Free-radical substitution

This question is about haloalkanes.

Haloalkanes can be synthesised by reacting alkanes with halogens in the presence of ultraviolet radiation.

An alkane reacts with bromine to form 2-bromo-2-methylpropane.

Write the equation for this reaction, showing the structures of the organic compounds.

Name the reaction mechanism and the type of bond fission that occurs.

Equation

Name of reaction mechanism........

Type of bond fission........

Describe two limitations of the synthesis of 2-bromo-2-methylpropane from an alkane and bromine.

This question is about hydrocarbons.

The boiling points of some hydrocarbons containing 6 carbon atoms are shown below.

State and explain the trend in boiling points shown by these hydrocarbons.

2-methylpentane reacts with bromine by radical substitution.

A mixture of organic products is formed, including 3-bromo-2-methylpentane, and compounds A and B.

Complete the table below to show the mechanism for the formation of 3-bromo-2-methylpentane and three possible equations for termination.

In your equations, use structural or skeletal formulae and ‘dots’ (•) for the position of

Organic compound A is formed by the substitution of all 14 H atoms in 2-methylpentane by Br atoms.

Write the equation, using molecular formulae, for the formation of compound A from 2-methylpentane.

Organic compound B is formed by the substitution of some of the 14 H atoms in 2-methylpentane by Br atoms.

0.8649 g of compound B is heated until it is vaporised.

Under the conditions used:

• compound B has a volume of 72.0 cm³

• the molar gas volume is 40.0 dm³ mol^–1.

Determine a possible molecular formula of compound B.

Which equation(s) could be part of the propagation step in the radical substitution of C₅H₁₂ to form C₅H₁₁Cl ?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1

2-Methylbutane is reacted with chlorine by radical substitution.

What is the number of structural isomers with the molecular formula C₅H₁₁Cl that could be formed?

A 2

B 3

C 4

D 5

Hydrocarbon A can be reacted with bromine in the presence of ultraviolet radiation to prepare (CH₃)₃CCHBrCH₃.

What is the systematic name for (CH₃)₃CCHBrCH₃?

(CH₃)₃CCHBrCH₃has stereoisomers.

Explain the term stereoisomers and name this type of stereoisomerism.

Explanation:........

Type of stereoisomerism:........

Draw 3D diagrams for the stereoisomers of (CH₃)₃CCHBrCH₃.

Complete the table to show the mechanism for the reaction of hydrocarbon A with Br₂ to form (CH₃)₃CCHBrCH₃.

Use skeletal formulae for all organic compounds. Use ‘dots’ (●) to show the position of unpaired electrons.

State two limitations of using radical substitution in organic synthesis.

Butane reacts with chlorine in the presence of ultraviolet radiation to form a mixture of organic products.

Which equation shows a propagation step in the mechanism for this reaction?

A Cl₂ → •Cl + •Cl

B •Cl + •C₄H₈Cl → C₄H₈Cl₂

C C₄H₉Cl + •Cl → C₄H₈Cl₂ + •H

D •Cl + C₄H₉Cl → •C₄H₈Cl + HCl

Ethane reacts with chlorine by radical substitution to form chloroethane.

Which radical(s) is/are present in the mechanism?

A 1, 2 and 3

B Only 1 and 2

C Only 2 and 3

D Only 1