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PyrrolePreaperation

1- from succinimide NH

O ONH

HO OH

dis

znNH

+ RNH2OR O R

Ketoform

H

R

HO

O RNH

R

2 – From 1,4 – Dicarbonyl compound

H

R

HO

ROHNH

R

enol form

-H2O

N |R

RR

subs - pyrrole

OCH3 O CH3

+ CH3NH2 N | CH3

CH3CH3

1,2,5 - Trimethylpyrrole

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3 – From α-aminocarbonyl compounds knorr synthesiscondensation of an α – amino – ketone with a ketone possessing a reactive methylene group α- amino ketone prepared by reducing the corresponding oximino compound with zinc

HNO2

-H2O

CH3 - C = O |

EtOOC - CH 2

CH3 - C = O |

EtOOC - C = NOH

H2

CH3 - C = O |

EtOOC - CH - NH 2

CH3 - C - OH ||

EtOOC - C - NH 2+

CH3 - C = O

CH2-Cl

||CH3 - C - OH

CH - Cl

-H2OCH3 - C - OH ||

EtOOC - C - NH 2+ ||

CH3 - C - OH

CH - Cl C - ClC

NH

CH3EtOOC

CH3 -

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Chemical propertiesPyrrole is a weaker base than pyrrolideine

NH

..NH

..

This is because of 1 – Resonance of π electrons

2 – Type of hybrid orbitals of nitrogen atomThe pair of electron in pyrrole occupies an sp2 orbital while in pyrrolideine occupies sp3orbital and as we know the electron occupies an sp2orbital is held more tightly and is less available for sharing with acid than the pair of electrons which occupies sp3orbital.

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Electrophilic subistitution :-

The reaction takes place predominantly at the α – position we could account for this orientation of the following basis : the controlling step is the attachment of the electrophilic reagent which takes place in such a way as to yield the most stable intermediate carbonium ion

Attack at position 3 yields carbonium ion that is a hybrid of structure I and II . Attack at position 2 yields a carbonium ion that is a hybrid not only of structure III and IV ( analogous ) to (I and II ) but also of structure V ; the extra stabilization conferred by V makes this ion the more stable one

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- = 2 attack

NH

+

+

Y+

3

2

I

N

E

H.. NH

E

H++

II

+NH H

E

III IV

NH H

E..

+ +

.. NH H

E

V

+

More stable ion

- = 3 attack

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NH

NH

NO2

+

NH

NO2

NH

Br+

NH

Br

More stable HNO3

Br2

+

+

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Furan

Synthesis

1 – Feist Benary synthesis Treating α – chloroketone with ethyl acetoacetate

CH3 - C = O | CH2Cl

+

EtOOC- CH 2 | C = O

CH3

CH3

EtOOC- CH || C - OH

CH3 - C - OH||

CH - Cl

+ CH - OOCEt

|| CH - CH 3HO

-HCl

-H2OPyridine

C - CH3

C -OOCEtC

HC O

CH3-

2,4 - di methyl-3-ethylcarbonyl furan

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O COOHHOOC

OHHO

HH

COOHHO

HO

HOOC

+ 3H2O

mucic acid

dry

distilation

OR O R'R'HOR OH

P2O5-H2O O R'R

2 – From 1,4 dicarbonyl compound

O COOH -CO2 O

Ag2O

O CHO

Furfural

3 -

4 –

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5 - Reaction

O

SO3

Pyridine O SO3H

Furan - 2 - Sulphonic acid

1 – Sulphonation

Furan decomposed by the usual strong reagent but the pyridine sulphur trioxide compound under mild condition react with furan to give 2 – sulphonic acid

2 – Halogenation

OCl Cl O Cl

+ Cl2

O

dioxan

Br2 OBr

2 - Bromo furan2 - Chloro furan2,5 - dichloro furan

Furan react vigorously with chlorine and bromine at room temperature

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3 – Acylation

O

CH3

2 - acetyl -3-methyl furan

AC2O

H3PO4O

CH3

COCH3

+

O

CH3

CH3CO

Carboxylic anhydrides or carbonyl halides normally react only in presence of Friedel – Crafts or orthophosphoric acid

all electrophilic subistitution in furan take placte at position 2 and 3 but 2 is more stable for the same reason as pyrrole .