Main Difference – Aromatic vs Aliphatic Compounds

Both Aromatic and Aliphatic Compounds refer to the main forms of organic chemical compounds, and they are primarily composed of Carbon and Hydrogen. The main difference between Aromatic and Aliphatic Compounds is that Aromatic compounds contain an aromatic ring which is a typical benzene ring whereas aliphatic compounds are simply the organic chemical compounds which do not contain an aromatic ring.

What are Aromatic Compounds

As mentioned above, aromatic compounds have a distinct aromatic ring which makes it different to other chemical compounds. This aromaticity arises due to the ‘benzene ring’. This is a typical chemical structure that contains six Carbon atoms, cyclically bonded with alternating double bonds. This system possesses unique characteristics and makes aromatic compounds behave very differently in chemical reactions than other chemical compounds. The nature of alternating double bonds is known as ‘conjugation’. It is because of conjugation that aromatic compounds are able to exhibit very different reaction mechanisms.

Compounds with a benzene ring are considered to have high potential. They are able to sustain additional charges by making them migrate around the ring system. However, the structure of the benzene ring is more complicated than it seems. It has been proven through experiments that the bonds between the six Carbon atoms are neither single bonds nor double bonds but have intermediate characteristics. The benzene ring is a planar structure as opposed to many other chemical compounds. But when an additional group is bound to the benzene ring, the entire structure would fall out of the plane. Some common examples of aromatic compounds are; benzene, toluene, xylene, aniline, etc.                                                                                                                                                                                                                

What are Aliphatic Compounds                                       

These compounds are the other class of organic chemical compounds which do not have a benzene ring in its structure. Aliphatic compounds can either be linear or cyclic. The Carbon atoms that take part in the formation of aliphatic compounds can have a mix of single, double or triple bonds between them. This means that they can be saturated or unsaturated. The term ‘saturated’ refers to the completion of bonding around Carbon atoms by H atoms, where the Carbons atoms are only bound through single bonds. Whenever there is a double or triple bond between the Carbon atoms, it cannot fulfil its bonding with H atoms as the bonding space has already been taken by the neighbouring Carbon atom, and these are called ‘unsaturated’ compounds.

Linear aliphatic compounds are often not planar in structure, and only some cyclic aliphatic compounds are planar in nature. In general, the linear aliphatic compounds are more stable and freely available than the cyclic aliphatic compounds. The reason for this is the high ring strain present in the cyclic aliphatic compounds. Halogens are the most common type of foreign group of elements that form side chains and side groups with aliphatic compounds. It is often easier to subject aliphatic compounds to a chemical reaction than the aromatic compounds.

Difference Between Aromatic and Aliphatic Compounds

Definition

Aromatic compounds contain an aromatic ring or ‘benzene ring’.

Aliphatic compounds are organic chemical compounds without benzene rings.

Reactions

Aromatic compounds need special conditions to react.

Aliphatic compounds react more freely and easily.

Types

Aromatic compounds are always cyclic as it contains the benzene ring as part of its structure.

Aliphatic compounds can be linear as well as cyclic.

Saturation Potential

Aromatic compounds are always unsaturated.

Aliphatic compounds can be saturated as well as unsaturated.

Conjugation

In aromatic compounds, the benzene ring is conjugated due to the presence of alternating double bonds.

The majority of aliphatic compounds are not conjugated.

Image Courtesy:

“Benzene-aromatic-3D-balls” by Benjah-bmm27 – Own work. (Public Domain) via Commons

“Butane 3D ball” by Jynto (talk) – Own workThis chemical image was created with Discovery Studio Visualizer.. (CC0) via Commons

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