Ch9 problems

Ch9 problems - Problems 377 [Ydride (strum ___|_ H,._...

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Unformatted text preview: Problems 377 [Ydride (strum ___|_ H,._ first method is best when 8N2 reactivity is high. 8. Sulfur has more diffuse orbitals than does oxygen. In ( / 'I" I'm: mm- case, elimination (dehydration) is a competing thiols, the 8—H bond is less polarized than the OHH bond » '” W1. .U higher temperatures. in alcohols, thus leading to diminished hydrogen bond- I'ull '- ' ing. Because the SWH bond is also weaker than the 0—H from! will?” and Cryptands are examples OfwMPhores’ bond, the acidity of thiols is greater than that of alcohols. ..~|-.-cr.|rcrs that coordinate around metal ions, thus render- “,h-rllcnr soluble in hydrophobic media. 9. Note on color use: Throughout the main parts of the text, " beginning in Chapter 6, reacting species in mechanisms and most examples of new transformations are color coded red for nucleophiles, blue for electrophiles, and green for leaving groups. Color coding is not used in exercises, summaries of new reactions, or chapter-end problems. | h. . w 1.6.1.“; nucleoPhilic ring opening of oxacyclopmpanes r' m- “units is at the less substituted ring carbon according H; [m- mias of the 8N2 reaction, acid-catalyzed opening fa— } W“. m; more substituted carbon, because of charge con- WI ,.|' lmclcophtltc attack. a I allltmfi 1”“ which side of the equation do you expect each of the following equilibria to lie (left in right]? ll ““ (“1”th + K5014 —‘— (CH3)3CO‘K+ + H20 “1’ mpg + NH3 3: CHBO’ + NH4+ (pK. = 9.2) I H | N' Li+ f N 1 IT! ('ilat'fl-IEOH + O n—- cHaCH20_Ll.+ 'l‘ O (pKa=40) on ways; = 35) + Natfl“ :2 Na+ "NH; + H2(pr<a ~ 38) tit-r,- the expected major product of each of the following reactions. - Cone. HI Cone. I-lBr K _ - - - in {'ligCHZCHzOH ——> (h) (CH3)2CHCH2CH20H ——> H c .HCl _' m f (a) (CH3CH2)3COH s OH RS-- all: | _ ‘ mam] disum, 2?. H1: each of the following alcohols, write the structure of the alkyloxonium ion produced ' after [animation by strong acid; if the alkyloxonium ion is capable of losing water read- ily, write the structure of the resulting carbocation; if the carbocation obtained is likely In 4H: susceptible to rearrangement, write the structures of all new carbocations that ought be reasonably expected to form. (IJI-I till (:1:chchon (b) CH3CHCl-I3 (c) CH3CH2CH2CH20H OH ulmriighct-ICHZOH (e) (CH3)3CCH2CH20H (f) f a secoansz CH3 nium ions I‘-'-'| , OH of loss nf‘fl-il (filly? OH H3C CH3 ' ' 's'L' t to glve '- lg] (h) H3 CH3 ,kanes can IT ("c l memo‘b 1“ I . y‘lfltl.‘ all products of the reaction of each of the alcohols in Problem 27 with concen- “illi'fl' H2804 under elimination conditions. )n ether 83"" y‘llllfl all sensible products of the reaction of each of the alcohols in Problem 27 with I s't Intern; atutl aqueous HBr. )K‘ top-iii lls‘ ‘\ Problems 379 (ll) limit-2d mechanisms and final products for the reaction of 3-methyl-2—pentanol _ (ill, ;;-..~h of the reagents that follow. l “Eh-“n Concentrated HBr - i'li'.‘_: (g SOClz - -“,.{L=;1.*mted H2804 at 130°C a flute H2804 in (CH3)3COH g 9 ll l'rinmri alcohols are often converted into bromides by reaction with NaBr in H2804. a: - ' hpm‘] how this transformation works and why it might be considered a superior Ill-crawl to that using concentrated aqueous HBr. NaBr, stoi m —"‘—> CH3CH2CH2CH2BI' o a: Mm are the most likely product(s) of each of the following reactions? C'IHg (IIH3 ' 3 z u 2 4 C AH! .n a“ )0“ m (b) CHfCHon ' 't g CH3 9 CHZOH °‘ at - (3 .H1 0., 80°C Hzo m I' i; (d) CH3C%CHCH3 —> f ' CH3 '1‘ Eit'l? the expected main product of the reaction of each of the alcohols in Problem 27 J‘ " with I’Brut. Compare the results with those of Problem 29. > - . ‘ @3jw; tin.- expected product(s) of the reaction of 1-pentanol with each of the following '. ' reagents. - In] K. " ' UC(CH3)3 (11) Sodium metal (c) CH3Li J: I it” Concentrated HI (e) Concentrated HCl (f) FSOgH I'm {Joltucnlrtllml H2804 at 130°C (h) Concentrated H2804 at 180°C (i) CH3802C1, (CH3CH2J3N l [jt FBI; K2CI'207 + H2804 'l' H20 {Int CHZClz (n) (CH3)3COH + H2504 (as catalyst) 5 _ J .15; {Eh-Lt the expected product(s) of the reaction of trans-3-methylcyclopentanol with each of g a“ 5;" 5;? the reagents in Problem 34. )——EO—:fi-—E' I 1 E Hungcslz a good synthetic method for preparing each of the following haloalkanes from ' the corresponding alcohols. (EH3 H30 Cl T m: CHgCHZCI-FZCI (b) CHgCHZCHCHZBr (c) 6 (d) CH3CHCH(CH3)2 D 1 . 73- Aime each of the following molecules according to IUPAC. m 1 /O ' {ill it l-IJJLCHOCHZCHg (b) CH30CH2CHZOH (c) 07040 ?“ H3C OCH; "'5 'CiU-bCHmO (e) 6 (r) CH30—<:>—OCH3 (g) CH30CH2CI ’2 'm' i"‘iftli‘htifl Why the boiling points of ethers are lower than those of the isomeric alcohols. “a “'ri'llltl you expect the relative water solubilities to differ in a similar way? 380 Chapter 9 FURTHER REACTIONS OF AltflHfllS AND THE CHEMISTRY 0E ETHERS Suggest the best syntheses for each of the following ethers. Use alcohols or haloalkanes or both as your starting materials. 4.11. Proper: (a) Now an /0\/\/\ (c) /’\0/\/\ .r— «f /\.0 N0 / ‘L r (d) (e) Y (o W .. ’ Hm syr . . . at. t'lt'wr'ai Write the expected malor product(s) of each of the followmg attempted ether synthesea km .El 0. Cl ,nxqteyul i MS I . l. I I (a) CH3CH2CH2C1 + CH3CH2CHCH2CH3 —D~—°> (b) CH3CH2CH20‘ + cngcnzcncnzcn3 mi) 4% Fef‘I-ltlh $ij :1 u H3C O— 0 {-1.1 L CH: 2 . ' (c) + CHsI Eds—O» (d) (CH3)1CHO’ + (CH3)2CHCH2CH2B1~ ‘ WHO“. c l CH3 [ J E H H I g DMSO 0' Cl . _¢ M I @or each synthesis proposed in Problem 40 that is not likely to give a good yield of ( ether product, suggest an alternative synthesis beginning with suitable alcohols or 0H haloalkanes that will give a superior result. (Hint: See Problem 22 in Chapter 7.) [3; ion ‘ 42. (a) What would be the product of reaction of trans-Z-bromocyclooctanol (margin) wit-f: | “Br NaOH? (b) Compare the effect of entropy on the transition state of this reaction with trans.2.B]-omocyclooctanol its effect in the reactions presented in Figure 9-6 and in Exercise 9-13. ‘9‘ Fur “'“I an were; @ Propose efficient syntheses for each of the following ethers, using haloalkanes or m J alcohols as starting materials. ' {'th E": ‘- c'I'C'HI; |I (EH3 CH3 0 . (a) CH3CH2CHOCH2CH3 (b) OCHZCH2CH2CH3 (c) O<CH3 (a) \E :. _ H CH3 9' lit] “‘1 0 Ct 44. Give the major product(s) of each of the following reactions. '5'? Name :31 Ex e . HI e . (a) CH3CH20CH2CH2CH3 (b) CH30CH(CH3)2 W {Lu 3- CH H ' . Excess cone. HI H“ 3 "H E HB ‘1 (c) CH30CH2CH20CH3 ———> (d) H—usm °°"°- ' w ll: sat-II .- Whll'i'i] is O "53‘- lihe was 1-1913 lion. o :- ~ (e) _—)Excass mac. HBr \ Excess cone. HBI’ i r :- CHZ —fi—"——’ , / 0 H CH2 45. Give the expected major product of reaction of 2,2-dimethyloxacyclopropane with 33“" .1 of the following reagents. . I Ell [ - (a) Dilute H2804 in CH3OH (h) Na+70CH3 in CH3OH (c) Dilute" aqueous-31hr“ ' H .1_ (d) Concentrated HBr (e) CHgMgI, then H+, H20 (f) CGHSLi, then H ~ E'f Problems 381 :hols or halnaljr, ill|.'I I ' I J _ - “@195. a synthests of 0H beginning w1th cyclohexanone, I j -' AOA\.J”- J ' >=0, and 3-bromopropanol. [Hint Beware of a possible pitfall in planning /0\/\\ _ “t- .. i mi‘ “tiff—fish (recall Section 8-9).] I 1m“ 0f mm but“ “hers requires the use of an aciueous acid (Chapter 7, Prob. 1”" and semen 9'8) Why do strong bases not cleave ethers (other than umpelopnqmnes)? :ted ether synlitcm- {CH CH ham-m 45 am. 1|“; major product(s) of each of the following reactions. (Hint: The strained oxa- 2 3 I gjflltlbllifliiéfl react like oxacyclopropanes.) D Na*'NHz,Nl-I3 (b) H 0 Na*'SCH,CH3,CI-[3CHIOH [all f - 5 " —"’—_’ . CH : —— —\ .2CHzBr a‘——""‘ “H; CH3 I m a"? Emswnc-HBr (d) O Dilute HCl in argon —*-—> ———-—> I '— CH3 nmso _“—’ CH3 I r [—0 Nac‘ocn3 in cugoa 0 1.1411114, (CH3CHQZO r —_~—> 2. H“, H o 1 CH3 6) AVCH3 —_>’ CH CH3 a good yield of 3 e alcohols or O L (qflmcmga' (CHJCHZhO 1. On. (cascngzo 1 Chapter 7., m {AV CH3 2.H ,Hzo (h) 0 leHzO tanol (margin)r will] CH3 A this reaction with _ . 13. H. the each alcohol in Problem 45 of Chapter 8, suggest a synthetic route that starts w1th Iltl osucycloptttpauc (if possible). iloalkanes or Ell-Girl: the major product(s) expected from each of the reactions shown below. Watch stereochemistry. 0 " 't O 0 1. LiA]D., (CH,CH,),0 T 3 Dilute H2504 in CH3CH20H 2. at, H20 . 44:“ ———-—> _ a ——> O/ -—.'__.I' ll” H, ‘CH3 H, 5CH3 CH3 H CH3 H mm each of the following compounds according to IUPAC. xcess cone. HBr -- —~—9 3 | [M D—CHZSH (b) CH3CH2CHSCH3 (c) CH3CH2CHZSO3H (a) CF3SOZCI fl, 51- ll.‘ each of the following pairs of compounds, indicate which is the stronger acid and which is the stronger base. (a) CHgSH, CH3OH; (b) HS_, HO‘; (1:) H3S+, H28. reasonable products for each of the following reactions. I One equivalent Nags Bl: /H m m CICHZCHZCHZCHZCI —~—~—> (b) EL,“ (00:0 ——>"“ 1 \H CH3 propane with ear-ii CHgCH2 / \ Excess H202 C H 2 lute, aqueous Har Ill] CHgCHZCBr —+ (e) CHgCIIHCHg »‘——> (f) o s —-> . + a“: | H5L1, then H . I . CH3CH2 SH 382 Chaplin 9 FURTHER REACTIONS 0E AltflHUlS AND THE CHEMISTRY 0E ETHERS | 54. Give the structures of compounds A, B, and C (with stereochemistry) from the informa. fin, {iii-e effici tion in the following scheme. (Hint: A is acyclic.) To what compound class does the eat-:Li start product belong? in} H'fi'i'i'.'|'-l mi A H3C CH3 I zenasozci, (CH3CH2)3N, CH2C12 Nags, H20, own: Excess 141202 I. A —-—> B —-~—> C —-—> [1:1 3-Ciiiu: 5 o / \ ,/ 0/ \O n f \ CsHmoz (18111138106 Cains “ L_ / S. @In an attempt to make l-chloro-lucyclobutylpentane, the following reaction sequence was employed. The actual product isolated, however, was not the desired molecule but an isomer of it. Suggest a structure for the product and give a mechanistic explanation for its formation. (Hint: See Chapter Integration Problem 9-23.) 13!. ii‘umpmt: tl Slate the at C] MgCl 1. CH3CH1CH1CH2CHO Mg, (CH3CH1);O 2. Ht H20 ——-—> —-—-—> OH C1 DAN Canal-[Cl not DAN fig. Sugars. lJL'i. Ft'i'jsfic Hf a uggest better methods for the final step in Problem 55. “MEL 15”“ ‘ :glgmnic aci 57. In an early study of the stereochemistry of nucleophilic displacements, ny- _ analysed b‘ tically pure (R)-l-deuterio-1—pentanol was treated with 4-methylphenylsulfonyl (tosyl1 ‘ {:1} How w: chloride to make the corresponding tosylate. The tosylate was then treated with excess acidic “mm ammonia to convert it to l-deuterio—l-pentanamine: Gin—Q—sozc: (R)—CH3CH2CH2CH2CHDOH __, w CH3CH2CH2CH2CHJJH ; (R)-l-Deuterio-1-pentanul l-Deuterio-l-pentanamin”_ (21) Describe the stereochenn’stry that you expect to observe at C1 of both the intennr- __ diate tosylate and the final amine. “1 “it Permit-in (b) When the reaction sequence is actually carried out, the expected results are no'l Hi1] ii. the I obtained. Instead, the final‘ amine is isolated as a 70:30 mixture of (S)— and (R)— it "-'~|i'im:- n1”- : 1—deuterio-l-pentanamine. Suggest a mechanistic explanation. (Hint: Recall that “'“M‘Lgnml reaction of an alcohol with a sulfonyl chloride displaces chloride ion, which is a nucleophile.) n 58. What is the product of the reaction shown in the margin? (Pay attention to stereochui'l" _ {IE} (I)— ? istry at the reacting centers.) What is the kinetic order of this reaction? I ll' ' Rm. .,, In. an“ I’CCHZCHZCHZC“ 59. Propose syntheses of the following molecules, choosing reasonable stal’-"'t rm“ ' J I \I‘DH materials on the basis of the principles of synthetic strategy introduced in precedinér hi 3 chapters, particularly in Section 8-9. Suggested positions for carbon—carbon bond fU'i'” CI i. lDMSO tiou are indicated by wavy lines. _ J; U: . I 51' 1 CH3CH2CH~§W CHZCHZSO3H CH3 R - NJ .fi I . (a) (b) CH3CH2CH2+CI+CHO H CH2CH3 | I“'""'£In- ...
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Ch9 problems - Problems 377 [Ydride (strum ___|_ H,._...

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