CHEM 281 - 2011-3 Problem Set 2 SOLUTIONS - WEEK 3

CHEM 281 - 2011-3 Problem Set 2 SOLUTIONS - WEEK 3 -...

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Unformatted text preview: CHEMISTRY 281-4 (2011-3). Dr. Pete Wilson ORGANIC CHEMISTRY 1: PROBLEM SET 2. WEEK 3 — LECTURE 7/3 Selected Problems from Past Inter—term Exams ssion in tutoria (Week 4) in addition to any other general may have abou he course material. > For dis questions For Proble Se?2>pleas o to: / O http://www.chemistry.sfu.ca urfls’gour CHEM 281 Notes: > Your first inter—term examination will consist of questi s that relate to the topics covered in class up to the end of Week 4. ‘i This problem set is representative, if not beyond (because of curriculum changes and that your examination is earlier than in previous years), of what you may expect in your first inter-term examination. SIMON FRASER UNIVERSITY Organic Chemistry 1, 2005—3 CHEM 281 Dr. Peter D. Wilson INTER-TERM EXAMINATION 1 (12.5 % of total course evaluation) 10:35 — 11:20 am. Wednesday 19, October 2005 Answer all of the Questions (8 questions). Your exam consists of 8 printed pages including this one (please check this when you are told to do so). Fill in your name and student number below. The use of a ‘ y of the periodic table, molecular models and an electronic calculator is allowed. . NAME. ....................................................................... .. STUDENT #: ................. ............................................ .. Question 1 2 3 4 5 6 7 9 8 6 TOTAL 50 TOTAL 12.5 Reese see We Hammer. AfFENh-M 5141M swarm-nod... . . .. 1. 3). Draw the chemical structures of the three stereoisorners of 1,2-dimethylcyclopropane. You should use wedged and hatched bonds to carefully show the stereochemistry (3 marks). . A ‘Pmr 0" Wadged (SUbSfitueT‘t "Up") = I hatched (subsiituent"down") z e" “and; 6.) Refer; M 1. b). One of the structures that you have drawn above represents an achiral compound (a non-chiral mesa compound). Draw a circle around this structure (1 mark). H' has an In‘I'OV'AnL m'irroraplw‘. SYMME‘W-tc l. c). What is the stereochemical relationship of the other -- - - isomers (tie. the ones that you have not drawn a circle around - are they diastereoisomerl mark)? 11.“) a", “a -gaf‘r mpualII-c- Mirror in“ r bl 0%ri * 2. Of the following, draw a circle around the chiral molecules (5 marks). MOM“; . . . . . . 5 Me Me CI ‘ ' Me H OH 7 F Me Me Mew Him H Me Me F Br . Me Me M‘s/\(K/ H OH Me Me Me Me 0 Me H H A/K/Me IE7 “9 H Me Mam Me Me 0 Me % Lb Me 1K Lila. A {4+ aha/.31.): a“; (calm. McLean—65).. 3. Draw the molecular structures of 10 different com onnds that have the molecular formula — Call”. You can include: cyclic and non-cyclic compounds, alkenes (including different E— and Z-isomers), different enantiomers and diastcreoisomers of a particular compound (5 marks). Cb H11 5": CA. #2“, A = é' O , . 'One. {1&7 or Opul— chub/i (noan I 3 29 > 2 A g: 0 f emu-'6': om; o‘\‘ - ‘A 0‘ ’9 Wims We}, morguu... 5}: 3. r g m u did 3+“! «2.3st 4. Consider the compound ("Peteane") below and answer the following questions. Note; all of the hydrogen atoms are omitted for clarity (10 marks). 4. a). What is the molecular formula of Peteane (1 mark)? CHM-L30 4. b). How many quaternary carbons does Peteane have (1 mark)? 1 a 4. c). How many tertiary hydrogens does Peteauc have (1 mark)? 1r 3 9. ¢ 4. d). How many primary carbons does Peteane have (1 mark)? I 4. 4. e). How many secondary carbons does Peteane have (1 mark)? :7. 4. 1). Is Peteane chiral o non-chiral) (1 mark)? 59W“. (not: asjmm’l‘ ""' 4. g). Provide the IUPAC name for Peteane (2 marks). 3- abdoéuJ-nbu 3,14..- Andanme 4. h). If Peteane was completely burnt in air (“cremated” - a combustion reaction) what would the products of this reaction be £151 how many molar equivalents of each product would be produced (2 marks)? Note; an excess of oxygen is involved — you are not being asked to calculate the amount of oxygen involved. I q. x C0; Hzo x IS' 5. Consider the compound below (an isotopically-laheled carboxylic acid) and answer the following questions (6 marks). 9 D\ /C D"? D \O-H 5. a). The reaction of the carboxylic acid with sodium hydroxide (NaOH) affords a salt. Draw the chemical structure of this salt (1 mark). :0: ill: 3ficX6-e- 5. c). Using “double-headed curly arrows” to illustrate the movement of electrons, show how these two ‘- resonance structures interconvert (in part b) (1 mark). ' 5. d). What is the byproduct of the above reaction (see part a, Le. what else is produced) (1 mark)? ” ‘.-t - ks ‘IVLS Eaflu'l- HAW 2m...” 5. e). If the three deuterium (D) atoms of this compound were replaced with fluorine atoms, would this compound (CF3C02H) be more or less acidic than the original compound (l mark)? F' .3 A‘ohowdsé-c MORE ,_ “b4. .muen-wtsfl mT-Hbfla‘d 5. 1’). Would the pKa value of CFJCOZH be more or less positive than the o ' 'nal compound (1 mark)? Lies; POSITIVZ the argued-1 6 , been-- no MEI-L. blimp-MN MfaCTtoNS'.. .. \> 6. a). By taking a view along the C2-C3 bond of butane (CH3CH2CH2CH3), draw the two energetically different ecli sed and the two different sta ered conformations that this molecule can adopt (tie. draw the Newman Eroiections) (2 marks). raw a circle around the most stable conformation that you have $ 6. b). Based on steric arguments, drawn above (1 mark). d the least stable conformation that you have drawn 1“ 6. c). Based on steric arguments, draw a box ar above (1 mark). 3% TM ’51?) 043,5“ ‘F‘M’ “PM/tn” #716 n n n " dos-L THIS Quémonl WP: mu. Mo-r as M! Weak Futu- M13754 tau-1M M 7. Consider the chiral nonracemic compound ("Donaldaue") below and answer the following questions. Donaldane has a melting point of 50 °C and a specific rotation ([ 1;") of _+ 100 (c 1.0, chloroform). Note, all of the hydrogen atoms are omitted for clarity (9 marks). 18° °L ' I ‘3 |t- 3 I: 1' ’24 ._._. 3 ‘ fl 1 5m: 9 g 7. a). Provide the IUPAC name of Denaldane. You should include R,S assignments and the substituents of the cyclohexane ring should be numbered to give the lowest possible numbering scheme (4 marks). 25,41?)- I, a- CUMQJ‘UL‘4-FC‘I-“MMLmhjchdoMM 7. b). Draw the two different chair-like conformations of Donaldane m draw a circle around the most stable conformation (3 marks). 3 F” F u. u A _‘/\/z ' CHHIKW W; HM. Mir!“ [30° '1 7. d). What would you expect the m lting point £151 specific rotation of the enantiomer of Donaldane (tie. the compound that you have draw 11 part c) to be (1 mark)? K Slim a sum: Imaué‘r'ubz _ 3 EL L OPPDSlTi, gauge “a 8. Consider the following compound and answer the following questions (6 marks). 8. a). What is the hybridization of atom A (1 mark)? 57:3 8. b). What is the hybridization of atom B (1 mark)? SP 7- 8. c). What is the hybridization of atom C (1 mark)? SP TH!N\<...... 8. d). What is the hybridization of atom D (1 mark)? 3'? z 8. e). The sigma bond between atom A and an attached hydrogen atom is due to the interaction of what types of hybrid and atomic orbitals (1 mark)? 8. t). The pi bond between atoms C and D is due to the interaction of what types of orbitals (1 mark)? “iv-'29 (flavlflvw There is no more to do — but do a back and check our answers! Some Additional Questions: 1. a). Draw the chemical structures of the three stereoisomers of 1,2-dimethylcyclohexane. You should use wedged and hatched bonds to carefully show the stereochemistry (3 marks). 1. b). One of the structures that you have drawn above represents an achiral compound (a meso compound). Draw a circle around this structure (1 mark). 1. c). For one of the other stereoisomers (tie. not the mesa compound), that you have drawn above (in part a), draw the gym chair-like con’fo\rmations that this stereoisomer can adopt (2 marks). \ 1. d). One of the conformations that ybn have drawn above (in part c) is more stable than the other. Draw a circle around this conformation (1 mark). a 2. Consider compound A below and answer the following questions. 5) *Go ' ndA UHH/ apou 2. a). What is the molecular formula of compound A (1 mark)? 2. b). How many quaternary carbon centres does compound A have (I mark). 2. c). How many tertiary hydrogens does compound A have (1 mark)? 2. d). Provide the IUPAC name for compound A and include R/S nomenclature. Note: You will need to use the prefix “tetra” somewhere in the compound’s proper name and the numbering system that is provided (4 marks). 10 3. Consider the following compound and answer the following questions (5 marks). G) H \\\OH O ©HSC 6H s O 3. a). Assign the absolute stereoehemistry of this compound (tie. is itR or S) (1 mark). 3. b). The reaction of this compound with sodium hydroxide (NaOH) affords a salt. Draw the chemical structure of this salt (1 mark). 3. c). Now draw the corresponding resonance structure of this salt (1 mark). 3. (1). Using “double-headed curly arrows”, show how these two resonance structures inter-convert (in part c) (1 mark). 3. e). What is the byproduct of the above reaction (fie. what else is produced) (1 mark)? 4. Consider the following compound and answer the following questions (7 marks). H , :03 ,H H A“ a H H germ: b bad 4. a). The carbon-carbon bond (a) is due to the interaction of what type of hybrid atomic orbitals (1 mark)? 4. b). The carbon-carbon sigma bond (b) is due to the interaction of what type of hybrid atomic orbitals (1 mark)? 4. c). The carbon-carbon pi bond (b) is due to the interaction of what type of atomic orbitals (1 mark)? 11 4. d). The carbon-hydrogen bond (c) is due to the interaction of what type of atomic and hybrid atomic orbitals (1 mark)? 4. e). The carbon-hydrogen bond (d) is due to the interaction of what type of atomic and hybrid atomic orbitals (1 mark)? 4. 1). What is the IUPAC name of this compound (you should include in the name a descriptor to account for the geometry of the double bond) (2 marks)? 12 SOLUTIONS 'r'o Ahbl‘noflfib P/LOBDEMS H 6. Hbc. 5 #193.” Up” ‘0'“ 455%! “ 9.4.3,- Base cancmoN gum... NOT 'BE A; K81) N yoga Mm'reaM Loa!‘ “9 1Q: 5 Namewamufii op “AflTIOMfie-Sl sfiazoaé magmas - MPEND I x STefl-Zoa-usMIs-m.y . Not—awhss HITH 4+ mar-era.er sugsfc‘rueN'rs Allow:- A ‘TE‘Tfl-AHebflAL. 644113031 AToM 4&2: CHMAL— (340“) 04-9 Mammal-th . . may MN 2357' As 51174611 A ‘Lefi-r—HMB‘ w ’ £1anr~ Mub‘ FOAM. [MV'bW-‘F‘EZSNTJ MI.th THEy Ag; NON-SUPEMMPOSABLL ® Mlkfioflanafis... ' @ ® are. Ajasmgo‘usws 04> Q 0““ @ (Kasai-yum: “W: . .. .. than-Ham; it I Mpwkd,ul§.h§4~\,a 64141:. MW bu} J- amil.“ “341m,” ...
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This note was uploaded on 12/07/2011 for the course CHEM 281 taught by Professor Williams during the Fall '11 term at Simon Fraser.

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CHEM 281 - 2011-3 Problem Set 2 SOLUTIONS - WEEK 3 -...

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