Sem 3 Real STPM 2016

This is only a suggestion answer please refer your teacher for the more precise answer schemes.

16. The refining of crude oil produces various type of hydrocarbons as shown in the diagram below. The hydrocarbons are used to manufacture other products.

(a) The catalytic cracking process of nonane produces ethene and X. Identify X.

(b) State the reagent which is used to convert ethene to ethane-1.2-diol.

(c) Write the equations for the conversion of methylbenzene to

(i) 2-chloromethylbenzene

(ii) benzylchloride

(d) During the preparation of 2-chloromethylbenzene, a compound Z, is also formed. Draw the structure of Z.

18 Bromination of ethylbenzene in the presence of ultraviolet light yields monobrominated products, P and Q. P rotates plane-polarised light but Q does not. When P and Q are refluxed separately with an aqueous solution of sodium hydroxide, R and S are formed respectively.

(a) Determine the structural formulae of P, Q, R and S.

(b) Describe the mechanism fbr the formations of P and Q.

(c) Determine the major product of the reaction.

(d) Suggest a chemical test to differentiate between R and S.

19 An optically active haloalkane, X, which has a molecular formula, C10H13Cl reacts with an aqueous solution of NaOH to form a compound, Y. X reacts wrth Mg in dry ether followed with CH3COCH3 and is hydrolysed to form Z.

(a) Deduce the structure ofX. Write the chemical equations for all the reactions involved.

(b) Write the reaction mechanism for the formation of Y.

(c) X also reacts with an ethanolic KOH solution. State the type of reaction and draw the structures of all possible products. Determine the major product of the reaction.


20 (a) The reactions scheme of a hydroxy compound, X is shown below.

(i) Draw the structural formula of X and state the reagents and the reaction conditions which are labelled as I and ll in the scheme above.

(ii) I is an optical isomer of X. Draw the structural formula of Y and explain how both isomers can be distinguished by a simple chemical test.

(b) The structural formula of Z is shown below.

(i) Give the IUPAC name of Z.

(ii) When benzenediazonium chloride is added to a solution Z, a bright coloured product is formed. State the reaction conditions. By using a reaction equation, explain your observation and name the reaction involved.



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