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Spring 2003 test 3 - Chemistry 228 Spring 2003 Test 3 Dr...

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Unformatted text preview: Chemistry 228 Spring 2003 Test 3, Dr. Wells, Name : [g Eff testsccre=cpscanx 45 +essay= I“. x 4.5 + [3' = fi‘ifi filmua’i Fflgmi) d Essa],r 1 (1' points) Consider the electrophilic aromatic substihrtion ofhromohenzenc. Draw the arenitun cation intermediate and resonance structures that result fi'ons meta attack and para attack of the {21+ electrophile that explain the expefimental observation that the hromc suhstihleat is not a meta director, hat is a para director. He sure to label your drawings and use words in your explanation. n as 3' 5-. ‘ - :i‘sr. :ffir: mew .. + a. (-3.1: flat ‘5‘?” fire is ——-i"- H Li L,- metaattack {it} amen mm a Mtge: I .r 'flor’ éa3¥n5.1.figé_ be; hhu’rihj 61': Fifi. 3’ - L‘ =.B:'. tfgra fl 6(l o II + 9,1: (3—) fr) para attack resfiwhmt 11 _fl__ a) lYfLrLalf—UL ,.-—--"'> {I}!!! tr ff" *remruflk in“) 5iei‘3115'E‘gé h f/ K] ..--' / too] were? (Br. / Essay 2 [’3 points} Batu-ran routinely administers Eat~lmockout drops to visitors before traveling to the Eat-cave in order to keep its location secret. Eat—knockout drops are nothing more than chloral dissolved in water. In most water i aldehyde mixtures the aldehyde is more abundant than the hydrate. See ethane] equilibrium shown below. However, with chloral, the hydrate is actually favored. In fact, chloral hydrate is stable enough to be isolated and purified. Note the relative size of the equilibrium arrows. I 7t Jill. H20 71 pf: 13—"0——'H __ H—f—f—H H ethaual H :0: I eflianal hydrate H -1 1 t' '- 1 : : f H20 )3 j) Cl—tlt—C—H ..._ cr—T—f—H or chloral 1 r - chloral hydrate C ”In. H Draw enough of the mechanism to explain why chloral hydrate is favored over chloral. Eapl IE 'I thl C- 1'36 t1 [12+ .. we * H r- el—éi—ce—H H—fl—H —" dag—— L——l“l l CI w Ll. Egg) / Ell-q ain in words too. a“ uwlhl‘ténwg'fij Pl Examine The reee’rien sequences below fer quesfiane 1 - 4. CH3CHCICH3 .I" AlClg I CH3CH2CH1C] .I" MCI; ’- /__ O {1ngka r’ “013 1 . Cempnuud l is most likel},I C, . Cl: 1'" FBClg 3 —i- If Hal“ “lg C}_J|:L1_ Cl CH3— 3—. —H inCHzCHg CHB— f'— CH3 2 . Compeund 2 is meet likely C fife I‘L i .r CH If CH Ci CEIH if E) 3— "— 3 Cl—Al—Ci HICHICHS H2CH1CH3 CH3— mail/hi Mg, ECG 0:?) 4‘ “9113"” [mill—1:_CH3'CH1CHECH3 Jill—C] CH3_?—H {EH [M 3 CH3 (:1 CH3 CM?! 3 . Cempound 3 is most liker C H H C 'I (11—m— Cl CH3— Cl CH3— —0 3 CH3—C—DH ‘30 a e 4. Compound 4 is most likely;r H c O‘\\»~rCHar:r~r3-— ? or cur- i1 {1:111:336pl= {pr-raga % E 131 l Cl 5 . The low yield of tbe crtho substituted product can be explained by 3— 3 3 3 5% lfl% 85% A. the nonplansu' benzene ring of the reactant E. considering the‘ ‘parasearchirrg” ability.»' of {31+ C/ {(3 considering the large size of the tert-butyl group —- El {3 1. if. 'j C} — In if it“ K I}. resonance stabilization by a lane pair E. the inductive effect of alkyl groups CB 6 . The ammonium group (-NHg) is a meta director because ® it is an electron densityr withdrawing group B. it is an electron density,r dcrrating group %( C. of sterics D. it is a carboxylate E. of resonance 7. Fluorine is an crtbur'para director because A. it is an electron density withdrawing group B. it is an electron density donating grcup C. of sterics D. of induction (9 of resonance B . Which compound below would oxhibit the most aromatic stability '? C, [l A and C o exhibit the some. aromatic stability. E. They all exhibit the some aromatic stability. Complete the reactions bellow. . . . . . . lllllll o n LIME: . fix 2? 9- CHE/CKH {or 2mm: ? \{\l \fihkfi' l? o NH i‘l NH: H N/ 2 {3111/ RH 0’! \NJ’H ll; ii \CH3 9 ,5? "'——-'—hI- 10_ CHa/ RH CH CH TI/ 3 aijCHj {ill—‘THE fig C [3 CH —*C—'CH _ C CHj/ RH (33/ H‘H a [ ZCHB/ M‘“ T or; “m {in H (130mm '—-"" c 9 11 Cfla/ “NH {2)H30" ' 1-I / {r r.) u HRC/CHE‘ “a. {‘9‘ H CH3/ H (2 CH3 D CH3 CH3/ "RH ® E E 5- Es. D \fhh H Ph’c‘h—o H 43);” J C 9 f“ ,, 12 CHj/ “HRH ‘(\7 Ph D D D RCJH Ph‘HCHH L fix “I “A u U? J2}; \. “a CHs'D A H 0/3 H OPE/@DH CH-j/rD‘H‘H CHg/E HRH 0 H {I} CH3CECENE C (2)14 0+ ‘7 13_ CHg/ EH 3 H\ 0 Elli: CHaHC/ c / H“ 14. Upticalljl' pure ketenes that are chiral at the alpha carbon can he racemized when exposed to basic solution because . ' A. kelones are less reactive than aldehydes B. there is no ring strain C. condensation reactions have a carhocation intermediate (1:33 on aehirai enoiate is formed Y) E. a chiral enoiate is formed 15. Ketones are less reactive than aldehydes because A. ketones are not IR. active 31"; B. ketooes arepianar )5; C, the carbonyl carbon has less positive charge f . ketones are less stericallv crowded ‘J‘K E. ketones do not contain alpha protons 7i. m (‘0 " l) excess o 5.. OH OH H+ Br 2) CH3Li 4) ...
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