{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

MidtermSpring2001Key

MidtermSpring2001Key - MW Jam CHEM 2364 1 Print your name...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 6
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 8
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Background image of page 10
Background image of page 11
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: MW Jam CHEM 2364 3/1/01 1 Print your name ANSWER KEY Print your TA's name . CHEM 2364 Organic Laboratory Midterm Examination March 1, 2001 Dr. Tamara Nauman Direetfiome: D© N©T (@PEN YCODUR TEST UNTIL EVERYCDNE HAS A C©PYE Prim yemr name and year Teeehing Aeeietemfie meme en. every page e ’W CHEM 2364 3/1/01 mé Print your name ANSWER KEY Print your TA's name Safety 1. (15 pts.) Describe the proper disposal method for each of the following: a. 10 mL of concentrated HCl Neutralize with sodium bicarbonate (NaHCO3) and then flush down the sink drain with water. b. a pair of torn gloves used during the qualitative analysis experiment Place them in the ordinary trash. c. 12 mL of t—butyl chloride Pour it into the liquid organic waste bottle. d. all parts of a broken thermometer Collect the broken glass and give it to Benn in the stockroom. Dust any spilled mercury with sulfur. Sweep up the mercury / sulfur mixture and place it in the mercury disposal jar and return the jar to Benn. e. a piece of filter paper used to remove drying agent in the cyclohexene experiment Place it in the ordinary trash. 2. (5 pts.) Describe the procedure that you would use for testing if a compound is water soluble or organic soluble in order to dispose of it in the appropriate place. Take a small test tube and put in a couple of mL of water. Add a drop or more of the compound to the water. If the compound dissolves in water then it is water soluble and should be disposed of down the sink drain with water. If the compound doesn't dissolve then dispose of it in the liquid organic waste. Wat ’jwm/ CHEM 2364 3/1/01 3 Print your name ANSWER KEY Print your TA's name Acetylsaligylic Acid and Caffeine 3. (25 pts.) Describe using a flow diagram how you would separate a 10 gram mixture of the following two compounds into the pure compounds. CH3 OOH Add DCM and NaOH (aq) 5 pts. and then separate. l Agueous Layer Organic Layer H20 and DCM and OONa 5 P t S. CH3 5 pts. ‘ id dilute HCl and ”CM and then separate 5 pts. 1) Dry over anh. MgSO4 2) Evaporate OR distill off DCM CH3 Aqueous Layer Organic Layer DCM and OOH Discard 1) Dry over anh. MgSO4 2) Evaporate OR distill 5 pts. off DCM OOH ‘7}1 - , CHEM 2364 3/1/01 ,JgW Print your name ANSWER KEY Print your TA's name ______________________________ 4. (15 pts.) Knowing the following solubility data for naphthalene, explain the best choice for a recrystallization solvent (use a solubility vs. temperature graph in your explanation): [sol = soluble; insol. = insoluble; T = temperature] :m [Mil-u lama solvent ~eaffe1nesolubility diethyl ether sol. at high T and insol. at low T water insol. at all T benzene very sol. at all T benzene / diethyl ethe solubility temperature The best choice of solvent is diethyl ether in which the solute is insoluble when the solvent is cold and soluble when the solvent is hot. The insoluble impurities can thus be removed from the solute when the solvent is hot by using filtration. All the solute recrystallizes when the solvent is cold. In benzene the solute is soluble in the solvent at all temperatures thus only a small crystal crop would result. In water the solute is insoluble in the solvent at all temperatures thus it is impossible to separate the solute from insoluble impurities. [GRADING INSTRUCTIONS: Give them 5 pts. for the sol. vs. temp. graph if labelled correctly. They also need for full credit to discuss the fact that diethyl ether is the best solvent but they must explain this well. If they also choose to explain the benzene and water but explain these incorrectly, deduct some points (around 5 pts. at most).] Thin Layer Chromatography 5. (5 pts.) Which one of the following solvents would acetaminophen be insoluble in: a) ethanol b) ethyl acetate c) acetone G1) pentane e) dichloromethane 6. (10 pts.) Place the following compounds in order of decreasing polarity by placing the corresponding letter of the compound in the blanks provided (most polar is #1 and least polar is #5). a) fi b) c) d) e) 13' CH3COCH2CH3 CH3CH20H CH3(CH2)3CH3 CH3CH20CH2CH3 CH3COH __e__ _L __a__ _d__ _c__ #1 #2 #3 #4 #5 my- flow CHEM 2364 3/1/01 5 Print your name ANSWER KEY Print your TA's name _________________________ 7. (10 pts. total) A graduate student used TLC to monitor the reaction progress of the following reaction which took an hour to complete. CH3 CH3 R ll A103 C(CH2)4CH3 + CH3 (CE‘IZ ) 4CC1 ——""——> CH3 CH3 4-methylanisole hexanoyl chloride standard 15 mins. 30 mins. 1 hour (4 pts.) Identify the spots on the standard plate given that 4—methy1anisole has an Rf of 0.25 and hexanoyl chloride has an Rf of 0.75 and place your answers in the blanks. Spot A: hexanoyl chloride Spot B: 4-methylanisole (6 pts.) From the TLC results of the reaction progress, determine which compound was the limiting reagent. [ustifi (explain) your answer. Spot A (hexanoyl chloride) is the limiting reagent. Spot A disappeared before spot B thus it limits the amount of product that can form because no further reaction can take place. flx/ZJW/ CHEM 2364 3/1/01 6 Print your name ANSWER KEY Print your TA's name Qualitative Analysis On Questions 8 through 12 circle only one answer. 8. (6 pts.) What qualitative analytical test(s) would give positive results with the following? 0 0 pts. a) 2,4-DNP; Tollen's 4 pts. _b) 2,4—DNP;FeC13 6 [email protected],4—DNP; Brz; FeCl3 0 pts. d) NaI/acetone; Lucas; 2,4—DNP 0 pts. e) none 9. (6 pts.) What qualitative analytical test(s) would give positive results with the following? H 0 pts. 21) Lucas; Jones 6 PtS®FeC13;]ones;Br2 4pts. c) Lucas; Jones; FeCl3; Brz 2 pts. d) NaI/acetone; AgNO3, Jones; FeC13; Brz 0 pts. e) none 10. (6 pts.) What qualitative analytical test(s) would give positive results with the following? O/CHZ Br 6 pts. @Jones; AgNO3; NaI/ acetone; Brz Opts. b) Lucas; Jones; Brz 15 pts. ‘3) Brz )tS. d) FeCl3 u pts. e) none CHEM 2364 3/1/01 7 Print your name ANSWER KEY Print your TA's name 11. (6 pts.) What qualitative analytical test(s) would give positive results with the following? O/COCI—Ia 0 pts. a) FeCl3; Tollen's; 2,4—DNP 0 pts. ‘ b) Jones; Tollen's; 2,4-DNP 0 pts. c) Tollen's; 2,4-DNP 0 193$ Brz; Tollen's; 2,4-DNP 6 pts. none 12. (6 pts.) What qualitative analytical test(s) would give positive results with the following? H3C\ /CHCH2CHZOH H3C 0 pts. a) NaI/acetone; AgNO3 2 pts. b) Lucas; Jones; Brz 0 pts. Lucas; NaI/ acetone 6 pts. Jones 0 pts. e none 13. (15 pts.) Compound A (C6H12) reacts with bromine to form Compound B (C6H123r2). Compound A also reacts with Jones reagent to form 2 moles of Compound C (C3H60). Compound C gives a positive 2,4-DNP test and a positive Tollen's test and further reacts with Jones reagent to form propanoic acid. What are the structures of Compounds A, B and C. CH3CH2 CHZCH3 Brz CH3CH2 Br — -—--—> H H H H Br CHZCH3 B Q; (E Jones (E CI’i 3CH Z—C—"H ——‘_* CH 3CH2—C —OH C propanoic acid CHEM 2364 3/1/01 Print your name ANSWER KEY Print your TA's name 14. (20 pts.) Give the product(s) of the following reactions in the box (INCLUDE STEREOCHEMISTRY! ) HCI/ ZnC12 I BIZ _.__.____> H 151 CH3CH 2.: Br NaI / acetone 1...; ' (EH3 éH3 ”742/ W CHEM 2364 3/1/01 9 Print your name ANSWER KEY Print your TA's name t—Butyl Chloride 15. A) (15 pts.) Identify the following carbocations by labeling them as Vinylic; 1°, 2° or 3° benzylic; 1°, 2° or 3" allylic; 1°, 2° or 3°: + O'CHZCHZ E>—:HCH3 0+ CH3CH=CH Q$CH2CH3 CH3 2° allylic vinylic 3° benzylic (GRADING NOTE: Each correctly labeled carbocation is worth 3 pts. If they have A allylic or benzylic but don't specify which type give 1.5 pts. instead of 3 pts.) B) (10p ts. ) Place these same carbocations in order of decreasing stability by circling the correct order. (#1 is the most stable and #5 IS the least stable). + + + + + CHZCHZ CHCH3 CHBCH=CH cCHZCH3 CH3 E a) EABCD b) DAECB c) EACBD @ECBAD e) BAECD (9 p13 O{ l”: b firm [0 pie ‘. p13 16 (5 pts. ) What was the final method of purification that you used for your t-butyl chloride product: @simple distillation b) fractional distillation c) recrystallization d) extraction e) refluxation Luminol 17. (5 pts.) (Circle the correct choice) In the luminol experiment, the major hazard involved with working with hydrazine is: a) it is a strong oxidizing agent b; it is extremely flammable it is a suspected carcinogen it becomes explosive when heated e) it is radioactive 777421 W CHEM 2364 3/1/01 10 Print your name ANSWER KEY Print your TA's name 18. (30 pts. total) The following reaction is the synthesis of a diamide: HOzC—CHZCHz-COZH 2 (>4012 +~———-> O-HNc—CHZCHz—CNHO + 21120 1.77 g ‘ 1.96 mL actual yield = 1.58 g (d = 0.863) (A) (4 pts.) Balance the above equation. (B) (5 pts.) Circle the limiting reagent in the equation above? (C) (15 pts.) What is the theoretical yield (in grams) of the diamide product. (D) (6 pts.) What is the percent yield of the diamide? (USE: C = 12.01 g/ mole, H = 1.01 g/ mole, O = 16.00 g/ mole and N = 14.01 g / mole. LABEL and SHOW ALL WORK!!!) [Grade by pts. given above; give partial credit] MWLE diacid ((241-1604) amine (C5H11N) diamide product (C14H2402N2) C4 12.01 x 4 = 48.04 (:5 12.01 x 5 : 60.05 C14 12.01 x 14 = 168.14 H6 1.01 x 6 = 6.06 H11 1.01 x 11 = 11.11 H24 1.01 x 24 = 24.24 04 16.00 X 4 = 64.00 N 14.01 x 1 = 14.01 02 16.00 X 2 = 32.00 118.10 g / mol 85.17 g/ mol N2 14.01 x 2 : 28.02 252.le g/ mol 1.77 g/ 118.10 g /mol = 0.0150 mol diacid (C4H604) (1.96 mL x 0.863 g/ mL)/ 85.17g/ mol = 0.0199 mol amine(C5H11N) (B) Limiting Reagent: 1.50 x 1013; (141—1604 x 1 mol C14H2402N2 = 1.50 x 10'2 mol C1 4142402102 1 mol C4H604 1.99 X 10—2 111019 CSHllN X 1 11101 C14H2402N2 = 9.95 X 10—3 H101 C14H2402N2 2. mol C5H11N The amine (C5H11N) gives the smallest yield of product thus it is the limiting reagent. (C) Theoretical Yield: 9.95 X 10;.3‘C14H2402N2 X 252.40 g C14H2402N2 = 2.51 g C14H2402N2 1 mol C14H2402N2 (D) Percent Yield: percent yield 2 actual yield x 100 theoretical yield 1.58 g/2.51 g x 100 = 62.9% CHEM 2364 3/1/01 11 Print your name ANSWER KEY Print your TA's name Cyclohexene 19. (10 pts.) In the preparation of cyclohexene from cyclohexanol, two by—products are possible. Draw the structures of these by-products and give their names. Org—<3 cyclohexyl dihydrogen phosphate dicyclohexyl ether [Give 4 pts. for each correct structure and 1 pt. for each correct name] 20. (25 pts.) Fill in the box with the structures of the products and draw an arrow— pushing mechanism for the major product of this reaction: fing; i141?) C|H3 (EH3 fiHz (EH3 CH3C1'12'(f_$—CH3 fl> CH3CH=C-$~CH3 + CH3CH2—C—fij——CH3 OH CH3 CH3 CH3 major product minor product H31304 + H 20 ~——-—~> 1130+ + H2130 4’ (showing hydronium ion formation not required) (EH3 $43 n+ EH3 (EH3 CH3CH2‘CE— “CH3 ' ————0H2 ——> CH3CH2—c—cf—CH3 —> :QH CIH3 H—Qfi CH3 + H3? EH3 $13 fill—I3 CH3?!”+— —CH3 ——~> CH3CH=C—-- ”CH3 H>K\CHB CH3 H20 OR H2P04' [5 pts. for the major and 5 pts. for the minor products shown in the box above. Each mechanism step is worth 5 pts.] ...
View Full Document

{[ snackBarMessage ]}