📝 Chapter Notes & Revision

Organic Chemistry – Some Basic Principles and Techniques

🏫 MP BoardClass 11Chemistry

📐 Formula & Cheat Sheet (English)

Quick Revision Notes & Formula Sheet

Class 11 Chemistry | Chapter: Organic Chemistry – Some Basic Principles and Techniques

1. Hybridization and Molecular Geometry (संकरण और ज्यामिति)

  • Hybridization of Carbon:

    • $sp^3$ Hybridization: 4 $\sigma$ bonds | Shape: Tetrahedral | Bond Angle: $109.5^\circ$ (e.g., Methane $\text{CH}_4$)
    • $sp^2$ Hybridization: 3 $\sigma$ bonds + 1 $\pi$ bond | Shape: Trigonal Planar | Bond Angle: $120^\circ$ (e.g., Ethene $\text{C}_2\text{H}_4$)
    • $sp$ Hybridization: 2 $\sigma$ bonds + 2 $\pi$ bonds | Shape: Linear | Bond Angle: $180^\circ$ (e.g., Ethyne $\text{C}_2\text{H}_2$)

  • Formula for Number of $\sigma$ and $\pi$ bonds:

    • Single bond = $1\sigma$ bond
    • Double bond = $1\sigma + 1\pi$ bond
    • Triple bond = $1\sigma + 2\pi$ bonds

2. IUPAC Nomenclature Basics (आईयूपीएसी नामकरण)

$$\text{IUPAC Name} = \text{Secondary Prefix} + \text{Primary Prefix} + \text{Root Word} + \text{Primary Suffix} + \text{Secondary Suffix}$$

  1. Root Word: Chain length ($C_1 = \text{meth-}, C_2 = \text{eth-}, C_3 = \text{prop-}, C_4 = \text{but-}$, etc.)
  2. Primary Suffix: Saturation/Unsaturation (-ane for single, -ene for double, -yne for triple bond)
  3. Secondary Suffix: Main functional group
  4. Prefix: Substituents / Side chains / Cyclic nature (cyclo-)

Priority Order of Functional Groups (Decreasing Order):

$$-\text{COOH} > -\text{SO}_3\text{H} > -\text{COOR} > -\text{COCl} > -\text{CONH}_2 > -\text{CN} > -\text{CHO} > >\text{C=O} > -\text{OH} > -\text{NH}_2 > >\text{C=C}< > -\text{C}\equiv\text{C}-$$

3. Isomerism (समावयवता)

  • Structural Isomerism (संरचनात्मक समावयवता):
    • Chain Isomerism: Carbon skeleton differs.
    • Position Isomerism: Position of functional group/double bond/triple bond differs.
    • Functional Isomerism: Same molecular formula, different functional groups (e.g., Alcohol & Ether).
    • Metamerism: Unequal distribution of alkyl groups around a polyvalent functional group (e.g., Ethers, Amines).
  • Stereoisomerism (त्रिविम समावयवता): Same bonding sequence, different spatial arrangement (Geometrical & Optical).

4. Electronic Displacement Effects (इलेक्ट्रॉनिक प्रभाव)

EffectNatureKey Feature / Driving Force
Inductive Effect ($I$-effect)PermanentTransmission of $\sigma$-electron density along a carbon chain.
Resonance Effect ($R$ or $M$-effect)PermanentDelocalization of $\pi$-electrons or lone pair electrons.
HyperconjugationPermanentDelocalization of $\sigma$-electrons of $\text{C}-\text{H}$ bond with adjacent $\pi$-system / empty p-orbital ($\alpha$-hydrogens).
Electromeric Effect ($E$-effect)TemporaryComplete transfer of $\pi$-electron pair in the presence of an attacking reagent.
  • $+I$ Power: $-\text{C(CH}_3)_3 > -\text{CH(CH}_3)_2 > -\text{CH}_2\text{CH}_3 > -\text{CH}_3$
  • $-I$ Power: $-\text{NO}_2 > -\text{CN} > -\text{COOH} > -\text{F} > -\text{Cl} > -\text{Br} > -\text{I} > -\text{OCH}_3 > -\text{OH}$

5. Reaction Intermediates & Stability Orders (अभिक्रिया मध्यवर्ती)

  • Carbocation ($R^+$) — $sp^2$ hybridized, planar: $$\text{Stability Order: } \text{Tertiary } (3^\circ) > \text{Secondary } (2^\circ) > \text{Primary } (1^\circ) > \text{CH}_3^+$$

  • Free Radical ($R^\bullet$) — $sp^2$ hybridized, planar: $$\text{Stability Order: } \text{Tertiary } (3^\circ) > \text{Secondary } (2^\circ) > \text{Primary } (1^\circ) > \text{CH}_3^\bullet$$

  • Carbanion ($R^-$) — $sp^3$ hybridized, pyramidal: $$\text{Stability Order: } \text{CH}_3^- > \text{Primary } (1^\circ) > \text{Secondary } (2^\circ) > \text{Tertiary } (3^\circ)$$

6. Purification Methods Summary (शोधन की विधियाँ)

  1. Sublimation: Separates sublimable solid from non-sublimable impurity (e.g., Camphor, Naphthalene, Benzoic acid).
  2. Crystallisation: Based on difference in solubilities in a suitable solvent.
  3. Simple Distillation: Liquids with large boiling point difference ($> 25^\circ\text{C}$).
  4. Fractional Distillation: Liquids with small boiling point difference ($< 25^\circ\text{C}$).
  5. Distillation under Reduced Pressure (Vacuum Distillation): For liquids that decompose at or below their boiling point (e.g., Glycerol).
  6. Steam Distillation: For steam-volatile and water-immiscible substances (e.g., Aniline).
  7. Chromatography: Based on differential adsorption/partition between stationary and mobile phases.

7. Qualitative Analysis (गुणात्मक विश्लेषण)

Sodium Fusion Extract (Lassaigne's Test) Formations:

  • Nitrogen: $6\text{NaCN} + \text{FeSO}_4 \rightarrow \text{Na}_4[\text{Fe(CN)}_6]$
    • Add $\text{Fe}^{3+}$ $\rightarrow$ Prussian Blue Color ($\text{Fe}_4[\text{Fe(CN)}_6]_3$)
  • Sulfur: $\text{S}^{2-} + \text{Sodium Nitroprusside} \rightarrow$ Violet / Purple color ($\text{[Fe(CN)}_5\text{NOS]}^{4-}$)
  • Halogens: Treat extract with dilute $\text{HNO}_3$ then $\text{AgNO}_3$:
    • White ppt (soluble in $\text{NH}_4\text{OH}$): Chlorine ($\text{AgCl}$)
    • Pale yellow ppt (sparingly soluble in $\text{NH}_4\text{OH}$): Bromine ($\text{AgBr}$)
    • Yellow ppt (insoluble in $\text{NH}_4\text{OH}$): Iodine ($\text{AgI}$)

8. Quantitative Analysis Formulas (मात्रात्मक विश्लेषण के सूत्र)

A. Carbon and Hydrogen (Liebig's Combustion Method)

  • Percentage of Carbon: $$% \text{ C} = \frac{12}{44} \times \frac{\text{Mass of } \text{CO}_2 \text{ formed (g)}}{\text{Mass of Organic Compound (g)}} \times 100$$

  • Percentage of Hydrogen: $$% \text{ H} = \frac{2}{18} \times \frac{\text{Mass of } \text{H}_2\text{O} \text{ formed (g)}}{\text{Mass of Organic Compound (g)}} \times 100$$

B. Nitrogen Estimation

  • 1. Dumas Method: $$% \text{ N} = \frac{28}{22400} \times \frac{V_1 \text{ (Volume of } \text{N}_2 \text{ at STP in mL)}}{\text{Mass of Organic Compound (g)}} \times 100$$

    • To convert $V$ at experimental temp ($T_1$) and pressure ($P_1$) to STP ($V_1$): $$\frac{P_1 V_1}{T_1} = \frac{P_0 V_0}{T_0} \implies V_0 (\text{at STP}) = \frac{(P - p) \times V \times 273}{760 \times T}$$ (where $p$ = aqueous tension)

  • 2. Kjeldahl Method: $$% \text{ N} = \frac{1.4 \times N \times V}{\text{Mass of Organic Compound (g)}}$$

    • $N$ = Normality of neutralized standard acid
    • $V$ = Volume of standard acid neutralized by ammonia (in mL)
    • (If Molarity $M$ is used for $\text{H}_2\text{SO}_4$: $N = 2 \times M$)

C. Halogens (Carius Method)

$$% \text{ Halogen} = \frac{\text{Atomic Mass of Halogen}}{\text{Molar Mass of AgX}} \times \frac{\text{Mass of AgX formed (g)}}{\text{Mass of Organic Compound (g)}} \times 100$$

  • For $\text{Cl}$: $\text{Molar Mass of AgCl} = 143.5 \text{ g/mol}$
  • For $\text{Br}$: $\text{Molar Mass of AgBr} = 188 \text{ g/mol}$
  • For $\text{I}$: $\text{Molar Mass of AgI} = 235 \text{ g/mol}$

D. Sulphur (Carius Method)

$$% \text{ S} = \frac{32}{233} \times \frac{\text{Mass of } \text{BaSO}_4 \text{ formed (g)}}{\text{Mass of Organic Compound (g)}} \times 100$$

E. Phosphorus

$$% \text{ P} = \frac{62}{222} \times \frac{\text{Mass of } \text{Mg}_2\text{P}_2\text{O}_7 \text{ formed (g)}}{\text{Mass of Organic Compound (g)}} \times 100$$

Alternative (as Ammonium Phosphomolybdate): $$% \text{ P} = \frac{31}{1877} \times \frac{\text{Mass of } (\text{NH}_4)_3\text{PO}_4\cdot 12\text{MoO}_3 \text{ formed (g)}}{\text{Mass of Organic Compound (g)}} \times 100$$

F. Oxygen

$$% \text{ O} = 100 - \left( % \text{ C} + % \text{ H} + % \text{ N} + % \text{ Halogens/S/P} \right)$$