Amines: Properties, Nomenclature, Spectroscopy, Uses, and Reactions - Prof. Thomas Albrigh, Study notes of Organic Chemistry

Download Amines: Properties, Nomenclature, Spectroscopy, Uses, and Reactions - Prof. Thomas Albrigh and more Study notes Organic Chemistry in PDF only on Docsity! Chapter 19 -THE END 1 NOTE: We are skipping sections 7,8,11B-C,14,16,17 YEAH!!! A. Properties 1. basicity A strongly basic amine is a good ... an ammonium ion that is a relatively competitor for H* and produces ... weak Bronsted acid (high pK,) \ \ R—NH, + HX —=™ RONH, + XP A weakly basic amine is aless effective competitor for H* and produces an ammonium ion that is a relatively strong Bransted acid (low pK,). a. inductive effects NH, < *NRH; < ~NRsH. <*NR3H Order of increasing gas-phase pK, Lowest pK, Highest pK, Chapter 19 -THE END Chapter 19 -THE END 5 2. structures sp3 hybridization at N: pyramidal i H AG* ~ 5 kcal/mol H; oy ep aoe g’< enc pod Nie, One enantiomer The other enantiomer HC O H3C CHs ©) H, Oa ao / = \ / HC O CH, H,C H;C 6 CH, The barrier to this inversion is unusually high, AG* = 18.5 kcal/mol “\enP _. a, a WHY _ _ ~~ H,C Ph H,C When the methyl on nitrogen is replaced by phenyl, AG* decreases to 11.2 kcal/mol Chapter 19 -THE END Chapter 19 -THE END 7 B. Nomenclature 1. common - name the alkyl portions and follow this by the suffix “amine”, i.e. 2. IUPAC - drop”e” in alkane name; add “amine” N 7 > O | | H H I Aziridine Azetidine Pyrrolidine Piperidine (azacyclopropane) (azacyclobutane) (azacyclopentane) (azacyclohexane) ei :Br: Tos 6b CH, O = . C J oe ( 3 1 " y H H CHsPh Morpholine 3-Methylpiperidine 3-Bromopyrrolidine 4-Benzylmorpholine (not 5-methylpipericine) (not 4-bromopyrrolidine) (N-benzylmorpholine) Chapter 19 -THE END 10 Chapter 19 -THE END 11 C. Spectroscopy 1. IR - 1° amines - 2 peaks 2° amines - 1 peak 2. 1H NMR - broad peak for NH d~1-4 ppm - exchanges with D2O D. Uses ~3200 - 3500 cm-1 Haber-Bosch process: makes 30 billion tons per year •••fertilizer N2 + H2 700°C 1000 atm. NH3 NH2 CH2CH2CH2CH2 NH2 NH2 CH2CH2CH2CH2CH2 NH2 putresciene cadaverine oder from decaying flesh -produced by bacteria You guessed it!! Chapter 19 -THE END 12 Alkaloid -any nitrogen containing compound extracted from plants. morphine opium alkaloids Chapter 19 -THE END 15 CH2 N Et Et CH2PhC O NHPh + PhCO2 - Bitrex - most bitter substance known •completely nontoxic • thumb sucking & fingernail biting Chapter 19 -THE END 16 D. Reactions of amines 1. formation of imines - see Chapter 18.16 •• know reaction mechanism!! (acid and base cat.) Note: 2. nucleophillic substitution fy $2 + _ (CHg)3N+ Cnrg), — (CH;);N—CH; | Tetramethylammonium iodide But... Sy2 + a NH, es + = H3N: CHys—1| —* H,N—CH; | —— H,NCH, + NH, I Primary amine 3 Sy2 rs - CHaNH, - + _ CH,NH, CHy—| ——= CH;NH;—-CH, | = HN(CH;), + CH;NH, | Secondary amine i Sy2 i _ (CH) .NH + _ (CH;),;NH CHy—!| —— (CH,);NH—CH, | {2 tN(CHz)3 +) (CHg)2NH. | Tertiary amine But HN: (CH;);¢—| O~ H3N—C(CH,), r Sy2 No S,2 for tertiary substrates! Chapter 19 -THE END 17 5. the Sandmeyer reactions or + *NHs 2Cli No NaONO/HCl eee Aniline Benzene- diazonium chloride N CN N; Br Np Cl CuCN CuBr CuCl > ee Set 00°C, 5h water/ CH;CN, acetone 65 °C -25 °C CH, CH, NOs NO, Cc. Cc. Hc “So Hj,c~ So (67%) (90%) (98%) Chapter 19 -THE END 20 Ne OH N, H;PO, cut —a———_—$__ Cu0/H,0 25 °C, 1 min CH; CH; Np CH; CH; (80%) (93%) | KI, 25-100 °C O Snel HBF 4, 0 °C (75%) > Schiemann reaction (69%) Chapter 19 -THE END 21 Chapter 19 -THE END 22 E. Preparation of amines 1. reduction of -NO2 and -CN compounds Chapter 19 -THE END 25 3. acylation - reduction R C O Cl NH3 pyr or NaOH R C O NH2 1) LiAlH4 2) H2O R CH2 NH2 R C O Cl NR'H2 pyr or NaOH R C O NHR' 1) LiAlH4 2) H2O R CH2 NHR' R C O Cl NR'2 pyr or NaOH R C O NR'2 1) LiAlH4 2) H2O R CH2 NR'2 Also: Chapter 19 -THE END 26 4. Gabriel synthesis - prevents over-alkylation Chapter 19 -THE END 27 6. reduction of azides 7. Hofmann rearrangement Chapter 19 -THE END 30 What happens using an amine, RNH2??? Chapter 19 -THE END 31 F. Summary 1. Basicity of amines a. inductive effects b. resonance/ aromaticity c. hybridization 2. Pyramidalization of amines 3. Nomenclature 4. Spectroscopy 5. Aromatic substitution a. using amides (acetamides) b. Sandmeyer reactions 6. Reduction reactions a. NO2 and CN compounds b. reductive animation c. acylation - reduction 7. Gabriel synthesis Chapter 19 -THE END 32 8. Reduction of azides 9. Hofmann rearrangement - mech. 10. Curtius rearrangement - mech.