CHEM 140B - Burkart

Final Exam

March 15, 2010

3:00 PM – 6:00 PM

This exam is comprised of 5 sections worth different amounts of points. You will have 2 hours

50 minutes for the exam. Look over the entire exam first. Note the problems that look

particularly easy or difficult to you and budget your time accordingly.

You will be provided with a one-page (front and back) answer sheet for recording your answers,

found at the back of this packet. Tear it off carefully. Please write your name and ID# on the

FRONT AND THE BACK page of the exam answer sheet. You will probably want to work

the problems out on these exam question pages or on the back before placing your answers in the

boxes on the answer sheet. Only what is marked within the boxes on the answer sheet will

be graded!

Exams will be returned on two days only, once during the week of March 21 and again in the

first week of the Spring quarter. Times and places will be posted on the course website.

Solutions will also be posted on the course website under exams. You may ONLY pick up your

graded exam at these times.

Good luck!

I. [60 points] Short answer.

Please draw the following molecules according to the IUPAC rules. Indicate stereochemistry where

necessary. Please use the boxes provided on the answer sheet.

g) Rank in order of increasing bond length. (x<y<z, where z is longest)

h) Rank in order of increasing pKa for each indicated proton . (x<y<z; x having the lowest pKa)

H

B

C

D

E

F

A

G

i) Which of the following will direct electrophilic aromatic substitution at the meta position?

j) Is splitting observed for Ha? (yes or no)

k) List in order of increasing chemical shift in the 1H-NMR spectrum. (w< x < y < z ; z being the highest

number)

l) Arrange the carbonyl hydration reaction (a or b) in order of increasing equilibrium constant (K)? (x <

y < z ; z being the highest number)

II. [70 Points] Reactions. Add the missing starting materials, reagents, or products (aqueous work-up is

assumed where necessary). Please use the boxes provided on the answer sheet. Don’t forget

stereochemistry!

a)

I

J

K

C

B

A

L

b)

c)

d)

e)

f)

g)

G

F

E

D

H

I

J

K

L

h)

i)

III. [70 Points] Mechanism. Explain the following observation by a detailed mechanism (i.e., write a scheme

with structures, use arrow-pushing, etc.) Please use the box provided on the answer sheet. Don’t forget to

show all intermediates and resonance forms!

s

a)

b)

c)

P

O

N

M

IV. [50 Points] Synthesis. Please show a multistep synthetic route from the starting material to the

product in five steps or fewer. Use the box provided on the answer sheet. Do not draw

mechanisms. Full credit will be given for the most efficient and logical pathway. Partial credit will

be given for plausible alternate strategies. Aqueous work-up and product purification is assumed

where necessary.

a)

b)

V. [50 Points] Given the spectra and chemical formula below, predict the structure. Please use the box

provided on the answer sheet. Don’t forget to show stereochemistry! Partial credit may be given for

proper interpretation of indicative peaks.

a) Molecular formula: C8H8O 1

H-NMR

s, 1H

d, 2H

d, 2H

s, 3H

FT-IR

a) What is the degree of unsaturation?

b) How many nearest neighbors should the protons at = 2.45 ppm have?

c) From the IR spectrum, what kind of functional group exists? Please list all that apply by

using the following letters.

a. carbonyl

b. alkane

c. alkene

d. ether

e. alcohol

f. nitrile

g. amine

h. ester

d) Draw the structure

b) Molecular formula: C5H8O 1H-NMR

D

B

A

C

s, 1H

t, 1H

d, 2H

d, 2H

ddd, 2H

FT-IR

e) What is the degree of unsaturation?

f) How many nearest neighbors should the protons at = 4.60 ppm have?

g) From the IR spectrum, what kind of functional group exists? Please list all that apply by

using the following letters.

a. carbonyl

b. alkane

c. alkene

d. ether

e. alcohol

f. nitrile

g. amine h. ester

h) Draw the structure

THE END.

H

F

G

E

Problem I. Draw the molecules or short answers. [60 Points]

D E F

G H

Problem II. Place chemical structures or reagent names in the given boxes. [70 Points]

H

G

Problem III. Write a detailed mechanism. [70 Points]

Name:_________________________ ID# ________________ 03/15/10

CHEM 140B Winter 2005 - Final Exam

A BH3 C

I

J K L

A B C

D E F

J KI

M

a) b)

P

N

L O

(E)-2-cyclopropyl-3-pentene

OH

1-Ethynylcyclopentanol

O2N NO2

NO22,4,6-trinitrotoluene

cis-2-pentene

O

1-phenyl-1-butanone

Cl

3-Chloro-4-isopropyl-4-penten-1-yne

b<c<e<d<a d<a<e<c<b b,c,d,e

No e<b<a<c<d b<a<c

heat

MnO2 or CrO3, aq. H2SO4

MeBr

Ph

Ph

O

HPh

Ph

O

OO

PPh3

NH

MeBr

H3O+

CO2Me

CO2Me

H+

H

ThermodynamicProduct

O

H2N NH2

O HN NH2

H

HO HN NH2

N N

H

HOH

N N

HHO H

N N

H

N N

OH

HO H

-N2

Et2CuLi

aq. NaOHO3; Me2S

Problem IV. Show a multistep synthetic route f rom the starting material to the productin less than five steps. [50 Points]

EXAM SCOREI.................... /60II.................. /70III................. /70IV................. /50V.................. /50Total............ /300

Name:_________________________ ID# ________________ 03/15/10

c)

Problem V. Draw the compound. Partial credit may be assigned for the proper assignment ofindicative peaks. Please show your work! [50 Points]

a)

b)

1) 2)

D

A

B

C

H

E

F

G

+

I

NC

NC

HH

O CN

CN OBuLi

Li+

Lindlar'scatalyst

H2

CN

CN

+heat

O3;SMe2

CN

CN

O

O

OH O O

MnO2 Et2CuLi;

MeBr

H2NNH2,

aq. NaOH

O

H

OH

5

0

a,c

2

2

b,c,d,e

OH

BrBr

Br

HO O

Br

H

O

Br