Hybridization Bond Data

$\text{Bond Energy: sp C-H} = 558 \text{ kJ/mol} > \text{sp}^2 \text{ C-H} = 444 \text{ kJ/mol} > \text{sp}^3 \text{ C-H} = 410 \text{ kJ/mol}$

$\%\text{s-character} = \frac{1}{\text{number of hybrid orbitals}} \times 100\%$

$\text{sp}^3: 25\% \quad \text{sp}^2: 33.3\% \quad \text{sp}: 50\%$

Key Reaction Schemes

Free Radical Halogenation (Alkane): CH4 + Cl2 --[UV light, hv]--> CH3Cl + HCl

Mechanism steps:

1. Initiation: Cl2 --[hv]--> 2 Cl• (homolytic fission)
2. Propagation: Cl• + CH4 → CH3• + HCl; CH3• + Cl2 → CH3Cl + Cl•
3. Termination: Cl• + Cl• → Cl2 (or CH3• + Cl• → CH3Cl)

Electrophilic Addition to Alkene (Markovnikov): CH3CH=CH2 + HBr --[room temp, no peroxide]--> CH3CHBrCH3 (major) + CH3CH2CH2Br (minor)

Rule: H adds to carbon with more H atoms; X adds to carbon with fewer H atoms.

Dehydrohalogenation (E2 Elimination): CH3CH2Br + KOH --[alcoholic KOH, heat]--> CH2=CH2 + KBr + H2O

Zaitsev's Rule: More substituted alkene is the major product.

Acid-Base Comparison:

$\text{pKa order}: \underbrace{\text{CCl}_3\text{COOH}}_{pKa \approx 0.7} < \underbrace{\text{CH}_2\text{ClCOOH}}_{pKa \approx 2.9} < \underbrace{\text{CH}_3\text{COOH}}_{pKa \approx 4.75} < \underbrace{(\text{CH}_3)_3\text{CCOOH}}_{pKa \approx 5.03}$

Carbocation Stability

$\text{Stability: } \underbrace{(\text{CH}_3)_3\text{C}^+}_{3°, \; 9\alpha\text{-H}} > \underbrace{(\text{CH}_3)_2\text{CH}^+}_{2°, \; 6\alpha\text{-H}} > \underbrace{\text{CH}_3\text{CH}_2^+}_{1°, \; 3\alpha\text{-H}} > \underbrace{\text{CH}_3^+}_{0\alpha\text{-H}}$

Carbanion Stability (Reverse Order)

$\text{Stability: CH}_3^- > \text{CH}_3\text{CH}_2^- > (\text{CH}_3)_2\text{CH}^- > (\text{CH}_3)_3\text{C}^-$