What is a Dimer?

Dimers are basic organic compounds, which are derivates of oligomers. It is formed by the combination of two monomers which could potentially be strong or weak and in most cases covalent or intermolecular in nature. Identical monomers are called homodimer, the non-identical dimers are called heterodimer. The method by which dimers are formed is known as “dimerization”.

Introduction to Organic Chemistry

In organic chemistry, which is derived part of the general chemistry, the use of p-block elements such as carbon, oxygen, nitrogen, etc. is used extensively. Starting from defining the nomenclature of an organic compound to using those organic compounds in chemical reactions, organic chemistry plays a vital role in processing them. Nomenclature of a compound can be basically defined as identifying the parent hydrocarbon chain, along with similarly identifying the parent functional group, if any, with the highest order of precedence, and lastly identifying the side-chains present in the compound. Hydrocarbons are those organic compounds that comprise of generally of hydrogen and carbon in them.

Classification of Organic Compounds

Organic Compounds are further branched into many different functional groups. The factorial idea on categorizing these compounds into functional groups is of prime importance in organic chemistry, which acts for classifying organic structures along with their determination of properties. A functional group is regarded as a cluster of different small molecular compounds, along with the reactive behavior with an exact similar number of molecules. Functional groups are further classified based on their attachment of different organic compounds along with the type of bonds to which they are attached. Groups such as “Aliphatic Compounds”, “Aromatic Compounds”, “Heterocyclic Compounds”, “Biomolecules” and “Polymers” are some of the major branches in which functional groups are classified. Dimer and Properties of Dimer, its types, and Applications Falls under the “Biomolecules” branch of the Organic Compounds.


Biomolecules are an important topic in organic chemistry which is more often analyzed and studied by biochemists in the world. Many complex multi-functional group molecules play a significant role as living organisms. Out of which some are termed to be the long-chain biopolymers, which consist of peptides, terpenoids, DNA, RNA, dimers, D-dimers along polysaccharides factors such as starch in animals and cellulose in plants. Secondly, functional groups such as amino acids (which are the prime source building blocks for peptides and proteins), carbohydrates (these comprise of large monomer type molecules which contain many single and double bonded structures known to be as saccharides), the nucleic acids (which are used for the preparation of structures like DNA), and the lipids. Therefore, Biochemistry is segregated into, animal biochemistry and micro-biochemistry.

Carboxylic Acids

Carboxylic acid is termed to be an organic compound categorized under the functional groups as acids. It comprises a carboxyl group (-COOH) attached to an alkyl group. Therefore, after stating the nomenclature and structure, the general organic formula of an organic carboxylic acid is R-COOH or R-COOH, with R meaning to be any alkyl or aromatic functional group. Carboxylic acids generally have higher boiling points than hydrocarbons compounds like water, which is because of their increase in surface area and their property to form stabilized dimers by hydrogen bonds. When two carboxylic acids react with each other at usually high operating conditions, they form an intermediate called Dimer.

" Structure of carboxylic acid dimer"


A Monomer is a molecule that forms the basic unit for any additional reaction involving large molecules, which can be polymers, acids, biomolecules, etc. They are thus, formed by the organic combination of two like or different carboxylic acids which are oppositely charged in nature. It can be observed that the two monomers which are used as reagents can be weak or strong in nature and also can be bonded by covalent (forces that bond carbon molecules) or by intermolecular forces (forces that bond all other molecules together), respectively. D-Dimers are one of the major clinical bifurcations of dimers. Along with covalent and non-covalent dimers, D-dimers also play a very significant role in dimers applications.


Fibrin which can also be termed as Factor (I-A) can generally be expressed as a non-globular and fibrous protein that is consumed in the blood clotting process. Consequently, the formation of fibrin is carried out through the action of protease thrombin on fibrinogen (a globular sub-protein), as a result of which it polymerizes. Further, the clinically polymerized fibrin, along with platelets, in a wound site creates a hemostatic plug or clot around to cover it. Subsequently, in a condition of the large generation of fibrin on to activating a cascade made out of coagulation further guides it deep vein thrombosis along with a vessel blockage (often regarded as a negative result) followed by agglutination of RBCs, platelets, polymerized fibrin, and similar components. Unsuccessful creation or premature clinical lysis of fibrin alleviates the occurrence of getting a hemorrhage.

Types of Dimers

While adding two carboxylic acids, if the two molecules i.e., acids are identical in nature, then the resulting dimer is termed as a “Homodimer”. Similarly, when the two carboxylic acids are not the same or are different in nature, the resulting dimer is termed as “Heterodimer”.


Clinically, D-Dimer is rather termed as a degradation product from a protein called Fibrin, which is a tiny protein bit present in the blood, which results in a formation of a blood clot which is then mortified by a process called fibrinolysis. The compound got its nomenclature from two D fragments (Dimers of D-Branches, that’s why the name D-Dimers) of the fibrin protein-coupled through a cross-linking structure. The concentration of D-Dimer can be computed by a blood test on assisting to verify deep vein thrombosis. As it was established in the late medieval era, this has taken its position of significance as an important test that is to be performed in patients with conjectured deep vein thrombotic disorders. If the test result turns out to be negative thrombosis is sacked out, while a positive result could potentially confirm the presence of deep vein thrombosis but does not eliminate other vital causes. Therefore, the pivotal utilization of this is to exculpate thrombolytic and thromboembolic disorders, respectively.

The level of D-dimer is found to be increased in conditions such as deep vein thrombosis (DVT), pulmonary embolism (PE). In DVT and PE, there occurs blood clots in the vessels due to the D-dimer factor. Thus, this factor is considered as a diagnostic biomarker for the detection of pulmonary embolism and DVT.

Covalent and Noncovalent Dimers

Covalent dimers are those which are found as a result of two identical monomers (heterodimers). Let’s take an example

2Y gives Y-Y

In the above reaction, monomer Y is said to dimerize to give the dimer Y-Y. Also, the above 2Y is formed by adding two monomers and creating such two compound monomers. Also, many non-metallic elements form as dimers, which are likely hydrogen, nitrogen, and halides. Noncovalent dimers are those which are found as a result of two different monomers (homodimers). Let’s take the example of dimerization of acetic acid. In the process of dimerization of acetic acid, two molecules of acetic acid dimerize to give a dimer of acetic acid. The dimer structure of acetic acid is given as,

" Dimer of acetic acid"

Common Mistakes

While adding the dimer, note that a check on its nomenclature should be made, so as to avoid any extra addition of carbon or hydrogen molecule. Also, while categorizing the dimers, ensure the monomers are the same or different, or else it will lead to negative results. If they are the same, they come under homodimers, if they are different, they come under, heterodimers. Make sure take the positive formation of intermediates after which the dimer is formed is correctly structured, otherwise, if negative formation if taken would hamper the structure of the dimers. For example, the removal of water molecules should be done correctly without leaving any room for negativities, so as to get the correct dimer for carboxylic acids.

 Context and Applications

 This topic is significant in the professional exams for both undergraduate and graduate courses, especially for;

Bachelors and Masters Chemistry, Biochemistry and Organic Chemistry.

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