SCES2260 : KAEDAH SPEKTROSKOPI DALAM KIMIA ORGANIK SPECTROSCOPIC METHODS IN ORGANIC CHEMISTRY

Transcription

1 UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE SESI AKADEMIK 2009/2010 : SEMESTER 1 ACADEMIC SESSION 2009/2010 : SEMESTER 1 SCES2260 : KAEDAH SPEKTROSKOPI DALAM KIMIA ORGANIK SPECTROSCOPIC METHODS IN ORGANIC CHEMISTRY November 2009 November 2009 MASA : 2 jam TIME : 2 hours ARAHAN KEPADA CALON : INSTRUCTIONS TO CANDIDATES : Jawab SEMUA soalan. Answer ALL questions. Bagi soalan 4b bahagian (iii) dan (iv) sila beri jawapan anda di atas Lampiran 1 dan 2 pada halaman 13. For question 4b section (iii) and (iv) please give your answer on Attachment 1 and 2 on page 13. Anggapkan jisim atom bagi C=12; H=1; O=16; Cl=35; Br=79 Assume that the atomic weight for C=12; H=1; O=16; Cl=35; Br=79 (Kertas soalan ini mengandungi 4 soalan dalam 12 halaman yang dicetak) (This question paper consists of 4 questions on 12 printed pages)

2 SCES2260/02 1. (a) Ramalkan maltiplisiti bagi hidrogen-hidrogen yang ditunjukkan pada spektra 1 H-NMR sebatian-sebatian berikut: Predict the multiplicities of the indicated hydrogens in the 1 H-NMR spectra of these compounds: CH 2 Cl H CH 2 Cl Cl H C Cl H C H Cl C Cl H Cl H C C H CH 2 CH 3 (b) Berapa banyak puncak yang anda jangkakan bagi setiap sebatian berikut pada spektra 1 H dan 13 C NMR masing-masing? How many signals would you expect for each of the following molecules in their 1 H and 13 C spectra respectively? I) (CH 3 ) 2 C=C(CH 3 ) 2 II) 1,1-dimethylcyclohexane III) CH 3 COCH 3 IV) (CH 3 ) 3 CCOOCH 3 O CH 3 V) VI) H 3 C Br CH 3 (c) Sebatian yang mana spektra 1 H NMR seperti ditunjukkan dibawah, mempunyai formula molekul C 3 H 6 Br 2, cadangkan strukturnya. The compound which 1 H NMR spectrum is shown has the molecular formula C 3 H 6 Br 2. Propose a structure.

3 SCES2260/03 (d) Cadangkan struktur bagi sebatian yang mempunyai formula molekul C 5 H 10 O 2 dan spektra IR dan NMR seperti berikut: Suggest a structure for the compound with the formula C 5 H 10 O 2 that has the following IR and 1 H-NMR spectra: (25 markah/ marks)

4 SCES2260/04 2. (a) Cadangkan struktur bagi sebatian yang sepadan dengan data 1 H NMR dan IR berikut: Propose structures for compounds that fit the following 1 H NMR and IR data: i. C 4 H 9 Cl: 3.35 ppm (doublet, 2H), 2.00 ppm (multiplet,1h), 1.00 ppm (doublet, 6H) ii. C 3 H 6 Br 2 : 3.6 ppm (triplet, 2H), 2.4 ppm (quintet, 1H) iii. C 4 H 10 O: 3.3 ppm (doublet, 2H), 2.4 ppm (singlet, 1H), 1.7 ppm (multiplet, 1H), 0.9 ppm (doublet, 6H); 3330 cm -1 (broad). iv. C 5 H 10 O: 2.6 ppm (septet, 1H), 2.1 ppm (singlet, 3H), 1.1ppm (doublet, 6H); 1716 cm -1 (b) Cadangkan struktur bagi sebatian C yang mempunyai M + = 86 pada spektum jisimnya, dan keserapan IR pada 3400 cm -1, dan data dari spektrum 13 C NMR: Propose a structure for compound C, which has M + = 86 in its mass spectrum, an IR absorption at 3400 cm -1, and the following 13 C NMR spectral data: Compound C Broadband-decoupled 13 C NMR: 30.2, 31.9, 61.8, 114.7, ppm DEPT-90: ppm DEPT-135: positive peaks at ppm; negative peaks at 30.2, 31.9, 61.8, ppm (c) Cadangkan struktur bagi sebatian yang berformula molekul C 6 H 10 O 2 yang mempunyai spektrum IR, 1 H NMR, dan 13 C NMR seperti berikut: Suggest a structure for the compound with the formula C 6 H 10 O 2 that has the following IR, 1 H NMR, and 13 C NMR spectra:

5 SCES2260/05 (25 markah/ marks) 3. (a) Tunjukkan persamaan yang menjelaskan pemecahan utama yang berlaku pada m/z = 97 dan m/z = 57 pada spektrum jisim sebatian 2,4, 4-trimetil-1-pentena (M + =112). Show equations to account for the major fragment ions that occur at m/z =97 and m/z = 57 in the mass spectrum of 2,4,4-trimethyl-1- pentene(m + =112).

6 SCES2260/06 (b) Nootkatone, adalah salah satu bahan kimia yang memberikan bau dan rasa seperti anggur, mempunyai ion molekul pada m/z = 218 dalam spektrum jisimnya dan mempunyai C, H, dan O. Cadangkan beberapa formula molekul yang mungkin bagi Nootkatone. Nootkatone, one of the chemicals responsible for the odor and taste of grapefruit, shows a molecular ion at m/z = 218 in its mass spectrum and contains C, H, and O. Suggest several possible molecular formulas for nootkatone. (c) Cadangkan struktur bagi sebatian yang berformula C 6 H 12 O 2 dan mempunyai spektrum IR, 1 H-NMR, dan 13 C-NMR seperti berikut: Suggest a structure for the compound with the formula C 6 H 12 O 2 that has the following IR, 1 H-NMR, and 13 C-NMR spectra:

7 SCES2260/07 (d) Spektrum 1 H NMR bagi sebatian H adalah seperti di bawah. Puncak pada m/z tertinggi dalam spektrum jisim H adalah 122 dan 124 dengan mempunyai keamatan yang sama. Tunjukkan struktur bagi H. The 1 H-NMR spectrum for compound H is as follow. The peak at the highest m/z in the mass spectrum of H appear at 122 and 124 with intensities in a ratio of about 1 to 1. Show the structure of H.

8 SCES2260/08 (e) Spektrum jisim bagi 3-metil-2-pentanon dan 4-metil-2-pentanon adalah seperti berikut. Jelaskan spektrum mana untuk sebatian yang mana. Apakah struktur bagi ion yang bertanggungjawab memberikan puncak pada m/z = 43 pada spektrum masing-masing? The mass spectra of 3-methyl-2-pentanone and 4-methyl-2-pentanone are as follow. Explain which spectrum goes with which compound. What is the structure of the ion responsible for the peak at m/z = 43 in each spectrum? (25 markah/ marks)

9 SCES2260/09 4. (a) Nitril bertindak balas dengan reagen Grignard, R MgBr. Hasil dari tindak balas antara 2-metilpropananitril dengan metilmagnesiumbromida mempunyai data-data spektroskopi seperti berikut. Cadangkan strukturnya. Nitriles (RCN) react with Grignard reagents (R MgBr). The reaction product from 2-methylpropanenitrile with methylmagnesium bromide has the following spectroscopic properties. Propose a structure. MS : M + = 86 IR : 1715 cm -1 1 H NMR : 1.05 (6 H, doublet, J =7 Hz); 2.12 (3 H, singlet); 2.67 (1 H, septet, J = 7 Hz) 13 C NMR : 18.2, 27.2, 41.6, CH 3 CH 3 CHC N 1. MeMgBr 2. H 3 O +? (b) Asid Cinnamic cis-3-heksenil ester mempunyai ion molekul pada m/z = 230. Spektrum 1 H, 13 C, 13 C DEPT, HSQC dan COSY bagi molekul ini adalah seperti berikut: Cinnamic acid cis -3-hexenyl ester has molecular ion at m/z = 230. The 1 H, 13 C, 13 C DEPT, HSQC and COSY spectrum for this molecule are given below: i. Ada berapa hidrogen setara yang berbeza dalam molekul tersebut? How many different chemical equivalent hydrogen is there in this molecule? ii. Ada berapa atom C dalam molekul ini? How many C atom does the compound has? iii. Menggunakan spektrum 13 C NMR yang dibekalkan (Lampiran 1), labelkan setiap puncak sama ada ianya C, CH, CH 2, CH 3 atau CO. Using the 13 C NMR spectrum provided (Attachment 1), assign each peak either they are C, CH, CH 2, CH 3 or CO. iv. Menggunakan spektrum 1 H NMR yang dibekalkan (Lampiran 2), labelkan setiap puncak sama ada ianya CH, CH 2 atau CH 3. Using the 1 H NMR spectrum provided (Attachment 2), assign each peak either they are CH, CH 2 or CH 3. v. Cadangkan formula molekul bagi sebatian ini. Propose the molecular formula of this compound. vi. Cadangkan struktur kimia bagi sebatian ini. Propose the chemical structure of this compound. (25 markah/marks)

10 SCES2260/10 1 H NMR spectrum of Cinnamic acid cis -3-hexenyl ester 13 C NMR spectrum of Cinnamic acid cis -3-hexenyl ester

11 13 C DEPT NMR spectrum of Cinnamic acid cis -3-hexenyl ester SCES2260/11

12 SCES2260/12 HSQC spectrum of Cinnamic acid cis -3-hexenyl ester COSY spectrum of Cinnamic acid cis -3-hexenyl ester TAMAT END

13 No. Pendaftaran : SCES2260 Lampiran 1: 13 C NMR spectrum of Cinnamic acid cis -3-hexenyl ester Lampiran 2: 1 H NMR spectrum of Cinnamic acid cis -3-hexenyl ester