Key Difference – Aniline vs Acetanilide
Aniline and Acetanilide are two benzene derivatives with two different functional groups. Aniline is an aromatic amine (with –NH2 group), and acetanilide is an aromatic amide (with –CONH- group). The difference in their functional group leads to other subtle variations in physical and chemical properties between these two compounds. They are both used in many industrial applications, but in various fields for different purposes. The key difference is that, in terms of basicity, acetanilide is much weaker than aniline.
What is Aniline?
Aniline is a benzene derivative with the chemical formula of C6H5NH2. It is an aromatic amine also known as aminobenzene or phenylamine. Aniline is a colorless to brown liquid with a characteristic pungent odor. It is a flammable, slightly water soluble and it is oily. Its melting point and boiling point are is -6 0C and 1840C respectively. Its density is higher than that of water, and the vapor is heavier than air. Aniline is considered as a toxic chemical and causes harmful effects through skin absorption and inhalation. It produces toxic nitrogen oxides during combustion.
What is Acetanilide?
Acetanilide is an aromatic amide with the molecular formula C6H5NH(COCH3). It is an odorless, white to gray flake solid or a crystalline powder at room temperature. Acetanilide is soluble in few solvents including hot water, alcohol, ether, chloroform, acetone, glycerol, and benzene. Its melting point and boiling point are 114 0C and 304 0C respectively. It can undergo self-ignition at 545 0C, but stable under most of the other conditions.
Acetanilide is used in several industries for different purposes; for example it is mainly used as intermediates in the synthesis of pharmaceuticals and dyes, as an additive in hydrogen peroxide, varnishes, and cellulose ester. Also, it is used as a plasticizer in the polymer industry and as an accelerator in the rubber industry.
What is the difference between Aniline and Acetanilide?
Structure:
Aniline: Aniline is an aromatic amine; a –NH2 group is attached to the benzene ring.
Acetanilide: Acetanilide is an aromatic amide with a –NH-CO-CH3 group attached to the benzene ring.
Uses:
Aniline: Aniline has several industrial applications. It is used to prepare other chemical substances such as photographic and agricultural chemicals, polymers and in dye industry and rubber industry. In addition, it is also used as a solvent and an antiknock compound for gasoline. It is also used as a precursor in manufacturing penicillin.
Acetanilide: Acetanilide is mainly used as an inhibitor of peroxides and as a stabilizer for cellulose ester varnishes. Also, it is used as an intermediate for the synthesis of rubber accelerators, dyes and dye intermediate and camphor. In addition, it is used as a precursor in penicillin synthesis and other pharmaceuticals including painkillers.
Basicity:
Aniline: Aniline is a weak base that reacts with strong acids producing anilinium ion (C6H5-NH3+). It has a much weaker base comparing to the aliphatic amines due to the electron withdrawing effect on the benzene ring. Despite being a weak base, aniline can precipitate zinc, aluminum, and ferric salts. Moreover, it expels ammonia from ammonium salts upon heating.
Acetanilide: Acetanilide is an amide, and amides are very weak bases; they are even less basic than water. This is due to the carbonyl group (C=O) in amides; C=O is a strong dipole than N-C dipole. Therefore, the ability of N-C group to act as H-bond acceptor (as a base) is restricted in the presence of a C=O dipole.
Image Courtesy:
1. Aniline By Calvero. (Selfmade with ChemDraw.) [Public domain], via Wikimedia Commons
2. Acetanilide By Rune.welsh at English Wikipedia [Public domain, GFDL, CC-BY-SA-3.0 or CC BY 2.5], via Wikimedia Commons
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