Haloalkanes and Haloarenes

HALOALKANES

Alkanes such as methane, ethane, and others are coupled with one or more halogen molecules, such as chlorine or fluorine, to generate organic halides, which are known as haloalkanes (also recognized as alkyl aldehydes). They’re saturated organic compounds with one bond connecting all chemical bonds to a carbon atom and one carbon atom to a halogen atom. The radical halogenation process produces haloalkanes from aliphatic alkanes. They have no odour. In the SN2 exchange process, they precipitate. Example: Methyl chloride (CH₃Cl), Ethyl Bromide (CH₃CH₂Br), Trichloromethane(CHCl₃).

HALOARENES

Haloarenes are compounds in which one or more hydrogen atoms attached to the aromatic ring are changed by the halogen group. The design and properties of haloarenes differ from those of haloalkanes. This combination serves a variety of functions. Aryl chloride is one of the most important haloarenes. Haloarenes are formed when aromatic rings are directly halogenated. They have a pleasant aroma. They have no effect on SN2 mutations. Examples: Bromobenzene, chlorobenzene, Iodobenzene.

Haloalkanes and haloarenes are distinguished by the fact that haloalkanes are made from open-chain hydrocarbons (alkanes), whereas haloarenes are made from aromatic hydrocarbons.

TYPES OF HALOALKANES AND HALOARENES

The following criteria can be used to classify haloalkanes and haloarenes: 

1.sp2 hybridisation with a carbon halogen bond 

2. Hybridised carbon halogen bond sp3 

3.The number of halogen atoms in the molecule.

Based on the sp2 hybridised carbon halogen bond, the following classifications apply:

The halogen atom is bonded to the sp2 hybridised carbon, C=C, in vinyl halide.

Aryl Halide: In an aromatic ring, the halogen atom is bonded to the sp2 hybridised carbon.

Based on the sp3 hybridised carbon halogen bond, the following classifications apply:

Halogen is attached to the alkyl chain in the alkyl halide.

Allylic halide (C=C): the halogen atom is connected to the sp3 hybridised carbon, which is located next to the sp2 hybridised carbon.

The halogen atom is attached to the sp3 hybridised carbon bonded to a benzene ring in benzylic halides.

The number of halogen atoms determines the classification:

One halogen atom is present in mono haloalkanes and mono haloarenes.

Two halogen atoms are found in di haloalkanes and haloarenes.

Three halogen atoms are present in tri haloalkanes and tri haloarenes.

PREPARATION OF HALOALKANES

PREPARATION OF HALOARENES

PHYSICAL PROPERTIES OF HALOALKANES

Solubility

1.Despite the fact that haloalkanes are polar, they are only very marginally soluble in water.

2.Energy is necessary to overcome the attractions between haloalkane molecules and break the hydrogen bonds between water molecules in order for a haloalkane to dissolve in water.

3.However, because haloalkanes are unable to create hydrogen bonds with water, when new attractions are formed between the haloalkane and the water molecules, less energy is released because the new attractions are not as strong as the initial hydrogen bonds in water molecules.

4.As a result, haloalkanes have a low water solubility.

Density

1.Bromides and polychloro derivatives are heavier than water, while simple fluoro and chloroalkanes are lighter.

2.Densities continue to rise as the number of carbon atoms increases. Densities continue to rise as the number of halogen atoms increases. Fluoride, chloride, bromide, and iodide are the densities that rise in order.

3.The density of halogens increases as their number and atomic mass increase.

Boiling Point

1.Organic halogen compounds have polar molecules in general.

2.The intermolecular forces of attraction (dipole – dipole and van der Waals) between the molecules in halogen derivatives of alkanes are stronger due to their polarity and larger molecular mass than the parent hydrocarbon.

3.As a result, the melting and boiling temperatures of chlorides, bromides, and iodides are much higher than those of comparable molecular mass parent hydrocarbons.

4.The boiling points of alkyl chlorides, bromides, and iodides for the same alkyl group are in the order RI >RBr>RCl>RF, where R is an alkyl group. This is due to the fact that as the size of the halogen increases, so does the amplitude of the van der Waals force.

5.The boiling temperatures of chloro, bromo, and iodo compounds generally rise as the number of halogen atoms increases.

6.The boiling points of haloalkanes increase as the size of alkyl groups increases for the same halogen atom.

PHYSICAL PROPERTIES OF HALOARENES

•  Colorless liquids or crystalline solids are the most common types.
• They are more dense than water.
•  Haloarenes’ melting and boiling points
•  Haloarenes’ melting and boiling values are virtually identical to those of alkyl halides with the same amount of carbon atoms.
• The boiling points of monohalogen derivatives are in order of: Iodo>bromo>chloro>fluoro
• As the size of the aryl group rises, the melting and boiling temperatures for the same halogen atom increase.

CHEMICAL PROPERTIES OF HALOALKANES

Reaction with metal

CHEMICAL PROPERTIES OF HALOARENES

IMPACT ON ENVIRONMENT

Although haloalkanes and haloarene chemicals are used in a variety of industries, the poisons in them can be hazardous to the environment. Compounds like methyl bromide, for example, can be used to make fumigants that are extremely hazardous to the environment, such as chlorofluorocarbons (CFCs), which deplete the ozone layer.

CONCLUSION

Haloalkanes and haloarenes are hydrocarbons in which the hydrogen atoms have been replaced by halogen atoms. It’s vital to distinguish between haloalkanes and haloarenes because haloalkanes are made from open-chain hydrocarbons (alkanes) while haloarenes are made from aromatic hydrocarbons (haloarenes). This article taught us about haloalkanes and haloarenes, as well as their properties, nomenclature, categorization, and applications.