Substitution Reactions For Alkanes (LEC) Flashcards
What is Sulfonation?
This is a reaction of organic compounds/alkanes with sulfuric acid (SO3) and H2O (water)
RH+ HOSO3H -> RSO3H + HOH
Alkanes react with SO3 to form:
Alkyl sulfonic acid or RSO3H
How is Sulfonation a Substitution Reaction?
RH+ HOSO3H -> RSO3H + HOH
SO3 is substituted in between alkane and its last H atom—therefore, the last H atom is joined to SO3 instead
What is Vapor Phase Nitration (Temp 400 C)?
It is the reaction between an alkane and hydroxized nitric acid (HONO2)
RH + HONO2 -> RNO2 + H2O
How is Vapor Phase Nitration a Substitution Reaction?
An H atom in the alkane and NO2 switch places
RH + HONO2 -> RNO2 + H2O
What is formed in Vapor Phase Nitration?
Nitroalkane (RNO2) and Water (H2O)
What is Halogenation?
Substitution of Halogens for Hydrogen
RH + X2 -> [heat or uv light] RX + HX
or RHX + X2 -> [heat or uv light] RX2 + HX
Halogenation is initiated by catalysts:
Heat or UV light
How is substitution present in Halogenation?
RH + X2 -> [heat or uv light] RX + HX
- One halogen atom switches with an H atom from the alkane
Halogens differ in their ability to undergo Halogenation.
What is the order of halogen reactivity and what does this entail?
F2 > Cl2 > Br2 > I2
- Fluorine is too reactive and Iodine is too unreactive
- Only Chlorine and Bromine are capable of being used
What does Halogenation yield?
Alkyl halides (RX)
In Halogenation, the reaction of methane and chlorine will give a mixture of:
Mono- di- tri- and tetra- substituted chloromethanes
However, if an excess of Cl is used, the reaction can be controlled to give all _____
Tetrachloromethane
However, if a large ratio of CH4 to Cl is used, the product will be predominantly _____
Chloromethane
What is Pyrolysis or Cracking?
It is the breaking down of alkanes into smaller molecules by heating them in high temperatures but without air.
