) (saturated compound only) b. \(\left(\mathrm{CH}_{2}\right)_{5} \mathrm{CHCH}_{3}\) (c) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}\left(\mathrm{CH}_{2}\right)_{6} \mathrm{CHC}_{2} \mathrm{H}_{5}\) d. The isomers of trimethylcyclobutane e. \(\left(\mathrm{CH}_{2}\right)_{6} \mathrm{CHCH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}_{2} \mathrm{CI}\) f. \(\left[\left(\mathrm{CH}_{2}\right)_{2} \mathrm{CH}\right]_{2} \mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{C}_{2} \mathrm{H}_{5}\)

Short answer

a. Expanded Structure: \( \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{3}\); IUPAC Name: decane. b. Expanded Structure: \( \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}= \mathrm{CH}\mathrm{CH}_{3}\); IUPAC Name: 7-methyl-1-heptene. c. Expanded Structure: \( \mathrm{CH}_{3}\mathrm{C}(\mathrm{CH}_{3})\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}= \mathrm{CH}\mathrm{CH}_{2}\mathrm{CH}_{3}\); IUPAC Name: 2,2-dimethyl-7-octene. d. Isomers of trimethylcyclobutane: 1,1,2-trimethylcyclobutane and 1,2,3-trimethylcyclobutane. e. Expanded Structure: \( \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}= \mathrm{CH}\mathrm{C}(\mathrm{CH}_{3})_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{Cl\); IUPAC Name: 9-chloro-2,7,7-trimethylnon-6-ene. f. Expanded Structure: \( \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{C}(\mathrm{CH}_{2}\mathrm{CH}_{3})\mathrm{C}(\mathrm{CH}_{2}\mathrm{CH}_{3})\mathrm(CH_{3})\); IUPAC Name: 2,2-bis(propan-2-yl)-1-ethyl-1-methylpropane.

Step-by-step solution

Draw the expanded structure

Since it's a saturated compound, there are ten carbon atoms connected in a single chain with single bonds (No double or triple bonds). \( \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{3}\)

Name the substance using IUPAC nomenclature

The name for the given compound is decane. b. \(\left(\mathrm{CH}_{2}\right)_{5} \mathrm{CHCH}_{3}\)

Draw the expanded structure

There are five carbon atoms connected with single bond followed by a carbon atom double bonded to another carbon atom which is bonded to a methyl group. \( \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}= \mathrm{CH}\mathrm{CH}_{3}\)

Name the substance using IUPAC nomenclature

The name for the given compound is 7-methyl-1-heptene. c. \(\left(\mathrm{CH}_{3}\right)_{2}\mathrm{C}\left(\mathrm{CH}_{2}\right)_{6} \mathrm{CHC}_{2} \mathrm{H}_{5}\)

Draw the expanded structure

Two methyl groups are bonded to one carbon atom, followed by six carbon atoms connected in a single chain. The next carbon is double bonded to another carbon, which has an ethyl group. \( \mathrm{CH}_{3}\mathrm{C}(\mathrm{CH}_{3})\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}= \mathrm{CH}\mathrm{CH}_{2}\mathrm{CH}_{3}\)

Name the substance using IUPAC nomenclature

The name for the given compound is 2,2-dimethyl-7-octene. d. The isomers of trimethylcyclobutane

Draw the expanded structures for isomers

Two possible isomeric structures for trimethylcyclobutane are: 1,1,2-trimethylcyclobutane:  1,2,3-trimethylcyclobutane:  e. \(\left(\mathrm{CH}_{2}\right)_{6} \mathrm{CHCH}_{2}\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}_{2} \mathrm{CI}\)

Draw the expanded structure

There are six carbon atoms connected in a single chain, followed by a carbon double bonded to another carbon, which is further bonded to two methyl groups and chloroethyl group. \( \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}= \mathrm{CH}\mathrm{C}(\mathrm{CH}_{3})_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{Cl}\)

Name the substance using IUPAC nomenclature

The name for the given compound is 9-chloro-2,7,7-trimethylnon-6-ene. f. \(\left[\left(\mathrm{CH}_{2}\right)_{2} \mathrm{CH}\right]_{2}\mathrm{C}\left(\mathrm{CH}_{3}\right) \mathrm{C}_{2} \mathrm{H}_{5}\)

Draw the expanded structure

Two propylene groups are bonded to a central carbon atom, which is further bonded to a methyl and ethyl group. \( \mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{C}(\mathrm{CH}_{2}\mathrm{CH}_{3})\mathrm{C}(\mathrm{CH}_{2}\mathrm{CH}_{3})\mathrm(CH_{3})\)

Name the substance using IUPAC nomenclature

The name for the given compound is 2,2-bis(propan-2-yl)-1-ethyl-1-methylpropane.

Key concepts

Expanded Structures

In chemistry, expanded structures provide a detailed view of the molecular arrangement in a compound. They show each carbon and hydrogen atom, along with the bonds connecting them. By displaying every single connection, you gain a better understanding of how atoms are arranged.

These structures can help you accurately determine the compound's properties and find its correct IUPAC name. For instance, if you look at the expanded structure for decane, it shows all ten carbon atoms linked in a continuous chain with single bonds, which is a hallmark of alkanes or saturated compounds. Understanding this helps in visualizing complex molecules and lays the groundwork for recognizing different types of bonds
in a compound.

Structural Isomers

Structural isomers are fascinating compounds that share the same molecular formula but differ in structural arrangements. They highlight how atoms can be put together in distinct ways to yield entirely different molecules.

Consider trimethylcyclobutane. Its isomers vary based on the positions of the methyl groups on the cyclobutane ring.
Here are a couple of examples:

• 1,1,2-trimethylcyclobutane
• 1,2,3-trimethylcyclobutane

These are distinct structures, each with unique properties despite having the same molecular formula. Understanding these differences is crucial
for predicting the reactivity and properties of the compounds.

Condensed Formulas

Condensed formulas are a streamlined way to represent molecules, saving space while retaining essential information. They emphasize the sequences of atoms without showing all individual bonds. For example, consider the formula data-laden compound: decane: \((\(\mathrm{CH}_{3}\)\)\mathrm...Here it is succinctly written as \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{3}\).

While comprehensively compact, condensed formulas might not always reveal...d bonding information compared to expanded structures. Therefore, expanded structures arean essential visual tool for chemists needing a complete picture of molecular form.

Saturated Compounds

Saturated compounds are characterized by having single bonds between carbon atoms, forming flexible, stable structures without room for additional bonds. Alkanes are a typical class of saturated compounds.

These compounds are fully "saturated" with hydrogen. In decane, each carbon atom forms four single bonds, filling all potential bond spaces.

The saturation provides specific properties:

• Relatively low reactivity compared to unsaturated compounds.
• Typically found in fuels due to their stable nature and energy release upon combustion.

Recognizing saturated compounds can help in deducing chemical behavior and potential reactions.