Chemistry 1020 LaboratoryChemistry 1020 Laboratory

Classification of Organic Compounds

HydrocarbonHydrocarbon Hydrocarbons are the fundamental

framework of organic compounds, which contain only hydrogen and carbon

Hydrocarbon ClassesHydrocarbon Classes Hydrocarbons can be classified into three

classes based on their structure and chemical behavior: alkane, alkene and alkyne, aromatic hydrocarbon

Various classes of hydrocarbons react differently with many reagents

AlkaneAlkane Saturated, single bond (C-C)

CnH2n+2: CH4, C2H6, C3H8……

H3C - CH3, H3C - CH2 - CH3

Alkene and AlkyneAlkene and Alkyne

Alkene: Unsaturated, double (C=C)CnH2n: C2H4, C3H6, C4H8……

H2C = CH2, H2C = CH - CH3, H2C = CH – CH2 - CH3

Alkyne: Unsaturated, triple bond (CC)CnH2n-2: C2H2, C3H4, C4H6

HC CH, HC C - CH3, HCC – CH2 - CH3

Aromatic HydrocarbonAromatic Hydrocarbon Benzene cyclic structure, hybridized bond

that are intermediate in behavior to single and double bonds

C6H5-CH3, C6H5-CH2-CH3

CombustionCombustion

The type and color of flame and smoke are different due to their different amount of carbon content

The extent of oxidation for the same hydrocarbon could be different:2C2H6 + 3O2 4C + 6H2O2C2H6 + 5O2 4CO + 6H2O2C2H6 + 7O2 4CO2 + 6H2O

SaturationSaturation

Bromine (Br2): - react very slowly with alkanes- easily adds to multiple bonds of alkenes and alkynes- react with aromatic hydrocarbon only in the presence of a catalyst (iron)

+: red-brown disappear- : remain red-brown

OxidationOxidation

Potassium permanganate (KMnO4) – a strong oxidizing agent: - react very slowly and lesser extent with alkanes- attack the more reactive double bonds of alkenes and alkynes, forming compounds of higher oxidation state- don’t react with aromatic hydrocarbon because of unusual stability of the aromatic ring structure

+: pink disappears - : remain pink

SafetySafety

Organic solvent used are very volatile and flammable, and their vapors are explosive in air so be extremely careful with open flames

The unknowns should be treated as if they are toxic and flammable, should be handled very carefully

Wastes should be collected and never thrown in the sink

Pre-lab QuestionsPre-lab Questions

You have to know the names and structures of a compound in different classes of hydrocarbons

You have to know the equation balance for different products in the combustion

You have to know the different classes of hydrocarbons have different reactivity

Know how to classify an unknown from the test results