Organic Chemistry

The root word of organic chemistry, 'Organic' means that the compounds were synthesized from living organisms in the past. Still now organic chemistry reactions are involving the synthesis of organic compounds from living organism like starch, cellulose etc. Introduction to organic chemistry Organic Chemistry is a sub division of Chemistry study and it deals with the scientific study of structure, properties and the compositions of compounds. This is also considered as the chemistry of carbon containing compounds. Every living organisms, irrespective of plants and animals are composed of organic compounds and anyone with an interest in life would definitely like to know more about the molecules involved in these life processes and also need to have the basic understanding of organic chemistry. What is Organic Chemistry? Organic chemistry is the branch of chemistry dealing with compounds containing carbon-carbon bonds. These carbon compounds are special in nature because most of them covalent in nature and they are highly volatile. As organic compounds have some distinguishing characters they are differentiated from rest of the chemistry and studies separately. The next interesting thing is the number of organic compounds. As carbon can from a long chain due to its catenation ability (an ability to form long chains with itself and with other atoms) it can form many number of compounds. Hence we have to study the properties of organic compounds separately. Organic Chemistry Definition Hence organic chemistry is the branch of chemistry dealing with organic compounds made up of covalent carbon chain. This branch is unique in studying the properties of organic compounds as all of them are covalent and they undergo different set of reactions from Inorganic compounds. Functional Groups in Organic Chemistry One of the special feature of organic chemistry which differentiates it from Inorganic chemistry is the compounds will form a pattern called homologous series. Every organic compound will have a specific part or group where the reactivity is more. This part is called as functional group in the organic compound. All the organic compounds with same functional group will fall under the same homologous series. They will have same chemical properties which make the study of organic chemistry much more easier. For example in the following compounds the hydroxy (-OH) is the functional group and all the compounds are called as alcohols with same physical and chemical properties. The special nature of functional group is all the compounds with same functional group will have same chemical properties. But the physical properties may differ with the number and nature of carbon chain. For example both methanol and butanol will fall under alcohol series. Both will react with sodium to liberate hydrogen gas. 2CH3OH + 2Na → 2CH3ONa + H2 2CH3CH2CH2OH + 2Na → 2CH3CH2CH2ONa + H2 Organic Chemistry Reactions Back to Top Organic chemistry reactions are different from inorganic chemistry reactions. As most of the organic compounds are covalent in nature, the organic chemistry reactions involves the cleavage of the covalent bonds and forming of new bonds. A covalent bond is made up of two electrons and cleavage of such bond may happen in such a way that both the electrons are taken away by one atom resulting in formation of ions. On the other hand the bonding electrons may be equally divided between atom giving rise to free radicals. Hence organic chemistry reactions proceed by the formation of ions or free radicals. 1. Hence the organic chemistry reaction may be classified as Free radical reaction where radicals are formed and initiate the reaction, For example bromination of methane involves formation of bromine free radical to proceed the reaction. Hence the reaction is free radical reaction. CH4 + Br. → CH3Br Nucleophilic reaction where negative ions are produced and attack on positive sides. For example the carbonyl carbon is partially positive charged and negative ions will attack on the carbon easily. Hence all the reactions in aldehyde and ketone are nucleophilic reactions involving negative ions. Electrophilic reaction where positive ions are produced and attack on negative sides. For example benzene ring is a rich source of Π electrons. Hence all the reactions will proceed with the attack of this electron by positively charged ions. Hence all the reactions in the benzene ring are electrophilic reactions. 2. The organic chemistry reactions may also further divided as Addition reaction: where an atom or group is added across an unsaturated bond. For example addition of bromine with ethylene gives di-bromo ethane. CH2=CH2 + Br2 → CH2Br-CH2Br Elimination reaction: where a molecule is eliminated from an organic compound to give unsaturated compound. For example ethyl bromide on elimination in the presence of alcoholic KOH gives ethene. CH3-CH2-Br → CH2=CH2 + HBr Oxidation reaction: It is the type of reaction where oxygen is added or hydrogen is removed from an organic compound. For example ethyl alcohol on strong oxidation in the presence of acidified potassium permanganate gives acetic acid. Reduction reaction: It is the type of reaction where oxygen is removed or hydrogen is added to an organic compound. For example acetone on reduction with lithium aluminium hydride gives 2-propanol. Condensation reaction: It is the type of reaction where two organic compounds combine together to give one compound by elimination of simple molecules like water, HCl etc. For example condensation of acid and alcohol gives ester. CH3-CH2-OH + CH3COOH → CH3CH2OCOCH3 + H2O Polymerization reaction: It is the reaction in which small organic molecules called as monomers combined together to give a large chain of macro molecule called as polymer. Polymerization of vinyl chloride gives polyvinyl chloride, shortly called as PVC. Substitution reaction: It is the reaction in which an atom or group is replaced by another atom or group in organic compound. For example chloromethane reacts with potassium hydroxide to give methanol and potassium chloride. CH3-Cl + KOH → CH3OH + KCl