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CIE Jun 2013 v2 Paper 4 Q7
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![Examiners For Use The techniques of mass spectrometry and NMR spectroscopy are useful in determining the structures of organic compounds. 14 (a) The three peaks of highest mass in the mass spectrum of organic compound L correspond to masses of 142, 143 and 144. The ratio of the heights of the M : M+1 peaks is 43.3 : 3.35, and the ratio of heights of the M : M+2 peaks is 43.3 : 14.1. (i) Use the data to calculate the number of carbon atoms present in L. (ii) Explain what element is indicated by the M+2 peak.Compound L reacts with sodium metal. The NMR spectrum of compound L is given below. 5/ ppm (iii) What does the NMR spectrum tell you about the number of protons in L and their chemical environments?UCLES 2013 9701/42/M/J/13<br />
15 (iv) Use the information given and your answers to (i), (ii) and (iii) to deduce a structure for L. Explain how you arrive at your answer. Examiners For Use structure of L (b) The molecular formula C3H6 represents the compounds propene and cyclopropane. [7] CH3CH CH2 H C H propene cyclopropane (i) Suggest one difference in the fragmentation patterns of the mass spectra of these compounds.(ii) Suggest two differences in the NMR spectra of these compounds.[3]UCLES 2013 9701/42/M/J/13 [Total: 10] [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/June_2013_v2_QP_-_Paper_4_CIE_Chemistry_A-level_7-0.jpg)
![7. Page 11 Mark Scheme GCE A LEVELMay/June 2013 Syllabus 9701 Paper 42 (a) (i) 43.3 = 100 3.35 1.1 x n n = 100 x 3.35 = 7.03 = 7 (calculation must be shown) 43.3 x 1.1 (ii) The M and M+2 peaks are in the ratio 3 : 1 hence the halogen is chlorine/Cl (iii) L contains 7 hydrogen atoms or there are 3 types/environments of proton/H [1] [1] [1] (iv) The multiplet with 4 hydrogens or peaks at7.3 suggests a benzene ring The singlet with 2 hydrogens or peak at4.7 suggests a CH2 group The singlet with 1 hydrogen or peak at2.3 suggests an OH group or reaction with Na suggests an OH group OH must be an alcohol, not a phenol (due to itsvalue) Since L also contains 7 carbon atoms and chlorine, this accounts for 126 of the 142 mass, the remaining atom must be oxygen Thus L is CH2OH Cl (allow the 2-, 3- or 4- isomer) (b) (i) we expect propene to have a CH3 peak or a peak at m/e 15 or cyclopropane would have fewer peaks (ii) cyclopropane would have 1 peak (ignore splitting) propene would have 2 (or 3, or 4) peaks or propene would have peaks in the4.5-6.0 (alkene) region no splitting of cyclopropane peak (any two points) (ignore splitting)Cambridge International Examinations 2013 [6] [9 max 7] [1] [2] [3] [Total: 10]<br />](https://learnah.org/wp-content/uploads/2018/08/June_2013_v2_MS_-_Paper_4_CIE_Chemistry_A-level_7.jpg)