Substitution Reactions For Alkanes (LEC) Flashcards

1
Q

What is Sulfonation?

A

This is a reaction of organic compounds/alkanes with sulfuric acid (SO3) and H2O (water)

RH+ HOSO3H -> RSO3H + HOH

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2
Q

Alkanes react with SO3 to form:

A

Alkyl sulfonic acid or RSO3H

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3
Q

How is Sulfonation a Substitution Reaction?

A

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

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4
Q

What is Vapor Phase Nitration (Temp 400 C)?

A

It is the reaction between an alkane and hydroxized nitric acid (HONO2)

RH + HONO2 -> RNO2 + H2O

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5
Q

How is Vapor Phase Nitration a Substitution Reaction?

A

An H atom in the alkane and NO2 switch places

RH + HONO2 -> RNO2 + H2O

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6
Q

What is formed in Vapor Phase Nitration?

A

Nitroalkane (RNO2) and Water (H2O)

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7
Q

What is Halogenation?

A

Substitution of Halogens for Hydrogen

RH + X2 -> [heat or uv light] RX + HX

or RHX + X2 -> [heat or uv light] RX2 + HX

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8
Q

Halogenation is initiated by catalysts:

A

Heat or UV light

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9
Q

How is substitution present in Halogenation?

A

RH + X2 -> [heat or uv light] RX + HX

  • One halogen atom switches with an H atom from the alkane
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10
Q

Halogens differ in their ability to undergo Halogenation.

What is the order of halogen reactivity and what does this entail?

A

F2 > Cl2 > Br2 > I2

  • Fluorine is too reactive and Iodine is too unreactive
  • Only Chlorine and Bromine are capable of being used
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11
Q

What does Halogenation yield?

A

Alkyl halides (RX)

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12
Q

In Halogenation, the reaction of methane and chlorine will give a mixture of:

A

Mono- di- tri- and tetra- substituted chloromethanes

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13
Q

However, if an excess of Cl is used, the reaction can be controlled to give all _____

A

Tetrachloromethane

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14
Q

However, if a large ratio of CH4 to Cl is used, the product will be predominantly _____

A

Chloromethane

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15
Q

What is Pyrolysis or Cracking?

A

It is the breaking down of alkanes into smaller molecules by heating them in high temperatures but without air.

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16
Q

In what temperature is Pyrolysis/Cracking achieved?

A

400-700 C

17
Q

What happens if air is present during Pyrolysis/Cracking?

A

The mixture will catch fire; combustion occurs

18
Q

What are alkanes’ relationship with addition reactions?

A

Because alkanes are saturated, they do not undergo addition reactions