ochem4 - PPrL 0H Your name ...................................

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Unformatted text preview: PPrL 0H Your name ................................ '| Your ID # ....................................... .. Chemistry 108A First mid-term mea version 1 =FHL§T M le-EP—«M key Manon a; TEST 2 4 .L O a - u o c a - n - total 170 - . roenta - BI Problem 1 (13 points) What kind of hybridization do you expect for the C. O and N atoms indicated by asterisks in the following molecules: 3 3 7, l. 3 i» S; a? sf * 5f ,6 Sf :1“ CH3 CH2? CHZCI-ls =*< CH3 01-12 CH3 SP SFJ 7. 7- 5??— 510 3 SF * S‘; 6(- 4-919 at- H20=CH—CECH (CH3)3N: SF * Problem 2 (13 points) ' 6—1 - =-| Calculate the formal charges for C, O and N atoms in the following molecules: q-q:0 6-3-5: F‘ q-.L‘:O LI_.3_2':-‘ 5-4:.11 r\ a .59 c2 s9 .69 @ a e we HzG=N=Ng :O_ _O‘:) Hac—NEC: _<:H3 —N 4/ ' " my“, / (Q) ll 52:4 :1“ .. '1 “I ' __ 4-4—0 @ :9. I 544:4 6 HP' b-Ll=+| Hg“) Problem 3 (10 points) Circle the reagents that are likely to act as Lewis acids and box the ones that are likely to act as Lewis bases. ' Problem 4 (10 points) Identify the acids and the bases in the following reactions: CH30H +“NHZ _ Cl-l30'+ NHa A: 14:44 A B CoidoB ' "Coma. A E" bale Z s + BH —-- Z 5 o 3 cl)+ 5 A 'BH3 + CH? C\=°—H +'HSO4 Cl-|30=0 + H2804 OH OH “is A ,4 and . B Probfem 5 (9 points) Identify the carbon atoms in the following molecules as primary, secondary, tertiary or quaternary: 3D lo 30 Q '0 {a I /l0 6,0 /7 {1 71 CHsCHCHgoH 213° I/Lfo Low :rlo O OH OCH 0 I / lo 10 3' 3l° 30" N) 2 CH 1 30 lo I I03 ’2 o 3 lo q l0 Problem 6 (15 points) Draw structures corresponding to the following IUPAC names: a) 3,4—dimethylnonane /\r)\/\A b) 3ethyl-4,4-dimethylheptane W c) 1-bromo-3-isopropylcyclopentane Problem 7 (10 points) Give IUPAC names for the following compounds. Include cis or trans when shown. a) Br 4.1%5rmo _ I, Z-dx'rmehflgl? Joluzxa nt b) . - N CH3 a f - //¢{—a’z«m€#?{ 67 do AQXQI’JQ CH3 Problem 8 (15 points) Consider 2,3-dimethylbutane. What are the relative energies of the three possible staggered conformations around the C2-C3 bond? ‘ In case you need it: 2 CH3 : CH3 eclipsing interaction costs 1 1 kJ/mol; a CH3: CH3 gauche interaction costs 3.8 kJ/mol; a H:H eclipsing interaction costs 4 kJ/mol; a H: CH3 eclipsing interaction costs 6 kJ/mol. Draw the three staggered conformations and show the calculation of the total energy cost for each one. CH3 CH CH5?;/¢2:.H at? 3 CH3 H 0435\m3 CH H H BK‘CHB CH3) 3-! Cku’chB H ‘ {3K aslnlml {3 x lamina] [2} 3,8) 5/“, 3*Cl-P3/Cllg. “Gila/W3 u sag/0:43, dd. amulet 30mm - ‘54“ ll-Lf U/Mu my, lax/Mu 4.6 kI/Ml Problem 9 (20 points) Consider the following energy diagram (free energy vs. reaction coordinate). a) Indicate all the transition state(s) (T S) and intennediate(s) (I). b) Indicate the AGO for the reaction. c) Is the reaction favorable from an equilibrium point of view? d) Indicate the AG“ for each step. e) If the AG'g for the individual steps is about 20 kJ/mol, would the reaction take place at room temperature? c A6°¢o ..—> fleacfl'mcr , ) +auOraéz/a [onl’lumc\ reaction coordinate Problem 10 (9 points) Assign E or 2 configuration to each double bond of the following alkenes: CK /-OCH3 c=c f H/ \Ofi-CHa 0 CI \c—fic/ r \ c—c/ \H / \CH20H3 Br 8 E Problem 11 (11 points) Propose a mechanism to account for the following reaction (include arrow pushing): Br \ '1. Br Ir- (w :3” 4-“ V Problem 12 (15 points) Predict the products of the following reactions. Indicate stereochemistry when relevant. (Do not show mechanisms). D2 {Pd [C \c —.-— HBr 0/ --—--—---——r—I- ether, LL 0’ r< ———-i- \—/ B peroxides ( o H 1) Hg(OAc)2 . H20 . THF (\v —————D- 2) NaBH4 ---../ OH H20 , H2504 d Problem 13 (10 points) I A compound A (C5H3) reacts with Hz‘ on Pd/C to give a compound B (C5H1z). When a mole of A is treated with ozone followed by Zn under acidic conditions, two moles of compound C (C3H402) are obtained. Propose a structure for A, B and C in agreement with the chemical data. Show the chemical reaction (without mechanism) for the transformation of A into C. A Mi: 612+2—é’ __3 J _— l i )0 “J94 L ' 3 2')2'\nH-30+ 2C. (CBHuolj 1w: 3rZ+L‘“l 5 2. hm; -_-. I 2.. A: [like :3 ~—. 0 O A; ||fl3—> ZHMH'C -\ 7 pr: ll A+ Problem 14 (10 points) Draw the most stable conformer of cis—1,3-dibromoc all the hydrogens as well as bromines. yclohexane. Indicate the position of ...
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ochem4 - PPrL 0H Your name ...................................

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