aromatic

In terms of molecular bonding and organic chemistry the term aromatic refers to the delocalisation of the electrons in the additional bonds of covalent double bonded carbon compounds such as benzene.

If there are two or more double bonds in a molecule and they correctly aligned (basically they are separated by one single bond and the double bonds are co-planar) then the bonding orbitals can overlap and the electrons can be delocalised over all the double bonds.

The bonds of the aromatic system are not single or double bonds but seem from length etc. to be a hybrid. This is particularly important as the aromatic double/single bonds are more stable than normal. This is because for them to react not only would the bond have to be broken but the extended aromatic system would have to be disrupted. This takes more energy. The best example of an aromatic compound is the ring compound benzene.

In botany, an aromatic refers to an oil that plants secrete. The compounds that were referred to as aromatics were originally investigated because many of them have a pleasant smell. Not all of these compounds, however, do.

All aromatics that plants have fit the definition of aromatic given above, that is, a benzene ring based structure. However, not all chemical aromatics are present in plants. Benzene, itself, for example, is not produced by any plant I know of.

Most aromatics are, of course, oil soluble due to the carbon ring structure. However, since many also have hydroxyl or corboxyl groups, some are also partly water soluble. The fact that most of these chemicals are relatively small with a single ring system and non-polar structure is what gives them their strong smell, because they diffuse into air very quickly. This is what seperates these essential oils from larger ring system fixed oils.

Most aromatics are or have been economically important for some reason or an other. Often this had to do with their aroma, such as in vanilla or peppermint, or sometimes to do with their medicinal value, as with aspirin.

Ar`o*mat"ic (#), Ar`o*mat"ic*al (#), a. [L. aromaticus, Gr. : cf. F. aromatique. See Aroma.]

Pertaining to, or containing, aroma; fragrant; spicy; strong-scented; odoriferous; as, aromatic balsam.

<-- p. 83 -->

Aromatic compound Chem., one of a large class of organic substances, as the oils of bitter almonds, wintergreen, and turpentine, the balsams, camphors, etc., many of which have an aromatic odor. They include many of the most important of the carbon compounds and may all be derived from the benzene group, C6H6. The term is extended also to many of their derivatives. -- Aromatic vinegar. See under Vinegar.

 

© Webster 1913.

---

Ar`o*mat"ic (#), n.

A plant, drug, or medicine, characterized by a fragrant smell, and usually by a warm, pungent taste, as ginger, cinnamon spices.

 

© Webster 1913.