Notes on Introduction of organic chemistry, classification of organic compounds | Grade 11 > Chemistry > Fundamental Principles of Organic Chemistry | KULLABS.COM

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### Introduction to organic chemistry

Almost all the substances that we come across in our daily life are chemical substances. Example: food like carbohydrates, fat, vitamins etc. things like steel, wood, glass, gold etc. Natural source of these chemical substances could be plants and animals or minerals and rocks. Depending upon the natural source chemical substances can be classified into two types:

1. The organic compound is those that are obtained from living plants and animals.
2. The inorganic compound is those that are obtained from a non-living source like minerals rocks.

Study of these organic compounds is known as organic chemistry.

Inorganic compound such as sodium chloride can be easily prepared in lab with the help of its constituent element as follows:

$$Na + Cl_2 \longrightarrow 2 NaCl$$

However, organic compounds such as ethyl alcohol cannot prepare in this way. It was concluded that organic compounds cannot be prepared in the lab. They are prepared in the body of living plants and animals. This led to digital force theory. According to this theory, organic compounds can be prepared by curing plants and animals only under the influence of a supernatural power called vital force or life.

In 1828, a German scientist named Fredrich Wohler synthesise urea from Ammonium cyanate. Urea was previously extracted from the urine of animals which is prepared in the kidney of a living animal. Fredrich Wohler was successful in preparing same organic compound from an inorganic source.

This reaction is significant in the development of organic chemistry as it proves that vital force theory wrong. Scientist started to work on the synthesis of organic compounds. In 1845, Kolbe synthesizes acetic acid in lab similarly, in 1856, Berthelot prepares methane gas in a lab. Today almost about 95% of organic compounds can be prepared in the lab.

#### Modern definition of organic chemistry

Hydrocarbons and their derivatives in which covalently bonded carbon is an essential constituent are called organic compounds. Branch of chemistry that deals with organic compounds is known as organic chemistry. Examples of organic compounds are as follows:

1. CH4 Methane
2. CH3CH2-OH ethyl alcohol
3. C2H6 Ethane
4. C6H12O6 Glucose
5. C3H5(OH)3 Glycerol
6. C3H8 Propane
7. C2H4 ethene

#### Differences between organic and inorganic compound

 Organic compound Inorganic compound Few elements like C, H, O, N, S, X, P and metals are involved in the formation of organic compounds still over 7 million organic compounds have been identified. It is mainly due to a unique property of carbon called catenation (self-linking property of carbon is called catenation). All the elements in the periodic table are involved in the formation of inorganic compounds yet only hundred thousand inorganic compounds are known. They are basically made up of a covalent bond forming long chain-like structure, ring-like structure more complicated structures propane, benzene etc. They are basically made up of an ionic bond. Example NaCl, CaBr2, MgI2etc. Mostly volatile liquid, few solid and rest are a gas at room temperature. Mostly solid, few liquid and rest are a gas at room temperature. Most of the organic compounds have ordered. Example: formalin, acetone, ethyl have their characteristics smell. Few inorganic compound has ordered. Example NH3(pungent), H2S (rotten egg) etc. In general, organic compounds are insoluble in a polar solvent like water. They are soluble in an organic solvent like ethyl alcohol, acetone, benzene, ether etc. They are soluble in a polar solvent like water. Organic solutions do not conduct electricity. Inorganic solutions conduct electricity. Organic reactions are slow and complicated. Example methane reacts with chlorine to give chloromethane only in the presence of light energy. Inorganic reactions are definite and instantaneous. Example When AgNO3solution is added to NaCl solution there is instant precipitation of AgCl. $$NaCl + AgNO_3\longrightarrow AgCl \downarrow + NaNO_3$$ Organic compounds can be classified into a number of classes or family depending upon the functional group present in the molecule. There is three class of inorganic compounds: acid, base, and salt. The organic compound exhibits a phenomenon called isomerism (organic compounds same molecular formula but different structural formula are called isomers and the phenomenon is called isomerism) example molecular formula C2H6O In general, inorganic compounds do not exhibit isomerism.

### Classification of organic compounds

Reference

Pulse, Tracy. Introduction to chemistry. u.s.a: flex book, 2010.

Pathak, Sita Karki. The Text Book of Chemistry. Kathmandu: Vidhyarthi Pustak Bhandar, 2012.

• Almost all the substances that we come across in our daily life are chemical substances.
• Study of organic compounds is known as organic chemistry.
• Hydrocarbons and their derivatives in which covalently bonded carbon is an essential constituent are called organic compounds.
• Organic reactions are slow and complicated. Example methane reacts with chlorine to give chloromethane only in the presence of light energy.
• In 1828, a German scientist named Fredrich Wohler synthesise urea from Ammonium cyanate.
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