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Chem 1152: Ch. 16

Chem 1152: Ch. 16. Amines. Nitrogen. Mostly inert gas (N 2 ) under standard conditions ~78% of atmosphere Found in: Ammonia (NH 3 ) Nitrates (fertilizers) Nitric acid (HNO 3 ) Propellants (N 2 O, nitrous oxide) Explosives (nitroglycerine) Cyanides (CN - )

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Chem 1152: Ch. 16

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  1. Chem 1152: Ch. 16 Amines

  2. Nitrogen • Mostly inert gas (N2) under standard conditions • ~78% of atmosphere • Found in: • Ammonia (NH3) • Nitrates (fertilizers) • Nitric acid (HNO3) • Propellants (N2O, nitrous oxide) • Explosives (nitroglycerine) • Cyanides (CN-) • 4th most abundant element in human body • Critical to building blocks of life/CNS function • Proteins • DNA • RNA • Neurotransmitters nitroglycerine Amino acid

  3. Amines • Organic derivatives of ammonia • One or more H atoms replaced by aromatic or alkyl group Secondary (2°) Primary (1°) Tertiary (3°) : : : : ammonia R-OH alcohols Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  4. Naming Amines – Common Names • Common names • For low MW amines • Alphabetically link names of alkyl or aromatic groups bonded to nitrogen, attach suffix –amine. methylamine ethylmethylamine trimethylamine methylphenylamine propylamine

  5. Naming Amines – IUPAC Names • Replace –e in alkane with –amine. • Number position of amino group lowest on parent chain. • If substituent on nitrogen, prefixed with N.

  6. Naming Amines – IUPAC Names • Replace –e in alkane with –amine. • Number position of amino group lowest on parent chain. • If substituent on nitrogen, prefixed with N. 3-Pentanamine 3-Methyl-1-butanamine 2-Hexanamine N,N-Dimethyl-2-hexanamine N-Methyl-2-butanamine N-Methyl-2-hexanamine 2,5-hexanediamine cyclohexylamine N-Ethyl-N-methyl-2-hexanamine

  7. Naming Amines – Aromatics • Usually named as substituted anilines • For groups on N of aniline, identify with N to indicate not attached to ring aniline N-Ethylaniline 2-Methylaniline 3-Ethylaniline N,N-dimethylaniline diphenylamine N-Ethyl-N-methylaniline N-Ethyl-2-methylaniline 3-phenyl-2-heptanamine 2-Ethyl-N-methylaniline

  8. Physical Properties of Amines • 1° and 2° amines form H-bonds among themselves • Bonds weaker for amines than alcohols (EN of oxygen > nitrogen) • BP’s of 1° and 2° amines lower than alcohols of comparable MW alcohol amine • Amines with fewer than 6 C’s (1°, 2° and 3°) soluble in water due to H-bonding • Amines stink! • Low MW amines smell like ammonia • Higher MW amines smell like rotten fish putrescine cadaverine

  9. Chemical Properties of Amines • Basicity: Amines are weak bases From Brønsted-Lowry Base accepts proton and becomes a conjugate acid

  10. Chemical Reactions of Amines • Amines reversibly react with water, form hydroxide ions • Amines form salts when they react with acids

  11. Amine Salts Naming: Change amine to ammonium and add name of negative ion derived from acid Ethyldimethylamine (common) N,N-dimethylethanamine (IUPAC) ethyldimethylammonium ethyldimethylammonium bromide • Amine salts are white crystalline solids with high MP’s. • Amine drugs usually given in form of salts to improve their ability to dissolve in body fluids Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  12. Amine Salts Amine salts are pH dependent, like CA’s. amine (high pH) amine salt (low pH) • Amine salts may have 4 alkyl/benzene groups  quaternary ammonium salts • Acetylcholine is important QA salt involved in transmission of nerve impulses • Some QA salts have antiseptic qualities that kill bacteria and fungii. • e.g. benzalkonium (Zephiran) chloride used by physicians to scrub before surgery and to sterilize instruments Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  13. Amides Amides are combination of CA and ammonia or amine joined by amide linkage. Amide Ester Carboxylic Acid Carboxylic Acid Ammonia or amine Alcohol Amide linkage Ester linkage Not formed by reaction between CA and amine (produces salt)

  14. Amines Form Amides • Amides are formed through reaction of primary and secondary amines with acid chlorides and acid anhydrides. • Similar to esterification reactions. Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  15. Amide Reactions No Rxn

  16. Synthesis of Nylon Carpeting Clothing Medical tubing Sutures Parachutes Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  17. Aspirin Substitutes Acetylsalicylic acid • Aspirin • Pain reliever • Fever reducer • Anti-inflammatory • Acetaminophen • Pain reliever • Fever reducer • Does not irritate intestinal tract • Harmful side effects • Allergic reactions • Gastrointestinal bleeding • Can induce Reye’s syndrome in children • Negatives • Not an anti-inflammatory • Overuse can lead to liver and kidney damage Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  18. Amines as Neurotransmitters • Neurotransmitters: Molecules that carry chemical messages between neurons in nervous system • released into synapse (gap between synaptic terminal of one neuron and Dendrite of another) in response to electrical signal • Diffuse across synapse and bind to receptors on dendrites of next neuron neuron Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  19. Amines as Neurotransmitters • In CNS (brain and spinal cord), the most important neurotransmitters are amines: • Acetylcholine • Norepinephrine • Dopamine • Serotonin • In addition to being chemical messengers, some neurotransmitters may also be partly responsible for moods, mental illness Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  20. Amines and Mental Illness • Neurotransmitters dopamine and norepinephrin both derived from tyrosine • Tyrosine essential AA obtained from diet (egg whites, turkey, soy) • Norepinephrine and epinephrine (adrenaline) act as drugs related to fight or flight response • directly increasing heart rate • triggers the release of glucose from energy stores • increases blood flow to skeletal muscle • increases the brain's oxygen supply • Excess norepinephrine (NE) results in feelings of elation • Low NE levels may cause depression Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  21. Amines and Mental Illness • Derived from the AA tryptophan, another essential AA obtained from diet • Influences sleeping, regulation of body temp., sensory perception • May be related to mental illness Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  22. Amphetamines • Amphetamines structurally and chemically similar to adrenaline • Raise glucose level in blood • Increase pulse rate • Increase blood pressure • May be legally prescribed to elevate mood or reduce fatigue • Street names: • Bennies, pep pills, Reds, red devils, speed, dexies, uppers Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  23. Alkaloids • Weakly basic amines derived from plants Stimulate CNS/Resp. systems Treatment of malaria Opiates CNS Depressants, used as painkillers Morphine derivative Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  24. Naming Amides • Simple amides named after corresponding carboxylic acids by changing –ic or –oic of acid to –amide. • Common names are used more often than IUPAC names. formic acid Common name formamide methanoic acid methanamide IUPAC name acetic acid Common name acetamide ethanoic acid ethanamide IUPAC name benzoic acid Common name benzamide benzoic acid benzamide IUPAC name

  25. Naming Amides • Simple amides named after corresponding carboxylic acids by changing –ic or –oic of acid to –amide. • Common names are used more often than IUPAC names. • Use italicized capital N to identify alkyl groups bonded to nitrogen. Common N,N-dimethylacetamide N-ethyl-N-methylbenzamide N-methylformamide N,N-dimethylethanamide N-methylmethanamide IUPAC N-ethyl-N-methylbenzamide

  26. Naming Amides • Simple amides named after corresponding carboxylic acids by changing –ic or –oic of acid to –amide. • Common names are used more often than IUPAC names. • Use italicized capital N to identify alkyl groups bonded to nitrogen. N,N-diethylethanamide N-isobutylbutanamide 2,N-dimethylbenzamide N-ethyl-N-phenylbenzamide

  27. Physical Properties of Amides • Unsubstituted amides can form complex networks of intermolecular H-bonds • Increases MP’s of these substances • Increasing the number of substituents on amide reduces H-bonding • Reduces MP’s and BP’s • Amides do form H-bonds with water • Increases solubility Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  28. Amide Hydrolysis • Most important rxn is hydrolysis • May involve either acid or base • One of the products will always be a salt Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  29. Amide Hydrolysis Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011

  30. Amide Hydrolysis acetamide Acetic acid Ammonium chloride Acetic acid N-methylacetamide methylammonium chloride N-methylacetamide methylamine Sodium acetate

  31. Amide Hydrolysis Ethylammonium chloride N-ethylbenzamide Benzoic acid Ethylamine N-ethylbenzamide Sodium benzoate

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