The structural formula of 1,2-Dibromopentane is CH₂Br-CHBr-CH₂-CH₂-CH₃.
Understanding 1,2-Dibromopentane
1,2-Dibromopentane is an organic compound classified as a halogenated alkane. Its name provides specific details about its molecular composition and arrangement:
- Pentane: This root signifies a continuous chain of five carbon atoms, forming the molecule's backbone. A pentane chain typically has a molecular formula of C₅H₁₂.
- Dibromo: This prefix indicates the presence of two bromine (Br) atoms attached to the carbon chain.
- 1,2-: These numbers are locants, specifying the exact positions of the bromine atoms. In 1,2-Dibromopentane, one bromine atom is bonded to the first carbon atom, and the other is bonded to the second carbon atom of the pentane chain.
The molecular formula for 1,2-Dibromopentane is C₅H₁₀Br₂, which arises from the replacement of two hydrogen atoms in pentane (C₅H₁₂) by two bromine atoms.
Visualizing the Structural Formula
The structural formula vividly depicts the arrangement of atoms and the bonds between them within a molecule. For 1,2-Dibromopentane, the five carbon atoms are arranged linearly, with the bromine atoms specifically bonded to the initial two carbons.
Consider the steps to build its structure:
- Carbon Chain: Start with a 5-carbon backbone: C-C-C-C-C.
- Bromine Placement: Attach one bromine atom to the first carbon (C1) and another to the second carbon (C2).
- Hydrogen Saturation: Fill the remaining valencies of each carbon atom with hydrogen atoms to ensure each carbon forms four bonds.
Here are the common ways to represent its structural formula:
1. Expanded Structural Formula (Text Representation):
This representation shows all atoms and bonds, highlighting the connectivity:
H H H H H
| | | | |
H --- C - C - C - C - C --- H
| | | | |
Br Br H H H
In this simplified text representation, 'C' stands for carbon, 'H' for hydrogen, and 'Br' for bromine. Dashes represent single covalent bonds.
2. Condensed Structural Formula:
The condensed structural formula simplifies the drawing by grouping hydrogen and other atoms attached to each carbon atom:
CH₂Br-CHBr-CH₂-CH₂-CH₃
Breaking down this condensed formula:
- CH₂Br: The first carbon atom (C1) is bonded to two hydrogen atoms and one bromine atom.
- CHBr: The second carbon atom (C2) is bonded to one hydrogen atom and one bromine atom.
- CH₂: The third carbon atom (C3) is bonded to two hydrogen atoms.
- CH₂: The fourth carbon atom (C4) is bonded to two hydrogen atoms.
- CH₃: The fifth carbon atom (C5) is bonded to three hydrogen atoms.
Importance of Naming Conventions and Isomers
The "1,2-" locants are critical in organic nomenclature as they differentiate 1,2-Dibromopentane from its constitutional isomers. For instance, 1,3-Dibromopentane (CH₂Br-CH₂-CHBr-CH₂-CH₃) and 2,3-Dibromopentane (CH₃-CHBr-CHBr-CH₂-CH₃) would possess the identical molecular formula (C₅H₁₀Br₂) but exhibit distinct atomic arrangements, leading to different physical and chemical properties. This exemplifies the necessity of precise IUPAC (International Union of Pure and Applied Chemistry) naming in chemistry.
Summary of 1,2-Dibromopentane's Structure
A quick overview of the key structural features of 1,2-Dibromopentane:
Feature | Description |
---|---|
Parent Alkane Chain | Pentane (5 carbon atoms) |
Substituents | Two bromine (Br) atoms |
Positions of Bromines | One bromine on Carbon 1, one on Carbon 2 |
Molecular Formula | C₅H₁₀Br₂ |
Condensed Structural Formula | CH₂Br-CHBr-CH₂-CH₂-CH₃ |