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Midterm

CHEM 2020 Test 2 Key Fall 2011 (2).pdf

15 Pages
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Department
Chemistry
Course Code
CHEM 2020
Professor
Michael Organ

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Description
safflyer Ch2020 Name: $~----------- '------:n2}ecem21,.1.911STUDENT #: DirectionFor each question, write your answers on the line or in the box. PledgeI have neither given nor received aid on this exam _ Questions Points Score 1-13 26 14 4 15 6 16 6 17 8 18 4 19 14 20-22 6 23 6 24 6 25 12 26 30 27 6 28 6 29 16 30 6 3] 8 Total 170 1 .J _. ... _ Yousaf/lyer Chem 2020 Name: _ Exam 2 December 21,201STUDENT #: Questions 1-13 (2pts each) t" c.t.f 1. In the first step of the f_-'"--__ ris the electropCH.~ -B1he nucleophile. H H r < + HRr H H aH+Br- QC+CH C,=Br- dHBr,nr eCH2= CH2Br 2. Which is the major expected product of this reaction? c. ~CH3 CH3 U Q ~ OH ~ e. 3. Which of the following undergoes the most E2 reaction? Br + -OH A - +> + H2O - a. b. /,,--/B r + H2O - + C I + -OH - c. @ ) /,,--/C I + _-OH e. '- 2 Yousafllyer Chem 2020 Name: _ Exam 2 December 21,2011 STUDENT #: ~agenl andcond:tix::est be usedforthisreaction' Cl a. H S0 b. NaOEt, EtOH, [email protected], ~ d. potassiumt-but-butanol, cold e. NaOEt, EtOH, ~ 5. Which forms the most stable carbocation? < > le, <> ~CI a. b. c. Br A d. e. 6. What is the preferred stereochemistry of the E2 elimination? a. inversion b. retention @antiperiplanar d. synperiplanae.gauche 7. What is the rate law for an E2 reaction of an alkyl halide with sodium ethoxide (NaOEt) in ethanol (EtOH)? a. ra=k[RX] b. ra=ek[RXf @rate=k[RX] [OEC] e. ra=k[OEC] 8. Which gives the highest ratio of substitution / elimination products? 0-' + -OH 0-' + CH J:OO- •• a. © heat 0-' + H2O 0-' + PhO- •• c. d. 0-' + CH£)- e. 3 Yousaf/lyer Chem2020 Name: _ Exam 2 December 21,2011 STUDENT #: ' 9. Which of the following is the most stable conformation of cis-l-isopropyl-3-methylcyclohexane? H 3 ~ rH, r(CH3)~ J (CHb CH3 D -::7' ~ ~CH(CH3)2 ~CH(CH3)2 H3C H3C 1 2 4 a.1 b.2 c.3 d.4 10. When I-pentanol is heated with HCI/ZnC12, l-chloropentane is the major organic product. This reaction proceeds throug\h 'V mechanism, and KbL 0 is produced as a byproduct. A) SNl, H20 --,-v--- @SN2,H20 C) SN1, H2 D)SN2,H2 E) E2,H2 11. Which nota product of this reaction? 1 eqHBr • Br ~ ~Br Br ~ a. b. c. Br~ Br~ @> e. 12. When 2,2-dibromobutane is heated at 200°C in the presence of molten KOH, what is the major organic product? A) 1-bromobut-1-yne !U I-bromobut-2-yne C) but-1-yne ~but-2-yne E) but-l-ene 13. How much oftReenantiomer is present in 109 of a mixture which has an enantiomeric excess of 20% of the S isomer? A) 19 © 4 g D) 6g 4 Yousaf/lyer Chem 2020 Name: _ Exam 2 December 21,201STUDENT#: 14. Provide the IUPAC name for the following compounds. Indicate E or Z and R or S, when needed. (2 pts each) - D~-J.--~ - C S) - E -J..- ~- 3-M~~- he,~-3- ~ 15. For the reaction below, propose a mechanism, including all intermediates and indicating flow of electrons with arrows. (6 pts) - '> 16. Compound A reacts significantly faster than compound B, and the rate of reaction of A is independent of nucleophile, where as the rate of reaction of B depends on nucleophile concentraProvide a mechanism for each reaction to explain the differences. (6 pts). A /O~CI H20• /O~OH od~;~ ~If ~) / 0,~--~1""l 'l. V- -M+' B~CI s. ~. , ; ) - 7 - ~ ( ] + H~D: /!·~vt Y --1' r~~~~ N~Q~~Q~~ -r ~OY\ -J1 5 -- --0 Yousaf/lyer Chem 20Name: _ Exam2Decembe21, 201STUDENT#: 17. Provide the necessary reagent(s) to carry out the following transformations (more than one step maben=s:~oCepcp:1fI~:;:ir~~H e r b) etJ- .. JCN /)fII$~ OH 9N O~ €...f 2.0 --- - R/~~VVv {f 0 --- (-; ij)NAgh~br\1~U 18. Consider the reaction of I-propene withh.",I•11"1i1't1II•) a. Put a box around the reaction coordinate diagram that best represents this reaction. b. On the selected reaction coordinate diagram, label the reactant (R), product (P), transition rate determining step for this reaction. on the diagram. Indicate the activation energy for the 1> E E
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