Organic Chemistry 🌿

Definition 📖

Organic chemistry is the study of carbon compounds except carbonates, carbon monoxide, carbon dioxide, carbon disulphide, etc. 🌍

Organic Compounds 🧪

Organic compounds are compounds which contain carbon except carbonates, carbon monoxide, carbon dioxide, carbon disulphide, etc. 🔬

Hydrocarbon 💧

A hydrocarbon is a compound which consists of the elements carbon and hydrogen only. Examples include: 🌟

Homologous Series 📊

A homologous series is a family of similar organic compounds. Each member in a family is called a homologue. 👨‍👩‍👧‍👦

A functional group is a group of atoms that determines the chemical properties of organic compounds. 🧬

Nomenclature of Organic Compounds 🏷️

Nomenclature is the standardized system of naming organic compounds. It includes prefixes and suffixes that describe the structure and functional groups of compounds. 📚

Alkanes 🌱

Alternative term: Saturated hydrocarbons
Alkanes have single carbon–carbon covalent bonds between carbon atoms. They are saturated because they contain the maximum number of hydrogen atoms. 💨

Preparation of Methane 🔥

Methane can be prepared by heating a mixture of anhydrous sodium ethanoate (CH₃COONa) and soda lime (NaOH). 🧑‍🍳

Reaction: CH₃COONa + NaOH → CH₄ + Na₂CO₃

Chemical Properties of Alkanes 🧪

Combustion 🔥

In a plentiful supply of air (complete combustion), alkanes react with oxygen to form carbon dioxide and water. 💧

Example: CH₄ + 2O₂ → CO₂ + 2H₂O

Substitution Reaction 🔄

A substitution reaction is a reaction where one atom or group of atoms in a molecule is replaced by another. 🔁

Example: Methane reacts with chlorine in the presence of ultraviolet light to form chloromethane and hydrogen chloride.

CH₄ + Cl₂ → 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. 💡

Types of Cracking 🔍

Thermal Cracking 🔥

This process uses heat to break down large molecules into smaller ones. 🌡️

Example: C₄H₁₀ → C₂H₆ + C₂H₄

Catalytic Cracking ⚗️

This process uses both heat and a catalyst to break down large molecules. Common catalysts include aluminium oxide (Al₂O₃) and silica (SiO₂). 🧪

Example: C₁₇H₃₆ → 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". 🔗

Preparation of Ethene Gas 💨

Catalytic Cracking of Alkanes ⚗️

This method uses a catalyst to break down large hydrocarbon molecules into smaller ones. 🔬

Reaction: C₁₇H₃₆ → 3C₂H₄ + C₃H₆ + C₈H₁₈

Conditions: Temperature: 600°C, Catalyst: Aluminium oxide (Al₂O₃)

Dehydration of Ethanol 💧

Ethene can also be prepared by the dehydration of ethanol using concentrated sulfuric acid. 🧪

Reaction: C₂H₅OH → C₂H₄ + H₂O

Conditions: Temperature: 180°C, Dehydrating agent: Concentrated sulfuric acid

Tests for Unsaturation 🔍

Test 1: Bromine Water 🧪

When an alkene is shaken with bromine water, the brown color of bromine disappears immediately, indicating the presence of a double bond. 🔗

Example: C₂H₄ + Br₂ → C₂H₄Br₂

Test 2: Acidified Potassium Permanganate 💧

The purple color of potassium permanganate turns colorless in the presence of an alkene, confirming unsaturation. 🧪

Chemical Properties of Alkenes 🧪

Combustion 🔥

Alkenes react with oxygen to form carbon dioxide and water. 💧

Example: C₂H₄ + 3O₂ → 2CO₂ + 2H₂O

Addition Reactions ➕

An addition reaction is one in which a molecule is added to an unsaturated molecule by breaking a double bond. 🔗

• Halogenation: Reaction with halogens, e.g., C₂H₄ + Cl₂ → C₂H₄Cl₂
• Hydrogenation: Reaction with hydrogen to form corresponding alkanes, e.g., C₂H₄ + H₂ → C₂H₆ (conditions: Ni catalyst)
• Hydration: Reaction with steam to form alcohols, e.g., C₂H₄ + H₂O → C₂H₅OH (conditions: phosphoric acid, 65 atm)

Alternative term: Alkanols
Alcohols have the general molecular formula C_nH_2n+1OH and contain the hydroxyl group (─ OH). They end with "anol". 🧪

Preparation of Ethanol 🍹

Hydration of Ethene 💧

Ethanol can be prepared by reacting ethene with steam. 🌡️

Reaction: C₂H₄ + H₂O → C₂H₅OH

Conditions: Phosphoric acid catalyst, 65 atm pressure

Fermentation of Sugars 🍇

Fermentation is the decomposition of sugars using enzymes in yeast to produce ethanol and carbon dioxide. 🍞

Reaction: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂

Physical Properties of Alcohols 🍷

• Colorless, inflammable liquids 💧
• Boiling points increase as the carbon chain lengthens 📈
• Solubility in water decreases as the carbon chain lengthens 🌊

Chemical Properties of Alcohols 🧪

Combustion 🔥

Alcohols burn in air to form carbon dioxide and water. This reaction is exothermic. 💧

Example: C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O

Oxidation 🔄

Ethanol can be oxidized to ethanoic acid by bacteria in the air or by using an oxidizing agent such as acidified potassium permanganate. 🧪

Reaction: C₂H₅OH + 2[O] → CH₃COOH + H₂O

• Used as a component in alcoholic beverages 🍷
• Used as a solvent in industrial and laboratory settings 🧪
• Used in making methylated spirits 🍸
• Used as a fuel and in the preservation and sterilization of food 🍽️

Alternative term: Alkanoics
Carboxylic acids have the general molecular formula C_nH_2n+1COOH and contain the carboxyl group (─ COOH). They end with "anoic acid" and are not hydrocarbons since they contain oxygen. 🌱

Preparation of Ethanoic Acid 🍏

Oxidation of Ethanol 🔄

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). 🧪

Reaction: C₂H₅OH + 2[O] → CH₃COOH + H₂O

In this reaction, acidified potassium dichromate (VI) changes color from orange to green. 🟠➡️🟢

Physical Properties of Carboxylic Acids 🍋

• They turn blue litmus paper red. 🔴
• They have pH values less than 7. 📉
• They have a sour taste. 😋

Chemical Properties of Carboxylic Acids 🧪

Reactions with Reactive Metals ⚡

Carboxylic acids react with reactive metals to form a salt and hydrogen gas. 💨

Example: 2Na + 2CH₃COOH → 2CH₃COONa + H₂

Reactions with Bases ⚖️

They react with alkalis to form a salt and water only. 💧

Example: CH₃COOH + NaOH → CH₃COONa + H₂O

Reactions with Carbonates 💨

Carboxylic acids react with carbonates and hydrogen carbonates to form a salt, water, and carbon dioxide. 💨

Example: CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂

Esterification 🍬

Carboxylic acids react with alcohols to form esters in a process called esterification. Esters are sweet-smelling compounds. 🍭

Example: Ethanoic acid reacts with ethanol to form ethyl ethanoate and water.

CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O

Special Property of Esters 🌸

• Esters have sweet smells, often used in perfumes and food flavorings. 🌼

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. 🔗

Types of Macromolecules 🔍

• Synthetic macromolecules: Man-made polymers, such as addition and condensation polymers. 🏭
• Natural macromolecules: Occur naturally in living organisms, e.g., proteins, fats, and carbohydrates. 🌱

Synthetic Macromolecules 🏭

Synthetic macromolecules are divided into two types: addition polymers and condensation polymers.

Addition Polymers ➕

Addition polymers are formed from smaller, identical unsaturated monomers without producing any other by-products. 🔗

Condensation Polymers 🔗

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. 💧

Examples of Condensation Polymers 📚

Nylon 🧵

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. 🧶

Terylene (Polyester) 🧵

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. ⛺

Natural macromolecules occur in living organisms and are essential for life. These include proteins, fats, and carbohydrates. 🍏

Proteins 🍗

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. 🍳

Hydrolysis of Proteins: When proteins undergo hydrolysis, they break down into amino acids. 🔄

Fats 🥑

Fats are complex esters formed from fatty acids and glycerol. Their structure is similar to that of Terylene. 🧈

Hydrolysis of Fats: Fats break down into fatty acids and glycerol through hydrolysis. 💧

Carbohydrates 🍞

Carbohydrates are sugars that include compounds like starch and cellulose, formed by the polymerization of simple sugars such as glucose. 🍬

Hydrolysis of Starch: When starch undergoes hydrolysis, it breaks down into glucose molecules. 🔄

Exercises for Carboxylic Acids and Esters 🍋

• Draw the structure of the compound with the IUPAC name: 2, 3, 4, 4 – tetramethylpentane. ✏️
• One of the hydrocarbons found in crude oil is undecane. Under suitable conditions, undecane undergoes the reaction shown below. Identify the reaction type and state two conditions necessary for this reaction to take place. 🔍

Exercises for Polymers 🧪

• The table below shows the structural formulae of various monomers and the polymers that can be made from them. Identify the monomers that are hydrocarbons, name the monomer W, draw the displaced structure for polymer Y, and identify the common feature among the monomers. 🔗
• Identify two advantages of synthetic polymers and discuss why recycling plastics is important. ♻️

Advantages of Synthetic Polymers 👍

• They are durable and do not rust, corrode, or decay. 💪
• They are lighter than materials like steel, wood, or stone. ⚖️
• They are thermal and electrical insulators. 🔌
• They are affordable, being produced as by-products of oil refining. 💰
• They offer flexibility in various applications. 🔄

Disadvantages of Synthetic Polymers 👎

• They are non-biodegradable, meaning they cannot decompose naturally, which complicates disposal and contributes to pollution. 🌍
• They burn easily, sometimes releasing toxic gases. For example, burning polyvinyl chloride (PVC) can release hydrogen chloride fumes, which can form hydrochloric acid in the eyes and throat. ⚠️

• Plastics are challenging to dispose of because they do not decompose naturally. Discarded plastics pollute the environment, especially in landfills and oceans. 🌊
• Some plastics release harmful gases when burned. For example, polyvinyl chloride (PVC) emits fumes of hydrogen chloride during combustion, which could lead to respiratory problems and environmental damage. 🚫