hoaÙ hoÏc hÖÕu cÔ organic chemistry chÖÔng 13 amines & hỢp chẤt diazoni

HOA HOC HU COrganic ChemistryCHNG 13AMINES & HP CHT DIAZONI

GII THIEU

Classification of AminesAlkylamineN attached to alkyl groupArylamineN attached to aryl groupPrimary, secondary, or tertiarydetermined by number of carbon atoms directly attached to nitrogen

AminesR-NH2Name the R group or groups with -yl endingsAdd the word amine

AminesMethyl amineDimethyl amine

Naming AminesMethylamine

Ethylamine

PropylamineAniline or aminobenzeneEthylmethylamine

Methylpropylamine

Dipropylamine

Nomenclature of Primary Alkylamines (RNH2)Two IUPAC styles1)analogous to alcohols: replace -e ending by -anamine2)name alkyl group and attach -amine as a suffix

Examples: some primary alkylamines(RNH2: one carbon directly attached to N)CH3CH2NH2ethylamine or ethanaminecyclohexylamine or cyclohexanamine1-methylbutylamine or 2-pentanamine

Nomenclature of Primary Arylamines (ArNH2)Name as derivatives of aniline.

Examples: some primary arylamines(ArNH2: one carbon directly attached to N)p-fluoroaniline5-bromo-2-ethylaniline

Amino groups as substituentsamino groups rank below OH groups and higher oxidation states of carbonin such cases name the amino group as a substituentp-aminobenzaldehydeHOCH2CH2NH22-aminoethanol

Secondary and Tertiary AminesName as N-substituted derivatives of parent primary amine.(N is a locant-it is not alphabetized, but is treated the same way as a numerical locant)Parent amine is one with longest carbon chain.

ExamplesCH3NHCH2CH3N-methylethylamine4-chloro-N-ethyl-3-nitroanilineN,N-dimethylcycloheptylamine

Ammonium SaltsA nitrogen with four substituents is positively charged and is named as a derivative of ammonium ion (NH4+).CH3NH3+methylammonium chlorideN-ethyl-N-methylcyclopentylammonium trifluoroacetate

Ammonium SaltsWhen all four atoms attached to N are carbon, the ion is called a quaternary ammonium ion and salts that contain it are called quaternary ammonium salts.benzyltrimethylammonium iodide

CAU TAO VA LIEN KET

Alkylamines147 pm106112

AlkylaminesMost prominent feature is high electrostatic potential at nitrogen. Reactivity of nitrogen lone pair dominates properties of amines.

Geometry at NPyramidal geometry at sp3-hybridized N in methylamine.Planar geometry at sp2-hybridized N in formamide.Compare geometry at N of methylamine, aniline, and formamide.sp3sp2CONH2HCNH2HHH

Geometry at NPyramidal geometry at sp3-hybridized N in methylamine.Planar geometry at sp2-hybridized N in formamide.Compare geometry at N of methylamine, aniline, and formamide.sp3sp2

Geometry at NNote: this is not the same as the HNH bond angleAngle that the CN bond makes with bisector of HNH angle is a measure of geometry at N.sp3sp2~125180

Geometry at NAngle that the CN bond makes with bisector of HNH angle is a measure of geometry at N.sp3sp2~125180142.5

Geometry at NGeometry at N in aniline is pyramidal; closer to methylamine than to formamide.142.5

Geometry at NHybridization of N in aniline lies between sp3 and sp2.Lone pair of N can be delocalized into ring best if N is sp2 and lone pair is in a p orbital.Lone pair bound most strongly by N if pair is in an sp3 orbital of N, rather than p.Actual hybridization is a compromise that maximizes binding of lone pair.142.5

Electrostatic Potential Maps of AnilineNonplanar geometry at N. Region of highest negative potential is at N.Planar geometry at N. High negative potential shared by N and ring.Figure 22.3 (page 862)

AminesIR spectrum of 1-butanamine (Fig 12.11)

Reduction to AminesLithium aluminum hydride reduces amides and nitriles to amines.Nitriles and 1 amides reduce to 1 amines.A 2 amide reduces to a 2 amine.A 3 amide reduces to a 3 amine.

LY TNH

Amines: Physical propertiesMost amines up to 5 or 6 carbons are water soluble due to hydrogen bonding with the water molecule.

Amines: Physical properties-2Amines have boiling points between alkanes and alcohols. They hydrogen bond but not as strongly as alcohols. Tertiary amines cannot hydrogen bond to each other and boil lower then 1o or 2o of similar molecular weight. C4H8 (58), bp 0 oC C3H7NH2 (59), bp 48 oC C3H7OH (60), bp 97 oC

Physical PropertiesAmines are more polar and have higher boiling points than alkanes; but are less polar and have lower boiling points than alcohols.CH3CH2CH3CH3CH2NH2CH3CH2OHdipole moment (m):boiling point:0 D1.2 D1.7 D-42C17C78C

Physical PropertiesBoiling points of isomeric amines decrease in going from primary to secondary to tertiary amines.Primary amines have two hydrogens on N capable of being involved in intermolecular hydrogen bonding. Secondary amines have one. Tertiary amines cannot be involved in intermolecular hydrogen bonds.CH3CH2NHCH3CH3CH2CH2NH2(CH3)3Nboiling point:50C34C3C

TNH BASE

Reactions of Amines: BasicityAmines are weak bases. They accept protons from water making solutions basic.

Reactions of Amines: Basicity

Reactions of Amines: NeutralizationAmines form salts by accepting a proton from strong mineral acids.Converting amines to salts often makes insoluble amines soluble!!!!!Name amine salts by replacing the suffix amine with ammonium and the name of the anion.E. g. propylammonium chloride

Reactions of Amine Salts: NeutralizationAmine salts revert to the amine (donate a proton) in strong base.

Amine Reactions: Quats3o amines react with alkyl chlorides to give quaternary ammonium salts which are very important in biochemistry.

Quats cont.Benzalkonium chloride (ZephiranTM) and choline are important examples.

Heterocyclic AminesHeterocyclic amines have at least one nitrogen in the ring. MANY are physiologically active and many are critical in biochemistry.

Examples of Heterocyclic Amines

Examples of Heterocyclic Amines-2

AmidesMost amides are solids at room temperature due to internal hydrogen bonding.They are not bases. A resonance structure shows why the N lone pair is unavailable to accept a proton.

Amide NamesNames are derived from the acid.Remove ic acid (common) or oic acid (IUPAC) and replace with amide.Nitrogen substituents are prefixed to the name and indicated by N.ethanamideoracetamideN-methylpropanamide

Preparation of Amides1o and 2o amines react with acid chlorides to give amides. The acid chloride transfers its acyl group to the N of the amine.

Preparation of Amides-21o and 2o amines react with acid anhydrides to give amides. E. g. with acetic anhydride.

Amino Acids and ProteinsAn alpha amino acid is a carboxylic acid with an amino group on the carbon alpha to the carboxylic acid .The alpha carbon also has an R group side chain except for glycine which has two Hs.

PeptidesA peptide is a polymer of about 2-100 amino acids linked by the peptide(amide) bond. As the amino group and the carboxyl group link, water is lost.

Hydrolysis of Amidesa) Amides hydrolyze with acid to give the carboxylic acid and the amine salt.b) Amides hydrolyze with base to give the carboxylic acid salt and the amine.

16.4 Amino Acids and Protein Synthesisa-amino acids are attached to transfer RNA molecules (t-RNA). The acyl group ( and the amino acid) are transferred to the nitrogen of another amino acid to form a peptide (amide) bond.

16.5 NeurotransmittersNeurotransmitters carry signals from a nerve cell to a target They can be excitatory or inhibitory. All contain nitrogen.catecholaminesA deficiency in dopamine results in Parkinsons disease. Too much is associated with schizophrenia. It is also associated with the high of drugs.

Neurotransmitters-cont.Catecholamines-cont.Epinephrine (adrenaline) and norepinephrine are involved in the fight or flight response.SerotoninA deficiency is associated with depression, bulemia and anorexia nervosa. It also affects pain perception, thermoregulation, and sleep.

Neurotransmitters-cont.Histamine is released during an allergic response.Benadryl is a typical antihistamine used for colds and other allergic responses.Acetylcholine functions at the neuromuscular junction to cause muscles to contract.

HOA TNH

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hoaÙ hoÏc hÖÕu cÔ organic chemistry chÖÔng 13 amines & hỢp chẤt diazoni

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