SCES1220 : ORGANIC CHEMISTRY I KIMIA ORGANIK I

Transkripsi

1 UNIVERSITY OF MALAYA UNIVERSITI MALAYA EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE WITH EDUCATION PEPERIKSAAN IJAZAH SARJANA MUDA SAINS DENGAN PENDIDIKAN ACADEMIC SESSION 2012/2013 : SEMESTER 1 SESI AKADEMIK 2012/2013 : SEMESTER 1 SCES1220 : ORGANIC CHEMISTRY I KIMIA ORGANIK I January 2013 Januari 2013 TIME : 2 hours MASA : 2 jam INSTRUCTIONS TO CANDIDATES : ARAHAN KEPADA CALON : Answer ALL the questions. Jawab SEMUA soalan. (This question paper consists of 5 questions on 7 printed pages) (Kertas ini mengandungi 5 soalan dalam 7 halaman yang dicetak)

2 SCES1220/02 1. (a)(i) Explain the formation of sp 3 and sp 2 carbon orbitals for the following compound and show the overlapping orbitals for the formation of pi, π, carbon-carbon bond and sigma, σ, carbon-carbon and carbon-hydrogen bonds. Jelaskan pembentukan orbital karbon sp 3 dan sp 2 bagi sebatian berikut dan tunjukkan pertindihan orbital bagi pembentukan ikatan pi, π karbonkarbon dan dan sigma, σ karbon-karbon dan karbon-hidrogen. Give the products of the reactions between n-propane with bromin in the presence of light and predict the percentage of each product. Berikan hasil bagi tindak balas diantara n-propana dengan bromin dalam kehadiran cahaya dan ramalkan peratusan hasil masing-masing. (iii) State the functionl groups present in the following infrared spectra. Nyatakan kumpulan berfungsi yang terdapat dalam spektrum inframerah berikut:

3 SCES1220/03 (b)(i) Explain the aromaticity of the following compounds: Jelaskan kearomatikan bagi sebatian berikut: Write the mechanism for the following acylation of benzene: Tuliskan mekanisme bagi pengasilan benzena berikut: (iii) Give the products of the following reaction: Beri hasil tindak balas bagi tindak balas berikut: 2. (a) Based on the structure of alkene C, answer the following questions: Berdasarkan kepada struktur alkena C, jawab soalan berikut: C

4 SCES1220/04 (i) State whether alkene C has Z or E configuration and give the IUPAC name for that alkene. Nyatakan sama ada alkene C mempunyai konfigurasi Z atau E dan berikan nama IUPAC bagi alkene tersebut. Give the hydration product of C in the presence of diluted sulphuric acid Beri hasil penghidratan alkena C dalam kehadiran asid sulfurik cair. (iii) Write the equation for the reaction of alkene C and BH 3 in THF followed by oxidation using H 2 O 2 /OH -. Give the mechanism for this hydroborationoxidation reaction. Tuliskan persamaan tindak balas antara alkena C dengan BH 3 dalam pelarut THF diikuti dengan pengoksidaan menggunakan H 2 O 2 /OH -. Berikan mekanisme tindakbalas penghidroboranan-pengoksidaan ini. (b) Complete the following reactions and state the rules of the reactions in and (iii). Lengkapkan tindak balas berikut dan nyatakan aturan yang diikuti bagi tindak balas dalam dan (iii):

5 SCES1220/05 3. (a) Give the structural formulae D, E, F, G and H for the following reactions. Berikan formula struktur D, E, F, G dan H bagi tindak balas berikut: (b)(i) Give the mechanism for the following reaction: Berikan mekanisme bagi tindak balas berikut: (5 marks/markah) Give the synthetic pathway for the preparation of trans-3-heptene starting from ethyne. Berikan laluan sintesis bagi penyediaan trans-3-heptene bermula dari etuna.

6 SCES1220/06 4. (a) Explain, with examples, each of the following: stereocentre, chiral centre and enantiomeric excess (ee). Dengan memberi contoh yang sesuai, terangkan tiap-tiap yang berikut: pusat stereo, pusat kiral dan lebihan enantiomer. (b) Draw enantiomers for each of the following compounds using Fischer projections. Indicate the configuration as either R or S for each enantiomer. Lukis enantiomer untuk setiap sebatian berikut menggunakan unjuran Fischer. Nyatakan konfigurasi sama ada R atau S untuk setiap isomer. (i) 2-methyl-1-butanol 2-metil-1-butanol CH 3 CH(OH)CO 2 H (c) For each of the following disubstituted cyclohexanes, show, with explanation, the relative stability of two chair conformers: Untuk setiap sikloheksana dwi-terganti berikut, tunjukkan bersama keterangan kestabilan relatif bagi dua konformasi kerusi. (i) (iii) cis-1-bromo-3-methylcyclohexane cis-1-bromo-3-metilsikloheksana trans-1-bromo-3-methylcyclohexane trans-1-bromo-3-metilsikloheksana trans-1,4-dimethylcyclohexane trans-1,4-dimetilsikloheksana (20 marks/markah) 5. (a) Give the structure of the products and indicate the configuration of chiral products as either R or S in the following reaction: Berikan struktur hasil dan nyatakan konfigurasi sama ada R atau S bagi hasil kiral dalam tindak balas berikut: (S)-2-bromobutane + HO - products (S)-2-Bromobutana + HO - hasil

7 SCES1220/07 (b) Draw and discuss the relative stability of the contributing resonance structures for the following compounds: Lukis dan bincangkan kestabilan relatif struktur resonans sumbangan bagi sebatian berikut: (c) Discuss the reaction mechanism for the following reaction and explain why o- and p-bromonitrobenzene can not form in the reaction. Bincangkan mekanisme tindak balas untuk tindak balas berikut dan jelaskan mengapa o- dan p-bromonitrobenzena tidak boleh terbentuk dalam tindak balas ini. (20 marks/markah) TAMAT END