Problem 32 - Chemistry Matter and Change

Question

Draw structures for these alkyl and aryl halides. $$ \begin{array}{l}{\text { a. chlorobenzene }} \\ {\text { b. } 1 \text { -bromo-4-chlorohexane }} \\ {\text { c. } 1,2 \text { -difluoro-3-iodocyclohexane }} \\ {\text { d. } 1,3 \text { -dibromobenzene }} \\ {\text { e. } 1,1,2,2 \text { -tetrafluoroethane }}\end{array} $$

Step-by-Step Solution

Answer

The structures of the given alkyl and aryl halides are as follows: 1. Chlorobenzene: ``` Cl \ C=C-C=C-C=C | | | C-C=C-C=C-H | H ``` 2. 1-bromo-4-chlorohexane: ``` Br-CH2-CH2-CH2-Cl-CH2-CH3 ``` 3. 1,2-difluoro-3-iodocyclohexane: ``` I | F-C-C-F \ / \ C C | | C C \ / C ``` 4. 1,3-dibromobenzene: ``` Br Br \ \ C=C-C=C-C=C | | | C-C=C-C=C-H | H ``` 5. 1,1,2,2-tetrafluoroethane: ``` F F | | C-C | | F F ```

Step 1: Drawing chlorobenzene

Chlorobenzene is an aryl halide compound consisting of a benzene ring and a chlorine atom. In chlorobenzene, a hydrogen atom attached to the benzene ring is replaced by the chlorine atom. Representation: ``` Cl \ C=C-C=C-C=C | | | C-C=C-C=C-H | H ```

Step 2: Drawing 1-bromo-4-chlorohexane

This compound is an alkyl halide containing a bromine atom at the 1-position and a chlorine atom at the 4-position of a hexane chain (6 carbons). Representation: ``` Br-CH2-CH2-CH2-Cl-CH2-CH3 ```

Step 3: Drawing 1,2-difluoro-3-iodocyclohexane

This compound is a cyclohexane with two fluorine atoms at the 1,2-positions and an iodine atom at the 3-position. Representation: ``` I | F-C-C-F \ / \ C C | | C C \ / C ```

Step 4: Drawing 1,3-dibromobenzene

This compound is an aryl halide containing a benzene ring and two bromine atoms. In 1,3-dibromobenzene, two hydrogen atoms attached to the benzene ring are replaced by the bromine atoms at the 1,3-positions. Representation: ``` Br Br \ \ C=C-C=C-C=C | | | C-C=C-C=C-H | H ```

Step 5: Drawing 1,1,2,2-tetrafluoroethane

This compound is an alkyl halide containing a two-carbon chain and four fluorine atoms. In 1,1,2,2-tetrafluoroethane, hydrogen atoms in the ethane molecule are replaced by the fluorine atoms at the 1,1,2,2-positions. Representation: ``` F F | | C-C | | F F

Key Concepts

Chlorobenzene

Chlorobenzene is an important member of the aryl halides group. It is a simple compound where a benzene ring is bonded to a chlorine atom. In this compound, one hydrogen atom in the benzene ring is replaced by chlorine. This leads to chlorobenzene having the chemical formula \( C_6H_5Cl \). Because of the presence of the benzene ring, chlorobenzene exhibits unique properties such as stability, and is widely used in industrial processes.

• The benzene ring provides rigidity and a planar structure, contributing to chlorobenzene's chemical behavior.
• It is a colorless, volatile liquid and has a distinct almond-like odor.
• Used mainly as a solvent and in the manufacture of pesticides and dyestuffs.

Hexane Derivatives

Hexane derivatives, such as 1-bromo-4-chlorohexane, are part of the alkyl halide group. They involve the addition of halogens to a straight-chain alkane, like hexane, which contains six carbon atoms arranged in a linear fashion. For 1-bromo-4-chlorohexane, the structure includes a bromine atom at the first carbon and a chlorine atom at the fourth carbon.

• This positioning affects both the physical and chemical properties of the compound.
• These derivatives are used in organic synthesis and as intermediates in pharmaceuticals.

Hexane derivatives can exhibit diverse reactivities based on the types and positions of substituents, which alter properties like boiling points, and solubility.

Cyclohexane Derivatives

Cyclohexane derivatives, such as 1,2-difluoro-3-iodocyclohexane, involve halogens attached to a cyclohexane ring, which is made up of six carbon atoms in a hexagonal arrangement. This compound has two fluorine atoms on the 1 and 2 carbon positions and an iodine on the third.

• The 3D conformation of these derivatives can lead to interesting chemical behaviors.
• The cyclohexane ring can adopt different conformations like chair and boat, influencing reactivity patterns.

These derivatives are often utilized for their unique chemical properties and are key in synthesizing more complex molecules in chemical research.

Dybromobenzene

Dibromobenzene, specifically the 1,3-dibromobenzene form, belongs to the aryl halides where a benzene ring is bonded to two bromine atoms. In this structure, two hydrogen atoms on the benzene ring are replaced by bromines at the 1 and 3 positions, giving it a symmetrical layout.

• Dibromobenzenes are important compounds in organic synthesis and manufacturing.
• This symmetry and the positioning of bromines affect reactivity and physical properties.

As aryl halides, they are less reactive than alkyl halides and find use in creating polymers, agrochemicals, and dyes.

Tetrafluoroethane

1,1,2,2-Tetrafluoroethane is a common example of an alkyl halide obtained from ethane where hydrogen atoms are replaced by fluorine at specific positions, resulting in the compound \( C_2H_2F_4 \).

• This molecule is predominantly known as a refrigerant in cooling systems.
• Its chemical stability and low toxicity are attributes that make it suitable for such applications.

Because of the substituted fluorine atoms, its boiling and melting points differ significantly from those of ethane. This compound serves as an excellent illustration of how changing atoms in a molecule can dramatically influence its physical properties and usability in industry.