CHEM 239 sample_exam_ex1_key

CHEM 239 sample_exam_ex1_key - Chemistry 239 Autumn, 2004 '...

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Unformatted text preview: Chemistry 239 Autumn, 2004 ' Sample Exam 1 Answer Key Your name: Student #: Sign here to indicate your approval of public return of your paper: 1 (16 pts.) Give IUPAC names for the compounds below. _ ICOZH CH3(CH2)3C02H HOCHZCHZCHCHZCHZCH3 4-hydroxyl-2-propylbutanoic acid acetyl chloride (also give condensed structural formula) ethanoyl chloride CH3C O C l CH3CH20COCH2CH2CH3 C6H4CONHCH3 ethyl butanoate N-methylbenzamide 2 (8 pts.) The pKa of benzoic acid is 4.2. The pKa of o-chlorobenzoic acid (0-C1C6H4C02H) differs by 1.3 pKa units from that of benzoic acid. a) Is o—chlorobenzoic acid a stronger acid or a weaker acid than benzoic acid? STRONGER b) What is the pKa of o—chlorobenzoic acid? 0) Write a balanced equation for the proton transfer reaction between benzoate anion and o—chlorobenzoic acid and indicate whether the equilibrium will be favorable (to the right) or unfavorable (to the left) for the process. FAVORABLE C6H5C02' + ClC6H4C02H -—<_:—> C6H5C02H + C1C6H4C02' Chem 239 Autumn, 2004 Sample Exam 1 Answer Key p. 2 3 (24 pts.) In the reactions below fill in the missing items (starting materia1[s], reagents ' and conditions over the arrow, or main organic product[s]). KMn04 or Cr03 PhCH20H ——————> PhCOzH l2, OH' 1) LiAIH4, ether 2) H20 PhCOzH ——————-——————> PhCHZOH CH3COCH2CH2C02H ————> = NH4", '020(CH2)3c02'. NH4+ ————> NH P4010 PhCONH2 —————> PhCN 1. Meng, E120 hi" heat, H30+ PhCN ——————> PhCMe —___> PhCOMe 2. H20 Chem 239 Autumn, 2004 Sample Exam 1 Answer Key p. 3 M 4 (4 pts.) Write a balanced reaction equation for the hydrolysis of a nitrile in aqueous -. base. RCN + OH' + H20 ————> RCOZ' + NH3 5 (12 pts.) Draw a curved arrow mechanism for the reaction below. Show all bond formation and bond rupture steps, unshared electron pairs and formal charges. ’ PhCOzEt + NH3 7:; PhCONH2 + EtOH 0 either above followed by proton transfer to form EtOH Chem 239 Autumn, 2004 Sample Exam 1 Answer Key p. 4 6 (4 pts.) Write the structures of the products from the reaction below and balance the reaction equation. Briefly explain why you would get the products you predict. CH3OH + CH3COOCOCF3 _> F3C02CH3+ CH3C02H r electron withdrawal makes this acyl group more reactive 7(12 pts.) A compound I, containing only carbon, hydrogen, nitrogen and oxygen, with a molecular weight of 143, had a strong peak in the IR spectrum near 1700 cm-1 , and gave the nmr spectrum below. Propose a structure for I, showing how it fits all the evidence above — show your nmr peak assignments and label the multiplicity of all peaks. 7H 4 H “H (islets-"iii: 7\ (xflj 35.} Sissiel‘v-‘L I €11 impiei CH3-N(CO-CH2CH3)2 IR consistent with imide carbonyl stretch mol. wt. C7H13N02 = (7x12) + 13 + 14 + (2X16) = 84 + 13 + 14 + 32 = 143 Chem 239 Autumn, 2004 Sample Exam 1 Answer Key p. 5 8 (20 pts.) Show how you would carry out the syntheses below. (Show the main product after each step, with reagents and any special conditions over each reaction arrow.) H0 H0 \|:>‘C02Me from \O—Br xs MeOH, HCI mite: Kl» Cam me C P335311;th H3O+ Ho mwéaxgiahm C02H <—————~— CN C’IWiflj 2L0 amia‘c «cm CHZCOOCOCHZ CHZCONHCHs Cl Cl 1 Cl ‘Q‘CHZCOZH , pyr CHZCOZCI SOCI 2 <———-————— ...
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CHEM 239 sample_exam_ex1_key - Chemistry 239 Autumn, 2004 '...

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