CHEMISTRY

CONTENT

Alkanes (Saturated Hydrocarbons)
General formula: CnH2n+2
n = number of carbon atoms
Examples: Methane (CH4), Ethane (C2H6), Propane (C3H8)
Physical properties:
Boiling point increases with molecular mass
Insoluble in water, soluble in organic solvents
Chemical properties:
Combustion: CnH2n+2 + (3n+1)/2 O2 → n CO2 + (n+1) H2O
Halogenation (substitution): CH4 + Cl2 → CH3Cl + HCl (in presence of sunlight)
Cracking: Long chain alkanes → shorter alkanes + alkenes (catalytic / thermal)
Isomerism:
Structural isomerism occurs from C4H10 onwards
Example: Butane → n-butane & isobutane (methylpropane)
IUPAC naming rules:
Find longest chain → parent name
Number chain to give substituents lowest numbers
Name substituents in alphabetical order
Example: 2-methylpropane (CH3-CH(CH3)-CH3)
Benzene (Aromatic Hydrocarbon, C6H6)
Structure: Planar hexagon, delocalized π electrons
Bond type: C-C bond length equal (1.39 Å) → resonance structure
Properties:
Physical: Colorless liquid, aromatic odor, insoluble in water
Chemical: Undergoes electrophilic substitution rather than addition
Key reactions:
Nitration: C6H6 + HNO3 → C6H5NO2 + H2O (conc. H2SO4 catalyst)
Halogenation: C6H6 + Cl2 → C6H5Cl + HCl (FeCl3 catalyst)
Friedel-Crafts Alkylation: C6H6 + R-Cl → C6H5-R + HCl (AlCl3 catalyst)
Friedel-Crafts Acylation: C6H6 + RCOCl → C6H5COR + HCl (AlCl3 catalyst)
Sulfonation: C6H6 + SO3 → C6H5SO3H (conc. H2SO4)
Reduction of Nitrobenzene: C6H5NO2 + 3H2 → C6H5NH2 + 2H2O (catalyst: Pd/C)
Resonance energy: ~152 kJ/mol → unusually stable
Nomenclature:
Benzene as parent: e.g., chlorobenzene, nitrobenzene
Substituted benzenes: ortho (o-), meta (m-), para (p-) positions
Example: o-dichlorobenzene, m-dinitrobenzene

TERMINAL JOINT

Terminal Joint

CHEMISTRY

This is a just started company , Support us by subscribing our channel

▶ YouTube

Terminal Joint

CHEMISTRY

This is a just started company , Support us by subscribing our channel ▶ YouTube

This is a just started company , Support us by subscribing our channel

▶ YouTube