CH310M-E2_KEY - CH 310/318M—Ex. 2 Patman—Sp.201l EID:...

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Unformatted text preview: CH 310/318M—Ex. 2 Patman—Sp.201l EID: Name (print): If you think you may want a regrade, please use blue or black PEN! Please write the first three letters of your last name in the boxes Please do not ask the proctors or TA ’5 to interpret questions for you. The goal of the exam is to test your understanding of the important concepts we have discussed thus far. Sufficient information is provided to make it clear what is being asked in each question. it is up to you to interpret and read each question carefully! Make sure you are completely aware of what we are asking you — only then will you be able to fully answer the question. Pace yourself and good luck! ! CH 310/318M — Ex. 2 Patman —Sp.2011 EID: 1). Mechanisms. Draw the mechanism for the following reactions, using curved arrows and showing all lone pairs and relevant charges where missing. Label the Lewis acid (LA), Lewis base (LB), Nucleophile (Nu') and Electrophile (E*). (Gpts) 8) CH3 CH3 "V eh one —_>. G.) ".v. :‘CIil .- Hsc \. L, LP; CH3 Rue. CH3 LA E8: b. ‘ ' w " Cl C!- flt '\Al/\@//CH3 . —>. _ Hsc CH3 1 I p. r 0 r “Cl: A?" I ‘ LVJ CH3 Nike ER“ 2) NSAIDs (non-steroidal inflammatory drugs), the most frequently prescribed painkillers, produce annual sales in excess of $20 billion worldwide. Usually one enantiomer is more effective than the other, and efforts are being made to develop asymmetric syntheses a better understand the reactivity of these enantiomers in biological systems. One such NSAID (Flurbiprofen, below) is prescribed as the racemate to treat arthritis and is an active ingredient in throat lozenges. However, the enantiomer shown below is currently in clinical trials for treatment of metastatic prostate cancer, a disease effecting 18% of American men each year. A recently reported synthesis produces this enantiomer in 96% ee. Answer the following: (3pts) Is this the R or S enantiomer ? R What percentages of R and S enantiomers are in the mixture? R: _98°/o__ S: _2°/o CH 310/318M - Ex. 2 Patman -Sp.2011 EID: 3) Acid-base reactions. Complete the net ionic equation for the following acid/ base reactions by giving the products. Identify the acid, base, conjugate acid and conjugate base. Over the equilibrium arrows, write "right" or "left" to indicate which side of the reaction is favored. Remember some atoms are present only as "spectator" counter-ions. (12pts) 8) b) Book 4.11c NH4+ L‘B‘CU‘ HacONa €74.56; H3C 9 CH3 Ye CH3 bask, \ \C‘i! Jr- . ‘I ‘ I I °“3°“3°“a J NH 33 cub-ac o a No P704311 C (5m!- ' Cm}: DALE. tit—ck 3w Lit-i, (71- NH -—"~_.._ , fl _ 1 t ‘3: LibC‘UH NAN it 1 CLQL'LL “I” ' ' H ;.i-—::‘« U l ; “ ' . Cu O UK 5 C W: muggy but; ‘ (tun- 4) Think! Glutamic acid is another amino acid found in proteins. As a di-carboxylic acid, it has two pKa's. One with pKa 2.10 and the other with pKa 4.07. Circle the carboxylic acid group with the lowest pKa. In no more than ofew words, explain why this acid is stronger than the other. Book 4.53. (3 pts) HO NH; gtutamic acid Your reasoning EWD ammonium stabilizes the anion that would result upon deprotonation of this carboxylic acid through sigma inductive effects. The more stable the anion, the stronger the corresponding acid. CH 310/318M —- Ex. 2 Patman — Sp.2011 EID: 5) pKa's— do you know them? For each molecule, consider the boxed protons and place an "X" over the most acidic proton in each molecule. You should be able to complete this question by knowing the pKa values, but it is possible to reason your way through it as well. b- n A . F E Fwo‘ \\ Bonus: What is the pKa (general value) of the most acidic proton in b? (1 pt) a 16 OCH3 Cysteine - an amino acid ' _ _ Vanlilln - primary component of vanilla extract 6) Circle which in each pair has the higher numerical value. HW - Book 4.14. a) pKa of a strong acid or pKa of a weak acid Ka of a strong aci - or Ka of a weak acid CH 310/318M — Ex. 2 Patman — Sp.2011 ElD: 7) Nomenclature. Name the following according to IUPAC rules by providing the name of each compound in the corresponding numbered spaces provided. Include stereochemistry when indicated. 1. (E)—3,7-dimethyl-1,3,6-octatriene 2. (35,Z)-3-iodo-7,8—dimethylnona—lfiadiene 3. (lR,2$)—2-isopropylcyclohexanamine 4. S-ethylcyclohexa—lfldiene Me 1 (HW - 4.2a) 2 (partly from HW 4.2d) CH 310/318M —Ex. 2 Patman—Sp.2011 EID: 8) Nomenclature. Draw the following molecules based on their IUPAC name and fill in the table below. Me Z - 4 ~(2-chIoroethyl)-2,3-dimethyl-3-heptene (from your notes) \ (2E,4Z)-hepta-2,4-diene 2-vinylcyclopentanol (from your notes) CH 310/318M — Ex. 2 Patman —Sp.2011 ED: 9) True or False. indicate whether the following statements are true or false. If the statement is true, check the "true" box, if it is false, check the "false" box. Only one answer is acceptable for each statement. True Optical purity is numerically equivalent to enantiomeric excess, but is experimentally determined. Dextrorotatory compounds are designated (-). A conjugate base is formed from the base after loss of H". Separation of racemic mixtures is possible through resolution. n-bonds cannot act as Bronsted bases. Equilibrium of acidlbase reactions always favors the side of the stronger acid. Nucleophiles always "attack" electrophiles. Meso compounds are non-superimposable, non-mirror images. Enantiomers rotate plane-polarized light in equal but opposite directions. A racemic mixture is optically active and the overall mixture is achiral. In a molecule, the total # DOU's is equal to # of rings or # of 7c- bonds. E D All chiral molecules are optically active when pure. Bonus question: What is one common use for the molecule shown below? From your notes! 0080800 8008 0808088 088053;" / A common use (2 pts.): Styrofoam, insulation, plastics It's common name (2 pts): __Styrene CH 310/318M — Ex. 2 Patman —Sp.2011 E10: 10) Identify. Square the mesa compounds in each set and answer the questions. HW 3.2! a. CHZOH H Cl H Cl Cl H CI CHZOH H Cl HOHZC Cl HOHzc H CHZOH CHZOH H 1 2 § :1. Which pairs are diastereomers? 1,2(4);____1,3 Which pairs are enantiomers? _3, 2(4) Which are identical? 2,4 b. with a small twist! Which pairs are diastereomers? 1(4), 2(3); 1(4), 5 Which pairs are enantiomers? _2(3),5 Which are identical? _1,4; 2,3 CH 310/318M — Ex. 2 Patman —Sp.2011 EID: 11.} Identify. Circle all the mesa compounds. From notes and book problems. 10 CH 310/318M — Ex. 2 12). Ranking. Rank the following based on the criteria listed. Patman — Sp.2011 a. Base strength {1 = strongest, 4 = weakest) H36 CH3 H3O A OLi x CH3 b. Acid strength (1 = strongest, 4 = weakest) C. CH3 0 H30 CH3 H3CMCH CIP priority (1 = highest, 4 = lowest) WON “ht/\Cl 11 EID: :HZSH [I] CH 310/318M — Ex. 2 Patman —Sp.2011 EID: 13.) Short answer. Hw 4.7 with a twist. a. Circle the strongest acid. 0 O O 0 ii ii H30 OH F3C 0H else on FClzc 0H Complete the sentence. The one you circled . . . (TLKCKJQCUIT is the strongest acid because of "5— Ln CLKVBJUW g *- b. Circle the most stable anion. 6 Hac/CHE / 9/\ Glue l . - ~ ' . ' i "W Complete the sentence. The one you circled . . . “Li 0; H Ch wax ' C. Complete the sentence. The one you circled . . . g l L. M.» \Ck l-“VL/Q/ AM mom-die (*3 CM UN {\Kgficm mm x: \L {i LE» 1 C\i’i\.L.L . ‘ has the most acidic proton due primarily to 12 CH 310/318M — EX. 2 Patman —Sp.2011 ED: 14. Think! - Acid/Base reactions. This question is inspired by HW 4.5. Suppose urea reacts with HBr according to the curved arrows shown below. In the space provided, draw the conjugate acid that would result from protonation of the nitrogen atom. If this conjugate acid is a resonance hybrid, please draw a_ll of the important contributing resonance structures. You do not need to show curved arrows indicating electron flow in the interconversion of the resonance structures. Please include all lone pairs and formal charges in every structure you draw, and square the most important resonance structure(s). O f‘ H—-—' 'r: 55.. fl - . . U Q HZN iii-I2 31“ ll LN -/\im'il.2_ urea Acid/Base reactions. Suppose urea reacts with HBr according to the curved arrows shown below. In the space provided, draw the conjugate acid that would result from protonation of the oxygen atom. if this conjugate acid is a resonance hybrid, please draw a_ii of the important contributing resonance structures. You do not need to show curved arrows indicating electron flow in the interconversion of the resonance structures. Please include all lone pairs and formal charges in every structure you draw, and square the most important resonance structure(s). “on/xl ('5- e-v. H The OXYGEN is the strongest base. I 0 I The NITROGEN is . ' the strongest base. HZN NH; urea ~ - - - - - - - - - - - - - - . - - - - - . - - - . - . . . . . . . . . . . . . . . . . . . . . . . . . . . . -- CH 310/318M — Ex. 2 Patman —Sp.2011 EID: 15. Circle the side of the reaction that is favored and calculate Keq — you should not need a calculator to do this. Hw - Book 14.19 3) CH3 CHzLi Lio/\ " H0/\ K =15.9 pKa = 41.2 10-253 p 3' Keq = b) ‘ o HO/\ CH3 pKa = 15.9 pKa = 20.2 M Keq = 10 C) CH3 /CH3 k é H3O . H LI 14 CH 310/318M — Ex. 2 Patman — Sp.2011 EID: 16. Calculate the DOU’s of the following compounds. These compounds are components of various flowers] essences. geraniol (rose) — CmngO caryophyllene (ylang ylang) — C15H24 benzyi acetate (jasmine) — Cngooz indole (jasmine) — CgHjN A derivative of bixin (achiote) — CstngIOg [A 1 VA ' an "organic" Butterfly Happy Springtime! END OF EXAM 15 ...
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This note was uploaded on 09/25/2011 for the course CH 318M taught by Professor Bocknack during the Spring '08 term at University of Texas.

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CH310M-E2_KEY - CH 310/318M—Ex. 2 Patman—Sp.201l EID:...

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