Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl Soluzioni ai problemi proposti nel libro Capitolo 23 23.1 Le ammine sono classificate come 1o, 2o, o 3o secondo il numero di gruppi alchilici legati all’atomo di azoto. 1o amine 2o amine a. H N 2 1o C6H5 H N N H NH2 b. CH3CH2O 2o amine O amine O NHCH3 O 2o amine c. N CH3 3o amine 23.2 L’atomo di N di un sale di ammonio quaternario è un centro stereogenico quando l’N è circondato da quattro gruppi diversi. Tutti i centri stereogenici sono cerchiati. CH3 OH + CH3 + a. CH3 N CH2CH2 N CH2CH3 CH3 H N HO CH3 OH H c. b. HO H N O N has 3 similar groups. O 23.3 CH3 NH2 NH2 NH2 + 3 more resonance structures 1.40 Å 1.47 Å partial double Because the lone pair on N can be delocalized bond character on the benzene ring, the C–N bond has partial double bond character, making it shorter. Both the C and N atoms must be sp2 hybridized (+ have a p orbital) for delocalization to occur. The higher percent s-character in both C and N shortens the bond as well. The C–N bond is formed from two sp3 hybridized atoms and the lone pair is localized on N. 23.4 NHCH2CH3 a. CH3CH2CH(NH2)CH3 2-butanamine or sec-butylamine b. (CH3CH2CH2CH2)2NH dibutylamine c. N(CH3)2 N,N-dimethylcyclohexanamine e. N-ethyl-3-hexanamine CH3 d. f. NHCH2CH2CH3 NH2 2-methyl-5-nonanamine N-propyl-2-methylcyclopentanamine 23.5 Le ammine aromatiche sono definite come derivati dell’anilina. Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl N-methylaniline a. b. m-ethylaniline NHCH3 3,5-diethylaniline c. NH2 CH3CH2 d. N,N-diethylaniline N(CH2CH3)2 NH2 CH2CH3 CH2CH3 23.6 Un gruppo NH2 se è considerato un sostituente è detto gruppo amminico. a. 2,4-dimethyl-3-hexanamine c. N-isopropyl-p-nitroaniline e. N,N-dimethylethylamine g. 1-propylcyclohexylamine NHCH(CH3)2 NH2 N O2N NH2 b. N-methylpentylamine d. N-methylpiperidine f. 2-aminocyclohexanone h. p-butyl-N-ethylaniline O NHCH2CH3 NH3 NHCH3 N 23.7 a. CH3NHCH2CH2CH2CH3 e. (CH3CH2CH2)3N NH2 1-octanamine (octylamine) c. NH2 4,6-dimethyl-1-heptanamine N H tripropylamine N-methyl-1-butanamine (N-methylbutylamine) b. i. CH2CH3 2-ethylpyrrolidine f. (C6H5)2NH diphenylamine N C(CH3)3 g. j. CH3CH2CH2CH(NH2)CH(CH3)2 2-methyl-3-hexanamine k. NH2 CH2CH3 3-ethyl-2-methylcyclohexanamine N-tert-butyl-N-ethylaniline CH3 d. N h. O NH2 l. N(CH2CH3)2 CH2CH2CH3 N-methyl-N-propylcyclohexanamine 23.8 4-aminocyclohexanone N,N-diethylcycloheptanamine Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl a. cyclobutylamine e. N-methylpyrrole h. 3-methyl-2-hexanamine NH2 NH2 N b. N-isobutylcyclopentylamine CH3 f. N-methylcyclopentylamine N i. 2-sec-butylpiperidine NHCH3 H c. tri-tert-butylamine N H g. cis-2-aminocyclohexanol N[C(CH3)3]3 j. (S)-2-heptanamine NH2 d. N,N-diethylaniline H NH2 OH N(CH2CH3)2 23.9 [* indica un centro stereogenico] a. * N CH3 b. CH2CH3 * *N CH2CH2CH2CH3 CH3CH2CHCH 2CH2CH2 CH3 CH3 1 stereogenic center 2 stereoisomers N H H CH3 CH3 N CH3 CH2CH2CH2 H CH3 N Cl CH2CH2CH2 N Cl CH3 CH2CH3 C CH3CH2 CH2CH2CH2CH3 CH2CH2CH2 H CH3 CH3 CH2CH3 C CH3CH2 CH3 Cl CH3 CH2CH3 C CH3CH2 CH3 H CH3 H CH3 2 stereogenic centers 4 stereoisomers Cl CH2CH2CH2CH3 CH3 CH2CH3 C CH3CH2 CH2CH2CH2CH3 N CH2CH2CH2 N Cl CH2CH2CH2CH3 23.10 Il pKa di molte ammine protonate è 10–11, il pKa dell’acido di partenza deve essere minore di 10 perché l’equilibrio favorisca i prodotti. Le ammine pertanto vengono prontamente protonate da acidi inorganici forti come HCl e H2SO4, ed anche da acidi carbossilici. a. CH3CH2CH2CH2 NH2 + HCl pKa = –7 b. C6H5COOH pKa = 4.2 + (CH3)2NH CH3CH2CH2CH2 NH3 + Cl– pKa ≈ 10 weaker acid products favored (CH3)2NH2 + pKa = 10.7 weaker acid products favored C6H5COO– c. + HO– + H 2O N H N H H pKa ≈ 10 pKa = 15.7 weaker acid reactants favored 23.11 Più debole è l’acido coniugato, maggiore è il suo pKa e più forte è la base. (I valori di pKa sono dell'acido coniugato di una data ammina). Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl a. CH3NH2 (pKa = 10.7) and CH3CH2NH2 (pKa = 10.8) weaker conjugate acid stronger base stronger conjugate acid weaker base b. (CH3CH2)3N (pKa = 11.0) weaker conjugate acid stronger base and (CH3)3N (pKa = 9.8) stronger conjugate acid weaker base 23.12 Le alchilammine 1o, 2o, e 3o sono più basiche di NH3 per l'effetto induttivo elettron donatore dei gruppi R. a. (CH3)2NH and NH3 b. CH3CH2NH2 1° alkylamine stronger base 2° alkylamine CH3 groups are electron donating. stronger base and ClCH2CH2NH2 1° alkylamine Cl is electron withdrawing. weaker base 23.13 Le arilammine sono meno basiche delle alchilammine perché la coppia elettronica sull'N è delocalizzato. Gruppi elettron donatori aumentano la densità elettronica del benzene, rendendo le arilammine più basiche dell'anilina. Gruppi elettron attrattori sottraggono densità elettronica dal benzene, rendendo le arilammine meno basiche dell'anilina. NH2 NH2 NH2 NH2 a. NH2 NH2 b. O2N CH3OOC CH3O electron donating group most basic arylamine intermediate basicity electron withdrawing group least basic electron withdrawing group least basic arylamine intermediate basicity alkylamine most basic 23.14 Le ammidi sono molto meno basiche delle ammine perché la coppia elettronica sull'N è altamente delocalizzata. CONH2 amide least basic NH2 arylamine intermediate basicity NH2 alkylamine most basic 23.15 sp2 hybridized more basic CH3 a. N N CH3 This N is also sp2 hybridized so the electron pair can delocalize onto the aromatic ring. Delocalization makes this N less basic. DMAP 4-(dimethylamino)pyridine 23.16 b. H N sp3 hybridized N CH3 stronger base N sp2 hybridized N higher percent s-character weaker base nicotine Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl This electron pair is delocalized, making it a weaker base. Br 2 H HO H NH2 stronger base sp3 hybridized N 25% s-character CH3O a. b. N N stronger base sp hybridized N 33% s-character N N stronger base sp3 hybridized N 25% s-character sp2 hybridized N 33% s-character This compound is similar to DMAP in Problem 25.27a. N(CH3)2 c. 23.17 a. (CH3CH2)2NH or c. HCON(CH3)2 or (CH3)3N N amide alkylamine weaker base stronger base sp3 hybridized N sp2 hybridized N stronger base weaker base b. C6H5NHCH3 or arylamine weaker base d. (CH3CH2)2NH C6H5CH2NH2 alkylamine stronger base or (ClCH2CH2)2NH 2° alkylamine Cl is electron withdrawing. weaker base 2° alkylamine stronger base 23.18 a. NH2 NH3 NH2 arylamine intermediate least basic basicity b. NH2 c. alkylamine most basic O2 N d. N H (C6H5)2NH N H N Cl electron withdrawing group least basic CH3 intermediate basicity C6H5NH2 diarylamine least basic delocalized sp2 hybridized N sp3 hybridized N electron pair on N intermediate most basic least basic basicity arylamine intermediate basicity 23.19 sp3 hybridized N stronger base sp3 hybridized N stronger base NH2 O a. C NH2 (CH3CH2)2NCH2CH2O delocalized electron pair b. HO CH3 OH N sp2 hybridized N NH2 NH2 electron donating group most basic NH2 alkylamine most basic Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl 23.20 Nc O C a. N NHNH2 Nb < Na < Nc Na Nc N NH2 b. Nb < Na < Nc N Nb Nb H Na Order of basicity: Nb < Na < Nc Nb – The electron pair on this N atom is delocalized on the O atom; least basic. Na – The electron pair on this N atom is not delocalized, but is on an sp2 hybridized atom. Nc – The electron pair on this N atom is on an sp3 hybridized N; most basic. Order of basicity: Nb < Na < Nc Nb – The electron pair on this N atom is delocalized on the aromatic five-membered ring; least basic. Na – The electron pair on this N atom is not delocalized, but is on an sp2 hybridized atom. Nc – The electron pair on this N atom is on an sp3 hybridized N; most basic. 23.21 The para isomer is the weaker base because the electron pair on its NH2 group can be delocalized onto the NO2 group. In the meta isomer, no resonance structure places the electron pair on the NO2 group, and fewer resonance structures can be drawn: O2N NH2 O2N NH2 NH2 O2N NH2 O2N O2N NH2 meta NH2 O2N NH2 O2N NH2 O para N O2N O NH2 O N O 23.22 NH2 NH2 O2N Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl N This two-carbon bridge makes it difficult for the lone pair on N to delocalize on the aromatic ring. N A B pKa of the conjugate acid = 5.2 pKa of the conjugate acid = 7.29 Resonance structures that place a double bond between the N atom and the benzene ring are stronger conjugate acid weaker conjugate acid destabilized. Since the electron pair is more weaker base stronger base localized on N, compound B is more basic. The electron pair of this arylamine is delocalized on the benzene ring, decreasing its basicity. N N B Geometry makes having a double bond here difficult. 23.23 La reazione SN2di un alogenuro alchilico con NH3 o un’ammina forma un ammina. NH3 Cl a. NH2 b. excess CH2CH2NH2 CH3CH2Br CH2CH2N(CH2CH3)3 Br– excess 23.24 O O NH KOH N O A O C6H5CH2Cl N O B COO –OH H2O H2N COO O C 23.25 La sintesi di Gabriel converte un alogenuro alchilico in un’ammina 1o attraverso un processo a due stadi: sostituzione nucleofila seguita da idrolisi. NH2 a. Br CH3O b. (CH3)2CHCH2CH2NH2 NH2 CH3O Br c. (CH3)2CHCH2CH2Br 23.26 I nitrili sono ridotti ad ammine 1o LiAlH4. I gruppi nitro sono ridotti ad ammine 1o per azione di una varietà di agenti riducenti. Le ammidi 1o, 2o, e 3o sono ridotte ad ammine 1o, 2o, e 3o rispettivamente, con LiAlH4. O a. CH3CHCH2NH2 CH3CHCH2NO2 CH3 CH3 CH3CHC N CH3CHCNH2 CH3 CH3 O b. CH2NH2 C N CH2NO2 C NH2 c. NH2 NO2 C N O NH2 23.27 Le ammidi 1o, 2o, e 3o sono ridotte ad ammine 1o, 2o, e 3o rispettivamente, con LiAlH4. Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl CONH2 O CH2NH2 a. NHCH3 c. NHCH3 O b. N N 23.28 General reaction: (CH3)2CHNH2 [H] R C N RCH2NH2 isopropylamine The amine needs 2 H's here. The C bonded to the N must have 2 H's to be formed by reduction of a nitrile. 23.29 L’amminazione riduttiva è un metodo a due stadi che converte aldeidi e chetoni in ammine 1o, 2o, and 3o. L’amminazione riduttiva sostituisce un C=O con un legame C–H ed uno C–N . a. NHCH3 CH3NH2 CHO c. NaBH3CN O b. O (CH3CH2)2NH N(CH2CH3)2 NaBH3CN NH2 NH3 NaBH3CN 23.30 a. C6H5CH2CH2CH2Br b. C6H5CH2CH2Br NH3 excess C6H5CH2CH2CH2NH2 [1] LiAlH4 C6H5CH2CH2CN c. C6H5CH2CH2CH2NO2 Pd/C [1] LiAlH4 [2] H2O NaCN H2 d. C6H5CH2CH2CONH2 [2] H2O C6H5CH2CH2CH2NH2 e. C6H5CH2CH2CHO C6H5CH2CH2CH2NH2 NH3 C H CH CH CH NH NaBH3CN 6 5 2 2 2 2 C6H5CH2CH2CH2NH2 23.31 a. (CH3CH2)2NH NH2 b. N(CH3)2 c. O CH3 C N(CH3)2 NH2 NHCH2CH3 O or d. H N H N O O CH3 N C H O 23.32 In una amminazione riduttiva, un gruppo alchilico sull’N deriva dal composto carbonilico. Il resto della molecola deriva dall’NH3 o dall’ammina. Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl NH2 a. H + NH3 O b. H N H C6H5 NH2 C6H5 or O (CH3CH2CH2)2NH or H H N H C O CH3CH2CH2 CH2CH3 O d. C6H5 O O c. (CH3CH2CH2)2N(CH2)2CH(CH3)2 H2N H N H NH2 H 23.33 NH2 a. C6H5 O b. NaBH3CN (CH3)2NH O C6H5 c. C6H5 b. CH2NH2 NH3 [1] LiAlH4 CH2NH2 [2] H2O CONH2 CH2NH2 [1] LiAlH4 c. [2] H2O CHO d. NH3 NaBH3CN CH2NH2 d. O excess CN C6H5 NH2 N(CH3)2 23.34 Br NH3 NaBH3CN NH NaBH3CN a. CHO CH2NH2 NaBH3CN NH Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl CH3 CH2Br e. CH2NH2 Br2 NH3 hν excess COOH CONH2 [1] SOCl2 f. [2] NH3 NH2 g. [2] H2O CN [1] NaNO2/HCl CH2NH2 [1] LiAlH4 [2] H2O [2] CuCN NO2 HNO3 h. CH2NH2 [1] LiAlH4 NH2 H2 then as in (g). Pd/C H2SO4 23.35 Le ammine attaccano i gruppi carbonilici per formare prodotti di addizione nucleofila o di sostituzione. CH3CH2CH2NH2 O a. O NCH2CH2CH3 O O O b. CH3 C O C CH3 COCl c. CH3CH2CH2NH2 CH3 CH3CH2CH2NH2 C O NHCH2CH2CH3 CH3 CONHCH2CH2CH3 C (CH3CH2)2NH N(CH2CH3)2 O O C O (CH3CH2)2NH CH3 CH3 C N(CH2CH3)2 CON(CH2CH3)2 COCl (CH3CH2)2NH 23.36 N2+ Cl– NH2 NaNO2 a. HCl CH3 b. CH3CH2 N CH3 H NaNO2 c. NaNO2 HCl CH3CH2 HCl N H CH3 N NO NaNO2 N CH3 d. HCl NO – N2 Cl NH2 23.37 + N N Y + N N H H N N H 23.38 Y + N N Y H + Y Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl OH NH2 N N a. b. NH2 c. HO OH N N HO HO N N OH 23.39 Per determinare quali reagenti sono necessari per sintetizzare un particolare azo composto, dividere sempre la molecola in due componenti: uno ha un anello benzenico con lo ione diazonio, e l'altro ha un anello benzenico con un gruppo fortemente elettron donatore. O 2N a. H2N Cl b. HO N N N N CH3 O2N H2N Cl HO N2 CH3 N2 23.40 H N N(CH3)2 f. CH3I (excess), followed by Ag2O and Δ N-ethylaniline H H N a. HCl + CH2=CH2 O Cl– H H N g. CH3CH2COCl N CH3COO– b. CH3COOH O h. The product in (g), then HNO3/H2SO4 O N c. (CH3)2C=O N N O 2N CH3 NO2 i. The product in (g), then [1] LiAlH4; [2] H2O N N d. CH2O/NaBH3CN e. CH3I (excess) CH3 CH3 N I– j. The product in (h), then H2/Pd O O N NH2 H2N 23.41 N Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl CH3 NH2 p-methylaniline AlCl3 f. CH3COCl/AlCl3 a. HCl CH3 NH2 NH3 Cl– O CH3 b. CH3COCl C CH3 NH CH3 O c. (CH3CO)2O C CH3 NH CH3 g. CH3COOH CH3 NH3 CH3COO– h. NaNO2/HCl CH3 N2+Cl– O i. step (b), then CH3COCl/AlCl3 d. excess CH3I e. (CH3)2C=O N(CH3)3 I– CH3 CH3 N C(CH3)2 b. CH3CH2CH2CH2NH2 c. CH3CH2CH2CH2NH2 d. CH3CH2CH2CH2NH2 e. CH3CH2CH2CH2NH2 f. CH3CH2CH2CH2NH2 23.43 ClCOC6H5 j. CH3CHO/NaBH3CN CH3CH2CH2CH2NHCOC6H5 O=C(CH2CH3)2 CH3CH2CH2CH2N=C(CH2CH3)2 [1] CH3I (excess) [2] Ag2O [3] Δ C6H5CH2Br CH3CH2Br CH3I excess C CH3 NH C O CH3 23.42 a. CH3CH2CH2CH2NH2 CH3 CH3CH2CH=CH2 CH3CH2CH2CH2NHCH2C6H5 CH3CH2CH2CH2NHCH2CH3 [CH3CH2CH2CH2N(CH3)3]+I– CH3 NHCH2CH3 Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl a. CH3(CH2)6NH2 CH3 [1] CH3I (excess) [2] Ag2O [3] Δ [2] Ag2O NH2 [3] Δ [2] Ag2O [3] Δ CH3 CH3 CH3 CH3 CH2 major product CH3 major product [1] CH3I (excess) N H [1] CH3I (excess) (E + Z) e. c. NH2 CH3 [1] CH3I (excess) b. d. CH3(CH2)4CH=CH2 β N H CH2=CH2 major product + (CH3)2CHN(CH3)2 [2] Ag2O [3] Δ β [1] CH3I (excess) β [2] Ag2O [3] Δ + N(CH3)2 major product (CH3)2N CH2=CHCH3 + CH3CH2N(CH3)2 + (E + Z) (CH3)2N (E + Z) 23.44 N(CH3)2 A: HN(CH3)2 mild acid O B: NH2CH2CH2CH3 NCH2CH2CH3 mild acid OH D: H2SO4 C: NaBH4/CH3OH E: mCPBA NH2 H: [1] CH3I (excess) G: NH3 [2] Ag2O/Δ NaBH3CN O O Br I: Br2 CH3COOH 23.45 OH O NHCH2CH2CH2CH3 J NH2CH2CH2CH2CH3 F: NH2CH3 NHCH3 Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl a. NH3 CH2CH2Cl f. CH2CH2NH2 C6H5CH2CH2NH2 + (C6H5CO)2O C6H5CH2CH2NHCOC6H5 excess O b. –OH Cl N H2O CO2 g. CO2 h. NO2 Sn Br NH2 [2] H2O CN CONHCH2CH3 NaBH3CN N CH2C6H5 O + N N H [1] LiAlH4 d. e. NH + C6H5CHO i. HCl N N O HCl NH2 O c.Br NaNO2 NH j. CH3CH2CH2 N CH(CH3)2 CH2NH2 [1] LiAlH4 [1] CH3I (excess) [2] Ag2O [3] Δ H CH2NHCH2CH3 CH3CH=CH2 [2] H2O (CH3)2NCH(CH3)2 CH3CH2CH2N(CH3)2 23.46 N2+ Cl– Cl a. H2O HO H Cl d. CuBr Cl b. H3PO2 Br A Cl h. C6H5NH2 N N NH2 N N OH Cl NC Cl F Cl e. CuCN i. C6H5OH Cl Cl c. CuCl Cl f. HBF4 I Cl j. KI I Cl g. NaI 23.47 Under the acidic conditions of the reaction, aniline is first protonated to form an ammonium salt that has a positive charge on the atom bonded to the benzene ring. The –NH3+ is now an electron withdrawing meta director, so significant amounts of meta substitution occurs. NH2 H OSO3H NH3 + HSO4– This group is now a meta director. 23.48 Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl N N aryl diazonium salt N N N N N N N N R N N alkyl diazonium salt The N2+ group on an aromatic ring is stabilized by resonance, whereas the alkyl diazonium salt is not. 23.49 Br a. Br H H Na+ N Br OH H N Br N H CH2CH3 Br Br + CH3CH2NH2 + H2O Na+ OH N + H2O + NaBr CH2CH3 H O O H N b. NH2 O H N proton transfer H OH2 proton source N H3B–H H H N + H2O H N + BH3 Fondamenti di chimica organica Janice Gorzynski Smith Copyright © 2009 – The McGraw-Hill Companies srl 23.50 NaNO2 HCl/H2O NH2 NH2 Cl H + HCl + N O N N O N N O H H N N O H H + H Cl + H Cl + OH + N N O OH + – N N OH2 + Cl N N O H H Cl + O H OH Cl– + HCl H + H + 1,2-H shift B A O H H H OH Cl– B H Cl– + HCl N N + + +N N A H OH OH + HCl + H2O