Organic chemistry is the study of carbon compounds except carbonates, carbon monoxide, carbon dioxide, carbon disulphide, etc. π
Organic compounds are compounds which contain carbon except carbonates, carbon monoxide, carbon dioxide, carbon disulphide, etc. π¬
A hydrocarbon is a compound which consists of the elements carbon and hydrogen only. Examples include: π
Hydrocarbon | Formula |
---|---|
Methane | CH4 |
Ethene | C2H4 |
Ethyne | C2H2 |
A homologous series is a family of similar organic compounds. Each member in a family is called a homologue. π¨βπ©βπ§βπ¦
A functional group is a group of atoms that determines the chemical properties of organic compounds. π§¬
Organic Family | Functional Group | Name of Functional Group |
---|---|---|
Alkanes | β C β C β | Single carbonβcarbon covalent bond |
Alkenes | C = C | Double carbonβcarbon covalent bond |
Alkynes | C β‘ C | Triple carbonβcarbon covalent bond |
Alkanols (Alcohols) | β OH | Hydroxyl group |
Carboxylic Acids | β COOH | Carboxyl group |
Esters | β COO β | Ester functional group |
Nomenclature is the standardized system of naming organic compounds. It includes prefixes and suffixes that describe the structure and functional groups of compounds. π
Prefix | Number of Carbon Atoms |
---|---|
Meth | 1 |
Eth | 2 |
Prop | 3 |
But | 4 |
Pent | 5 |
Hex | 6 |
Suffix | Organic Family |
---|---|
ane | Alkanes |
ene | Alkenes |
yne | Alkynes |
anol | Alcohols |
anoic | Carboxylic Acids |
anoate | Esters |
Alternative term: Saturated hydrocarbons
Alkanes have single carbonβcarbon covalent bonds between carbon atoms. They are saturated because they contain the maximum number of hydrogen atoms. π¨
Alkane | Molecular Formula | Structural Formula | Condensed Formula | Mr |
---|---|---|---|---|
Methane | CH4 | CH4 | CH4 | 16 |
Ethane | C2H6 | CH3CH3 | CH3CH3 | 30 |
Propane | C3H8 | CH3CH2CH3 | CH3CH2CH3 | 44 |
Butane | C4H10 | CH3(CH2)2CH3 | CH3(CH2)2CH3 | 58 |
Methane can be prepared by heating a mixture of anhydrous sodium ethanoate (CH3COONa) and soda lime (NaOH). π§βπ³
Reaction: CH3COONa + NaOH β CH4 + Na2CO3
In a plentiful supply of air (complete combustion), alkanes react with oxygen to form carbon dioxide and water. π§
Example: CH4 + 2O2 β CO2 + 2H2O
A substitution reaction is a reaction where one atom or group of atoms in a molecule is replaced by another. π
Example: Methane reacts with chlorine in the presence of ultraviolet light to form chloromethane and hydrogen chloride.
CH4 + Cl2 β CH3Cl + HCl
Cracking is the process of breaking down large hydrocarbon molecules into simpler and smaller molecules. It can produce alkenes, short-chain alkanes, and hydrogen gas. π‘
This process uses heat to break down large molecules into smaller ones. π‘οΈ
Example: C4H10 β C2H6 + C2H4
This process uses both heat and a catalyst to break down large molecules. Common catalysts include aluminium oxide (Al2O3) and silica (SiO2). π§ͺ
Example: C17H36 β 3C2H4 + C8H18 + C3H6
Alternative term: Unsaturated hydrocarbons
Alkenes have one or more double bonds between carbon atoms, making them unsaturated. They have two hydrogen atoms less than their corresponding alkanes and end with "ene". π
Alkene | Molecular Formula | Structural Formula | Condensed Formula | Mr |
---|---|---|---|---|
Ethene | C2H4 | CH2=CH2 | CH2=CH2 | 28 |
Propene | C3H6 | CH2=CHCH3 | CH2=CHCH3 | 42 |
Butene | C4H8 | CH2=CHCH2CH3 | CH2=CHCH2CH3 | 56 |
This method uses a catalyst to break down large hydrocarbon molecules into smaller ones. π¬
Reaction: C17H36 β 3C2H4 + C3H6 + C8H18
Conditions: Temperature: 600Β°C, Catalyst: Aluminium oxide (Al2O3)
Ethene can also be prepared by the dehydration of ethanol using concentrated sulfuric acid. π§ͺ
Reaction: C2H5OH β C2H4 + H2O
Conditions: Temperature: 180Β°C, Dehydrating agent: Concentrated sulfuric acid
When an alkene is shaken with bromine water, the brown color of bromine disappears immediately, indicating the presence of a double bond. π
Example: C2H4 + Br2 β C2H4Br2
The purple color of potassium permanganate turns colorless in the presence of an alkene, confirming unsaturation. π§ͺ
Alkenes react with oxygen to form carbon dioxide and water. π§
Example: C2H4 + 3O2 β 2CO2 + 2H2O
An addition reaction is one in which a molecule is added to an unsaturated molecule by breaking a double bond. π
Alternative term: Alkanols
Alcohols have the general molecular formula CnH2n+1OH and contain the hydroxyl group (β OH). They end with "anol". π§ͺ
Alcohol | Molecular Formula | Structural Formula | Condensed Formula |
---|---|---|---|
Methanol | CH3OH | CH3OH | CH3OH |
Ethanol | C2H5OH | CH3CH2OH | CH3CH2OH |
Propanol | C3H7OH | CH3(CH2)2OH | CH3(CH2)2OH |
Ethanol can be prepared by reacting ethene with steam. π‘οΈ
Reaction: C2H4 + H2O β C2H5OH
Conditions: Phosphoric acid catalyst, 65 atm pressure
Fermentation is the decomposition of sugars using enzymes in yeast to produce ethanol and carbon dioxide. π
Reaction: C6H12O6 β 2C2H5OH + 2CO2
Alcohols burn in air to form carbon dioxide and water. This reaction is exothermic. π§
Example: C2H5OH + 3O2 β 2CO2 + 3H2O
Ethanol can be oxidized to ethanoic acid by bacteria in the air or by using an oxidizing agent such as acidified potassium permanganate. π§ͺ
Reaction: C2H5OH + 2[O] β CH3COOH + H2O
Alternative term: Alkanoics
Carboxylic acids have the general molecular formula CnH2n+1COOH and contain the carboxyl group (β COOH). They end with "anoic acid" and are not hydrocarbons since they contain oxygen. π±
Carboxylic Acid | Molecular Formula | Structural Formula | Condensed Formula |
---|---|---|---|
Methanoic Acid | HCOOH | HCOOH | HCOOH |
Ethanoic Acid | CH3COOH | CH3COOH | CH3COOH |
Propanoic Acid | C2H5COOH | CH3CH2COOH | CH3CH2COOH |
Ethanoic acid can be prepared by the oxidation of ethanol using bacteria in the air or an oxidizing agent such as acidified potassium dichromate (VI). π§ͺ
Reaction: C2H5OH + 2[O] β CH3COOH + H2O
In this reaction, acidified potassium dichromate (VI) changes color from orange to green. π β‘οΈπ’
Carboxylic acids react with reactive metals to form a salt and hydrogen gas. π¨
Example: 2Na + 2CH3COOH β 2CH3COONa + H2
They react with alkalis to form a salt and water only. π§
Example: CH3COOH + NaOH β CH3COONa + H2O
Carboxylic acids react with carbonates and hydrogen carbonates to form a salt, water, and carbon dioxide. π¨
Example: CH3COOH + NaHCO3 β CH3COONa + H2O + CO2
Carboxylic acids react with alcohols to form esters in a process called esterification. Esters are sweet-smelling compounds. π
Example: Ethanoic acid reacts with ethanol to form ethyl ethanoate and water.
CH3COOH + C2H5OH β CH3COOC2H5 + H2O
Alternative term: Polymers
Macromolecules are giant molecules formed by joining smaller units called monomers. The process of creating these large molecules is known as polymerization. π
Synthetic macromolecules are divided into two types: addition polymers and condensation polymers.
Addition polymers are formed from smaller, identical unsaturated monomers without producing any other by-products. π
Polymer | Monomer | Example |
---|---|---|
Polyethene | Ethene | Used in making plastic bags and bottles ποΈ |
Polyvinyl chloride (PVC) | Vinyl chloride | Used in making pipes, electrical insulators, and seat covers π° |
Polypropene | Propene | Used in making ropes and textiles 𧡠|
Polytetrafluoroethene (PTFE or Teflon) | Tetrafluoroethene | Used in non-stick coatings for cookware π³ |
Condensation polymers are formed when two different types of monomers combine and eliminate a small molecule, often water, during polymerization. These polymers do not have the same empirical formula as the monomers. π§
Nylon is a polyamide with amide linkages formed by the reaction of a diamine and a dicarboxylic acid.
Uses of Nylon: Used in making fabrics, ropes, and bristles for brushes. π§Ά
Terylene is a polyester containing ester linkages, formed by the reaction of a diol and a dicarboxylic acid.
Uses of Terylene: Used in making fabrics, sails, and tents. βΊ
Natural macromolecules occur in living organisms and are essential for life. These include proteins, fats, and carbohydrates. π
Proteins are natural polymers formed by condensation polymerization. They are polyamides with amide linkages, similar to nylon, and consist of long chains of amino acids. π³
Hydrolysis of Proteins: When proteins undergo hydrolysis, they break down into amino acids. π
Fats are complex esters formed from fatty acids and glycerol. Their structure is similar to that of Terylene. π§
Hydrolysis of Fats: Fats break down into fatty acids and glycerol through hydrolysis. π§
Carbohydrates are sugars that include compounds like starch and cellulose, formed by the polymerization of simple sugars such as glucose. π¬
Hydrolysis of Starch: When starch undergoes hydrolysis, it breaks down into glucose molecules. π