FnlFl07Ques copy - NAME (Print):...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: NAME (Print): _____________________________ SIGNATURE: _____________________________ Chemistry 310M/318M Dr. Brent Iverson Final December 17, 2007 Please print the first three letters of your last name in the three boxes 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. Note: You must have your answers written in pen if you want a regrade!!!! Page Points 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Total % T Score (25) (16) (23) (29) (19) (31) (19) (-) (26) (32) (29) (30) (43) (14) (10) (22) (18) (12) (398) HW (HW score + Exam Grade) Total Grade 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) O O O O O O O O Dr. Iverson Chelsea O Sean Stevan O O O O O Ellie Brittany Mark It has been a pleasure getting to know you this semester. We have all come a very long way, starting with the octet rule and finishing with epoxide reaction regiochemistry and stereochemistry. Mastering organic chemistry requires a new way of thinking and a lot of work. We appreciate your collective effort and enthusiasm, and sincerly wish you well on this final. As you go through the test, use good test taking strategy by: 1) Remaining as relaxed and calm as possible 2) Working problems worth the most points first 3) Concentrate on finishing all the problems you are most certain about 4) Leave the ones you have doubts about for last 5) Do not second guess yourself Have a safe holiday and remember to excercise every chance you get. If you stay in shape throughout your life, you will thank yourself more than you can imagine!!! Brent Iverson Use this page to write down your roadmap if you would like. Compound Hydrochloric acid Protonated alcohol Hydronium ion Acetic acid Ammonium ion Thiols !-Dicarbonyls Ethyl ammonium ion !-Ketoesters pKa -7 -2 -1.7 4.8 9.2 10-12 10 10.8 11 13 15.7 15-19 16 18-20 18-20 23-25 25 40 44 51 H-Cl RCH2OH2 H3O O CH3CO-H H4N RCH2SH O O RC CH2 CR' H3N O O CH2CH3 O O RC CH2 COR' ROC CH2 COR' HOH RCH2OH O RCH2 CCl O RCH2 CH O RCH2 CR' O RCH2 COR' RC C H !-Diesters Water Alcohols Acid chlorides Aldehydes Ketones Esters Terminal alkynes LDA Terminal alkenes Alkanes H-N(i-C3H7)2 R2C C H H CH3CH2-H Signature_________________________ Pg 1 _____________(25) 1. (5 pts) The most important question is chemistry is: ________________________________________________________________________________ 2. (2 pts each) In the spaces provided, indicate the type of bond, and the hybridized orbitals that overlap to form the bond. For example, one answer could be: ! 3 Csp -H1s H O N O O O H H O Clavulanic Acid (A drug developed to overcome certain types of antibiotic resistance) 3. (2 pts each) In the spaces provided, write the hybridization state of the atoms indicated by the arrow. H H H H C C C C H C O Signature_________________________ Pg 2 _____________(16) 4. (1 pt each) Circle all the True statements. (Do not circle any false statements) You may notice these resemble Rules of the Day! These are worth a lot of points so please take your time and be careful. Read them carefully, but do not second guess yourself as we are not trying to trick you. A. More electronegative atoms attract the majority of electron density in a bond, thereby answering the most important question in chemistry. B. A sigma bond has the majority of electron density above and below the bond axis, while a pi bond has the majority of electron density between atomic nuclei. C. Constitutional isomers are molecules with the same molecular formula, but have the atoms connected differently. D. The preferred staggered conformations of butane are the "gauche" conformations, rather than the "anti" conformation. E. Stereoisomers have the same connectivity (they are the same constitutional isomer), but the atoms are arranged differently in space. F. Dispersion forces are proportional to surface area , so the smaller the surface area of an alkane, the greater the attraction between molecules and the higher the boiling point. G. Substituted cyclohexanes prefer to have as many substituents axial as possible, with the larger substituents dominating. H. Trans alkenes are more stable than cis alkenes because cis alkenes have some non-bonded interaction strain. I. The enol form of a compound rapidly tautomerizes to the more stable keto form. J. The keto form of a compound rapidly tautomerizes to the more stable enol form. K. The keto form of a compound rapidly mesmerizes to the more stable enol form. L. In organic synthesis, A KEY PARADIGM is the that functional groups (OH group, Pi bond of an alkene, etc.) react the same in large complex molecules as they do in simple structures. M. Ethers can be synthesized using an SN2 reaction between a primary alkyl halide and an alkoxide (called the Williamson ether synthesis) O. Ethers are synthesized using an SN1 reaction between a tertiary alkyl halide and an alkoxide (called the Williamson County ether synthesis) P. Epoxides are important because the ring strain within epoxides allows them to react with nucleophiles. Q. Running 3-5 miles a week EVERY WEEK as an adult dramatically increases your fitness level and improves your heatlh throughout your life. Doing this and enjoying a healthy life is even more important than getting an A on this organic final! Signature_________________________ Pg 3 _____________(23) 5. (23 pts total) The following are contributing structures for important resonance hybrids. Draw the other important resonance contributing structure in the box provided. Draw arrows on the structures on the left that indicate the flow of electrons that produce the contributing structures you drew to the right. Be sure to show all lone pairs and formal charges. A. H H C H C O O B. H H C H C. H H H C H C C H O N O Did you remember to put arrows on the structures on the left? O D. H H C H C C H H E. H H C H C C H O H Yes, put arrow(s) on this structure to show how it is transformed to the structure to the right! Signature_________________________ Pg 4 _____________(29) 6. The following molecule is called glutathione. It is found in high concentration in living cells where it helps maintain the proper oxidation potential as well as providing protection from oxidants such as free radicals. In the boxes, fill in the proper number of bonds to H atoms, lone pairs, and formal charges to show the protonation state of glutathione at pH 7.0. Use the pKa table provided at the beginning of the test for reference. A.(12 pts) O O N O N H O Glutathione S H N O O B. (2 pts) What is the total charge on glutathione at pH 7.0? C. (2 pts) How many chiral centers does glutathione have? D. (4 pts) Glutathione is found as the single stereoisomer shown. Write an "R" or "S" next to each chiral center on the structure above. 7. (9 pts) For each acid-base reaction, circle the side of the equation that predominates at equilibrium. Feel free to consult the pKa table provided at the beginning of the test for reference. H Cl + H O H Cl + H O H H O H3C C O CH3 + H3C O H2C O C O CH3 + H3C OH H H H H H H H + H H H3C C C H H + H3C C C H pKa = 15 Signature_________________________ Pg 5 _____________(19) 8. (5 pts) A hydrogen bond is the strongest interaction seen among neutral molecules. In the space provided, draw two molecules of methanol (CH3OH) and show a hydrogen bond between them. Use a dashed line ( ) to indicate the hydrogen bond. Show all lone pairs. 9. (14 pts) Alcohols are good solvents for SN1 and E1 reactions of secondary and tertiary alkyl halides in part because they interact strongly with the carbocation intermediate and halide anion formed in the first mechanistic step. These strong interactions lower the energy of the carbocation intermediate. For the following SN1/E1 reaction, draw the carbocation intermediate and halide anion. Next draw a molecule of methanol interacting with the carbocation, and a different molecule of methanol hydrogen bonding to the halide anion. Use a dashed line ( ) to indicate a relatively strong interaction . Show all lone pairs and formal charges. CH3 H3C C CH3 Cl H3C O heat H Draw the carbocation interacting with a methanol molecule here Draw the halide anion interacting with a methanol molecule here In the box provided draw the products of the above SN1/E1 reaction. CH3 H3C C CH3 Cl CH3OH heat Product(s) Signature_________________________ Pg 6 _____________(31) 10. (8 pts total) The following two carbocations can rearrange. In the space provided draw the most stable rearranged carbocation. H H3C C CH3 C CH3 H H 11. (10 pts) Draw the two chair conformations of the following cyclohexane derivative, and circle the one that is lower in energy, i.e. predominates at equilibrium. You do not need to show all of the hydrogen atoms on the ring, but you may if it helps. Make sure your drawing clearly indicates which groups are equatorial and which are axial. If we cannot interpret your drawing we will have to mark it wrong. H3C (H3C)3C 12. (13 pts) Draw a circle around all of the chiral molecules. Label the chiral centers as R or S if indicated by an arrow and box. HO HO2C O H H3C H CH3 H H3C H H OH CO2H O CH3 H O H H3C H CH2CH3 O H H3C CH3 CH3 H HO2C OH H CO2H OH OH CO2H OH H H HO2C Signature_________________________ Pg 7 _____________(19) 13. (19 pts total) Rank the following species in terms of the stated property from 1 to 4 (or 3) as described, with intermediate numbers to rank the species in between. Please make sure you know what we want, as you will get no credit if you get the numbers backwards! Stability of alkene: Place a 1 under the most stable (i.e. least reactive to H2/Pt) and a 4 under the least stable (i.e. most reactive to H2/Pt) H H H3C H H3C CH3 H3C CH3 C C C C C C C C H H H CH3 H H H CH3 Relative reaction rate with a nucleophile in an SN2 reaction, with a 1 under the fastest and a 4 under the slowest. H CH3 H CH3 CH3 C H Br H C H Br CH3 C CH3 Br CH3 C H Br Relative Acidity: Place a 1 under the most acidic molecule and a 3 under the least acidic molecule. F H F H O H O H O H F C C C F C C H C C O O O F H F H Relative Acidity: Place a 1 under the most acidic molecule and a 4 under the least acidic molecule. H H H H H O H H C C H H C O H H C N H H C C O H H H H H H Relative carbocation stability: Place a 1 under the most stable carbocation and a 4 under the least stable carbocation. CH3 Are you sure you ranked them in the correct order according to the directions???? Shown below are four different energy diagrams. Each is labeled with a letter. Use these letters to answer questions on the next two mechanism pages. Sorry about the lame curves, imagine they are more smooth! A Potential Energy Potential Energy B Reaction Coordinate Reaction Coordinate C Potential Energy Potential Energy D Reaction Coordinate Reaction Coordinate Signature_________________________ Pg 9__________(26) 14. (26 pts.) Read these directions carefully. Read these directions carefully. (It was worth repeating) For the following two reactions, fill in the details of the mechanism. Draw the appropriate chemical structures and use an arrow 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. 2 or 3 Alcohol Dehydration O H H H H H H HO H H H H O S O OH H H O NOTICE! NOTICE! H3C C C H H H3C Products The reaction diagram from page 8 that best describes this reaction is: Energy Diagram Letter Epoxide Formation H O O O C CH3 Products The reaction diagram from page 8 that best describes this reaction is: Energy Diagram Letter Signature_________________________ Pg 10__________(32) 15. (34 pts.) Read these directions carefully. Read these directions carefully. (It was worth repeating) For the following two reactions, fill in the details of the mechanism. Draw the appropriate chemical structures and use an arrow 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 produccts of each step. Acid-Catalyzed Epoxide Opening O H3C H3C C C H H H O H H H O H NOTICE! Products H O H The reaction diagram from page 8 that best describes this reaction is: Energy Diagram Letter Alkene Hydrohalogenation H H3C C C CH3 H + Br Br H O H NOTICE! Products H O H The reaction diagram from page 8 that best describes this reaction is: Energy Diagram Letter Signature_________________________ Pg 11 _____________(29) 16. (3 or 5 pts each) Fill in the box with the product or products that are missing from the following chemical reaction equations. Draw only the predominant product or products and please remember that you must draw the structures of all the predominant product stereoisomers. When a racemic mixture is formed, you must write "racemic" under both structures EVEN THOUGH YOU DREW BOTH STRUCTURES. If a scrambled mixture is produced, you need to write "scrambled". 1) Hg(OAc)2 / H2O 2) NaBH4 CH3CO3H 1) OsO4 2) NaHSO3 1) O3 2) (CH3)2S H2/Pt CH3OH H2SO4 (catalytic amount) H H O C C OH H CH3 H2O Signature_________________________ Pg 12 _____________(30) 16. (cont). (3 or 5 pts each) Fill in the box with the product or products that are missing from the following chemical reaction equations. Draw only the predominant product or products and please remember that you must draw the structures of all the predominant product stereoisomers. When a racemic mixture is formed, you must write "racemic" under both structures EVEN THOUGH YOU DREW BOTH STRUCTURES. If a scrambled mixture is produced, you need to write "scrambled". Watch the regiochemistry and stereochemistry on these! Br2 / H2O 1) BH3 2) H2O2 HO Br2 PBr3 HO O H3C S Cl O H2CrO4 H H2O PCC H2SO4 . Signature_________________________ Pg 13 _____________(43) 16. (cont). (3 or 5 pts each) Fill in the box with the product or products that are missing from the following chemical reaction equations. Draw only the predominant product or products and please remember that you must draw the structures of all the predominant product stereoisomers. When a racemic mixture is formed, you must write "racemic" under both structures EVEN THOUGH YOU DREW BOTH STRUCTURES. If a scrambled mixture is produced, you need to write "scrambled". Br2 h! NaCN H2O heat NaOCH3 RCO3H NBS h! H3O Br2 NaSH 2 NaNH2 H2SO4 HgSO4 H2O Pg 14 __________(14) Signature_________________________ 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. 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. If a racemic mixture is produced at any point in the synthesis,you must indicate it by drawing both enantiomers and writing "racemic". A. (7 pts) Br ? Br B. (7 pts) CH3 ? OH CH3 H OH racemic CH3 OH OH H Signature_________________________ Pg 15 __________(10) 17. (cont.) 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. 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. If a racemic mixture is produced at any point in the synthesis,you must indicate it by drawing both enantiomers and writing "racemic". C. (10 pts) Note that in this one, as always, the product shown must be the major product. H Br H CH3 H ? Signature_________________________ Pg 16 __________(22) 17. (cont.) 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. 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. If a racemic mixture is produced at any point in the synthesis,you must indicate it by drawing both enantiomers and writing "racemic". D. (22 pts) All of the carbons in the products must come from the starting materials. OH OH ? + CH3OH OH Racemic OH Signature_________________________ Pg 17 __________(18) 17. (cont.) 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. 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. If a racemic mixture is produced at any point in the synthesis,you must indicate it by drawing both enantiomers and writing "racemic". E. (18 pts) All of the carbon atoms of the product must come from ispropanol OH ? O O Signature_________________________ Pg 18 __________(12) 18. (12 pts) As we emphasized at the end of the semester, a key paradigm in organic chemistry is that reactions of functional groups work the same in complex molecules as they do in the simpler molecules we usually examine in first semester courses. The following complex molecules and reactions were used in actual syntheses. Draw the product of the reactions in the boxes provided. O HN H S N H Cl NaCN 1) (sia)2BH O 2) H2O2/NaOH (Assume these reagents react only once) O 1) BH3 2) H2O2/NaOH 3) H2CrO4 ...
View Full Document

Ask a homework question - tutors are online