UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZA SARJANA MUDA SAINS EXAMINATION FOR TE DEGREE OF BACELOR OF SCIENCE SESI AKADEMIK 2014/2015 : SEMESTER 1 ACADEMIC SESSION 2014/2015 : SEMESTER 1 : KIMIA ORGANIK FIZIK PYSICAL ORGANIC CEMISTRY Disember 2014/Januari 2015 December 2014/Januari 2015 Masa : 2 jam Time : 2 hours ARAAN KEPADA CALON : INSTRUCTIONS TO CANDIDATES : Jawab semua soalan. Answered all questions (Kertas ini mengandungi 4 soalan dalam 6 halaman yang dicetak) (This question paper consists of 4 questions on 6 printed pages)
1. (a) Pertimbangkan hidrolisis (a), dan (c) di bawah. Consider the hydrolysis (a), and (c) below. (i) (ii) (iii) Nyatakan jenis pemangkinan ini. Describe the type of this catalysis. Kirakan pemalar kadar, k 2 sekiranya kepekatan berkesan tindak balas ini ditentukan sebagai 1.6 x 10 8 M dan t 1/2 untuk tindak balas ialah 30 minute. Calculate the rate constant, k 2 if the effective molarity of the reaction was determined at 1.6 x 10 8 M and t 1/2 for reaction is 30 minutes. Tindakbalas adalah 1200 kali ganda lebih pantas daripada (c). Kirakan pemalar kadar, k 3. Jelaskan mengapa ia berbeza. Reaction is 1200 time faster than (c). Calculate the rate constant, k 3. Explain why they are different. (12markah/marks) Empat sebatian suksinat A, B, C dan D telah disintesis. idrolisis suksinat tersebut menghasilkan anhidrida siklik dan fenolat. Cadangkan kereaktifan tindak balas sebatian tersebut dalam turutan menaik serta berikan alasan kepada jawapan anda. Four succinates A, B, C and D have been synthesized. ydrolysis of these succinates leads to the formation of cyclic anhydride and phenolate. Sort these compounds according to reactivity and explain your answer. 2/6
(8 markah/marks) 2. Bincangkan dan lukiskan mekanisma bagi tindak balas bermangkin di bawah. Discuss and draw the mechanism of the following catalyzed reactions. (a) Metanolisis sebatian, E dalam kehadiran enzim tiruan, F. Methanolysis of compounds,e in the presence of an artificial enzyme, F. idrolisis fenil salisilat, G pada p~10 dalam kehadiran asid borik. ydrolysis of phenyl salicylate, G at p~10 in the presence of boric acid. 3/6
(c) Penghidratan piridina aldehid, kepada hasil dwialkohol dalam kehadiran ion zink. ydration of pyridine aldehyde, into a dialcohol product in the presence of zinc ions. (30 markah/marks) 4/6
3. (a) Bincangkan mekanisma benzuna untuk tindak balas berikut: Discussed the benzyne mechanism involved in the following reaction. C 6 5 Cl + NaN 2 N 3 C 6 5 N 2 + NaCl Cadang dan bincangkan suatu pendekatan eksperimen yang boleh menyokong secara tidak langsung kehadiran perantaraan benzuna pada laluan tindak balas tersebut. Describe and discuss an experimental approach that could indirectly support the presence of benzyne intermediate on the reaction path. (15 markah/marks) Cadangkan mekanisma tindak balas yang mungkin boleh menjelaskan pemerhatian berikut: Propose a possible reaction mechanism which could explain the following observations: O + 50% 50% (10 markah/marks) 4. (a) Untuk tindak balas berikut: For the following reaction: hukum kadar empirikal adalah empirical rate law is [ - O] k obs = (1) 1 + [ - O] 5/6
di mana k obs ialah pemalar kadar tertib-pseudo-pertama, dan adalah pemalar empirikal. Cadangkan satu mekanisma tindak balas yang boleh menghasilkan persamaan kinetik yang setara dengan persamaan (1) where k obs is pseudo-first-order rate constant, and are empirical constants. Propose a possible reaction mechanism that could lead to a kinetic equation similar to equation (1). (10 markah/marks) Tuliskan mekanisma tindakabalas yang mungkin bagi tindakbalas berikut: Write possible reaction mechanisms for the following reaction: C 6 5 COOC( ) 3 + O - 30 o C 2 O C 6 5 COO - + ( ) 3 CO Dengan menggunakan kaedah pelabelan isotop, bincangkan mekanisma bagi tindak balas di atas. Using isotopic labeling technique, discuss the possible reaction mechanisms for the above reaction. (15 markah/marks) TAMAT END 6/6