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Toluic acid

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Identification
Molecular formula
C8H8O2
CAS number
118-90-1 (para-toluic acid); 99-04-7 (ortho-toluic acid); 99-05-8 (meta-toluic acid)
IUPAC name
2-methylbenzoic acid;3-methylbenzoic acid;4-methylbenzoic acid
State
State

All in solid state at room temperature with slight differences in crystal formation depending on the isomer. They are typically used in the form of white crystalline powders.

Melting point (Celsius)
110.00
Melting point (Kelvin)
383.15
Boiling point (Celsius)
275.50
Boiling point (Kelvin)
548.65
General information
Molecular weight
136.15g/mol
Molar mass
136.1490g/mol
Density
1.0461g/cm3
Appearence

2-Methylbenzoic acid: White to off-white crystalline powder.

3-Methylbenzoic acid: Also known as meta-toluic acid, appears as solid, white needles.

4-Methylbenzoic acid: Known as para-toluic acid, typically appears as a white crystalline solid.

Comment on solubility

Solubility of Methylbenzoic Acids

The solubility of 2-methylbenzoic acid, 3-methylbenzoic acid, and 4-methylbenzoic acid varies due to their structural differences. Here is a breakdown of their solubility characteristics:

  • 2-Methylbenzoic Acid (o-toluic acid):
    • Moderately soluble in water at room temperature.
    • Enhanced solubility in polar solvents.
  • 3-Methylbenzoic Acid (m-toluic acid):
    • Less soluble in water compared to o-toluic acid.
    • Soluble in organic solvents like ethanol and acetone.
  • 4-Methylbenzoic Acid (p-toluic acid):
    • Low solubility in water, typically needing heats to dissolve.
    • Highly soluble in non-polar organic solvents.

Factors influencing their solubility include:

  1. Functional Groups: The carboxylic acid group (-COOH) increases polarity.
  2. Molecular Structure: The position of the methyl group influences steric hindrance and solvation.
  3. Temperature: Generally, higher temperatures increase solubility for these compounds.

Overall, while methylbenzoic acids share a similar core structure, their solubility profiles demonstrate significant diversity influenced by their position and interactions with solvents.

Interesting facts

Interesting Facts about Methylbenzoic Acids

The methylbenzoic acids represent three isomers of a simple aromatic carboxylic acid, identified as 2-methylbenzoic acid, 3-methylbenzoic acid, and 4-methylbenzoic acid. Despite their similar names, each of these compounds exhibits unique properties and applications due to the different positions of the methyl group on the benzene ring. Here are some intriguing facts about each isomer:

1. Structural Distinctions

  • 2-Methylbenzoic Acid: Also known as o-toluic acid, it features the methyl group adjacent to the carboxylic acid group, influencing its reactivity and intermolecular interactions.
  • 3-Methylbenzoic Acid: Known as m-toluic acid, this compound has the methyl group positioned one carbon away from the carboxylic acid, leading to different physical properties compared to its ortho and para counterparts.
  • 4-Methylbenzoic Acid: Commonly referred to as p-toluic acid, the methyl group is opposite to the carboxylic acid group on the benzene ring, which results in unique solubility characteristics and reactivity patterns.

2. Applications in Industry

These acids play crucial roles in several industrial processes:

  • 2-Methylbenzoic Acid
  • : Used in the synthesis of flavoring agents and fragrances, exhibiting sweet and floral notes.
  • 3-Methylbenzoic Acid
  • : Employed in the production of pharmaceuticals and agricultural chemicals, demonstrating its importance in diverse sectors.
  • 4-Methylbenzoic Acid
  • : Often utilized as a precursor to various polymers and surfactants, showcasing its versatility in materials science.

3. Environmental Impact

While these acids have valuable industrial applications, it is important to consider their environmental effects:

  • Studies indicate that the biodegradability of methylbenzoic acids can vary, with implications for their persistence in the environment.
  • Monitoring of their presence in waste streams can aid in assessing the environmental footprint of manufacturing processes.

4. Interesting Reactions

Methylbenzoic acids can undergo various chemical reactions, enhancing their utility:

  • Decarboxylation: Under certain conditions, they can lose a carbon dioxide molecule, leading to the formation of substituted toluenes.
  • Esterification: Interaction with alcohols can produce esters, which are influential in the fragrance and flavor industries.

In summary, methylbenzoic acids are essential building blocks in organic chemistry, displaying diverse properties and applications that make them significant in both scientific research and industrial applications.

Synonyms
SCHEMBL15130012