SAMPLE EXAM 1A Organic Chemistry I 2425 Egosterol Egosterol Ergosterol is a component of fungal cell membranes serving the same function that cholesterol serves in animal cells The presence of ergosterol in fungal cell membranes coupled with its absence in animal cell membranes makes it a useful target for antifungal drugs Ergosterol is also present in the cell membranes of some protists such as trypanosomes 2 This is the basis for the use of some antifungals against West African sleeping sickness 1 ORGANIC CHEM 2425 EXAM 1A Sample Name Chapters 12 15 Score DIRECTIONS Please answers all questions in the space provided as completely and clearly as possible Show all your work for the writing portions of the exam PART I Multiple choice 3 points each 1 How many sets of equivalent protons are there for CH2Cl CH2 CH2 Cl A 1 B 2 C 4 D 6 2 Which of the following is an example of a conjugated dienes A C B D 3 Which of the following is the most likely fragment ion formed at 57 A CH3 CH2 B CH3 CH2CH2CH2 C CH3 CH2CH2 D CH CH2 4 In the proton NMR spectrum for1 chlorobutane which of the proton has the lowest field resonance lowest chemical shift CH2Cl CH2 CH2 CH3 I II III IV A I B II C III D IV 5 What is the structure for a compound C4H8Br2 which has the following proton NMR spectrum Doublet 1 7 6 H A 1 1 dibromobutane C 1 3 dibromobutane and Quartet 4 4 2 H B 1 2 dibromobutane D 2 3 dibromobutane 6 What kind of compound has a sharp IR absorption band in the region of 1710 cm 1 and a broad band at 3300 cm 1 A Ethanol B Acetic Acid C Acetone D Diethyl ether 7 Examining the Proton NMR spectrum of a compound allows us to A Determine the types of functional groups present in the compound B Determine the C H framework of the compound 2 C Determine the molecular weight of the compound D Determine the nature of the conjugated pi electrons system in the compound 8 Given M 156 the possible formula of compound which include only one oxygen is A C13H14O B C11H8O C C12H10O D C10H4O 9 An organic compound is composed of C H and N It shows a molecular ion at m z 112 amu in the mass spectrum What is the plausible molecular formula for this compound A C7H14N2 B C6H12N2 C C6H10N2 D C7H12N2 10 Which of the following statements is true about the molecular ion A a compound that lost a pair of electrons B a compound that gained one electron C a compound that lost one electron D a compound that carries a free radical and a negative charge 11 Which of the following dienes is most stable A D C B 12 Which of the following dienes cannot be used as the diene component in Diels Alder Reaction D C B A 13 Which of the following is expected to be aromatic A B D C 14 Which of the following is a correct description of benzene A B C D The molecule is planar The molecule is aromatic The CCC bond angles are all 120o and each carbon is sp2 hybridized All of the above 15 Which is not a required for aromaticity A The structure must be bicyclic 3 B Each atom in the ring must have an unhybridized p orbital C The network must contain 4n 2 pi electrons where n is a whole number D The structure must be planar PART II Show all your work for complete credit 16 Refer to the mass spectrum of CxHy shown below to answer the following questions 4 points a What peak represents M o b What peak represents the base peak c What peak represents the parent peak 4 17 Suggest a structure which is consistent with all the spectral data given below for CxHyO2 4 points 5 18 Suggest a structure which is consistent with the IR and 1H NMR spectra shown below C11H14O2 4 points 6 19 Suggest a structure which is consistent with the 1 H NMR spectra shown below 4 points C4H8O2 20 How many different type of hydrogens in different environments are there in the following compounds 4 points a cis 1 3 dibromopropene b 2 chloropropane 21 Propose structure that fit the following 1H NMR data 4 points 7 C8H9Br 3 H doublet at 2 0 1 H quartet at 5 0 5 H singlet at 22 What diene and dienophile would you react to give the product below 4 points CO2CH3 CH3 23 Provide the structures of the major product s in the following reactions 15 points a CN b 1 NBS CCl4 2 KOH c C N C N d HBr 1 4 addition e CH3 2 HCl 2 equivalents CH3 8 7 3 24 Nomenclatures 12 points I Give the correct names IUPAC CH3 NH2 CH3 CH3 OH Cl II Give the correct structures a m nitroaniline b 2 4 6 trinitrophenol c 3 bromo 3Z 5E octadiene Bonus question 10 points Provide a detailed stepwise mechanism for the reaction shown below Please show all your work including electron flow CH3 HBr 9 CHEM 2425 EXAM 1 Sample Chapters 12 15 Answers PART I 1 B 2 B PART II 3 B 4 E 16 a m z 66 5 D 6 B 7 B b m z 64 8 B 9 B 10 C 11 D 12 D 13 C c m z 66 17 MW 116 The band at 1737 cm 1 indicates a carbonyl At m z 57 high intensity peak presents O O CH3CH2 C CH3CH2 C O CH2CH2CH3 propylpropanoate or ethylpropyl ester possibly an ester 18 The band at 1684 cm 1 indicates a carbonyl The wide band from 3300 2500 cm 1 is characteristic of the O H stretch of carboxylic acids The bands at 3000 2850 cm 1 indicate C H alkane stretches The bands in the region 1320 1000 cm 1 indicate the C O stretch of carboxylic acids The band unmarked on the graph below just to the left of 3000 cm 1 indicates aromatic C H stretch Aromatics also show bands in the regions 1600 1585 cm 1and 1500 1400 cm 1 C C in ring stretch and 900 675 cm 1 C H out of plane para t butylbenzoic acid or para 1 1 dimethylethyl benzoic acid 19 C4H8O2 Degree of unsaturation 4 8 2 1 1 one double bond carbonyl group C O possibly ester O CH3 C O CH2 CH3 CH2Br Br C C 20 a H 3 22 Br b CH3 CHCl CH3 H 21 2 O H C OCH3 CH3 Ethyl acetate H 10 CH CH3 14 E 15 A 23 CN c No reaction benzene too stable to undergo Diel s Alder reaction b a CH3 d and CH2 CH CH CH3 Br CH2 CH CH CH3 1 4 addition Br 1 2 addition e Cl CH3 CH3 and Cl Cl Cl CH3 CH3 24 I 5 methyl 1 3 …