Skip to main content

IUPAC naming of Alkenes and Alkynes.

Approximately 4 billion to 2.5 billion years ago a geological process began acting on the remains of plants and animals and as a result of such a long process occurring under layers of earth's crust, today we have fossil fuels. Coal, petroleum, natural gas, and crude oil are the fossil fuels which we use in our daily life in one or the other form and knowingly or unknowingly we have become slaves of this fossil fuels. 
Organic compounds such as alkanes, akenes, alkynes and polymers  also known as hydrocarbons, which are mainly derived from fossil fuels. This, hydrocarbons are the organic compounds majorly formed of hydrogen and carbon atoms. To know about IUPAC nomclature of alkanes you can check out my earlier blogs.
In this blog we will study alkenes and alkynes. Let's start:
Alkenes and alkynes are the hydrocarbon compounds with at least one double and triple bond respectively. 

Alkanes, Alkanes and Alkynes

Figure1.1

For example: we will see first member of alkene family, called Ethene and also known by a common name Ethylene. The simplest alkene, Ethene contains two adjacent carbon atoms bonded by double bonds and 4 hydrogen atoms of which two hydrogen atoms attached to each carbon atoms. And, thus the empirical formula for Ethene is C2H4.
The double bond between 2 carbon atoms is formed by sharing of 2 valence electrons from each carbon atom. The molecule ethene has a flat geometry because all carbon and hydrogen atoms in the molecule found to be in one plane.
A hydrocarbon having triple bond between two carbon atoms is called alkyne. For example we will see first member of alkyne called ethyne, in which two carbon atoms bonded by three covalent bonds and two hydrogen atoms of which 1 hydrogen atom attached to each carbon atom. Thus, empirical formula of ethyne is C2H2. The there covalent bonds formed between two carbon atoms of an alkyne is formed by sharing of 3 electrons from each carbon atom.(refer figure 1.1)
 
IUPAC naming of Alkenes and Alkynes:

we shall name the structural formula in the figure as follows:

IUPAC naming Of Alkenes.

Figure: 1.2

The IUPAC naming process can be divided into three steps:

No.1: We have to identify the longest carbon chain with double or triple bond in the given structure.(refer figure 1.3)

IUPAC naming of Organic compounds
Figure: 1.3

No.2:We have to start numbering the carbon atoms which are closest to the double or triple bond. Here in the figure double bond is nearer to the carbon from right. So we shall start numbering from left and the number of the first carbon of the two carbon bonded with double or triple bond, is used to give the location of the double or triple bond. In the figure the double bond happens to be on the 2 carbon atom and hence, 2-Pentene is the name of the longest carbon chain.
Alkenes or alkynes such as ethene or propene or ethyne having two or three carbon do not need as location of double bond is quiet predictable and obvious.(refer figure 1.4)

IUPAC naming of Organic compounds

Figure: 1.4

No.3: In the structure there is a branch of methyl group attached to the fourth carbon. Hence, we shall give the location and name of the substituent methyl group in the alphabetical order as a prefix to the name of alkene or alkyne.(refer figure 1.5)

IUPAC naming of Organic compounds

Figure: 1.5

On the basis of all above 3 steps the final name of the given structure is 4-methyl-2-pentene.

We have completed a full process of IUPAC nomenclature of a alkene or akyne.Hope you got the clear picture of how to name a hydrocarbon with double or triple bond. 
I would love to hear from you. Your each feed back would urge me to give you a better scientific content each time.

Comments

Post a Comment

Popular posts from this blog

IUPAC naming Of Aromatic Compounds

Definition of Aromatic Compounds: "Compounds containing benzene ring have distinctive fragrances. Hence, benzene family compounds are called Aromatic compounds . Example: Toluene, Aniline and Phenol". Figure 1.1 Long form of IUPAC: "International union of pure and applied chemistry". Aromatic compounds having benzene in their structural formula have been important in Chemistry. In the IUPAC naming of  aromatic compounds  common names of derivatives of benzene, such as Toluene, Aniline and Phenol, are used to name the whole compound. Figure  below shows the structure of Toluene, Aniline and Phenol: Let's see how these derivatives of benzene are named: No.1)   Figure 1.2 W hen benzene ring has only one substituent, there is no need of numbering. And as per IUPAC, first comes the name of substituent, followed by the common name  benzene. Example: Toluene, Aniline, and Phenol. No.2)   Figure 1.3 When benzene ring has more than one substituent, then, start ...
Post a Comment
Read more

Photosynthesis Timeline.

Process of photosynthesis with no if and but, without any doubt, will retain a position forever, among one of the most important chemical reactions occurring on the planet earth. Let's go through historical timeline of who, how and when, great people contributed to understand exactly what happens during Photosynthesis: In c350BC, Aristotle proposes plants, like animals, require food. In c300BC, Theophrastus writes that plants gets food through their roots. In 1450, Nicholas of cusa he proposes an experiment which he never performed, in which the plant is weighed and then planted in the weight amount of soil in the container. Plant, soil and applied water are weighed after a period of growth. He speculated this experiment will proove that the mass gained in the plant, is only due to water and not the soil. In 1648, Jean Baptist Van Helmont performs the experiment originally proposed by Nicholas Cusa, 200 years earlier. The experiment was performed on willow tree, which prooved that ...
Post a Comment
Read more