Chemistry 9701 · AS & A Level · Hydrocarbons

Hydrocarbons — practice question

C and D are alkenes that share the same molecular formula, $\text{C}_5\text{H}_{10}$. Their structures appear in Fig. 4.1.
(a(i))[1]

Give D’s systematic name.

(a(ii))[1]

Explain why C and D do not display geometrical ($cis/trans$) isomerism.

(a(iii))[1]

Draw a structure for a molecule that is a positional isomer of C and D.

(a(iv))[1]

Give the structural formula for the compound produced when D reacts with $\text{H}_2(g)$ in the presence of a Pt catalyst.

(a(v))[1]

C can undergo addition polymerisation. Draw one repeat unit of this addition polymer.

(b)[2]

The mass spectrum for C contains a molecular ion peak at $m/e = 70$. Its relative intensity is 48.7. The $[M+1]$ peak has relative intensity 2.7. Show that these data are consistent with the molecular formula of C.

(c(i))[3]

C reacts with HBr to form E. Finish the diagram in Fig. 4.2 to show the mechanism for this reaction. Draw the structure of the organic intermediate. Include charges, dipoles, lone pairs of electrons and curly arrows where appropriate.

(c(ii))[1]

D reacts with HBr to give F, a chiral bromoalkane. Draw the structure of F.

(c(iii))[2]

Explain why HBr reacts with C and D to give different major products.

(d)[3]

C can be employed to make H. A possible route to H is shown in Fig. 4.5. Different sections of C are used in reactions 1 and 3. The resulting products are then joined to make H. Fig. 4.5 omits all inorganic products from the reactions. Complete Table 4.1 with the reagents and conditions needed for each reaction shown in Fig. 4.5.

Worked solution & mark scheme

This 16-mark question has a full step-by-step worked solution and mark scheme. One marking point: Systematic name: $\mathrm{3\text{-}methylbut\text{-}1\text{-}ene}$

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI