You must have your answers written in PERMANENT ink if you ...iverson.cm.utexas.edu/courses/310M/OldExams/FinalFl010Ques.pdfas a guide to help budget your time. Please print the first

Chemistry 310M/318MDr. Brent IversonFinal examDecember 8, 2010

NAME (Print): _____________________________

SIGNATURE: _____________________________

Please Note: This test may be a bit long, but there is a reason. I would like to give you a lot of little questions, so you can find ones you can answer and show me what you know, rather than just a few questions that may be testing the one thing you forgot. I recommend you look the exam over and answer the questions you are sure of first, then go back and try to figure out the rest. Also make sure to look at the point totals on the questions as a guide to help budget your time.

Please print the first three letters of your last name in the three boxes

You must have your answers written in PERMANENT ink if you want a regrade!!!! This means no test written in pencil or ERASABLE INK will be regraded.

Please note: We routinely xerox a number of exams following initial grading to guard against receiving altered answers during the regrading process.

FINALLY, DUE TO SOME UNFORTUNATE RECENT INCIDENCTS YOU ARE NOT ALLOWED TO INTERACT WITH YOUR CELL PHONE IN ANY WAY. IF YOU TOUCH YOUR CELL PHONE DURING THE EXAM YOU WILL GET A "0" NO MATTER WHAT YOU ARE DOING WITH THE PHONE. PUT IT AWAY AND LEAVE IT THERE!!!

15

14

13

12

11

10

9

8

7

16

6

TotalPts

TScore

HW

17

18

19

TotalGrade(HW score + Exam Grade)

%

5

4

3

2

1Page Points

(26)

(14)

(19)

(19)

(16)

(27)

(27)

(13)

(19)

(26)

(42)

(30)

(21)

(14)

(14)

(10)

(16)

(16)

(8)

(8)

(385)

20

Honor Code

The core values of the University of Texas at Austin are learning, discovery, freedom, leadership, individual opportunity, and responsibility. Each member of the University is expected to uphold these values through integrity, honesty, trust, fairness, and respect toward peers and community.

(Your signature)

CH3CH2-H

R2C CH

H

H-N(i-C3H7)2

RC C H

COR'

O

RCH2

CR'O

RCH2

CH

O

RCH2

CCl

O

RCH2

RCH2OHHOH

ROC

O

COR'

O

CH2

RC

O

COR'

O

CH2

RC

O

CR'

O

CH2

H4N

CO-HO

CH3

RCH2OH2

H3O

H-Cl

10

51

-7

Compound pKa

4.8

15.7

16

18-20

11

23-25

18-20

13

15-19

40

Acetic acid

β-Dicarbonyls

β-Ketoesters

β-Diesters

Water

Alcohols

Acid chlorides

Aldehydes

Ketones

Esters

LDA

Alkanes

Terminal alkynes 25

Terminal alkenes 44

9.2Ammonium ion

Hydronium ion

Hydrochloric acid

Protonated alcohol -2

-1.7

H3N 10.8Ethyl ammonium ion

CH2CH3

Here is a page in which you could write down your roadmap if you would like

Pg 1 _____________(26)

1. (4 pts) What is the most important question in organic chemistry?

Signature_________________________

2. (10 pts) Amides are best represented as the hybrid of three contributing structures. Draw the second and third important contributing structures in the spaces provided, including all lone pairs and formal charges. For the two structures on the left in each problem, use arrows to indicate the movement of electrons to give the structures you drew. There is no need to draw any circles around any of these contributing strucures. You might want to read these directions again to make sure you know what we want

C

H

H

H

C

O

N

H

H

3. (1 pt. each ) On the following structure, indicate the hybridization state of each atom indicated.

NH

CH3

O

H

4. (1 pt. each )On the following structure, describe the bonds indicated in terms of overlap between

hybrid orbitals (the valence bond approach). For example, an answer might beσCsp3-Csp3

H

O

Signature_________________________

5. (14 pts) Shown below are three different amino acids. At the pH values indicated, draw the predominant species at each indicated pH value BY DRAWING ALL H ATOMS, ALL LONE PAIRS, AND ALL FORMAL CHARGES. (You do not have to add anything such as H atoms to atoms not drawn in the boxes.) This problem is testing your understanding of the relationship of protonation state to pH to pKa values for certain functional groups we have discussed. Next, in the spaces provided, write the overall charge on each structure at the indicated pH. For your reference, here are the relevant pKa values:

H3CC

OH

O

pKa = 4.76

H3C NH3

pKa = 10.64

pH = 7

pKa = 0.5

Pg 2 __________(14)

N

O

O

O N

O

H3C NH3

Total charge on molecule:______

pH = 2

N

O

O

O N

Total charge on molecule:______

Signature_________________________

6. (19 pts total) The following molecule contains a guanidine group. The guanidine group can add a proton to create a resonance stabilized cation. Draw the three most important contributing structures, making sure to show all lone pairs and formal charges. Draw arrows on the structures to indicate the movement of electrons required to produce the next contributing structure. (Of the four contributing structures, only the structure on the right will not have arrows)

Pg 3 __________(19)

H3CN

CN

N

H H

H

H

H

H3CN

CN

N

H H

H

H H

H3C NH2H

NH3C

H

H

H

Amines will also react with protons as shown.

Amine

Guanidine group

(5 pts) Predict which will be easier to protonate (i.e. is more basic), the guanidine or amine. In no more than two sentences, explain your answer.

7. (1 pt. each) Fill in the following with the word or words that best completes the statements.

Signature_________________________ Pg 4 __________(19)

Moving charge creates a ___________________________ field.

Atomic ___________________________ with an odd atomic mass or odd atomic number have a

quantum mechanical property called _________________________.

The difference in energy between the +1/2 and -1/2 _________________________ states of a 1H nucleus

is proportional to the _________________________________ field strength.

_________________________________ in NMR refers to the phenomenon of absorption of energy

when a nuclear _______________________ "flips".

A nucleus with more electron density around it will be _____________________________ more from

the external magnetic field, a phenomenon that results from the small but significant

______________________________ field created when the electron density

_____________________________ due to the external magnetic field.

An MRI image is a picture of the relative density of __________ atoms in the tissues being

imaged, and especially the amount of ____________________ and ____________________ because

these two types of molecules have the greatest proportion of ____________ atoms in them.

For either the NMR experiment in the laboratory or the acquisition of an MRI image in the clinic,

the sample or patient is placed in a strong _____________________________ field, then the

_________________________ of energy is measured as ____________________________

spins flip from the _______________ to the -1/2 _______________________ states.

_____________________________ every weekend for the rest of your adult life is the best way

to stay fit, the secret to true success in life. (Notice you cannot get this one wrong unless your activity

involves a couch!!!!!!!)

C HH3C

H3CC CH3

H3C

H3CC H

H

H3C

8. (16 pts. total) Rank the following species in terms of the stated property from 1 to 4 with intermediate numbers to rank the species of intermediate stability activity. Please make sure you know what we want, as you will get no credit if you get the numbers backwards!

Signature_________________________ Pg 5 _____________(16)

Stability of carbocations: Place a 1 under the most stable carbocation and a 4 under the least stable carbocation.

Relative Acidity: Place a 1 under the most acidic molecule and a 4 under the least acidic molecule.

H C

H

H

C

H

H

H

C CHH3C

H3C

CH2

H C

H

H

S H F C

F

F

S H H C

H

H

O H

Radical Stability: Place a 1 under the most stable radical and a 4 under the least stable radical.

C HH3C

H3CC CH3

H3C

H3CC H

H

H3CC CH

H3C

H3C

CH2

Reaction with nucleophiles: Place a 1 under the molecule that is most reactive in an SN2 reaction and a 4 under the molecule that is least reactive in an SN2 reaction.

Cl Cl Cl I

Signature_________________________ Pg 6 _____________(27)

9. (5 or 7 pts each) The following reactions all involve chemistry of alkyl halides. Fill in the box above the arrow with the mechanism that will be followed (SN2, E2, etc.). Then draw only the predominant product or products and please remember that you must draw the correct stereoisomers. For SN1/E1 reactions you must draw all significant products (including all stereoisomers).

A.

B.

C.

D.

E.

Br

Br

Cl

+ CN

+ CN

+ OH

Br

Br

+ O

+ O

10. (27 pts total) On the line provided, state the stereochemical relationship between each pair of molecules: enantiomers, diastereomers, or the same molecule. I recommend you assign R and S to each chiral center to help answer this question. Circle all meso compounds.

RelationshipO

H

O

H

H

HO OHCl

ClH

OH

Cl ClH

HHO

H

Br ClBr

ClH

H

Cl ClBr

BrH

Signature_________________________ Pg 7 _____________(27)

Now that your stereochemistry Mojo is warmed up, here is a reaction that has a variety of products. Draw all products you would expect from the following reaction. Use wedges and dashes to show the different stereoisomers created. Write racemic if appropriate.

Br2

H2O

Shown below are four different energy diagrams. Each is labeled with a letter. Use these letters to answer questions at the bottom of the page, and on the next TWO mechansim pages.

Signature ______________________________ Pg. 8______ (13)

Reaction Coordinate

PotentialEnergy

Reaction Coordinate

PotentialEnergy

Reaction Coordinate

PotentialEnergy

Reaction Coordinate

PotentialEnergy

A B

C D

11. (13 pts.) For the reaction shown below, fill in the details of the mechanism. Draw the appropriate chemical structures and use arrows to show how pairs of electrons are moved to make and break bonds during the reaction shown. Draw all non-bonded electrons as dots around the appropriate atoms and include all formal charges. MAKE SURE TO FILL IN THE BOX AT THE BOTTOM.

Product(s)

NOTICETHIS

CC

H H

H3C CH3

CCH3O

OOH

The reaction diagram from page 8 that best describes this reaction is:

Energy Diagram Letter

Signature_________________________ Pg 9__________(19)12. (19 pts.) Read these directions carefully. Read these directions carefully. (It was worth repeating) For the following two reactions, fill in the details of the mechanisms. Draw the appropriate chemical structures and use arrows to show how pairs of electrons are moved to make and break bonds during the reaction. Make sure to show all lone pairs and all formal charges. Indicate stereochemistry where appropriate. Draw all products of each step. IF A RACEMIC MIXTURE OF INTERMEDIATES IS FORMED, YOU ONLY NEED TO DRAW ONE ENANTIOMER BUT WRITE RACEMIC. IF A RACEMIC MIXTURE OF PRODUCTS IS FORMED DRAW BOTH ENANTIOMER PRODUCTS AND WRITE RACEMIC! In the boxes provided next to the arrows, state what kind of mechanistic element is being described, i.e. make a bond, etc.

Products

NOTICETHIS



OHH

OHH

C CO

H CH3

H HH

H O

H

Signature_________________________ Pg 10__________(26)13. (22 pts.) Alcohols will react similar to water in most reactions. For the following reaction, fill in the details of the mechanism. Draw the appropriate chemical structures and use arrows to show how pairs of electrons are moved to make and break bonds during the reaction. Make sure to show all lone pairs and all formal charges. Indicate stereochemistry where appropriate. Draw all products of each step. In the boxes provided next to the arrows, state what kind of mechanistic element is being described, i.e. make a bond, etc. IF A RACEMIC MIXTURE OF INTERMEDIATES IS FORMED, YOU ONLY NEED TO DRAW ONE ENANTIOMER BUT WRITE RACEMIC. IF A RACEMIC MIXTURE OF PRODUCTS IS FORMED DRAW BOTH ENANTIOMER PRODUCTS AND WRITE RACEMIC! In the boxes provided next to the arrows, state what kind of mechanistic element is being described, i.e. make a bond, etc.

Products

NOTICETHIS



CC

CC

H

H

H

H HH

HH

+ Cl Cl

H3C O

H

H3C O

H

Did you remember to draw both product enantiomers?

Cl2

HBr

ROOR

1) BH3

2) H2O2 / HO

hν

Signature_________________________ Pg 11 _____________(42)

1) Hg(OAc)2 H2O

2) NaBH4

CH3 CO

3 H

H2Pd°

14. (3 or 5 pts each) For the following, complete the reactions with the predominant product or products. You must indicate stereochemistry with wedges and dashes. You must draw all stereoisomers produced as predominant products and write "racemic" under the structures when appropriate. Assume no rearrangments take place.

NBShν

H2OH2SO4 (cat.)

CH3CH2OHH2SO4 (cat.)

HI

2 eq. Cl2

2 eq.

HBr

1) (sia)2BH

2) H2O2

Signature_________________________ Pg 12 _____________(30)

HgSO4 H2O, H2SO4

1) NaNH2

H 2Li

ndla

r's ca

taly

st


H2SO4 (cat.)

OH

PBr3

H3C SO

OCl

PCC

2)

Br

HO

Signature_________________________ Pg 13 _____________(21)


OH3O

O

O

OH

1) OsO4

2) H2O, NaHSO3

Br2

Br2

Signature_________________________ Pg 14 _____________(14)

1) HBr, ROOR, hν

16. (7 pts each) For the following sequences of reactions, work through all the different steps and then write the final product(s). Assume only the predominant product is formed at each step. You must indicate stereochemistry with wedges and dashes. You must draw all stereoisomers produced as predominant products and write "racemic" under the structures when appropriate. Assume no rearrangments take place.

2)3) H2O, H2SO4, HgSO4

H Na

1) CH3O2) NBS, hν

Br

This next one may look simple, but it is not. You might consider saving it until the end!!

Signature_________________________ Pg 15 _____________(14)

17. These are synthesis questions. You need to show how the starting material can be converted into the product(s) shown. You may use any reactions we have learned provided that the product(s) you draw for each step is/are the predominant one(s). Show all the reagents you need. Show each molecule synthesized along the way and be sure to pay attention to the regiochemistry and stereochemistry preferences for each reaction. You must draw all stereoisomers formed, and use wedges and dashes to indicate chirality at each chiral center. Write racemic when appropriate.

A) (7 pts)

B) (7 pts)

?

?

OH

OH

Signature_________________________ Pg 16 _____________(10)


C) (10 pts)

?

For this one, all of the carbon atoms in the product must come from the starting material shown.

OH

OH

OH

OH racemic

Signature_________________________ Pg 17 _____________(16)


D) (16 pts)

Br?


Signature_________________________ Pg 18 _____________(16)


E) (16 pts)

?


O

Oracemic

N

NN

O

R'

H3CO

O

O R

OH

O

H

OO

OHO

OHO

OH

OH

O

H

OO

N

NN

O

R'

H3CO

O

O R

HO

HO

Signature_________________________ Pg 19 _____________(8)

18. (8 pts) The key paradigm of organic synthesis is that individual functional groups react the same in complex molecules as they do in simple ones. The following transformations were used to construct complex molecules of interest in medicine and biology. In the space provided, fill in the reagents we have learned this semester that would bring about the desired reactions.

racemic

racemic

racemic

From the synthesis of analogs of leukotriene A4, C4, and D4

Journal of the American Chemical Society, 1980, 102, 6607.

From the synthesis of 11-desoxyprostaglandins

Journal of Organic Chemistry, 1974, 39, 256.

Signature_________________________ Pg 20 _____________(8)

19. (8 pts) Here is an apply what you know question to finish the semester. You have not seen this reaction, but you know enough to get it correct. If you do get it correct, trumpets will play a fanfare!!! Write the product or products of the following reaction. HInt: try to not second guess yourself here, trust your intuition.

1)

2) Very mild acid

O

CH3HHH

Have a glorious and relaxing holiday.

Remember to run every chance you get!!

In only one sentence, explain your reasoning. NOTICE THIS

Documents

You must have your answers written in PERMANENT ink if you ...iverson.cm.utexas.edu/courses/310M/OldExams/FinalFl010Ques.pdfas a guide to help budget your time. Please print the first