SAJC Prelim P3_Questions

1 Name: Class: ST ANDREW’S JUNIOR COLLEGE JC2 Preliminary Examinations Chemistry Higher 2 9647/03 14 September 2015 Paper 3 2 hours Candidates answer on separate paper. Additional Materials: Writing paper, Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and civics group on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer any four questions. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. This document consists of 15 printed pages including this page. [Turn over

2 [Blank Page] [Turn over

3 1 (a) Organic compounds have various applications. For instance, Ketoprofen is a kind of nonsteroidal anti-inflammatory drug, which can be used as a substitute for aspirin. (i) Friedel Craft Acylation was first discovered by Charles Friedel and James Crafts in 1877. This reaction allowed for the acylation of an aromatic ring with acyl chloride. One such example is given below. Benzophenone, which can be used to synthesise Keto profen, has the structure below. Suggest the reagent needed to convert 2 moles of benzene into 1 mole of benzophenone. [1] [Turn over

4 1 (a) (ii) Ketoprofen may be synthesised from benzophenone in the following route. State the reagents and conditions for Steps 1 to 3. Draw the structural formula of A. [4] (iii) Ketoprofen is commonly sold as its sodium salt form for better absorption by the body, which is made up of 70% water. Explain, with the aid of a diagram, how this better absorption comes about. [2] (iv) Nitrogen-containing derivatives of Ketoprofen may be synthesised and some examples are as shown. Describe a simple chemical test to distinguish between compound D and compound E. [2] (v) Ketoprofen can react with cold alkaline HCN to form a product which exists as a mixture of 4 stereoisomers. Give the structure of the product formed. Hence, state the type of isomerism exhibited by this product and draw the stereoisomers. [4] [Turn over

5 1 (b) Another use of organic compounds is in the area of food preservation. To prevent food spoilage, the pH of food should not fluctuate too much. Hence, a mixtu