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Dr. Wolf's CHM 201 & 20221-*Chapter 21Amines
Dr. Wolf's CHM 201 & 20221-*
Amine Nomenclature
Dr. Wolf's CHM 201 & 20221-*AlkylamineN attached to alkyl groupArylamineN attached to aryl groupPrimary, secondary, or tertiarydetermined by number of carbon atoms directly attached to nitrogenClassification of Amines
Dr. Wolf's CHM 201 & 20221-*Two IUPAC styles1)analogous to alcohols: replace -e ending by -amine2)name alkyl group and attach -amine as a suffixNomenclature of Primary Alkylamines (RNH2)
Dr. Wolf's CHM 201 & 20221-*Examples: some primary alkylamines(RNH2: one carbon directly attached to N)CH3CH2NH2ethylamine or ethanaminecyclohexylamine or cyclohexanamine1-methylbutylamine or 2-pentanamine
Dr. Wolf's CHM 201 & 20221-*Name as derivatives of aniline.Nomenclature of Primary Arylamines (ArNH2)p-fluoroaniline5-bromo-2-ethylaniline
Dr. Wolf's CHM 201 & 20221-*Amino groups as substituentsp-aminobenzaldehydeamino groups rank below OH groups and higher oxidation states of carbonin such cases name the amino group as a substituentHOCH2CH2NH22-aminoethanol
Dr. Wolf's CHM 201 & 20221-*Name 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.Secondary and Tertiary Amines
Dr. Wolf's CHM 201 & 20221-*ExamplesCH3NHCH2CH3N-methylethylamine4-chloro-N-ethyl-3-nitroanilineN,N-dimethylcycloheptylamine
Dr. Wolf's CHM 201 & 20221-*A nitrogen with four substituents is positively charged and is named as a derivative of ammonium ion (NH4+).Ammonium SaltsCH3NH3+methylammonium chlorideN-ethyl-N-methylcyclopentylammonium trifluoroacetate
Dr. Wolf's CHM 201 & 20221-*When 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.Ammonium Saltsbenzyltrimethylammonium iodide
Dr. Wolf's CHM 201 & 20221-*
Structure and Bonding
Dr. Wolf's CHM 201 & 20221-*147 pm106112Alkylamines
Dr. Wolf's CHM 201 & 20221-*Most prominent feature is high electrostatic potential at nitrogen. Reactivity of nitrogen lone pair dominates properties of amines. Alkylamines
Dr. Wolf's CHM 201 & 20221-*Compare geometry at N of methylamine, aniline, and formamide.sp3sp2Geometry at NPyramidal geometry at sp3-hybridized N in methylamine.Planar geometry at sp2-hybridized N in formamide.CONH2HCNH2HHH
Dr. Wolf's CHM 201 & 20221-*Compare geometry at N of methylamine, aniline, and formamide.sp3sp2Geometry at NPyramidal geometry at sp3-hybridized N in methylamine.Planar geometry at sp2-hybridized N in formamide.
Dr. Wolf's CHM 201 & 20221-*Angle that the CN bond makes with bisector of HNH angle is a measure of geometry at N.sp3sp2Geometry at N~125180Note: this is not the same as the HNH bond angle
Dr. Wolf's CHM 201 & 20221-*Angle that the CN bond makes with bisector of HNH angle is a measure of geometry at N.sp3sp2Geometry at N~125180142.5
Dr. Wolf's CHM 201 & 20221-*Geometry at N in aniline is pyramidal; closer to methylamine than to formamide.Geometry at N142.5
Dr. Wolf's CHM 201 & 20221-*Geometry at N142.5Hybridization 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.
Dr. Wolf's CHM 201 & 20221-*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.
Dr. Wolf's CHM 201 & 20221-*
Physical Properties
Dr. Wolf's CHM 201 & 20221-*Amines are more polar and have higher boiling points than alkanes; but are less polar and have lower boiling points than alcohols.Physical PropertiesCH3CH2CH3CH3CH2NH2CH3CH2OHdipole moment ():boiling point:0 D1.2 D1.7 D-42C17C78C
Dr. Wolf's CHM 201 & 20221-*Boiling 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.Physical PropertiesCH3CH2NHCH3CH3CH2CH2NH2(CH3)3Nboiling point:50C34C3C
Dr. Wolf's CHM 201 & 20221-*
Basicity of Amines
Dr. Wolf's CHM 201 & 20221-*Effect of Structure on Basicity1. Alkylamines are slightly stronger bases than ammonia.
Dr. Wolf's CHM 201 & 20221-*AmineConj. AcidpKaNH3NH4+9.3CH3CH2NH2CH3CH2NH3+10.8Table 22.1 (page 920)Basicity of Amines in Aqueous SolutionCH3CH2NH3+ is a weaker acid than NH4+; therefore, CH3CH2NH2 is a stronger base than NH3.
Dr. Wolf's CHM 201 & 20221-*Effect of Structure on Basicity1. Alkylamines are slightly stronger bases than ammonia.2. Alkylamines differ very little in basicity.
Dr. Wolf's CHM 201 & 20221-*AmineConj. AcidpKaNH3NH4+9.3CH3CH2NH2CH3CH2NH3+10.8(CH3CH2)2NH(CH3CH2)2NH2+11.1(CH3CH2)3N(CH3CH2)3NH+10.8Table 22.1 (page 920)Basicity of Amines in Aqueous SolutionNotice that the difference separating a primary, secondary, and tertiary amine is only 0.3 pK units.
Dr. Wolf's CHM 201 & 20221-*Effect of Structure on Basicity1. Alkylamines are slightly stronger bases than ammonia.2. Alkylamines differ very little in basicity.3. Arylamines are much weaker bases than ammonia.
Dr. Wolf's CHM 201 & 20221-*AmineConj. AcidpKaNH3NH4+9.3CH3CH2NH2CH3CH2NH3+10.8(CH3CH2)2NH(CH3CH2)2NH2+11.1(CH3CH2)3N(CH3CH2)3NH+10.8C6H5NH2C6H5NH3+4.6Table 22.1 (page 920)Basicity of Amines in Aqueous Solution
Dr. Wolf's CHM 201 & 20221-*Decreased basicity of arylamines
Dr. Wolf's CHM 201 & 20221-*H2NDecreased basicity of arylamines++Stronger acidWeaker acidWhen anilinium ion loses a proton, the resulting lone pair is delocalized into the ring.
Dr. Wolf's CHM 201 & 20221-*H2NDecreased basicity of arylamines++Aniline is a weaker base because its lone pair is more strongly held.
Dr. Wolf's CHM 201 & 20221-*Decreased basicity of arylaminesC6H5NH2(C6H5)2NH(C6H5)3NIncreasing delocalization makes diphenylamine a weaker base than aniline, and triphenylamine a weaker base than diphenylamine.
Dr. Wolf's CHM 201 & 20221-*Effect of Substituents on Basicity of Arylamines1. Alkyl groups on the ring increase basicity, but only slightly (less than 1 pK unit).XpKa of conjugate acidH4.6CH35.3
Dr. Wolf's CHM 201 & 20221-*Effect of Substituents on Basicity of Arylamines2. Electron withdrawing groups, especially ortho and/or para to amine group, decrease basicity and can have a large effect.XpKa of conjugate acidH4.6CF33.5 O2N1.0
Dr. Wolf's CHM 201 & 20221-*p-NitroanilineLone pair on amine nitrogen is conjugated with p-nitro groupmore delocalized than in aniline itself. Delocalization lost on protonation.
Dr. Wolf's CHM 201 & 20221-*Effect is CumulativeAniline is 3800 times more basic than p-nitroaniline.Aniline is ~1,000,000,000 times more basic than 2,4-dinitroaniline.
Dr. Wolf's CHM 201 & 20221-*Heterocyclic Amines is more basic than
Dr. Wolf's CHM 201 & 20221-*Heterocyclic Amines is more basic thanimidazolepyridinepKa of conjugate acid:7.0pKa of conjugate acid:5.2
Dr. Wolf's CHM 201 & 20221-*ImidazoleWhich nitrogen is protonated in imidazole?H+H++
Dr. Wolf's CHM 201 & 20221-*ImidazoleProtonation in the direction shown gives a stabilized ion.H++
Dr. Wolf's CHM 201 & 20221-*
Tetraalkylammonium Saltsas Phase-Transfer Catalysts
Dr. Wolf's CHM 201 & 20221-*Phase-Transfer CatalysisPhase-transfer agents promote the solubility of ionic substances in nonpolar solvents. They transfer the ionic substance from an aqueous phase to a non-aqueous one. Phase-transfer agents increase the rates of reactions involving anions. The anion is relatively unsolvated and very reactive in nonpolar media compared to water or alcohols.
Dr. Wolf's CHM 201 & 20221-*Phase-Transfer CatalysisQuaternary ammonium salts are phase-transfer catalysts. They are soluble in nonpolar solvents.+ClMethyltrioctylammonium chloride
Dr. Wolf's CHM 201 & 20221-*Phase-Transfer CatalysisQuaternary ammonium salts are phase-transfer catalysts. They are soluble in nonpolar solvents.ClBenzyltriethylammonium chloride
Dr. Wolf's CHM 201 & 20221-*ExampleThe SN2 reaction of sodium cyanide with butyl bromide occurs much faster when benzyl- triethylammonium chloride is present than when it is not.CH3CH2CH2CH2Br+NaCNCH3CH2CH2CH2CN+NaBrbenzyltriethylammonium chloride
Dr. Wolf's CHM 201 & 20221-*MechanismCl(aqueous)(aqueous)CN+
Dr. Wolf's CHM 201 & 20221-*CN(aqueous)Mechanism
Dr. Wolf's CHM 201 & 20221-*(in butyl bromide)CNMechanismCH3CH2CH2CH2Br+
Dr. Wolf's CHM 201 & 20221-*
Reactions of Amines:A Review and a Preview
Dr. Wolf's CHM 201 & 20221-*Preparation of AminesTwo questions to answer:1) How is the CN bond to be formed?2) How do we obtain the correct oxidation state of nitrogen (and carbon)?
Dr. Wolf's CHM 201 & 20221-*Methods for CN Bond FormationNucleophilic substitution by azide ion (N3) (Section 8.1, 8.13)Nitration of arenes (Section 12.3)Nucleophilic ring opening of epoxides by ammonia (Section 16.12)Nucleophilic addition of amines to aldehydes and ketones (Sections 17.10, 17.11)Nucleophilic acyl substitution (Sections 19.4, 19.5, and 19.11)Nucleophilic substitution by ammonia on a-halo acids (Section 20.15)
Dr. Wolf's CHM 201 & 20221-*
Preparation of Aminesby Alkylation of Ammonia
Dr. Wolf's CHM 201 & 20221-*Alkylation of AmmoniaDesired reaction is:2 NH3+RXRNH2+NH4X
Dr. Wolf's CHM 201 & 20221-*Alkylation of AmmoniaBut the method doesn't work well in practice. Usually gives a mixture of primary, secondary, and tertiary amines, plus the quaternary salt. NH3RXRNH2RXR2NHRXR3NRX
Dr. Wolf's CHM 201 & 20221-*ExampleCH3(CH2)6CH2BrNH3CH3(CH2)6CH2NH2(45%)As octylamine is formed, it competes with ammonia for the remaining 1-bromooctane. Reaction of octylamine with 1-bromooctane gives N,N-dioctylamine.
Dr. Wolf's CHM 201 & 20221-*
The Gabriel Synthesis of Primary Alkylamines
Dr. Wolf's CHM 201 & 20221-*gives primary amines without formation of secondary, etc. amines as byproductsuses an SN2 reaction on an alkyl halide to form the CN bondthe nitrogen-containing nucleophile is N-potassiophthalimideGabriel Synthesis
Dr. Wolf's CHM 201 & 20221-*gives primary amines without formation of secondary, etc. amines as byproductsuses an SN2 reaction on an alkyl halide to form the CN bondthe nitrogen-containing nucleophile is N-potassiophthalimideGabriel Synthesis
Dr. Wolf's CHM 201 & 20221-*the pKa of phthalimide is 8.3N-potassiophthalimide is easily prepared by the reaction of phthalimide with KOHN-PotassiophthalimideOO KOH
Dr. Wolf's CHM 201 & 20221-*N-Potassiophthalimide as a nucleophileOON +SN2
Dr. Wolf's CHM 201 & 20221-*Cleavage of Alkylated Phthalimide+acid or baseimide hydrolysis is nucleophilic acyl substitution
Dr. Wolf's CHM 201 & 20221-*Cleavage of Alkylated Phthalimidehydrazinolysis is an alternative method of releasing the amine from its phthalimide derivative+
Dr. Wolf's CHM 201 & 20221-*Example+C6H5CH2ClDMF
Dr. Wolf's CHM 201 & 20221-*Example+C6H5CH2NH2H2NNH2(97%)
Dr. Wolf's CHM 201 & 20221-*
Preparation of Amines by Reduction
Dr. Wolf's CHM 201 & 20221-*almost any nitrogen-containing compound can be reduced to an amine, including:azides nitriles nitro-substituted benzene derivatives amidesPreparation of Amines by Reduction
Dr. Wolf's CHM 201 & 20221-*SN2 reaction, followed by reduction, gives a primary alkylamine.Synthesis of Amines via AzidesNaN3(74%)azides may also be reduced by catalytic hydrogenation
Dr. Wolf's CHM 201 & 20221-*SN2 reaction, followed by reduction, gives a primary alkylamine.Synthesis of Amines via NitrilesCH3CH2CH2CH2BrNaCN(69%)CH3CH2CH2CH2CNnitriles may also be reduced by lithium aluminum hydride
Dr. Wolf's CHM 201 & 20221-*SN2 reaction, followed by reduction, gives a primary alkylamine.Synthesis of Amines via NitrilesCH3CH2CH2CH2BrNaCN(69%)CH3CH2CH2CH2CNthe reduction also works with cyanohydrins
Dr. Wolf's CHM 201 & 20221-*Synthesis of Amines via NitroarenesHNO3(88-95%)ClH2SO4nitro groups may also be reduced with tin (Sn) + HCl or by catalytic hydrogenation
Dr. Wolf's CHM 201 & 20221-*Synthesis of Amines via Amides(86-89%)1. SOCl22. (CH3)2NHonly LiAlH4 is an appropriate reducing agent for this reaction
Dr. Wolf's CHM 201 & 20221-*
Reductive Amination
Dr. Wolf's CHM 201 & 20221-*The aldehyde or ketone equilibrates with the imine faster than hydrogenation occurs.Synthesis of Amines via Reductive Amination+NH3fast+H2OIn reductive amination, an aldehyde or ketone is subjected to catalytic hydrogenation in the presence of ammonia or an amine.
Dr. Wolf's CHM 201 & 20221-*Synthesis of Amines via Reductive Amination+NH3fast+H2OThe imine undergoes hydrogenation faster than the aldehyde or ketone. An amine is the product.
Dr. Wolf's CHM 201 & 20221-*Example: Ammonia gives a primary amine.+NH3H2, Niethanol(80%)
Dr. Wolf's CHM 201 & 20221-*Example: Primary amines give secondary aminesH2, Niethanol(65%)
Dr. Wolf's CHM 201 & 20221-*Example: Secondary amines give tertiary aminesH2, Ni, ethanol(93%)+
Dr. Wolf's CHM 201 & 20221-*Example: Secondary amines give tertiary aminespossible intermediates include:
Dr. Wolf's CHM 201 & 20221-*
Reactions of Amines:A Review and a Preview
Dr. Wolf's CHM 201 & 20221-*Reactions of AminesReactions of amines almost always involve the nitrogen lone pair.
Dr. Wolf's CHM 201 & 20221-*Reactions of Aminesbasicity (Section 21.4)reaction with aldehydes and ketones (Chapter 17) reaction with acyl chlorides, anhydrides, and estersReactions already discussed
Dr. Wolf's CHM 201 & 20221-*
Reactions of Amines with Alkyl Halides
Dr. Wolf's CHM 201 & 20221-*Reaction with Alkyl HalidesAmines act as nucleophiles toward alkyl halides. X+
Dr. Wolf's CHM 201 & 20221-*Example: excess amine+(85-87%)NaHCO390C(4 mol)(1 mol)
Dr. Wolf's CHM 201 & 20221-*Example: excess alkyl halide+3CH3I(99%)methanolheat+
Dr. Wolf's CHM 201 & 20221-*
The Hofmann Elimination
Dr. Wolf's CHM 201 & 20221-*The Hofmann Eliminationa quaternary ammonium hydroxide is the reactant and an alkene is the productis an anti eliminationthe leaving group is a trialkylaminethe regioselectivity is opposite to the Zaitsev rule.
Dr. Wolf's CHM 201 & 20221-*Quaternary Ammonium Hydroxidesare prepared by treating quaternary ammmonium halides with moist silver oxide
Dr. Wolf's CHM 201 & 20221-*The Hofmann Elimination160C+HOon being heated, quaternary ammonium hydroxides undergo elimination
Dr. Wolf's CHM 201 & 20221-*MechanismH
Dr. Wolf's CHM 201 & 20221-*RegioselectivityElimination occurs in the direction that gives the less-substituted double bond. This is called the Hofmann rule.
Dr. Wolf's CHM 201 & 20221-*RegioselectivitySteric factors seem to control the regioselectivity. The transition state that leads to 1-butene is less crowded than the one leading to cis or trans-2-butene.
Dr. Wolf's CHM 201 & 20221-*Regioselectivitylargest group is between two H atoms
Dr. Wolf's CHM 201 & 20221-*Regioselectivity HHHCH3largest group is between an H atom and a methyl groupCH3
Dr. Wolf's CHM 201 & 20221-*
Electrophilic Aromatic Substitutionin Arylamines
Dr. Wolf's CHM 201 & 20221-*Nitration of AnililneNH2 is a very strongly activating groupNH2 not only activates the ring toward electrophilic aromatic substitution, it also makes it more easily oxidizedattemped nitration of aniline fails because nitric acid oxidizes aniline to a black tar
Dr. Wolf's CHM 201 & 20221-*Nitration of AnililneStrategy: decrease the reactivity of aniline by converting the NH2 group to an amide
Dr. Wolf's CHM 201 & 20221-*Nitration of AnililneStrategy: nitrate the amide formed in the first step
Dr. Wolf's CHM 201 & 20221-*Nitration of AnililneStrategy: remove the acyl group from the amide by hydrolysis
Dr. Wolf's CHM 201 & 20221-*occurs readily without necessity of protecting amino group, but difficult to limit it to monohalogenationHalogenation of Arylamines(82%)
Dr. Wolf's CHM 201 & 20221-*Monohalogenation of Arylamines(74%)Decreasing the reactivity of the arylamine by converting the NH2 group to an amide allows halogenation to be limited to monosubstitution
Dr. Wolf's CHM 201 & 20221-*Friedel-Crafts ReactionsThe amino group of an arylamine must be protected as an amide when carrying out a Friedel-Crafts reaction.(57%)NHCCH3OCH3
Dr. Wolf's CHM 201 & 20221-*
Nitrosation of Alkylamines
Dr. Wolf's CHM 201 & 20221-*Nitrite Ion, Nitrous Acid, and Nitrosyl Cation
Dr. Wolf's CHM 201 & 20221-*Nitrosyl Cation and Nitrosation
Dr. Wolf's CHM 201 & 20221-*Nitrosyl Cation and Nitrosation+
Dr. Wolf's CHM 201 & 20221-*Nitrosation of Secondary Alkylaminesnitrosation of secondary amines gives an N-nitroso amine
Dr. Wolf's CHM 201 & 20221-*ExampleNaNO2, HClH2O(88-90%)
Dr. Wolf's CHM 201 & 20221-*Some N-Nitroso Amines
Dr. Wolf's CHM 201 & 20221-*Nitrosation of Primary Alkylamines+analogous to nitrosation of secondary amines to this point
Dr. Wolf's CHM 201 & 20221-*Nitrosation of Primary AlkylaminesRHthis species reacts further
Dr. Wolf's CHM 201 & 20221-*Nitrosation of Primary Alkylaminesnitrosation of a primary alkylamine gives an alkyl diazonium ionprocess is called diazotization
Dr. Wolf's CHM 201 & 20221-*Alkyl Diazonium Ions alkyl diazonium ions readily lose N2 to give carbocations+
Dr. Wolf's CHM 201 & 20221-*Example: Nitrosation of 1,1-Dimethylpropylamine
Dr. Wolf's CHM 201 & 20221-*There is no useful chemistry associated with the nitrosation of tertiary alkylamines.Nitrosation of Tertiary Alkylamines
Dr. Wolf's CHM 201 & 20221-*
Nitrosation of Arylamines
Dr. Wolf's CHM 201 & 20221-*reaction that occurs is electrophilic aromatic substitutionNitrosation of Tertiary Arylamines
Dr. Wolf's CHM 201 & 20221-*similar to secondary alkylamines;gives N-nitroso aminesNitrosation of N-AlkylarylaminesNaNO2, HCl, H2O, 10C
Dr. Wolf's CHM 201 & 20221-*Nitrosation of Primary Arylaminesgives aryl diazonium ionsaryl diazonium ions are much more stable than alkyl diazonium ionsmost aryl diazonium ions are stable under the conditions of their formation (0-10C)
Dr. Wolf's CHM 201 & 20221-*Example:HSO4
Dr. Wolf's CHM 201 & 20221-*Synthetic Origin of Aryl Diazonium Salts
Dr. Wolf's CHM 201 & 20221-*
Synthetic Transformationsof Aryl Diazonium Salts
Dr. Wolf's CHM 201 & 20221-*Transformations of Aryl Diazonium Salts
Dr. Wolf's CHM 201 & 20221-*Preparation of PhenolsH2O, heat
Dr. Wolf's CHM 201 & 20221-*Example2. H2O, heat1. NaNO2, H2SO4 H2O, 0-5C(73%)
Dr. Wolf's CHM 201 & 20221-*Transformations of Aryl Diazonium Salts
Dr. Wolf's CHM 201 & 20221-*Preparation of Aryl Iodidesreaction of an aryl diazonium salt with potassium iodideKI
Dr. Wolf's CHM 201 & 20221-*Example2. KI, room temp.1. NaNO2, HCl H2O, 0-5C(72-83%)IBr
Dr. Wolf's CHM 201 & 20221-*Transformations of Aryl Diazonium Salts
Dr. Wolf's CHM 201 & 20221-*Preparation of Aryl Fluoridesheat the tetrafluoroborate salt of a diazonium ion;process is called the Schiemann reaction
Dr. Wolf's CHM 201 & 20221-*Example(68%)2. HBF41. NaNO2, HCl, H2O, 0-5C3. heat
Dr. Wolf's CHM 201 & 20221-*Transformations of Aryl Diazonium Salts
Dr. Wolf's CHM 201 & 20221-*Preparation of Aryl Chlorides and Bromidesaryl chlorides and aryl bromides are prepared by heating a diazonium salt with copper(I) chloride or bromidesubstitutions of diazonium salts that use copper(I) halides are called Sandmeyer reactions
Dr. Wolf's CHM 201 & 20221-*Example(68-71%)NH2NO22. CuCl, heat1. NaNO2, HCl, H2O, 0-5CClNO2
Dr. Wolf's CHM 201 & 20221-*Example(89-95%)2. CuBr, heat1. NaNO2, HBr, H2O, 0-10CBrCl
Dr. Wolf's CHM 201 & 20221-*Transformations of Aryl Diazonium Salts
Dr. Wolf's CHM 201 & 20221-*Preparation of Aryl Nitrilesaryl nitriles are prepared by heating a diazonium salt with copper(I) cyanidethis is another type of Sandmeyer reaction
Dr. Wolf's CHM 201 & 20221-*Example(64-70%)2. CuCN, heat1. NaNO2, HCl, H2O, 0CCNCH3
Dr. Wolf's CHM 201 & 20221-*Transformations of Aryl Diazonium Salts
Dr. Wolf's CHM 201 & 20221-*Transformations of Aryl Diazonium Saltshypophosphorous acid (H3PO2) reduces diazonium salts; ethanol does the same thingthis is called reductive deamination
Dr. Wolf's CHM 201 & 20221-*Example(70-75%)NaNO2, H2SO4, H3PO2
Dr. Wolf's CHM 201 & 20221-*Value of Diazonium Salts1) allows introduction of substituents such as OH, F, I, and CN on the ring2) allows preparation of otherwise difficultly accessible substitution patterns
Dr. Wolf's CHM 201 & 20221-*Example
Dr. Wolf's CHM 201 & 20221-*
Azo Coupling
Dr. Wolf's CHM 201 & 20221-*Azo CouplingDiazonium salts are weak electrophiles.React with strongly activated aromatic compounds by electrophilic aromatic substitution.
Dr. Wolf's CHM 201 & 20221-*Example+Cl
Dr. Wolf's CHM 201 & 20221-*
Spectroscopic Analysis of Amines
Dr. Wolf's CHM 201 & 20221-*the NH stretching band appears in the range 3000-3500 cm-1primary amines give two peaks in this region, one for a symmetrical stretching vibration, the other for an antisymmetrical stretchInfrared Spectroscopy
Dr. Wolf's CHM 201 & 20221-*Infrared Spectroscopyprimary amines give two NH stretching peaks, secondary amines give one
Dr. Wolf's CHM 201 & 20221-*compare chemical shifts in:1H NMR
Dr. Wolf's CHM 201 & 20221-*13C NMRCarbons bonded to N are more shielded than those bonded to O.CH3NH2CH3OH
Dr. Wolf's CHM 201 & 20221-*max 204 nm 256 nmmax 230 nm 280 nmmax 203 nm 254 nmAn amino group on a benzene ring shifts max to longer wavelength. Protonation of N causes UV spectrum to resemble that of benzene.UV-VIS
Dr. Wolf's CHM 201 & 20221-*Mass SpectrometryCompounds that contain only C, H, and O have even molecular weights. If an odd number of N atoms is present, the molecular weight is odd.A molecular-ion peak with an odd m/z value suggests that the sample being analyzed contains N.
Dr. Wolf's CHM 201 & 20221-*Mass SpectrometryNitrogen stabilizes carbocations, which drives the fragmentation pathways.e
Dr. Wolf's CHM 201 & 20221-*Mass SpectrometryNitrogen stabilizes carbocations, which drives the fragmentation pathways.e
Dr. Wolf's CHM 201 & 20221-*End of Chapter 21
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