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CHEM 353. BRIEF REVIEW. OF. ORGANIC REACTIONS. METHODS OF SYNTHESIS FOR THE MAJOR FUNCTIONAL GROUPS OF ORGANIC CHEM. THIS SET OF SLIDES IS STILL UNDER CONSTRUCTION. PLEASE BE PATIENT. ACID HALIDES. SYNTHESIS OF ACID CHLORIDES. thionyl chloride. + SO 2. + HCl.

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CHEM 353

BRIEF REVIEW

OF

ORGANIC REACTIONS

METHODS OF SYNTHESIS FOR THE MAJOR

FUNCTIONAL GROUPS OF ORGANIC CHEM


THIS SET OF SLIDES IS STILL

UNDER CONSTRUCTION.

PLEASE BE PATIENT


ACID

HALIDES


SYNTHESIS OF ACID CHLORIDES

thionyl chloride

+ SO2

+ HCl

Thionyl chloride is a liquid.

You can do the reaction without a solvent

or sometimes benzene is used.

All of the other acid derivatives can be made

from the acid chloride.



SYNTHESIS OF ALCOHOLS

H2 Ni

catalytic

hydrogenation

2 atm 40o

ketone or

aldehyde

low reactivity

water and

alcohol solvents

are OK

1. NaBH4

sodium

borohydride

2. H3O+

reduces only aldehydes or ketones

lithium

aluminum

hydride

1. LiAlH4

ether solvent

required

2. H3O+

reduces aldehydes and ketones and

many other polar functional groups

CAUTION:


SYNTHESIS OF ALCOHOLS - 2

gives low yields,

hydration of

an alkene

oxymercuration

is a better method

H2SO4

Markovnikov rule

oxymer-

curation

1.

2.

Markovnikov


SYNTHESIS OF ALCOHOLS - 3

H2O

solvolysis

of halides

tertiary, allylic

or benzylic

Grignard

Reaction

H3O+

+

Mg

ether

alkyllithium compounds

react just like the Grignard

Li

Alkyllithium

Compounds

ether or pentane or benzene solvent


SYNTHESIS OF ALCOHOLS - 4

ether

hydroboration-

oxidation

3

H2O2

NaOH

H3O+

3

anti-Markovnikoff

Grignard +

epoxide

1. RMgX / ether

2. H3O+

SN2

terminal alcohols




SYNTHESIS OF ALDEHYDES

Sarrett Reagent

primary

alcohol

Jones Reagent does not

stop at the aldehyde and

gives a carboxylic acid.

Other oxidizing agents usually continue to the acid RCOOH.




SYNTHESIS OF ALKENES

E2

elimination

heat

NaOMe

stereospecific

anti

MeOH

X = Cl, Br, I

Saytzev Rule

strong bases such as NaOH, NaOR required

dehydration

watch for

rearrangements

H2SO4

not

stereospecific

heat

acid-assisted

E1 elimination

Saytzev Rule

strong acids such as H2SO4 and H3PO4 required


SYNTHESIS OF ALKENES - 2

catalytic

hydrogenation

H2

Lindlar

cis

Lindlar = Pd / BaSO4 / quinoline

syn addition

H2

won’t

stop

Pd

REMEMBER

2X

dissolving metal

reduction

Na/NH3

trans

anti addition


SYNTHESIS OF ALKENES - 3

Wittig

reaction

R

R

1

benzene

2

+

_

:

+

(C

H

)

P

(

C

H

)

P

C

R

X

R

C

X

6

5

3

6

5

3

2

1

heat

H

H

-

..

Triphenylphosphine

:

O-CH3

halide

..

ether

strong base

R

-

+

..

1

(

C

H

)

P

C

6

5

3

R

ylide

2

Wittig reagent

reaction assembles

the two halves



C

a

C

O

C

a

O

+

C

O

3

2

C

a

O

+

2

C

C

a

C

+

C

O

2

C

a

(

O

H

)

C

a

C

H

O

+

+

2

2

2

2

H

C

C

H

SYNTHESIS OF ACETYLENES

Acetylene from

limestone

D

calcium oxide

calcium carbonate

D

calcium carbide

lime

acetylene


SYNTHESIS OF ACETYLENES - 2

alkylation of

acetylene

elimination of dihalides






SYNTHESIS OF ANHYDRIDES

acid chloride

and sodium

salt

-

+

sodium salt

Section 19.25

acid chloride

anhydride

+ NaCl


SYNTHESIS OF ANHYDRIDES - 2

dehydration of

carboxylic acids

works for small

symmetric anhydrides

only



CARBOXYLIC

ACIDS


SYNTHESIS OF CARBOXYLIC ACIDS

Jones Reagent

cannot

isolate

primary

alcohol

oxidation continues

Sarrett Reagent will stop

at the aldehyde.

carboxylic acid

oxidation of

an aldehyde

[Ox]

Many oxidizing agents will oxidize aldehydes

including: CrO3, K2Cr2O7, KMnO4, H2O2,

Ag(NH4)OH (Tollen’s).


SYNTHESIS OF CARBOXYLIC ACIDS - 2

Grignard or

R-Li + CO2

1) CO2

R-MgX

R-COOH

2) H3O+

1) CO2

R-COOH

R-Li

2) H3O+

cleaving double

and triple bonds

(oxidation)

KMnO4

KMnO4

cannot

isolate

oxidation

continues

Alkenes must have

hydrogen on the

double bond.

…..


SYNTHESIS OF CARBOXYLIC ACIDS - 3

D

hydrolysis

of a nitrile

NaCN

H2O

R-X

R-CN

R-COOH

H2SO4

acetone

NaOH

D

H2O

H3O+

-

+

R-COO Na

hydrolysis of

acid derivatives

H2O

or

or

H2O

H2SO4

or

NaOH


SYNTHESIS OF CARBOXYLIC ACIDS - 4

oxidation of a

side chain on

an aromatic

ring

KMnO4

or

CrO3/H2SO4



SYNTHESIS OF EPOXIDES

peracid

cis

cis

stereospecific

via

bromohydrin

cis

anti

addition

stereospecific

overall

cis



Fischer synthesis

acid chloide or anhydride + alcohol


GLYCOLS

DIOLS



SYNTHESIS OF HALIDES

*

#

thionyl chloride

pyridine

inversion of configuration SN2

*

*

+

+

thionyl chloride

ether

retention of configuration

SNi

phosphorous

halides

1o, 2o alcohols

inversion of configuration

SN2


SYNTHESIS OF HALIDES - 2

watch for rearrangements !

concentrated

acids

the halide

is often

racemized

1o, 2o alcohols proceed by SN2

3o, allylic, benzylic alcohols by SN1

(acid assisted)


SYNTHESIS OF HALIDES - 3

addition of HX

to alkenes

also HBr, HI

Markovnikov rule

free radical

halogenation

+

hn

rate = 3o H > 2o H > 1o H

usually not a

good laboratory

synthetic method

chain reaction



oxidation of

alcohols

cleavage of

alkenes


hydrolysis of imines

don’t forget nitrile + Grignard

don’t forget organocadmium + ester



NaCN is soluble in acetone,

or DMSO could be used

SN2 displacement

with cyanide

acetone

+

Primary or

secondary

halides

cyanohydrins



CYCLOHEXENES

Diels-Alder

CYCLOPROPANES

Diazomethane

a-Eliminations

Simmons-Smith


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