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CHE-302 Review. Nomenclature Syntheses Reactions Mechanisms Spectroscopy. Aromatic Hydrocarbons (Electrophilic Aromatic Substitution) Spectroscopy (infrared & H-nmr) Arenes Aldehydes & Ketones Carboxylic Acids Functional Derivatives of Carboxylic Acids

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Nomenclature

Syntheses

Reactions

Mechanisms

Spectroscopy


Aromatic Hydrocarbons (Electrophilic Aromatic Substitution)

Spectroscopy (infrared & H-nmr)

Arenes

Aldehydes & Ketones

Carboxylic Acids

Functional Derivatives of Carboxylic Acids

Acid Chlorides, Anhydrides, Amides, Esters

Carbanions

Amines & Diazonium Salts

Phenols


Mechanisms:

Electrophilic Aromatic Substitution

Nitration

Sulfonation

Halogenation

Friedel-Crafts Alkylation & Acylation

Nucleophilic Addition to Carbonyl

Nucleophilic Addition to Carbonyl, Acid Catalyzed

Nucleophilic Acyl Substitution

Nucleophilic Acyl Substitution, Acid Catalyzed


Aromatic Hydrocarbons

hydrocarbons

aliphaticaromatic

alkanesalkenesalkynes


Aliphatic compounds: open-chain compounds and ring compounds that are chemically similar to open-chain compounds. Alkanes, alkenes, alkynes, dienes, alicyclics, etc.

Aromatic compounds: unsaturated ring compounds that are far more stable than they should be and resist the addition reactions typical of unsaturated aliphatic compounds. Benzene and related compounds.


Nomenclature for benzene:

monosubstituted benzenes:

Special names:


  • Electrophilic Aromatic Substitution (Aromatic compounds)

  • Ar-H = aromatic compound

  • 1. Nitration

  • Ar-H + HNO3, H2SO4 Ar-NO2 + H2O

  • Sulfonation

  • Ar-H + H2SO4, SO3 Ar-SO3H + H2O

  • Halogenation

  • Ar-H + X2, Fe  Ar-X + HX

  • Friedel-Crafts alkylation

  • Ar-H + R-X, AlCl3 Ar-R + HX



Common substituent groups and their effect on EAS:

-NH2, -NHR, -NR2

-OH

-OR

-NHCOCH3

-C6H5

-R

-H

-X

-CHO, -COR

-SO3H

-COOH, -COOR

-CN

-NR3+

-NO2

ortho/para directors

increasing reactivity

meta directors









Mechanism for Friedel-Crafts with alkene & acid:

electrophile in Friedel-Crafts alkylation = carbocation


Arenes

alkylbenzenes

alkenylbenzenes

alkynylbenzenes

etc.




Use of phenyl C6H5- = “phenyl”

do not confuse phenyl (C6H5-) with benzyl (C6H5CH2-)



  • Alkylbenzenes, syntheses:

  • Friedel-Crafts alkylation

  • Modification of a side chain:

  • a) addition of hydrogen to an alkene

  • b) reduction of an alkylhalide

  • i) hydrolysis of Grignard reagent

  • ii) active metal and acid

  • c) Corey-House synthesis




  • Friedel-Crafts limitations:

  • Polyalkylation

  • Possible rearrangement

  • R-X cannot be Ar-X

  • NR when the benzene ring is less reactive than bromobenzene

  • NR with -NH2, -NHR, -NR2 groups



  • Alkylbenzenes, reactions:

  • Reduction

  • Oxidation

  • EAS

  • a) nitration

  • b) sulfonation

  • c) halogenation

  • d) Friedel-Crafts alkylation

  • Side chain

  • free radical halogenation


Alkylbenzenes, EAS

-R is electron releasing. Activates to EAS and directs ortho/para



  • Alkenylbenzenes, syntheses:

  • Modification of side chain:

  • a) dehydrohalogenation of alkyl halide

  • b) dehydration of alcohol

  • c) dehalogenation of vicinal dihalide

  • d) reduction of alkyne

  • (2. Friedel-Crafts alkylation)



  • Alkenylbenzenes, reactions:

  • Reduction

  • Oxidation

  • EAS

  • Side chain

  • a) add’n of H2 j) oxymercuration

  • b) add’n of X2 k) hydroboration

  • c) add’n of HX l) addition of free rad.

  • d) add’n of H2SO4 m) add’n of carbenes

  • e) add’n of H2O n) epoxidation

  • f) add’n of X2 & H2O o) hydroxylation

  • g) dimerization p) allylic halogenation

  • h) alkylation q) ozonolysis

  • i) dimerization r) vigorous oxidation





100 syn-oxidation; make a model!


Alkynylbenzenes, syntheses:

Dehydrohalogenation of vicinal dihalides


  • Alkynylbenzenes, reactions:

  • Reduction

  • Oxidation

  • EAS

  • Side chain

  • a) reduction e) as acids

  • b) add’n of X2 f) with Ag+

  • c) add’n of HX g) oxidation

  • d) add’n of H2O, H+







Nomenclature:

Aldehydes, common names:

Derived from the common names of carboxylic acids;

drop –ic acid suffix and add –aldehyde.

CH3

CH3CH2CH2CH=O CH3CHCH=O

butyraldehyde isobutyraldehyde

(α-methylpropionaldehyde)


Aldehydes, IUPAC nomenclature:

Parent chain = longest continuous carbon chain containing the carbonyl group; alkane, drop –e, add –al. (note: no locant, -CH=O is carbon #1.)

CH3

CH3CH2CH2CH=O CH3CHCH=O

butanal 2-methylpropanal

H2C=O CH3CH=O

methanal ethanal


Ketones, common names:

Special name:acetone

“alkyl alkyl ketone” or “dialkyl ketone”


(o)phenones:

Derived from common name of carboxylic acid, drop –ic acid, add –(o)phenone.


Ketones: IUPAC nomenclature:

Parent = longest continuous carbon chain containing the carbonyl group. Alkane, drop –e, add –one. Prefix a locant for the position of the carbonyl using the principle of lower number.


  • Aldehydes, syntheses:

  • Oxidation of 1o alcohols

  • Oxidation of methylaromatics

  • Reduction of acid chlorides

  • Ketones, syntheses:

  • Oxidation of 2o alcohols

  • Friedel-Crafts acylation

  • Coupling of R2CuLi with acid chloride


Aldehydes synthesis 1) oxidation of primary alcohols:

RCH2-OH + K2Cr2O7, special conditions  RCH=O

RCH2-OH + C5H5NHCrO3Cl  RCH=O

(pyridinium chlorochromate)

[With other oxidizing agents, primary alcohols  RCOOH]





Ketone synthesis: 2) Friedel-Crafts acylation

Aromatic ketones (phenones) only!



  • Aldehydes & ketones, reactions:

  • Oxidation

  • Reduction

  • Addition of cyanide

  • Addition of derivatives of ammonia

  • Addition of alcohols

  • Cannizzaro reaction

  • Addition of Grignard reagents

  • 8) (Alpha-halogenation of ketones)

  • 9) (Addition of carbanions)


nucleophilic addition to carbonyl:


Mechanism:nucleophilic addition to carbonyl

1)

2)


Mechanism:nucleophilic addition to carbonyl,acid catalyzed

1)

2)

3)


  • 1) Oxidation

  • Aldehydes(very easily oxidized!)

  • CH3CH2CH2CH=O + KMnO4, etc.  CH3CH2CH2COOH

  • carboxylic acid

  • CH3CH2CH2CH=O + Ag+ CH3CH2CH2COO- + Ag

  • Tollen’s test for easily oxidized compounds like aldehydes.

  • (AgNO3, NH4OH(aq))

Silver mirror


b) Methyl ketones:

Yellow ppt

test for methyl ketones



Reduction

b) To hydrocarbons



4) Addition of derivatives of ammonia




Formaldehyde is the most easily oxidized aldehyde. When mixed with another aldehyde that doesn’t have any alpha-hydrogens and conc. NaOH, all of the formaldehyde is oxidized and all of the other aldehyde is reduced.

Crossed Cannizzaro:



New carbon-carbon bond


HX

Mg

ROH

RX

RMgX

larger

alcohol

H2O

ox.

R´OH

-C=O


CH3 HBr CH3 Mg CH3

CH3CHCH2OH CH3CHCH2Br CH3CHCH2MgBr

H+

K2Cr2O7 CH3

CH3CH2OH CH3CH=O CH3CHCH2CHCH3

special cond. OH

4-methyl-2-pentanol



  • Carboxylic acids, syntheses:

  • oxidation of primary alcohols

  • RCH2OH + K2Cr2O7 RCOOH

  • 2. oxidation of arenes

  • ArR + KMnO4, heat  ArCOOH

  • 3. carbonation of Grignard reagents

  • RMgX + CO2 RCO2MgX + H+  RCOOH

  • 4. hydrolysis of nitriles

  • RCN + H2O, H+, heat  RCOOH


  • oxidation of 1o alcohols:

  • CH3CH2CH2CH2-OH + CrO3 CH3CH2CH2CO2H

  • n-butyl alcohol butyric acid

  • 1-butanol butanoic acid

  • CH3 CH3

  • CH3CHCH2-OH + KMnO4  CH3CHCOOH

  • isobutyl alcohol isobutyric acid

  • 2-methyl-1-propanol` 2-methylpropanoic acid


note: aromatic acids only!


  • carbonation of Grignard reagent:

  • R-X RMgX RCO2MgX RCOOH

  • Increases the carbon chain by one carbon.

  • Mg CO2 H+

  • CH3CH2CH2-Br CH3CH2CH2MgBr CH3CH2CH2COOH

  • n-propyl bromide butyric acid

Mg CO2 H+


  • Hydrolysis of a nitrile:

  • H2O, H+

  • R-CN R-CO2H

  • heat

  • H2O, OH-

  • R-CN R-CO2- + H+ R-CO2H

  • heat

  • R-X + NaCN  R-CN + H+, H2O, heat  RCOOH

  • 1o alkyl halide

  • Adds one more carbon to the chain.

  • R-X must be 1o or CH3!


  • carboxylic acids, reactions:

  • as acids

  • conversion into functional derivatives

  • a)  acid chlorides

  • b)  esters

  • c)  amides

  • reduction

  • alpha-halogenation

  • EAS


  • as acids:

  • with active metals

  • RCO2H + Na  RCO2-Na+ + H2(g)

  • with bases

  • RCO2H + NaOH  RCO2-Na+ + H2O

  • relative acid strength?

  • CH4 < NH3 < HCCH < ROH < HOH < H2CO3 < RCO2H < HF

  • quantitative

  • HA + H2O  H3O+ + A- ionization in water

  • Ka = [H3O+] [A-] / [HA]



  •  esters

  • “direct” esterification:

  • RCOOH + R´OH  RCO2R´ + H2O

  • -reversible and often does not favor the ester

  • -use an excess of the alcohol or acid to shift equilibrium

  • -or remove the products to shift equilibrium to completion

  • “indirect” esterification:

  • RCOOH + PCl3 RCOCl + R´OH  RCO2R´

  • -convert the acid into the acid chloride first; not reversible


  •  amides

  • “indirect” only!

  • RCOOH + SOCl2 RCOCl + NH3  RCONH2

  • amide

  • Directly reacting ammonia with a carboxylic acid results in an ammonium salt:

  • RCOOH + NH3 RCOO-NH4+

  • acid base


  • Reduction:

  • RCO2H + LiAlH4; then H+ RCH2OH

  • 1o alcohol

  • Carboxylic acids resist catalytic reduction under normal conditions.

  • RCOOH + H2, Ni  NR


  • Alpha-halogenation: (Hell-Volhard-Zelinsky reaction)

  • RCH2COOH + X2, P  RCHCOOH + HX

  • X

  • α-haloacid

  • X2 = Cl2, Br2


5.EAS: (-COOH is deactivating and meta- directing)



Nomenclature: the functional derivatives’ names are derived from the common or IUPAC names of the corresponding carboxylic acids.

Acid chlorides: change –ic acid to –yl chloride

Anhydrides: change acid to anhydride


Amides: change –ic acid (common name) to –amide

-oic acid (IUPAC) to –amide

Esters: change –ic acid to –ate preceded by the name of the alcohol group


Mechanism: Nucleophilic Acyl Substitution

1)

2)


Mechanism:nucleophilic acyl substitution, acid catalyzed

1)

2)

3)


Acid Chlorides

Syntheses:

SOCl2

RCOOH + PCl3 RCOCl

PCl5


  • Acid chlorides, reactions:

  • Conversion into acids and derivatives:

  • a) hydrolysis

  • b) ammonolysis

  • c) alcoholysis

  • Friedel-Crafts acylation

  • Coupling with lithium dialkylcopper

  • Reduction






  • Anhydrides, syntheses:

  • Buy the ones you want!

  • Anhydrides, reactions:

  • Conversion into carboxylic acids and derivatives.

  • a) hydrolysis

  • b) ammonolysis

  • c) alcoholysis

  • 2) Friedel-Crafts acylation



Amides, synthesis:

Indirectly via acid chlorides.


Amides, reactions.

1) Hydrolysis.


  • Esters, syntheses:

  • From acids

  • RCO2H + R’OH, H+ RCO2R’ + H2O

  • From acid chlorides and anhydrides

  • RCOCl + R’OH RCO2R’ + HCl

  • From esters (transesterification)

  • RCO2R’ + R”OH, H+ RCO2R” + R’OH

  • RCO2R’ + R”ONa RCO2R” + R’ONa


“Direct” esterification is reversible and requires use of LeChatelier’s principle to shift the equilibrium towards the products. “Indirect” is non-reversible.



  • Esters, reactions: by exchanging the alcohol function.

  • Conversion into acids and derivatives

  • a) hydrolysis

  • b) ammonolysis

  • c) alcoholysis

  • Reaction with Grignard reagents

  • Reduction

  • a) catalytic

  • b) chemical

  • 4) Claisen condensation


Esters, reaction with Grignard reagents by exchanging the alcohol function.



Carbanions by exchanging the alcohol function.

|

— C: –

|

The conjugate bases of weak acids,

strong bases, excellent

nucleophiles.


1. Alpha-halogenation of ketones by exchanging the alcohol function.


Carbanions. by exchanging the alcohol function. The conjugate bases of weak acids; strong bases, good nucleophiles.

1. enolate anions

2. organometallic compounds

3. ylides

4. cyanide

5. acetylides


Aldehydes and ketones: by exchanging the alcohol function.nucleophilic addition

Esters and acid chlorides: nucleophilic acyl substitution

Alkyl halides: SN2

Carbanions as the nucleophiles in the above reactions.



a) Aldol condensation. aldehydes and ketones: The reaction of an aldehyde or ketone with dilute base or acid to form a beta-hydroxycarbonyl product.



Crossed aldol aldehydes and ketones: condensation:

If you react two aldehydes or ketones together in an aldol condensation, you will get four products. However, if one of the reactants doesn’t have any alpha hydrogens it can be condensed with another compound that does have alpha hydrogens to give only one organic product in a “crossed” aldol.

NaOH


N.B. If the product of the aldol condensation under basic conditions is a “benzyl” alcohol, then it will spontaneouslydehydrate to the α,β-unsaturated carbonyl.


Ph = phenyl



Mechanism for the Claisen condensation: substitution of esters and acid chlorides.


Crossed Claisen condensation: substitution of esters and acid chlorides.


Carbanions II substitution of esters and acid chlorides.

Carbanions as nucleophiles in SN2 reactions with alkyl halides.

a) Malonate synthesis of carboxylic acids

b) Acetoacetate synthesis of ketones

c) 2-oxazoline synthesis of esters/carboxylic acids

d) Organoborane synthesis of acids/ketones

e) Enamine synthesis of aldehydes/ketones


Amines substitution of esters and acid chlorides.

(organic ammonia) :NH3

:NH2R or RNH2 1o amine (R may be Ar)

:NHR2 or R2NH2o amine

:NR3 or R3N 3o amine

NR4+ 4o ammonium salt


NB amines are classified by the class of the substitution of esters and acid chlorides.nitrogen, primary amines have one carbon bonded to N, secondary amines have two carbons attached directly to the N, etc.

Nomenclature.

Common aliphatic amines are named as “alkylamines”


  • Amines, syntheses: substitution of esters and acid chlorides.

    • Reduction of nitro compounds 1o Ar

  • Ar-NO2 + H2,Ni  Ar-NH2

    • Ammonolysis of 1o or methyl halides R-X = 1o,CH3

      • R-X + NH3 R-NH2

    • Reductive amination avoids E2

    • R2C=O + NH3, H2, Ni  R2CHNH2

    • Reduction of nitriles + 1 carbon

    • R-CN + 2 H2, Ni  RCH2NH2

    • Hofmann degradation of amides - 1 carbon

    • RCONH2 + KOBr  RNH2


1. Reduction of nitro compounds: substitution of esters and acid chlorides.


  • Ammonolysis of 1 substitution of esters and acid chlorides.o or methyl halides.


3. Reductive amination: substitution of esters and acid chlorides.

Avoids E2


  • Reduction of nitriles substitution of esters and acid chlorides.

  • R-CN + 2 H2, catalyst  R-CH2NH2

  • 1o amine

  • R-X + NaCN  R-CN  RCH2NH2

  • primary amine with one additional carbon

  • (R must be 1o or methyl)


5. Hofmann degradation of amides substitution of esters and acid chlorides.


  • Amine, reactions: substitution of esters and acid chlorides.

  • As bases

  • Alkylation

  • Reductive amination

  • Conversion into amides

  • EAS

  • Hofmann elimination from quarternary ammonium salts

  • Reactions with nitrous acid


  • As bases substitution of esters and acid chlorides.

  • a) with acids

  • b) relative base strength

  • c) Kb

  • d) effect of groups on base strength


2. Alkylation (ammonolysis of alkyl halides) substitution of esters and acid chlorides.


3. Reductive amination substitution of esters and acid chlorides.


  • Conversion into amides substitution of esters and acid chlorides.

  • R-NH2 + RCOCl  RCONHR + HCl

  • 1o N-subst. amide

  • R2NH + RCOCl  RCONR2 + HCl

  • 2o N,N-disubst. amide

  • R3N + RCOCl  NR

  • 3o


  • EAS substitution of esters and acid chlorides.

  • -NH2, -NHR, -NR2 are powerful activating groups and ortho/para directors

  • a) nitration

  • b) sulfonation

  • c) halogenation

  • d) Friedel-Crafts alkylation

  • e) Friedel-Crafts acylation

  • f) coupling with diazonium salts

  • g) nitrosation


a) nitration substitution of esters and acid chlorides.


b) sulfonation substitution of esters and acid chlorides.


c) halogenation substitution of esters and acid chlorides.




g) nitrosation substitution of esters and acid chlorides.


h) coupling with diazonium salts substitution of esters and acid chlorides. azo dyes



7. Reactions with nitrous acid substitution of esters and acid chlorides.


Diazonium salts substitution of esters and acid chlorides.

synthesis

benzenediazonium ion


  • Diazonium salts, reactions substitution of esters and acid chlorides.

  • Coupling to form azo dyes

  • Replacements

  • a) -Br, -Cl, -CN

  • b) -I

  • c) -F

  • d) -OH

  • e) -H

  • f) etc.


coupling to form azo dyes substitution of esters and acid chlorides.


Phenols Ar-OH substitution of esters and acid chlorides.

Phenols are compounds with an –OH group attached to an aromatic carbon. Although they share the same functional group with alcohols, where the –OH group is attached to an aliphatic carbon, the chemistry of phenols is very different from that of alcohols.


Nomenclature. substitution of esters and acid chlorides.

Phenols are usually named as substituted phenols. The methylphenols are given the special name, cresols. Some other phenols are named as hydroxy compounds.


  • phenols, syntheses: substitution of esters and acid chlorides.

  • From diazonium salts

  • 2. Alkali fusion of sulfonates


  • phenols, reactions: substitution of esters and acid chlorides.

  • as acids

  • ester formation

  • ether formation

  • EAS

  • a) nitration f) nitrosation

  • b) sulfonation g) coupling with diaz. salts

  • c) halogenation h) Kolbe

  • d) Friedel-Crafts alkylation i) Reimer-Tiemann

  • e) Friedel-Crafts acylation


as acids: substitution of esters and acid chlorides.

with active metals:

with bases:

CH4 < NH3 < HCCH < ROH < H2O < phenols < H2CO3 < RCOOH < HF


  • ester formation substitution of esters and acid chlorides.(similar to alcohols)


  • ether formation (Williamson Synthesis) substitution of esters and acid chlorides.

  • Ar-O-Na+ + R-X  Ar-O-R + NaX

  • note: R-X must be 1o or CH3

  • Because phenols are more acidic than water, it is possible to generate the phenoxide in situ using NaOH.



b) halogenation substitution of esters and acid chlorides.


c) sulfonation substitution of esters and acid chlorides.

At low temperature the reaction is non-reversible and the lower Eact ortho-product is formed (rate control).

At high temperature the reaction is reversible and the more stable para-product is formed (kinetic control).


d) Friedel-Crafts alkylation. substitution of esters and acid chlorides.


e) Friedel-Crafts acylation substitution of esters and acid chlorides.


Fries rearrangement of phenolic esters substitution of esters and acid chlorides..


f) nitrosation substitution of esters and acid chlorides.


g) coupling with diazonium salts substitution of esters and acid chlorides.

(EAS with the weak electrophile diazonium)


h) Kolbe reaction (carbonation) substitution of esters and acid chlorides.


i) Reimer-Tiemann reaction substitution of esters and acid chlorides.


Nomenclature substitution of esters and acid chlorides.

Syntheses

Reactions

Mechanisms

Spectroscopy


Aromatic Hydrocarbons (Electrophilic Aromatic Substitution) substitution of esters and acid chlorides.

Spectroscopy (infrared & H-nmr)

Arenes

Aldehydes & Ketones

Carboxylic Acids

Functional Derivatives of Carboxylic Acids

Acid Chlorides, Anhydrides, Amides, Esters

Carbanions

Amines & Diazonium Salts

Phenols


Mechanisms: substitution of esters and acid chlorides.

Electrophilic Aromatic Substitution

Nitration

Sulfonation

Halogenation

Friedel-Crafts Alkylation & Acylation

Nucleophilic Addition to Carbonyl

Nucleophilic Addition to Carbonyl, Acid Catalyzed

Nucleophilic Acyl Substitution

Nucleophilic Acyl Substitution, Acid Catalyzed


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