Density Functional Theory (DFT) Calculations on p-Tolunitrile
Density Functional Theory (DFT) Calculations on p-Tolunitrile
Blog Article
Introduction
In the ever-evolving field of organic chemistry, nitrile compounds play a crucial role due to their versatility and wide applicability. One such compound, p-Tolunitrile, also known as 4-methylbenzonitrile, stands out as a valuable intermediate in the synthesis of pharmaceuticals, agrochemicals, dyes, and specialty materials.
With a relatively simple aromatic structure and a reactive nitrile functional group, p-Tolunitrile serves as a gateway to more complex organic molecules. In this article, we’ll explore its chemical structure, physical and chemical properties, methods of synthesis, key applications, and safety considerations.
Chemical Identity and Structure
p-Tolunitrile is an aromatic nitrile derived from toluene, where a methyl group and a nitrile group (-CN) are substituted on the benzene ring in a para (1,4) position.
Basic Information:
Common Name: p-Tolunitrile
IUPAC Name: 4-Methylbenzonitrile
Chemical Formula: C₈H₇N
Molecular Weight: 117.15 g/mol
CAS Number: 104-85-8
Structure: A benzene ring with a methyl (-CH₃) group at position 1 and a nitrile (-CN) group at position 4 (para-position)
This para-substitution pattern gives p-Tolunitrile a symmetrical and relatively non-polar character, while still retaining high chemical reactivity due to the nitrile group.
Physical and Chemical Properties
Understanding the physical and chemical properties of p-Tolunitrile helps explain its behavior in chemical reactions and industrial processes.
Physical Properties:
Appearance: White to pale yellow crystalline solid
Boiling Point: ~218°C (424°F)
Melting Point: ~44°C (111°F)
Solubility: Slightly soluble in water, soluble in organic solvents like acetone, ethanol, and ether
Density: Approximately 1.01 g/cm³
Odor: Slight aromatic/nitrogenous odor
Chemical Properties:
The nitrile group is electron-withdrawing, making the molecule reactive toward nucleophilic attack, hydrolysis, and reduction.
The methyl group is electron-donating, which slightly activates the aromatic ring toward electrophilic substitution reactions.
The para-orientation influences reactivity and selectivity in substitution reactions, offering a controlled synthetic route.
Synthesis of p-Tolunitrile
There are multiple methods for synthesizing p-Tolunitrile, depending on the desired scale and available resources.
1. Ammoxidation of p-Xylene (Industrial Method)
This is the most widely used method in large-scale production. It involves the reaction of p-xylene with ammonia (NH₃) and oxygen (O₂) at elevated temperatures in the presence of a catalyst, usually a vanadium-molybdenum oxide.
Reaction:
This method is efficient, cost-effective, and suited for continuous production.
2. Sandmeyer Reaction (Laboratory Method)
This is a classical synthetic method used in the lab, starting from p-toluidine (4-methylaniline).
Steps:
Diazotization: p-Toluidine is treated with sodium nitrite (NaNO₂) and hydrochloric acid to form a diazonium salt.
Cyanation: The diazonium salt is then reacted with copper(I) cyanide (CuCN) to introduce the nitrile group.
Overall reaction:
This method is commonly used in academic research due to its precision and clean conversion.
3. Dehydration of Aldoximes
In this method, p-tolualdehyde is converted to its oxime derivative, which is then dehydrated using a reagent like phosphorus oxychloride (POCl₃) or thionyl chloride (SOCl₂) to yield p-Tolunitrile.
This is an alternative lab-scale method with good yields.
Applications of p-Tolunitrile
p-Tolunitrile serves as a core intermediate in the synthesis of more complex molecules across several industries.
Pharmaceuticals
Used in the synthesis of drug candidates, especially those containing nitrile groups.
Precursor for molecules with anti-inflammatory, antimicrobial, or anti-cancer activity.
Provides a foundation for heterocyclic chemistry.
Agrochemicals
Employed in the synthesis of selective herbicides, fungicides, and insecticides.
Helps create stable aromatic compounds that degrade slowly in environmental conditions.
Dye and Pigment Industry
Precursor for azo dyes, where its structure contributes to stable chromophores with enhanced lightfastness and color clarity.
Utilized in formulations of specialty pigments and textile dyes.
Polymers and Resins
The nitrile group contributes to chemical resistance and thermal stability in advanced polymer systems.
Used in resin formulations for coatings, adhesives, and high-performance plastics.
Laboratory Research
Frequently used in academic and industrial R&D for testing reactions like nucleophilic addition, Grignard reactions, and cross-coupling reactions.
Safety and Handling
While p-Tolunitrile is not highly toxic, it still requires standard laboratory safety procedures due to its flammability and potential to irritate the skin, eyes, and respiratory system.
Precautions:
Wear gloves, lab coat, and safety goggles.
Use in a well-ventilated area or fume hood.
Avoid inhalation or prolonged skin contact.
Store in tightly sealed containers away from heat or ignition sources.
Always consult the SDS (Safety Data Sheet) for full hazard information and emergency handling procedures.
Conclusion
p-Tolunitrile may appear to be a simple organic molecule, but its utility in modern chemistry is vast. Whether used as a synthetic intermediate for pharmaceuticals or a foundational compound in materials science, it demonstrates the power of well-designed aromatic chemistry.
Thanks to its symmetrical para-substitution, chemical stability, and reactive nitrile functionality, p-Tolunitrile offers an excellent balance of reactivity, selectivity, and industrial feasibility. Its importance continues to grow as chemistry moves toward more efficient, targeted synthesis strategies in pharmaceuticals, agrochemicals, and advanced materials.
Report this page