View solution to the question:

CHEM321-Exam3(Spring2015)

user
CHEM321-Exam3(Spring2015)
Question

CHEM 321

Organic Chemistry I

Name: (Last, First)__________________________

Midterm Exam 3

Spring 2015

04/30/15

Take-Home Exam: Due May 5, 2015 at 5:15 pm

Problem

Points

01 (20)

_____

02 (10)

_____

03 (40)

_____

04 (15)

_____

05 (10)

_____

06 (10)

_____

07 (10)

_____

08 (05)

_____

09 (05)

_____

Total (125)

_____

___________________________________________________________________________________

Directions: 1. Make sure there are 8numbered pages and 9questions to this exam. 2.Printyour name(last name, first name) on this page of the exam only. 3. Sign your name below acknowledging that you will honor the pledge and the terms of this take-home exam. 4. Read each question carefully. Mark your answers concisely and legibly and show all your work where required in order to receive partial credit; however, write the answer only in the space provided. You may use the back of each page as scratch paper, but it will not be graded. 5. VERY IMPORTANT: This is a take- home exam. Accordingly, you are permitted to use your textbook, class notes, handouts, calculator, molecular models and other resources for this exam only. However, you MUST work alone, and your answers must represent entirely your own efforts. You may not collaborate, work with, or discuss the questions with anyone.

Pledge:On my honor, I will not receive or give aid on this examination.

___________________________________________________________________________________

Kasey Kangaroo says, "The following information may be useful":

Rings and Double Bonds/Double Bond Equivalents (DBE) formula: R = (n+1) - [(x-t)/2] where n = number of carbon atoms; x = number of (hydrogen + halogen) atoms; t = number of nitrogen atoms.

Pauling Electronegativity values: H (2.1), C (2.5), N (3.0), O (3.5), F (4.0), Cl (3.0), Br (2.8), I (2.5).

A values: CH3 (Me) = 1.74; Cl = 0.55; Br = 0.48


1


01. For each pair of compounds, circle the one that is predicted to be the stronger acid (i.e., lower pKa). The protons to be compared (H ) are shown in bold type. HINT: Exam the anions (i.e., conjugate bases in each pair of compounds) and compare their relative stabilities. (20 pts)

a. CH3CO2H vs. HF

b. H2C=CHCH3 vsH3C H

c. CH2ClCO2H vs CH2FCO2H

d. CH3OH vs (CH3)3CSH

e. CH4 vs NH3

f. CF3CH2OH vs CH3CO2H

g.

O CH2

H Hvs

h.

OH OH vs

NO2

i. CH3SO3H vs CH3CO2H

j. HCN (i.e, hydrogen cyanide) vs HCCH (i.e., acetylene or ethyne)


2


02. Of the following statements, which are true for nucleophilic substitutions occurring by the SN2 mechanism? Write T or F below each statement. (10 pts)

a. Primary alkyl halides react faster than secondary.

b. The absolute configuration of the product is opposite to that of the reactant if an optically active substrate is used.

c. The intermolecular reaction shows second order kinetics.

d. The rate of the reaction depends on the nucleophilicity of the attacking nucleophile.

e. The probable mechanism involves only one step.

f. Carbocations are intermediates.

g. The rate of the reaction does not depend on the nature of the leaving group.

h. The rate is usually faster in polar, protic solvents.

i. Branching at the?-carbon has little or no effect on the rate of the reaction.

j. Hyperconjugation is mainly responsible for stabilizing the intermediate.

3


03. Give the expected major product or products in each of the following transformations. Clearly show stereochemistry where appropriate (e.g., by using wedged or dashed bond lines, or by writing axial or equitorial bonds).If no reaction is expected, write “NR”. (40 pts)

a.

Cl

CH3CH2OH

CH3

75 °C

H3C

b.

H H NaI (excess)

F Cl acetone

c.

Cl

CH3OH

H3CH2C

Cl

0 °C

H3C

d.

CH3CH2OH(CH3)3CBr0 °C

e.

CH3O-

50 °C

Br

H

H

f.

CH3O-

MeCl CH3OH, 50 °C

Me

g.

Cl

Br

NaI (1 molar equivalent)

acetone


h.

CH3CH2CH2Br


SCN-


4


i.

CH3CH2CH2Br Ph3P

j.

Cl

NaI

acetone

CH3

04. Answer the following questions concerning nuclephilic substitution reactions.

(a) For each of the following pairs of reactions, circle the one that is expected to be faster. (09 pts)

a.

Cl

CH3CH2OH

OCH2CH3

Br

CH3CH2OH

OCH

CH

3

2

b.

I

Me3P

PMe3+I-

I

NMe3+I-

Me3N

c.

Cl

I

NaI

SN2

Cl

I

NaI

SN2

(b) For each reaction below, write above the arrow whether the mechanism follows SN1 or SN2 (03 pts) Then below each arrow indicate the molecularity of each process. (03 pts)

i.

CH Br

+ CH NH

2

(CH ) NH+

Br-

3

3

3 2

2

ii.

CH2Br

Br-

+

NH2

N

H

H


5


05. When the deuterium-labeled compound shown below is subjected to elimination (E2) with sodium methoxide (a strong base), the only product obtained is 1- deuterio- 3-methycyclohexene (deuterium is an isotope of H). (a) Justify your answer for this result by drawing structures and mechanims (electron-pushing arrow formalism). (10 pts). HINT: Start by first drawing the starting material in the most stable chair conformation.

Br

H3CD CH3O- H3CD

06. (a) Circle the compound below that reacts faster by the SN2 mechanism. (10 pts) (b) Draw chair cyclohexane structures for the nucleophilic attack to justify your choice. (10 pts)

Br Br

A B


6


07. In the potential energy (PE)/reaction coordinate (RC) template below, label the indicated parts for a substitution reaction that occurs by the SN1 mechanism. If there are none of the requested features, then state “none”. (10 pts)

PE

Reaction Coordinate

1. Substrate (S) and reaction product (P).

2. Transition state for a unimolecular process.

3. G°

4. Intermediate.

5. Activation energy for the rate determining step.

08. Classify each compound below as polar protic, or polar aprotic. (05 pts)

a. Hexafluoroacetone, CF3(C=O)CF3

b. 2-Butanol, CH3CH2CH(OH)CH3

c. Dimethylsulfide (DMS), CH3SCH3

d. Trichloroethanol, CCl3CH2OH

e. Hexamethylphosphoric triamide (HMPT), [(CH3)2N]3P=O


7


09. Characterize each of the following alcohols, amines, and thiols as being primary (1°), secondary (2°), or tertiary (3°). (05 pts)

a.

MeOH

b.

CH3

NHMe

c.

SH

d.

OH

e.

O

N

CH3

8

This question was answered on Jun 24, 2016.Purchase Solution @ 38.99 USD
CHEM321-Exam3(Spring2015)
Tutorial Preview……
Attachments
ogranic_fix_(1).doc (271 KB)
Preview: mt5Nanea1fOqPf0r)W@mLRLen8MG xxxxxxxxxx qTvmB24-5VJS_OSoIjlhufXfS-W3cqqx-jdim xxxxxxxxxxxxxxxxxxxxxxx sx17KQ/VZRK 1POYO xxxxxxxxxxxxxxxxxxxxxxxxx jEROiuu-fa/e1pueQX /7ayRH(DkXSfv(f5FFzNGtoPN xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx bf x xxx EHBUcnlu7X(uwZX@X72XCoB xxxxxxxxxxxxxxxxxxxxx izbAo/6271_(p hll5kVtt_1Do53uRIunhLAQ3JCVWNl xxxxx HIFXa@in_i_O s xxxxxxxxx mN xx xxxxxx lD6i xxxxxxx zKOV(IktPXte 8wK xxxxxxxxxxxxxxxxxxxx _eL5RXgVN_wapE -F2zMxvgX3SW_WXy/YWR75pgt1Q)MKGOhRKmY8PwN035nYRhHfH58koG///tKmgNu2MS6mtM7xcz_s xxx of xx xxxxxxxxxxxxxxxxxxxxxxxx MvhQhFkPs5q7ZMwLxIII xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx j7_sqMpyMY1 IOl)rvLiynw30S1Y/vl xxxxxxxxxxxxxxxxxxxxx /0SV-39uUn__bqogFielib umVTC07o@PAOQNP2Pw/,vIyF3w29D xxxxxxxxxxxxxxxxxxxx ooF4Jv7W1gdMQ-uR xxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx m-t5eRPZ5 xxxxxxxxxxxxxxxxxxxxx m)4z iOQdFqKQR9UfJ3J-YO xx g8P/Un)qDjLEK6aTVz8XEhlMhb2-((ddu(_iMB2i19iIb/P3cptlm KGA)Oum5o xxxxxxxxxxxx zwU7q)RHmK7nLwEA-9tN/Ck xxxxxxxxxxxxxxxxxxxxxx x ceJwIhKRU,kGBWeCpOuXY xxx m46dQX 0yecVLg-uRZH2tl3veMokY7WHGZ_doDQExZT xxx Sdi,MM DG7dOkQVZ-7tDK- xx 3pfzkAbLT0VVlMI9ibVhpek-7JB1mb xxxx xxx 1qLgG67kcL(1Vi4zDk3)EU xxxxxxxxxxxxxxxx 2uxJf ,K(gh xxxxxxxxxxxxxxxxxx sum-Br mCcl6WfEz xxxxxxxxxxxxxxx zLeL1)jIrD-3LI xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxx zK@d6CE1d/Mnim9LU8mehgoplkDanA xxxxxxx 43RuHK,q YM/d1cCi xxxxxxxxxxxxxxxxxxxxxxxxxxx vJ/H3@f pf xxxxxxxxxxx QZgGU1GZs(_F xxxxx xxx rww-@@VD xxxxxx rLALdzLE2@w5a 3zhnmwjc7Rwkk xxxx N w xxxx G xxxxxxxxxxxxxx xxxxxxxxxxxxx GsZ7N-KX@1nE(, xxxx @hPm4,XT3TUN46qZUV6plSSMB @A/wqEF0 xxxxxxxxxxxx 0fFdi1EtoOuTfT8T1G vS-Laxw xxxxxxx qoYOD3GoL8U(4zKG xxxxx xxxxxxxxxx _ xxxxxxxxxxxxxxxxxx q7ywtVKQ ))7n_1bGkTJO xxxxxxxxxxxxxxx xCHYICaQQQbhsI9TyiV6CP2o6) jMM/nTNm4ewJ,wMGMb xxxxxxxxx TCcQFw6TYiYQQs3SvE6, xxxxx xxxxxxxxxxxxxxxxxxxxxxx (v9DnVY,9jZy6OFbM5, xxx (T5xIfd) LO,VV93bUnWTi_8F91(WmYeiN04 xxxxxxxx 9nq8_JVnY tJ/TpSJtUszJI_i xxxxxxxxxxxxxxx wg4eqg4F0RDiTSYq xxxxxxx xxxxxxxxxxxxxxxxxxxxxx StAJ5EmNNl xxxxx ve/wyxk4S2QBadN)U99pf _5 xxxxxxxxxxxxxxxxx UMs uEEfe xx dk/)juLrHQbqo2nrOt xxxxxxxxxxxxxxxxxxxxx xxxx EI)I xxx ,tgEYWVXmtiYugQqsUVQYDIYhwCQCVqTf4ReN_S Yug8sZ8QY xx JI1DTV qu2uK4I-yzFy xxxxx 22LKNV xxxxxxxxxxxx xxxx YN)Lh xxxxxxxxxxxxxxxxxxxxxxxx P13jD3kf 4h2ID2HeF)SL_QGOEZvtP2nRi3 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 2ja2/pkf fcR2DHcI xxxxxxxxxxxxxxxxxxxxxxxxxxxx NHt_Clhf-E_4JhMi8Iloi@nMq7 xxxxxxxxxxxxxxxxx xxxxxxxx 7DJs7CXnC7M4 xxxxxxx /bvZGTw3-lYE)RS9mz/pzaAB4 K-fheyy9h8qBu xxxxxxxxxxxx K8/@vTEu0 -0w4qchveeN4ki@D xxxxxxxxxxxx NjQuJqH xxxxxxxxxxxxxxxxxxx xxxxx OZXSoU6iU2W)G9T,UDNb xxxxxxxxxxx II _MnSOPeuE)RS9WcJEAn8o3-gY0op xxxxxxxxxxxxxxxx qZeiOYXn3n-Swlfdj3qOhG1i8zYMfxco7R2 p15ZBfNOXZZJuY2GXl4AoxogzL7whV(U, xxxxxxxxxxxx ooTNvklrIX xxxxxxxxxxxxxxx xxxxxxxxxxx j5kuKJUU xxxxxxxxxxxxxxxxxxxxxxx uCc-WZ Gx@888W-M0XsivClvgnt_tuM)kX37uj_4E xxxxxxxxxxx Wmx iGSUwR xxx g xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx KOJ xxxxxxxxxxxxxxx 1 xC xxxxxxx G@l QCVDJ04xhHHcKon97J39ez1sXz-/K-qS5c xxxx 0Thl-I/Az2-DC7ChIZYpI xxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx N8KMLLK/RlbI7GySNq_M xxxxxxxx zj2CwMh8ECspMu4qcLnj531gwvs55 H-Y/h-U xxxxxxxxxxxxxxx vasGYs, w/ xxxxxxxxxx aoZZ5k7(offmmmJVondu xxxxxxxxxxxxx xxx 6C_RVxKx-lsu,ntT xxxxxxxxxxxxxxx wZWS7k638_yKW4yBVs-1NvqqYD6/,CwA b4qnWwnsRYYiF3gRGtlC5nGStDK7EUj@SOX/ xxxxxxxxxxx nwdy8/_nbADNYxXNgxh yn_ x u xxxxxxxxx xxxxxxxxxx GnhlR-)@rMZ- x tRTutbd2t yr513Gkk87nzkdI(ah_ xxxx TYgyGMDXe4AR99y 3mNcccwq7oRg xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx kOaH_oo/0Ac x xx f-rKI3k7VOLZoXuWYtCSOb xxxxxxxxxxx Qw0_UAErBFwHC TBuK xxxxx SGbGQfkMMCV_,pZ3ebm 5vKQ x ye/u8,x8r_BjwllzWfFv xxxxxxx xxxx /gQO/9WWEp xx /6lx@Bv ruZ9 xxxxxxxxxxxxxxxx EU,/J2SKU6PO0UfF_C3nh JaR xxxxxxxxxxxxxxxxxxxxxxxx -zmnwG9ggbue3noQpsUguK)ynF@fLj9iEzMl xxxxx xx CSDyDg(os2_Ur4zw@EFh91dH xx mVre)f5_W5EEwSd 43i_lTS xxxxxxxxxxxxx OvQ_u3-KLZuAEs YEtVplO_tUep9iI/sEFcptL xxxxxxxxxxxxxxxxxxxxxxxxxxxx GA,lWR99 xxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxx ZyeUmqlt8kfljf xxxxxxxxxx M pQmox x J cxfrvc-ihQi)aMyE,1K8 xxxxxxxxxx

About this Question

STATUS

Answered

CATEGORY

Chemistry

EXPERT

Professor Ted

ANSWER RATING

Need an Operations Management tutor?

Average reply time is less than an hour.

Get Homework Help