Preparation Methods

Hydrocarbons are organic compounds that compose two different kinds of atoms, including hydrogen and carbon. These are generally colourless and possess a weak odour. They belong to one of the major branches of Chemistry is organic chemistry which mainly revolves around structures, properties, and reactions of organic compounds with covalent bonds and carbon atoms. There are several methods considered to prepare hydrocarbons which we will be discussing today. But moving directly onto the preparation methods would be unfair; therefore, here is the brief introduction of hydrocarbons and alkanes. 

What are hydrocarbons? 

Hydrocarbons can be defined as organic compounds which are formed of primarily two essential atoms. These include hydrogen and carbons. Generally, these are colourless gases with nearly no odour. Based on their types, hydrocarbons may possess simple or complex structures. In everyday life, hydrocarbons play a significant role, and their study provides a deep insight into the properties and preparation of its functional groups.  

Further, hydrocarbons are divided into six major categories including Saturated hydrocarbons, Unsaturated hydrocarbons, Cycloalkanes, Aromatic hydrocarbons, Aliphatic hydrocarbons, and Alicyclic hydrocarbons. 

What are Alkanes? 

Alkanes are referred to as an organic compound which possesses the single-bonded hydrogen along with carbon compounds. It is further divided into three major groups, including cycloalkanes, branched alkanes, and chain alkanes. CnH2n+2 is the formula of Alkanes.

Here is the list of alkanes along with their molecular formula – 

Preparation of Alkanes

As mentioned earlier, alkanes are saturated hydrocarbons which means they are hydrocarbons whose carbon atoms are closely bonded to different sets of carbon atoms with the sigma bonds only. In alkanes, the first four members, starting from C1 to C4, are gases only, whereas from C5 to C17, they are liquids. Whereas those which have 18 and more than that are solids. They do not hold any colour or odour and are prepared in several industries using different techniques. 

Preparation of Alkanes from the unsaturated hydrocarbon

From alkenes and alkynes

To prepare alkane from alkene and alkyne, the process called hydrogenation is used. Here, the dihydrogen gas is mixed with alkynes and alkenes to the catalyst, which is like palladium and nickel to form alkanes. Because of the presence of nickel, the reaction occurs at an increased temperature. Whereas, in the case of palladium, the reaction occurs at room temperature only.

Preparation of Alkanes from alkyl halides

Alkanes can be prepared through two major ways. These are as follows – 

1. Another method to prepare alkanes through alkyl halides is called the Wurtz reaction. In the dry ethereal solution, when alkyl halides are treated with sodium metal, the alkanes production is more. With even carbon numbers, higher alkanes can be achieved. Here is the chemical equation for the same 

CH3-Br + 2Na + Br-CH3 → CH3-CH3 + 2NaBr

2. All alkanes, excluding fluorides, are prepared from the alkyl halide through reduction with dilute hydrochloric acid and zinc. Here is the chemical equation for the same 

CH3-Cl + H2 → CH4 + HCl

Preparation of alkanes from carboxylic acids

There are two means through which the alkanes can be prepared from the carboxylic acid. These are as follows – 

1. To prepare alkanes from the carboxylic acid, carbon dioxide is removed. This process is called decarboxylation. The alkane is produced with less amount of carbon atoms which are present in the carboxylic acid. Here is the chemical equation for the same –

2. In Kolbe’s electrolytic method, the method of electrolysis of potassium salt or sodium of carboxylic acid is used to produce alkane. This reaction was named after Rudolf Schmitt and Hermann Kolbe. Here is the chemical equation for the same – 

Concept of Hydrogen Bonding 

Hydrogen bonding can be described as the process of forming hydrogen bonds that are an attractive intermolecular force’s special class which arises because of the dipole-dipole interaction between the hydrogen atom and highly electronegative atom. There are mainly two types of hydrogen bonding including – 

• Intramolecular Hydrogen Bonding

• Intermolecular Hydrogen Bonding

Explain the Clemmensen’s Reduction

Clemmensen’s reduction is the reaction that is used for reducing ketones or aldehydes to the alkanes taking use of zinc amalgam and hydrochloric acid. This reaction is named after Erik Christian Clemmensen, a Danish chemist. 

Conclusion 

With this, we come to an end to our today’s topic, preparation methods. In today’s modern life, it is nearly impossible to overstate the uses or the importance of hydrocarbons. Many times, hydrocarbons are referred to as the driving force of western civilisation, which means they open doors for new, unexplored innovations. On the other hand, alkanes are organic compounds that possess single-bonded hydrogen and carbon compounds. 

To prepare Alkane from alkene and alkyne, the process called hydrogenation is used. There are two ways to prepare alkanes through alkyl halides. Firstly, through reduction with dilute hydrochloric acid and zinc. Another one is called the Wurtz reaction. In the end, we also discussed the preparation of alkanes from carboxylic acids and a brief explanation about hydrogen bonding. We hope this study material and preparation methods have helped you attain a better understanding of the concept of preparation of alkanes.