HydrocarbonsThose compounds which contain only carbonand hydrogen.There are two types of hydrocarbons:1- saturated hydrocarbons: in which allcarbon bonds are sigma (σ)bonds,include alkanes and cycloalkanes.
2- unsaturated hydrocarbons: which contain sigmaas well as pi-bonds, include alkenes (paraffin) andAlkynes (acetylenes).
Nomenclature of organic :compoundsThe IUPAC rules for alkanes3. The general name for acyclic saturated hydrocarbon is Alkanes. The – ane ending is used for all saturated hydrocarbons
2: alkanes without branches arenamed according to the number ofcarbon atoms.
3- HalogenationChlorine and bromine are readily addeto the double bond in the darkCH2 = CH2 + Br2 CH2Br – CH2Br
alkynes NomenclaturesAlkynesName Formula Structural FormulaEthyne C2 H 2 CH ≡ CH(Acetylene)Propyne C3 H 4 CH≡ C-CH31-Butyne C4 H 6 CH≡ C-CH2-CH32-Butyne C4 H 6 CH3-C≡ C-CH3
General methods for preparation of alkynes1- By the action of potassium hydroxideon gem or Vicinal dihalidethe reaction proceeds in two steps ethanolBrCH2CH2Br + KOH CH2=CHBr ethanolCH2= CHBr + KOH CH≡CH+2KBr+H2O Acetylene
2- DehalogenationBy the action of zinc dust and heat ontetrahalogeno alkanesCH3CBr2-CHBr2 + 2 Zn Heat -2ZnBr2 CH3 – C≡ CH
Chemical properties of alkynes :Undergo the same reaction as alkenes butusing two moles of the reagent1- CH3C = CH 2H2/Pd CH3CH2CH3Propyne n- propane 2Cl22- CH = CH + Cl2CH-CHCl2 2HBr3- CH3C = CH CH3CBr2CH3
Aromatic hydrocarbonsAromatic are cyclic, they are unsaturated,usually have three conjugated double bonds foreach ring of carbon atoms , not all aromatic arehydrocarbon e.g pyridine N Pyridine
BenzeneBenzene is the an example for aromatichydrocarbons.Benzene has six pi electrons two from eachof the double bonds benzene
Fused ring systemThose are aromatic similar to benzene with morethan one benzene ring e.g naphthalein andanthracene anthracene naphthalene
Substituted benzeneThe benzene ring minus one hydrogen (C6H5-)is named as phenyl group. In general groupderived from aromatic compounds by removingOne hydrogen from carbon called aryl group.When one hydrogen replaced by other group iscalled monosubstituted
O OH O H Cl CH3chlorobenzene benzoic acid toluene benzaldehyde O NH2 NH2 OCH3 benzamide aniline anisole