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

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

Organic Chemistry

What is Organic? The word organic is derived from the word Organism. Organic is something which is directly obtained from Nature or derivative of a nature. All Organic substances you will find are majorly formed of carbon and hydrogen. We all use organic substances/compounds such as all fossil fuels(diesel, petrol, gasoline, and natural gas), clothing, drugs, and cosmetics. What is an Organic Chemistry? Now, as you are well aware of the word Organic, it is easy for you to understand Organic Chemistry. Compounds containing carbon and hydrogen atoms are called Organic compounds. These organic compounds along with carbon and hydrogen may also contain oxygen and other non metallic elements such as Nitrogen, Sulphur, Halogens and Phosphorous in trace amounts. The branch of chemistry which studies properties, and reactions of organic compounds is called an Organic Chemistry. Carbohydrates, fats, proteins, caffeine, heroine, oxytocin, glucose, fructose, DNA, RNA, alcohols, Carboxylic acids an
Post a Comment
Read more

Alkanes

Alkanes: I have discussed definition of Organic compounds in my earlier blogs but still we will go through the definition once again. So, The organic compounds are the compounds containing carbon and hydrogen atoms. These organic compounds may also contain oxygen, sulphur, nitrogen, phosphorous, and halogens. Alkanes are the organic compounds formed of carbon and hydrogen, bonded only by single bonds. Carbon chain in alkanes contains only single bond and this is a unique characteristic which differentiates alkanes from other types of organic compounds. Let's see who are the members of alkane family in the figure as follows: You can see in the figure above all the condensed structural formulas of alkanes from Methane to Decane shows all carbons attached by single bond in a straight chain. But there are the type of alkanes with a structure having a branch or group(functional group) attached to such a single chain structure. Hence, keeping this in mind, structure of alkanes can be of
Post a Comment
Read more