322b_09fall_sample_lab_quiz1_key

322b_09fall_sample_lab_quiz1_key - CHEMISTRY 322bL...

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Unformatted text preview: CHEMISTRY 322bL 4%nnfinflf777‘2008 —¥aéi—GGO& [9 far/flz-Z— FIRSTVQUINZ' s r m KEY 1.(14) 2.(12) Lab time 3.(11) T.A._____________________________ 4. (9) 5.(14) This test comprises this sheet TOTAL (60) and five numbered pages. 3224 LQl, 10"“ @f‘Ffi/g) pg 2= ML 1. (7) Recall the Grignard synthesis of 2*methyl—2ehexanol, CH3(CH2)3C(OH)(CH3)2, from n‘BuBr and acetone, CH3COCH3. (a)(3) A Grignard reaction mixture includes a little 12. State two behaviors one observes if the reaction starts rapidly without (/éa. Gaga exEErnal heating. Use < 12 words total. 3 J— 0'1 Marw‘n [Of/Md Ch’” VG‘ ‘Téflinfi‘ f1. Edi/{fig} 9"“ (b) (2) If the addition of n-Bu~Br is too fast, a large am nt of the "coupling aide product" forms. Write a balanced equation for its formation and give the product's structure. {gt D 4-34Ma0r + .4‘ fl" 4* Mela-2404.665 Mr Mufflv’d 3"») (c) (2) Tell why the aq soln used to convert the Grignard/acetone adduct to the product should be cold, dilute, and only weakly acidic. Use <10 words. 12 ¢uo“{/pNJ)(/‘1f 2. (7) Recall the Period 2 alkylation of aniaole, Ph-OMe, by Ph3COH in ROM: with catalytic 32304 to give n—MeO-CGHfCPha. (a)( ) Put "rev(ersible)" or "irr(eversib1e)" in each blank: The rxn “l at. fails in anon because its rxn with 9113C:+ is 1 r1 . A The prep as done succeeded because mm of Ph3c" with HOAc is 6‘5 I‘D AL , and its rxn with anieole is (‘V‘V . d (b) (5) Given ratio Desired Prod to Side Prod is 50:1 at 20°. 1:]. at 80°. and is exponential in AT: Calculate T (3 Big figs) to give DP:SP = 10:1. In defining AT, note that DP:SP goes up as T goes down. Show calculation; OK to take loglos - 0.70. 4- .m/J Io/xs) 4g. Pm. 1.521) fizz“ fljée/L 85% SA 3. ) For 1~hexyne, n-C4H9CaCH — « ~ ‘ — —a> 2-hexanone, n~C439vCO—u (a)(3) '-action of l-hexyne with the vinyl cation (VC) is :'-nificant he - even though its activation energy is much '- er than is that " VC + H20, which leads to ketone. - -1ain in <15 words; r: ill that the aq phase is nearl :1 H2304:HZO. LL) ., 0A ’14ga,r 416%7lflfib75nfldtzé4(’ 7‘» lfifigm ' “WW/Km. (b)(2) A student carries a the rxn un‘T all the l-hexyne odor is gone. S/he te: : a drop of the rxn "xt with 2,4-DNPH re- agent, get ' 9 only a trace of ppt. I 0 words, tell what s/he s ’. d do with the rxn mixt next and I .- zl -/ ‘ ‘ o v '$) “ ‘4 4. (S) For drying by distillation of dilute w solns in an OS: Given y = amt W. x a amt pot soln, and r a the vapor—to-liquid W conc ratio, 1n(y/yo) a r[1n(x/xo)l. For r a 10, calculate the traction of the soln one must distill, rd (3 1 — (x/xo)), to distill 90% of the Water, i.e., to make (Y/Yo) a 0.10. n (a!) = Io Mir) :7 4.3 = MAGS.) MCch 5. (2) For 1A a 13 a 1C: Exactly 60 mmol A produces 300 mL of a solution containing B. Reaction of 100 mL produces 15 mmol pure C. Calculate the % yield of C based A. 37,16 Lal. fir“ fl/r Fifiell (6) Recall the isatin/acetophenone aldol condensation: O u CR3-C-Ph Isatin Acetophenone MW :- 147; mp :- 193—195" MW a 120; d =- 1.03 1L ‘L (3) Draw the structure of cpd I, the initial aldol product. ‘at( (b) Calculate the MW of cpd I solely from its stoichiometric Mat '6’ relationship to the starting materials; show calculation. ‘ (c) When the (nearly) colorless aoln of cpd I is warmed with rh‘ aq/alc HCl, the 30111 turns deep red, producing cpd II. In < \- 12 words, tell what electronic structural change is occurring. {4‘ {q} (4) ".0 cugw‘pk (fix I CA “(leaf “3 F J], (M(=3mw=-ll1‘:3 W H (CI {zfléw @fivmmg. 7. (5) Consider the reaction below: A + B~————--—-’ C + D [initial] 1.0 10.0 o O {equilibrium} 1 — x 10 - x x x (a) (2,) Calculate [1i]ecI for Keq a 4.00. To simplify the calculation, take 2: =- 1.0 in all terms my; 1 - x, then solve for x. (b) (3) Tell what the calculation means. given that m A is hard to separate from products. (Note that if [Ali :- [Eli then [C]eq = [meg =- 2/3IA11, and [Meg a l/3[A]i.) x1— I .. (a) CMcm-x) “f 6’ awn“ (7%- >L :7 x =- 2}; a 0.627 We!“ W M} = 0.0344, <54» a4 WIxJ/wu. (I43;=£63£ dmfi‘fl sa/Imafi'mo’l 4 (aw flflJdcé’. 3224 am, I’m ’3???“ F09 8. (9) Recall the methyl benzoate prep as done: flji‘7 1 9 32504 PnCOOH + 16 g HOMe ——-———————-—a- PhCOOMe + Hon Mu a 122 MW - 32 MW a 98 MW 2 136 bp a 66° hp a 199° (a)(4) If one takes 40 mmol PhCOOH, obtains 3.81 g ester. and recov— ers 1/6 of the starting acid, calculate—— :2 ‘¢%/’ (1) the percentage of benzoic acid converted to product. .1 T: 3‘10" M 3 M76“ W: 2—31)“th mug/K— “ - ’L a! {amw’wm— (be; 70% (2) the yield of ester as a percentage of theory. W = 72/95?- 15:. is} (“A (b)(3) Using (a) chemical equation(a) and < 20 words, explain why aq Na2C03 extracted PhCOOH. but not the enter, from the DCM (CH2C12) Solution containing bath. Munoz; AM Mcoa‘SWacp 7' Pkwo ML " A) e (,4? Alma] mum acid, éwf‘wofu/fa, / 7‘3 a) Kala We U4. {1% (c)(2) Eggplets of aq Nazcoa were removed from DCM soln of the ester just before distillation. How and why was this done? <25 wda. an u 50 f w mmw/ 67 ( Ydm'fl)“ pm} 9g“; Manta1 T’b 6ND]! AW 54(14 + at thcofl 414*“ 57 E121 Lia-.101. om ‘ fi‘lbfim. 21‘ La, file ‘huf m fir F6? 3 I — s — 9. (14) PhCHO was converted to Dilantin m benzoin and benzil. (a) (5) The last intermediate in the benzoin prep likely decomposes to Ph-Cmom—Co-Ph and the T163 mm: in a fast single w. (1) Show the electron movement on the drawing below. (2) In < 15 words, tell why thin step must be fast for henzoin pro- duction to be effici t. O H .. H ' OH 5 =0?) Con. '51 (“an Phi/#bflx figél Dk‘ CH “‘ C \g ‘ I pig/“‘4 PL {7‘40 r-e/W R C 1 M1 660‘ C, fi hr {L'W‘fa fit a”; hymns r JA (b) (6) Summarize the copper~catalyzed benzoin oxidation by filling in the blanks: Compared to 2~propanol, benzoin in easily oxi— dized because its carbinol fl, \pn-u-OH, is a to a Y, :OC'P . Q“ " 1 t t " 1k l I ‘ In two one e ec ron stepa the a d etone benzil (writigK (q (E) C24". 1 :3th —--~>) ‘(O'CO‘ , is produced as? reduced to cm". In (re)oxidiaing 2 Cu", NH‘NO3 (in excess) is reduced to mama, which deacmposea to ___fl;,__ gas and water. age Ea to N02‘ is reduction of the brown gas «02 by C' + a; '4 95, . am, only after rxn+i€ complete because then there in nothing left to reduce (c) (3) Note the structure of Dilantin®belov. Boiling with strong aq Nam-I cleaves all gamma. C-N bonds. producing a pungent, basic gas, a one-carbon dianion, and an organic species. Draw the structures of all these a: m m 1; p3 .- 14. Ph pair—3’: Mu [c —- c006 NIL/3 CO3: WXGXH NHL ...
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322b_09fall_sample_lab_quiz1_key - CHEMISTRY 322bL...

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