June 1998 Module 4 ExamReturn to AS and A2 Chemistry1. Three different reactions
of propan-2-ol are shown below.
(a) For each of the reactions I, II and III, give suitable reagents and conditions. Reaction I Reagents ...................................................................................................................................... Conditions ...................................................................................................................................... Reaction II Reagents ...................................................................................................................................... Conditions ...................................................................................................................................... Reaction III Reagents ...................................................................................................................................... Conditions ......................................................................................................................................(6) (b) If 2-methylpropan-2-ol, (CH3)3COH, was used as the starting material in (a) instead of propan-2-ol, identify the organic products, if any, of reactions I, II and III. You should indicate if no reaction occurs.
...................................................................................................................................... Reaction II ...................................................................................................................................... Reaction III ......................................................................................................................................(3) (c) Propan-2-ol and 2-methylpropan-2-ol have boiling points of 82.2oC and 82.5oC respectively. (i) Draw a fully labelled sketch of the boiling point/composition diagram you would expect for mixtures of these two liquids.  (3) (ii) Justify the sketch in (c)(i) in terms of the intermolecular forces present. ...................................................................................................................................... ......................................................................................................................................(2) (iii) Comment on the possibility of separating this mixture by fractional distillation. ...................................................................................................................................... ......................................................................................................................................(2) Total 16 marks 2. (a) Outline the reaction of propanone with the following reagents. Give the equation for the reaction, the conditions, and the name of the organic product. (i) Hydrogen cyanide Equation: ...................................................................................................................................... Conditions: ...................................................................................................................................... Name of product: ......................................................................................................................................(3) (ii) Sodium tetrahydridoborate(III) (sodium borohydride) Equation (you may represent NaBH4 as [H]): ...................................................................................................................................... Conditions: ...................................................................................................................................... Name of product: ......................................................................................................................................(3) (b) (i) Give the mechanism
for the reaction in (a)(i).
(3) (ii) What type of mechanism is this? ......................................................................................................................................(1) (iii) What feature of the carbonyl group makes this type of mechanism possible? Explain how this feature arises. ...................................................................................................................................... ......................................................................................................................................(2) (iv) Explain briefly, by reference to its structure, why ethene would not react with HCN in a similar way. ...................................................................................................................................... ......................................................................................................................................(1) Total 13 marks 3. (a) Consider the following
reaction sequence, then answer the questions which follow.
(i) Give the reagents and conditions necessary for: Step 1 Reagents: ............................................................................................................. Conditions: ..................................................................................................................... Step 2 Reagents: ............................................................................................................. Conditions: ..................................................................................................................... Step 5 Reagents: ............................................................................................................. Conditions: .....................................................................................................................(7) (ii) Identify A. ......................................................................................................................................(1) (b) Nylon 6:6, a polyamide, has a structure containing the following repeat unit: -[-CO-(CH2)4-CONH-(CH2)6-NH-]- (i) Give the structures of
the monomers from which this polymer could be made.
(2) (ii) What type of polymer is this? ......................................................................................................................................(1) (c) (i) Show the structure
of poly(tetrafluoroethene)
(2) (ii) State one use of this polymer. ......................................................................................................................................(1) (d) Which of the two polymers in (b) and (c) is the easier to break down and hence constitutes the smaller environmental hazard? Give a reason for your answer. ...................................................................................................................................... ...................................................................................................................................... ......................................................................................................................................(2) Total 16 marks 4. Organic compounds which are used as drugs in medicine often have their structures modified in order to make them more hydrophilic (soluble in water) or lipophilic (soluble in fatty tissue). One such drug is chloramphenicol, A. The -CH2OH group in the molecule can be altered in the following ways:  (a) (i) Suggest which one of the compounds A, B, C or D would be most soluble in water and hence suitable for intravenous injection. ......................................................................................................................................(1) (ii) Explain your reasoning. ...................................................................................................................................... ......................................................................................................................................(2) (b) (i) Which one of the compounds A, B, C or D would you expect to be least soluble in water and hence suitable to be administered to patients as a suspension in water? ......................................................................................................................................(1) (ii) Give a reason for your answer. ......................................................................................................................................(1) (c) (i) The conversion of A to B and that of A to C involves the same type of reaction. What type of reaction is this? ......................................................................................................................................(1) (ii) Under what conditions is this type of reaction often brought about in the laboratory? ......................................................................................................................................(2) (iii) Give the formulae for the reagents required for the conversion of A to B ........................................................................................................................... C to D ...........................................................................................................................(2) (d) (i) Outline a practical procedure by which a solid sample of D could be purified in the laboratory. ...................................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ......................................................................................................................................(3) (ii) Suggest how the purity of this sample might be checked. ......................................................................................................................................(1) (e) No matter which of the forms B, C or D is taken, the compound A is re-formed in the acidic conditions in the stomach by the same type of reaction. What type of reaction is this? ......................................................................................................................................(1) Total 15 marks |
