Organic Chemistry- Some Basic Principles and Techniques

Chemistry for class 11 has this chapter named Organic Chemistry- Some Basic Principles and Techniques and it is very crucial for the students to score well in their examinations. Understanding the basics of organic chemistry will help them comprehend all the topics associated with it. In this article, we will cover some basic principles and techniques of Organic Chemistry in the simplest manner making it interesting.

Many entrance examinations such as IIT, NEET and other state board entrance tests will have MCQs on this chapter and all the students will get answers to the important questions after going through the organic chemistry some basic principles and techniques notes class 11 provided here.

What is Organic Chemistry?

• Organic Chemistry is a subset of chemistry dealing with compounds of carbon. Therefore, we can say that Organic chemistry is the chemistry of carbon compounds and is 200-225 years old. Carbon forms bonds with itself to form long chains of hydrocarbons, e.g.CH4, methane and CH3-CH3 ethane. Carbon has the ability to form carbon-carbon bonds quite elaborately. Polymers like polyethylene is a linear chain where hundreds of CH2 are linked together. 

• Carbon can form bonds with other elements of the periodic table such as with H, N, S, O, P and halogens. The compounds formed will also be called organic compounds.

• Lipids, DNA, proteins and carbohydrates also belong to the category of organic compounds which are essential for the sustenance of lives. 

• Vital Force Theory- It was proposed by the Swedish scientist named Berzelius in the year 1780. According to this theory, if you want to make an organic compound, you need to have a living system like a plant or animal. As earlier organic molecules were typically isolated from nature, plant material or animals or any other living organisms, this theory was believed to be in existence for several decades.

Organic Synthesis

(Making Organic compounds in the laboratory)

Later in the year 1828, another scientist named Frederich Wohler who performed a path-breaking experiment  to disprove this theory which stated that living organisms are necessary to produce organic compounds. 

1. The experiment included mixing NH4Cl + KCNO to get NH4CNO and upon heating the resulting compound, Urea was obtained. Urea is the first laboratory synthesized organic compound. This proved that there is no necessity of living organisms to synthesize organic compounds.

2. In 1885, Kolbe was involved in the synthesis of acetic acid (CH3COOH) also known as vinegar in the laboratory.

3. In 1856, Berthelot experimented to synthesise methane (CH4) from Aluminium Carbide (Al4C3) after undergoing hydrolysis. 

Importance of Organic Chemistry

Organic chemistry is applicable in a variety of areas including-

• Medicines: Example- Aspirin which is a headache medicine and Ibuprofen is a painkiller, both are organic compounds. Other examples include paracetamol.

• Food: Example- Starch which is a carbohydrate is an organic compound and a constituent of rice and other grains. It is the source of energy.

• Clothing: Example- Nylon, Polyester and Cotton are forms of organic compounds.

• Fuels: Examples- Gasoline, Petrol and Diesel are organic compounds used in the automobile industry at large.

Shapes of Organic Molecules

Organic molecules may be three dimensional (3D), two dimensional (2D) or one dimensional, depending upon the kind of carbon we are dealing with. 

As we already know that tetravalence of carbon and the formation of covalent bonds by it are talked in terms of its electronic configuration and the hybridisation of s and p orbitals. It can also be recalled that formation and the shapes of different molecules like methane (CH4), ethene (C2H4) and ethyne (C2H2) can be well explained in terms of the use of sp3, sp2 and sp hybrid orbitals by carbon atoms in the respective molecules. 

Hybridisation influences the bond length and bond enthalpy, also known as its strength in organic compounds. The sp hybrid orbital consists of more s character and hence it is closer to its nucleus; it forms stronger and shorter bonds than the sp3 hybrid orbital. The sp2 hybrid orbital is intermediate in s character, usually between sp and sp3 and,therefore, the length and enthalpy of the bonds it forms, are also intermediate between them. 

The alteration in hybridisation affects the electronegativity of carbon. The more the s character of the hybrid orbitals, the more is the electronegativity. Thus, a carbon atom with an sp hybrid orbital with 50% s character has higher electronegativity than that possessing sp2 or sp3 hybridised orbitals. This relative electronegativity is reflected in various physical and chemical properties of the molecules concerned. It will be covered in later chapters of Chemistry.

Further, NCERT books for Chemistry has covered many other topics such as classification of organic compounds, naming the compounds according to the IUPAC system of nomenclature, derivation of structures from their names, types of organic reactions, techniques of purification of organic compounds, etc. 

Students can add a few more sub topics from organic chemistry, some basic principles and techniques, notes from class 11 NCERT books. Also, they can refer to our NCERT solutions for the problems associated with this chapter.