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Ch 16 Amines Organic and Biochemsity Section 16.1 Introduction • Amines – Nitrogen found in amine group is the fourth most common element in organic chemistry – Known for their basicity Section 16.2 Classification and Structure • Primary 1⁰ R NH2 • Secondary R 2⁰ R • Tertiary NH R 3⁰ R N R • Aliphatic Amines – All carbon groups bonded to the nitrogen are ALKYL groups • Aromatic Amines – One or more groups bonded to the nitrogen are ARYL groups • Heterocyclic Amines – Nitrogen is a part of the RING Identify these examples: NH2 CH3 CH3 NH N CH3 1⁰ Aromatic Amine Aniline 2⁰ Aromatic Amine 3⁰ Aliphatic Amine Amphetamines • 3 examples Amphetamine Methamphetamine Phentermine • Common physiological effect: – Reduce fatigue and diminish hunger by raising glucose levels • Prescribed to: – Counter mild depression – Reduce hyperactivity in children – Suppress appetites NH2 Amphetamine CH3 CH3 NH Methamphetamine CH3 NH2 CH3 H3C Phentermine found in “Fen-Phen” • Illegally used to: – Reduce Fatigue – Elevate moods – mood enhancement • ADDICITIVE: Concentrated in Brain and CNS leads to sleeplessness, weight loss, & paranoia • Why? How does it work? – Action similar to Epinepherine – Excreted by adrenal gland – Makes glucose more available – Immediate glucose action – Commonly called “Adrenalin” HO HO OH NH CH3 Heterocyclic Amines • Heterocyclic Aliphatic Amines pyrrolidine piperidine N H N H • Heterocyclic Aromatic Amines pyrrol pyridine N H N 1. How many hydrogens does piperidine have? – 11 C5H11N 2. How many hydrogens does pyridine have? – 5 C5H5N 3. Write the molecular formula of each. 4. How many hydrogens does pyrrolidene have? – 9 C4H9N 5. How many hydrogens does pyrole have? – 5 C4H5N 6. Write the molecular formula of each. Alkaloids • Naturally occurring amine compounds – Found in roots, bark or fruits – Nitrogen found in ring – “Alkaloid” because compounds are BASIC • Coniine – Water Hemlock – Causes weakness, labored respiration, paralysis and death • Nicotine – Tobacco plant – Addictive in small doses – Large doses cause depression, nausea, vomiting • Cocaine – Leaves of Coca plant – CNS stimulant H H N N H CH3 N (s) Coniine CH3 (s) Nicotine H H H H H H O H H H H O O N H H H O H H H H H H H H Cocaine Section 16.3 Nomenclature • Same naming system as ALCOHOLS • Drop the “ending” or “e” of the parent chain and add “amine” H3C NH2 H3C NH2 NH2 CH3 H2N 1,6-hexandiamine 2-propanamine 1-phenyl-1-ethanamine Write the name or formula 1. CH3(CH2)5NH2 1-hexanamine H3C 2. 1-phenyl-2-propanamine NH2 3. Cyclohexanamine NH2 4. 1,4-butandiamine NH2 H2N • IUPAC nomenclature retains the common name: NH2 NH2 Aniline H3C CH3 • __Toluidine___ is methyl substituted aniline – 2-methyl aniline = o-toluidine • Largest group bonded to nitrogen is the parent amine when nitrogen has 2 or more carbon groups bonded to it (IUPAC) • Groups attached to Nitrogen are numbered as “N” NH2 CH3 • N-methylaniline HN H3C • N,N-dimethyl cyclopentanamine N CH3 • N-ethyl-2-propanamine H3C CH3 HN • N-ethyl-N-methyl ethanamine CH3 CH3 N H3C CH3 Common Names • Common names for aliphatic amines list the groups bonded to the nitrogen in alphabetical CH order. H 3C 3 H3C H3C NH2 Methylamine C CH2 NH2 N H 2C CH3 tert-butylamine • Draw the structure of Cyclohexylmethylamine Isopropylamine Triethylamine CH3 CH3 diethylmethylamine Amine Salts • When 4 atoms or groups are bonded to the nitrogen • Named as a salt with an “anion” (chloride) • Ending “amine” is replaced with -ammonium_ • Ending “aniline” is replaced with -anilinium • Ending “pyridine” is replaced with -pyridinium • Ammonium chloride H H Cl + N - H H • Tetramethyl ammonium chloride H C 3 CH3 + N CH3 • Pyridinum chloride • Anilinium chloride + H + Cl N H H Cl N H - - Cl CH3 - Section 16.4 Physical Properties • Amines are ___POLAR__ molecules • Primary and Secondary amines will form ____H-Bonds___ between themselves • Tertiary amines will NOT form __H-Bonds____ between themselves • ALL amines will form _____H-Bonds___ with WATER! • The N-H h-bond is WEAKER than the O-H hbond. • Methanamine vs. Methanol CH3NH2 CH3OH Molar Mass 31.1 32.0 Boiling Point -6.3⁰C 65.0⁰C • Why? •Stronger H-Bonding between Methanol Molecules Section 16.5 Basicity • Amines are _Slightly Strong to Weak Bases__ • Example: H H3C N H + H O H + H3C N H H H • Base dissociation constants [CH 3 NH 3 ][OH ] 4 Kb 4.37 x10 [CH 3 NH 2 ] + - HO • 2 ways to measure “base” strength – pKb -Log of Kb • Smaller values = Stronger Bases <3 = Very Strong base >6 = Weak Base – pH • Larger values = Stronger Bases 13-14 = Very Strong base 8-10 = Weak Base Amine pKB Base Nature Aliphatic 3.0-4.0 Slightly Strong Ammonia 4.74 Aromatic 8.5-9.5 Weak For each Set, choose which is the more “basic” NH2 NH2 CH3 N N H NH2 H3C NH3 • Basicity and Blood – Most Aliphatic amines are fairly strong bases – How will they be found in the blood stream? • In their “Ionic” or “Ammonium” Form • Example: Dopamine HO HO NH2 HO HO H+ NH H HO Section 16.6 REACTIONS • Amines react with strong acids to form watersoluble salts HO HO H NH2 + HO HO H H H + N H H Cl + HO (R) Norepinephrine Only Slightly water soluble (R) Norepinephrine hydrochloride Very water soluble Cl - Solubility of amine type DRUGS • Many drugs have “∙HCl” in their chemical formula • WHY? – High molecular weight amines are insoluble in blood – Treated with an acid – they form a water/blood soluble salt – Amines are also susceptible to oxidation from atmospheric O2. – Amine salts are less likely to be oxidized and retain a longer shelf life – LOOK AT LABELS! • Examples – Phenylephrine∙HCl H H HO N HO CH3 HCl • Is it (R) or (S)? – (Neo-Synephrine) – Procaine∙HCl – (Novocain) CH3 O N O CH3 HCl H2N O CH3 – Methadone ∙HCl – (Methadone) N CH3 HO – Albuterol ∙HCl – (Proventil) CH3 HCl CH3 H N CH3 HO CH3 HCl CH3 HO Chapter 17: Aldehydes & Ketones Naming Introduction Aldehydes • Terminal –CHO group • Suffix: “al” • Naming similar to alcohols O H3C CH3 C C H3C Ketones • Internal –C=O group • Suffix: “one” • Naming similar to alcohols H O Name the Following CH3 O O H3C CH3 CH3 CH3 H3C H H3C CH3 O CH3 Cl O Draw the Following • 1,6-dichloro-3-hexanone • 5-methylheptanal • 1,6-hexandial • 3-bromo-2-butanone Sections 17.1-17.3 • Order of Precedence of Main Functional Groups Class Group Suffix if highest Prefix if Lower Carboxylic acid Highest -COOH -oic acid Never Lower! Aldehyde -CHO -al oxo Ketone -C=O -one oxo Alcohol -OH -ol hydroxy Amine -NH2 -amine amino • Examples: Draw the following – 2-aminohexanal – 1-amino-2-hydroxyl-3-pentanone – 5-hydroxyl-2-hexenal – 3-methyl-2-oxobutanal – 4-amino-3-penten-2-one • Name the following H3C O O CH2 H3C CH3 OH O OH O CH3 O OH NH2