Difference Between Aniline and Acetanilide

Main Difference – Aniline vs Acetanilide

Aniline and acetanilide are nitrogen-containing organic compounds. They have very different chemical and physical properties. Aniline has many uses in different industries. Aniline is an aromatic amine since it is composed of a phenyl group attached to an amine group. Acetanilide is an aromatic amide. It is very weak base, and the basicity is even less than water. It is a solid compound at room temperature. The major production process of acetanilide involves the reaction between acetic anhydride and aniline. The main difference between aniline and acetanilide is that aniline is a yellowish brown oily liquid at room temperature whereas acetanilide is a white to gray solid compound.

Key Areas Covered

1. What is Aniline
     – Definition, Chemical Properties, Production
2. What is Acetanilide
     – Definition, Chemical Properties, Production
3. What is the Difference Between Aniline and Acetanilide
     – Comparison of Key Differences

Key Terms: Acetanilide, Acetic Anhydride, Amide, Amine Group, Ammonia, Aniline, Antifebrin, Benzenamine, Chlorobenzene, Diazonium Salts, Hydrogenation, Nitrobenzene, Nitrogen, N-Phenylacetamide

What is Aniline

Aniline is a nitrogen-containing organic compound having the chemical formula C₆H₇N. It is composed of a phenyl group bonded to an amine group. Since it is composed of a benzene ring, aniline is an aromatic compound. One of the major uses of aniline includes its use as a precursor for the production of polyurethane.

The molar mass of aniline is 93.129 g/mol. Aniline is the preferred IUPAC name given for this compound but the systemic IUPAC name is benzenamine. At room temperature, aniline is a yellowish brown liquid. It is an oily liquid with a pungent odor. The melting point of aniline is -6 °C and the boiling point is 184.1 °C.

Aniline is a planar molecule. It is a weak base due to the presence of a lone pair on the nitrogen atom. Aniline is industrially produced via catalytic hydrogenation of nitrobenzene. When producing aniline, nitrobenzene is first produced from benzene nitration using a mixture of nitric acid and sulfuric acid at 50-60^oC. Then nitrobenzene is hydrogenated in the presence of a metal catalyst.

Figure 1: Aniline Production from Nitrobenzene

The reaction between ammonia and chlorobenzene is another method for the production of aniline. The reaction is as follows. Here, specific temperature and pressure conditions are required.

Figure 2: Aniline Production from Chlorobenzene

Since aniline is a weak base, it can form salts from the reactions between aniline and mineral acids. In the acidic medium, diazonium salts can be produced from aniline by the reaction between aniline and nitrous acid. Diazonium salts are very important components for many dye productions.

What is Acetanilide

Acetanilide is an amide having the chemical formula C₈H₉NO. At room temperature, it is an odorless solid compound. It has a white to gray color. Acetanilide has a slight burning odor. It has a leaf-like appearance.

Figure 3: Chemical Structure of Acetanilide

The molar mass of acetanilide is 135.166 g/mol. The melting point of acetanilide is 114.3^oC and the boiling point is 304^oC. The IUPAC name of this compound is N-Phenylacetamide. The trade name of acetanilide is Antifebrin.

Acetanilide can be produced by the reaction between acetic anhydride and aniline. But when producing, the reaction should be carried out under a fume hood because aniline is toxic and can be absorbed through the skin.

C₆H₅NH₂ + (CH₃CO)₂O → C₆H₅NHCOCH₃ + CH₃COOH

Difference Between Aniline and Acetanilide

Definition

Aniline: Aniline is a nitrogen-containing organic compound having the chemical formula C₆H₇N.

Acetanilide: Acetanilide is an amide having the chemical formula C₈H₉NO.

Physical State

Aniline:  At room temperature, aniline is an oily liquid.

Acetanilide: At room temperature, Acetanilide is a white to grey solid.

Molar Mass

Aniline: The molar mass of aniline is 93.129 g/mol.

Acetanilide: The molar mass of acetanilide is 135.166 g/mol.

Category

Aniline: Aniline is an amine.

Acetanilide: Acetanilide is an amide.

Melting Point and Boiling Point

Aniline: The melting point of aniline is -6 °C and the boiling point is 184.1 °C.

Acetanilide: The melting point of acetanilide is 114.3^oC and the boiling point is 304^oC.

Production

Aniline: Aniline can be produced from nitrobenzene or chlorobenzene.

Acetanilide: Acetanilide is produced from aniline.

Basicity

Aniline: Aniline is a weak base.

Acetanilide: Acetanilide is a very weak base.

Conclusion

Aniline and acetanilide are aromatic organic compounds. Both these compounds are basic compounds but acetanilide is very weakly basic than aniline. The main difference between aniline and acetanilide is that aniline is a yellowish brown oily liquid at room temperature whereas acetanilide is white to gray solid compound.

Reference:

1. “ANILINE.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.
2. “Aniline.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 26 Sept. 2013, Available here.
3. Lancashire, Robert John. The preparation of acetanilide from aniline, Available here.

Image Courtesy:

1. “Aniline production” By Navstar at English Wikipedia – Transferred from en.wikipedia to Commons. (Public Domain) via Commons Wikimedia
2. “Aniline from Chlorobenzene” By Michał Sobkowski – Own work (Public Domain) via Commons Wikimedia
3. “Acetanilide” By Rune.welsh at English Wikipedia – Own work (Public Domain) via Commons Wikimedia