Characteristic Organic Reactions (Cambridge (CIE) AS Chemistry): Exam Questions

4-Methylpent-2-ene reacts with hydrogen bromide to form 2-bromo-4-methylpentane as shown.

CH₃CH(CH₃)CH=CHCH₃ + HBr → CH₃CH(CH₃)CH₂CHBrCH₃

Complete the diagram to show the mechanism for this reaction. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. Draw the structure of the organic intermediate.

State the role of HBr in the reaction in (a).

The halogenoalkane produced in (a) can be converted back into 4-methylpent-2-ene.

State the reagents and conditions required for this reaction to occur.

i) State two characteristics of a homologous series.

[2]

ii) State the homologous series to which propene belongs.

[1]

Propene reacts to form a mixture of 1-chloropropane and 2-chloropropane.

i) State a suitable reagent for this reaction.

[1]

ii) Suggest which halogenoalkane is formed as the major product of this reaction. Explain your answer.

[2]

i) State the reagents and conditions required for the conversion of 1-chloropropane into butanenitrile, CH₃CH₂CH₂CN.

[2]

ii) 2-chloropropane can be converted into a structural isomer of butanenitrile.

Name this isomer and draw its displayed formula.

[2]

A reaction scheme involving butanone is shown in Fig. 3.1.

Butanone  X Y 2-chlorobutane

Fig. 3.1

i) State suitable reagents and conditions for reactions 1 and 2.

[2]

ii) State the type of reaction that occurs in reaction 2.

[1]

i) Name the mechanism for reaction 3 in Fig. 3.1.

[1]

ii) Complete the diagram to show the mechanism for reaction 3. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. Draw the structure of the organic intermediate.

[4]

Describe a chemical test and observation which would distinguish between butane and Y in Fig. 3.1.