Full Organic Chemistry Notes (Part - 2) – Aldehydes to Chemistry in Everyday Life | Class 12 & JEE 2026

 

🔖 Organic Chemistry Shorts Notes (Part - 2) |Class 12 & JEE 2026

1️⃣ Aldehydes, Ketones, and Carboxylic Acids

2️⃣ Chemistry in Everyday Life 

 are among the most important organic chemistry chapters in Class 12. This topic includes oxidation–reduction, nucleophilic addition, name reactions, and reagent-based conversions antibiotics, antiseptics, sweeteners, chemicals in food, and important biological processes influenced by chemistry that are frequently asked in JEE, NEET, CBSE Boards, and school exams.

✅ SECTION 1 - ALDEHYDES, KETONES & CARBOXYLIC ACIDS

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🔵 1. Reduction Reactions (Most Important Table)

This table tells which reducing agent works on which functional group.

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⭐ Reduction Table 

Functional Group	Product Formed	LAH (ether)	NaBH₄ (aq)	B₂H₆ (THF)	H₂ / Ni / Δ
R–X (1° alkyl halide)	RH	+	–	–	+
C≡C (alkyne)	→ alkenes / alkanes	–	–	+	+
C=C (alkene)	Alkane	–	–	+	+
–CHO (aldehyde)	1° alcohol	+	+	+	+
>C=O (ketone)	2° alcohol	+	+	+	+
–COOH (acid)	1° alcohol	+	–	+	+
–COOR (ester)	alcohols	+	–	+	+
–COCl (acid chloride)	1° alcohol	+	+	–	+
–CONH₂ (amide)	Amines	+	–	+	+
(RCO)₂O (anhydride)	2 alcohol molecules	+	–	+	+
–CN (nitrile)	1° amine	+	–	+	+
Oxime (>C=NOH)	Amine	+	–	–	+

🔍 Notes 

• B₂H₆ (diborane) cannot reduce cyclic esters.

• NaBH₄ is mild but can reduce imines.

• Hydrogenation reactivity order:
  –C≡N > –C–O–R

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🔵 2. Important Named Reduction Reactions

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⭐ 1. Wolff–Kishner Reduction

Reagent:

• Hydrazine (N₂H₄), then

• KOH + heat
  

Converts:
Carbonyl group (C=O) → –CH₂

Used when substrate is stable under strong basic conditions.

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⭐ 2. Clemmensen Reduction

Reagent:

• Zn(Hg) + concentrated HCl
  

Converts:
Carbonyl → –CH₂
Opposite conditions of Wolff–Kishner (acidic).

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⭐ 3. Mozingo Reduction (Thioketal Method)

The carbonyl is converted to thioketal then reduced using Raney nickel to form an alkane.

This method avoids harsh acidic/basic conditions.

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⭐ 4. Stephen’s Reduction

Reagent:

• SnCl₂/HCl → iminium salt

• Followed by H₃O⁺
  

Converts:
Nitrile (R–C≡N) → Aldehyde (R–CHO)

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⭐ 5. Rosenmund Reduction

Reagent:

• H₂

• Pd–BaSO₄ (poisoned catalyst)
  

Converts:
Acid chloride (RCOCl) → Aldehyde (RCHO)
Selective: Does not reduce aldehyde further.

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⭐ 6. DIBAL–H (–78°C)

Reagent: Diisobutyl aluminium hydride

At –78°C:

• Esters → Aldehydes

• Nitriles → Aldehydes

• Acid chlorides → Aldehydes

At higher temperature: complete reduction to alcohols.

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⭐ 7. MPV Reduction (Meerwein–Ponndorf–Verley)

Reagent:

• Aluminium isopropoxide in isopropanol
  

Converts:
Aldehydes/Ketones → Alcohols
(Reverse is Oppenauer oxidation)

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⭐ 8. Bouvet / Bouveault–Blanc Reduction

Reagent: Na + ethanol

Reduces esters to alcohols.

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⭐ 9. Hydroboration Reduction

Reagent:

• B₂H₆ / AcOH, H₂O
  

Used for the reduction of:

• Esters

• Acids

• Nitriles

• Carbonyls

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⭐ 10. Transfer Hydrogenation

Reagent:

• N₂H₄ / H₂O₂
  

Used when direct hydrogen gas is not used.

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🔵 3. Characteristic Reactions: Aldehydes & Ketones

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⭐ Nucleophilic Addition Reactions

Aldehydes and ketones undergo addition reactions due to their electrophilic carbonyl carbon.

Common additions include:

• HCN → cyanohydrin

• NaHSO₃ → bisulfite adduct

• NH₃ derivatives → imines, oximes, hydrazones

• Alcohols → hemiacetal & acetal formation

• Grignard reagent → alcohols

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⭐ Oxidation

• Aldehydes → acids (KMnO₄ / K₂Cr₂O₇ / Tollens)

• Ketones are oxidized only under strong conditions (cleavage)

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🔵 4. Carboxylic Acids – Key Points

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⭐ Reduction of Carboxylic Acids

(Already in table above)

Most reducing agents → 1° alcohol

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⭐ Reduction of Esters

• LAH reduces to 2 alcohol molecules

• DIBAL–H partially reduces to aldehyde

• Bouveault–Blanc fully reduces using Na/ethanol

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🟩 5. Most Important Conversions

The major conversions you can include in board revision:

• Aldehyde → alcohol → alkane

• Ketone → alcohol → alkane

• Acid → aldehyde (DIBAL) or → alcohol (LAH)

• Nitrile → aldehyde (Stephen) or → amine (LAH)
  

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🟦 6. Exam Revision Points

• LAH is the strongest reducing agent.

• NaBH₄ is mild → use for aldehydes/ketones only.

• DIBAL–H is selective at low temperature.

• Rosenmund: acid chloride → aldehyde.

• Stephen: nitrile → aldehyde.

• Wolff–Kishner (base) and Clemmensen (acid) convert carbonyl → CH₂.

• B₂H₆ cannot reduce cyclic esters.

• Nitriles reduce to amines with LAH.

• Hydrogenation using H₂/Ni works strongly on triple bonds.

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✅ SECTION 2 - CHEMISTRY IN EVERYDAY LIFE 

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🔵 1. Dr#gs and Their Classification

A dr#g is a chemical substance used to diagnose, prevent, or treat diseases. 

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⭐ A. Analgesics (Pain Relievers)

Analgesics reduce or eliminate pain without causing loss of consciousness.

✔ Common examples :

• Novalgin – a common analgesic for pain relief.

• Paracetamol – both analgesic (pain reliever) and antipyretic (fever reducer).

• Morphine – belongs to opioid analgesics, used for severe pain.
  

Important fact:
Morphine is a narcotic dr#g, but Diclofenac sodium is NOT a narcotic — it is a non-steroidal anti-inflammatory dr#g (NSAID).

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⭐ B. Antipyretics (Fever-Reducing Dr#gs)

They help bring down fever.

✔ Examples:

• Paracetamol

• Aspirin (2-acetoxybenzoic acid) – reduces fever, pain, and inflammation.
  

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⭐ C. Antibiotics

Antibiotics are chemical substances produced by microorganisms that kill or inhibit pathogenic bacteria.

✔ Example 

• Streptomycin – antibiotic

• Chloromycetin – antibiotic (used for typhoid)

• Penicillin – antibiotic

• Ampicillin – broad spectrum, β-lactam antibiotic (NOT a natural antibiotic)
  

Broad-spectrum antibiotics work against many types of microorganisms.

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⭐ D. Antiseptics & Disinfectants

These prevent or kill microorganisms.

✔ Examples :

• Dettol’s antiseptic action is due to chloroxylenol – an effective antiseptic.
  

Difference:

• Antiseptics are used on living tissues (skin).

• Disinfectants are used on non-living surfaces.

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⭐ E. Tranquilizers

Tranquilizers are used to treat anxiety, mental stress, and emotional disorders.

✔ Function: Produce calmness and reduce anxiety.

Examples include benzodiazepines and barbiturates.

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⭐ F. Antimalarial Dr#gs

• Chloroquine – widely used to treat malaria.
  

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⭐ G. Stimulants & Antidepressants

These affect the central nervous system.

• Cocaine was historically used as an antidepressant in early USA medical practices.
  

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🔵 2. Artificial Sweeteners

These sweeteners provide sweetness but have very low or zero calorie value.

✔ Example:

• Aspartame – stable only at low temperatures.
  

This means aspartame cannot be used in cooking or baking at high temperatures.

Other examples (for completeness):

• Saccharin

• Sucralose

• Alitame

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🔵 3. Important Biological Processes

⭐ Glycogenolysis

• Breakdown of glycogen into glucose

• Occurs mainly in the liver

• Stimulated by adrenaline (emergency/fight-or-flight hormone)
  

This increases blood sugar level quickly during stress or danger.

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🔵 4. Important Medicines 

Medicine	Type	Use
Streptomycin	Antibiotic	Bacterial infections
Chloromycetin	Antibiotic	Typhoid
Penicillin	Antibiotic	Gram-positive bacteria
Ampicillin	Broad spectrum β-lactam antibiotic	Wide bacterial range
Novalgin	Analgesic	Pain relief
Paracetamol	Analgesic + Antipyretic	Pain & fever
Morphine	Opioid analgesic	Severe pain
Diclofenac sodium	Non-narcotic analgesic	Muscle & joint pain
Chloroquine	Antimalarial	Malaria
Aspirin (2-acetoxybenzoic acid)	Analgesic + Antipyretic	Pain, fever, inflammation
Chloroxylenol	Antiseptic	Used in Dettol
Aspartame	Artificial sweetener	Low-temp sweetener

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🔵 5. Quick Revision Points 

• Diuretics increase urine production to remove sodium and water.

• Broad-spectrum antibiotics act on a variety of pathogens.

• Dettol’s antiseptic action comes from chloroxylenol.

• Morphine is a narcotic opioid analgesic.

• Diclofenac sodium is non-narcotic.

• Paracetamol works for both fever and pain.

• Chloroquine is a major antimalarial dr#g.

• Ampicillin is a semi-synthetic, not natural, antibiotic.

• Tranquilizers reduce anxiety and bring calmness.

• Glycogenolysis occurs in the liver and is stimulated by adrenaline.

• Aspartame is stable only at low temperature.