An asymmetric carbon is a carbon atom that is attached to four different chemical elements to each other. In this structure, the carbon atom is in the center, linking the rest of the elements through it.
The bromochloro domethane molecule is a clear example of asymmetric carbon. In this case, the carbon atom is linked to the bromine, chlorine, iodine and hydrogen atoms, through unique bonds.
This type of formation is very common in organic compounds, such as glyceraldehyde, a simple sugar that is obtained as a product of the photosynthesis process in plants.
Characteristics of an asymmetric carbon
Asymmetric carbons are tetrahedral carbons that are connected to four different elements from each other.
This configuration is similar to a star: the asymmetric carbon functions as the core of the structure, and the rest of the components depart from it to form the respective branches of the structure.
The fact that the elements do not repeat each other gives this formation the connotation of asymmetric or chiral. In addition, certain conditions must be met in the constitution of the links, which are detailed below:
- Each element must be attached to the asymmetric carbon through a single bond. If the element were attached to carbon through a double or triple bond, then the carbon would no longer be asymmetric.
- If an asymmetric structure is attached twice to a carbon atom, the latter could not be asymmetric.
- If a chemical compound has two or more asymmetric carbons, the presence of chilarity is induced in the total structure.
Chilarity is that property that objects have of not overlapping with the image that it reflects in a mirror. That is, both images (real object versus reflection) are asymmetric to each other.
Consequently, if you have a pair of structures with asymmetric carbons, and each of their elements are equal, both structures cannot be superimposed on each other.
Furthermore, each structure is called an enantiomer or optical isomer. These structures have identical physical and chemical properties, they only differ in their optical activity, that is, the response they present to polarized light.
Examples
This type of structure is common in organic compounds such as carbohydrates, for example. They are also present in ethyl groups, as for example in the structure of -CH2CH3, -OH, -CH2CH2CH3, -CH3, and -CH2NH3.
Likewise, asymmetric carbons are also present in drugs, such as pseudoephedrine (C 10 H 15 NO), a drug used in the treatment of nasal congestion and pressure in the paranasal sinuses.
This nasal decongestant is made up of two asymmetric carbon atoms, that is, two formations whose center is given by the carbon atom, which, in turn, binds four different chemical elements together.
One of the asymmetric carbons is attached to the -OH group, and the remaining asymmetric carbon is attached to the nitrogen atom.
References
- Asymmetric Carbon, Sterioisomer and Epimer (nd). Recovered from: faculty.une.edu
- Barnes, K. (nd). What is an Asymmetric Carbon? - Definition, Identification & Examples. Recovered from: study.com
- Definition of asymmetric carbon atom (sf). Recovered from: merriam-webster.com
- Franco, M., and Reyes, C. (2009). Molecular Chirality. Recovered from: itvh-quimica-organica.blogspot.com
- Wikipedia, The Free Encyclopedia (2017). Asymmetric Carbon. Recovered from: es.wikipedia.org