Derivatives of Benzene Handwritten Notes (Organic Chemistry 2)
Download comprehensive handwritten notes on Derivatives of Benzene for Organic Chemistry 2 (B.Pharm, 3rd Semester). This unit explores the three main types of benzene derivatives: monosubstitution, polysubstitution, and disubstitution derivatives, with detailed explanations. Access these essential chemistry notes as a PDF or view them online for free.
Keywords: benzene derivatives, handwritten notes, organic chemistry 2, B.Pharm, 3rd sem, monosubstitution, polysubstitution, disubstitution, benzene chemistry, download PDF, free notes, chemistry study material.
Detailed Notes on Derivatives of Benzene (Organic Chemistry 2, B.Pharm 3rd Sem)
This comprehensive set of handwritten notes provides an in-depth understanding of the Derivatives of Benzene, a core topic in Organic Chemistry 2 for B.Pharm students in their 3rd semester. Benzene, with its unique aromatic stability, undergoes various reactions to form a wide array of derivatives, each possessing distinct chemical and physical properties. These derivatives are broadly categorized based on the number and positions of substituents on the benzene ring.
Understanding Benzene Derivatives
A benzene derivative is formed when one or more hydrogen atoms on the benzene ring are replaced by other atoms or groups of atoms. The type and position of these substituents significantly influence the derivative's reactivity, physical state, and biological activity. These notes delve into the three primary classifications of benzene derivatives:
1. Monosubstitution Derivatives
Monosubstitution derivatives are formed when only one hydrogen atom of the benzene ring is replaced by a single substituent. In such cases, all six carbon atoms of the benzene ring are equivalent before substitution. Once a substituent is attached, the positions relative to this substituent are defined as ortho, meta, and para, though these terms are more relevant for disubstituted compounds. Examples of monosubstitution derivatives include:
- Toluene: Benzene with a methyl (-CH₃) group.
- Phenol: Benzene with a hydroxyl (-OH) group.
- Aniline: Benzene with an amino (-NH₂) group.
- Chlorobenzene: Benzene with a chlorine (-Cl) atom.
- Nitrobenzene: Benzene with a nitro (-NO₂) group.
These notes detail the nomenclature, general properties, and common methods of formation for these fundamental building blocks of aromatic chemistry.
2. Disubstitution Derivatives
Disubstitution derivatives are formed when two hydrogen atoms on the benzene ring are replaced by two substituents. When two identical or different substituents are present, their relative positions become crucial. These positions are designated using the prefixes:
- Ortho (o-): When the two substituents are on adjacent carbons (1,2-positions).
- Meta (m-): When the two substituents are separated by one carbon (1,3-positions).
- Para (p-): When the two substituents are on opposite sides of the ring (1,4-positions).
The notes provide detailed examples such as xylenes (dimethylbenzenes), dichlorobenzenes, and nitrophenols, explaining how the nature of the first substituent (whether it's an activating/deactivating group and ortho/para or meta director) influences the position of the second substituent in electrophilic aromatic substitution reactions. This section also explores isomerism (positional isomerism) in disubstituted benzenes and the practical implications for synthesis.
3. Polysubstitution Derivatives (or Trisubstitution and Higher)
Polysubstitution derivatives refer to benzene rings where three or more hydrogen atoms have been replaced by substituents. While the term "polysubstitution" often encompasses "disubstitution," it is particularly used for compounds with three, four, five, or six substituents. For trisubstituted benzenes, numerical positions (e.g., 1,2,3-trimethylbenzene) are typically used, or common names might exist. The relative positions of multiple substituents can lead to a greater number of isomers, making their nomenclature and synthesis more complex.
Examples include:
- 1,3,5-Trichlorobenzene
- Picric acid (2,4,6-trinitrophenol)
- Hexachlorobenzene
The notes elaborate on how the directing effects of multiple substituents interact to determine the outcome of further substitution reactions. This often involves considering the most activating group or the least hindered position. Understanding polysubstitution is vital for synthesizing complex organic molecules and predicting their properties.
By classifying and providing detailed insights into monosubstitution, disubstitution, and polysubstitution derivatives, these notes offer a clear and structured approach to mastering the rich chemistry of benzene derivatives, making them an indispensable resource for pharmacy students.
Info!
If you are the copyright owner of this document and want to report it, please visit the copyright infringement notice page to submit a report.
