Organic preparation based on name reaction


Textbook, 2013

36 Pages, Grade: A-C


Excerpt

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Dr. Purvesh J. Shah

Organic Chemistry Practicals
[PJS]
Page 2
Organic Preparation
Page
1
p-Iodo nitrobenzene from p-Nitro aniline
[Diazotization]
3
2
Dibenzalacetone from Benzaldehyde
[Ciaisen-Schmidt Reaction]
6
3
Benzlanilide from Benzophenone
[BECKMANN REARRANGEMENT]
8
4
1-Phenylazo-2-
QDSKWKRO IURP -Naphthol
[DIAZOTIZATION and COUPLING]
11
5
9,10-dihydroanthracene-
-succinic anhydride from
$QWKUDFHQHGLK\GURDQWKUDFHQH VXFFLQLF DQK\GULGH
from Anthracene
[DIELS-ALDER REACTION]
12
6
SANDMEYER REACTION of Aromatic amines
14
7
7-hydroxy-4-methylcoumarin from Resorcinol
[PECHMANN CONDENSATION]
16
8
1,2,3,4-Tetrahydrocarbazole from Cyclohexanone [FISCHER
INDOLE SYNTHESIS]
18
9
Iodoform from Acetone
[Haloform Reaction]
20
10
2-Hydroxy-4-methylquinoline from Aceto acetanilide [Knorr
Quinoline Synthesis]
22
11
2,4-Dihydroxybenzoicacid from Resorcinol.
[Kolbe - Schmitt Reaction]
24
12
Benzyl alcohol and Benzoic acid from
Benzaldehyde [Cannizzaro Reaction]
26
13
Chalcon from acetophenone
[Aldol Condensation]
27
14
-dimethyl amino propinphenone hydrochloride from
acetophenone [Mannich Reaction].
29
15
Purification of organic compounds
31
A) Heating under reflex
31
B) Distillation
31
C) Extraction by solvent
33
D) Recrystallition
34
E) Tests of purity
35

Organic Chemistry Practicals
[PJS]
Page 3
Practical-1: Preparation of p-Iodo nitrobenzene from p-
Nitroaniline.
Diazotization:
Diazonium salts were prepared first by Peter Griess in
1858 by the action of nitrous acid on the salts of an aromatic amine.
Most
of
Diazonium
salts
are
unstable
at
room
temperature.
So
reaction
is
carried
out
at
0
0
c
and
solution
used
immediately.
Coupling takes place only in weakly acidic or alkaline
solution. In strongly acid solution the hydroxyl group is undissociated and
the amino group present as its salts.
Coupling takes place in the unhindered para position of the coupler. If
the para position occupied coupling takes place at ortho position. If both
positions are occupied coupling not takes place occasionally the group in the
para position is displaced.
The process of converting an amine into the Diazonium salt is called
diazotization.
The
dry
diazonium
salt
is
unstable
and
explosive.
Aryldiazonium salts are highly reactive compounds and undergo many
useful reactions. They have proved to be valuable synthetic intermediates for
the preparation of a fairly wide range of aromatic derivatives.

Organic Chemistry Practicals
[PJS]
Page 4
Reaction Scheme:
Requirements:
p-nitro aniline : 1g
0% NaNO
2
solution : 5 ml
Conc.H
2
SO
4
: 1 ml
20% KI solution: 10 ml
Procedure:
Mix p-nitro aniline and concentrated sulphuric acid thoroughly to Make-it
into a paste in a 50 ml beaker. Add 10 ml Water to it and stir to dissolve p-
nitro aniline completely, (Heat gently, if required). Cool the solution to 0
qC in
an ice bath and diazotize by adding the solution of sodium nitrite drop by
drop to it with constant stirring. The temperature should be controlled below
5
qC throughout the experiment. Take potassium iodide solution in a 250 ml
beaker and cool it to 5
qC. Drop wise add diazonium salt solution to
potassium iodide solution with vigorous stirring. The reaction proceeds with

Organic Chemistry Practicals
[PJS]
Page 5
evolution of N
2
(Frothing occurs). After the addition is over, allow the
reaction mixture to stand at room temperature for 30 minutes. Collect the
precipitated product by filtration, wash with water and crystallise from
ethanol.
Melting Point: crystallized form melts at 171°C.

Organic Chemistry Practicals
[PJS]
Page 6
Practical-2:
Preparation
of
Dibenzalacetone
from
Benzaldehyde. [Ciaisen-Schmidt Reaction]
Ciaisen-Schmidt Reaction:
7KH FRQGHQVDWLRQ RI DURPDWLF DOGHK\GHV KDYLQJ QR K\GURJHQ ZLWK
aliphatic aldehyde, ketone or ester having active hydrogen in presence of
DONDOL VROXWLRQ JLYH
XQVDWXUDWHG DOGHK\GH RU NHWRQH LV NQRZQ DV
claisen-Schmidt reaction.
By using this reaction we can synthesis many natural products,
perfumery compound.
Reaction Scheme:
Requirements:
Benzaldehyde
: 2.0 ml
Acetone: 0.8 ml
10% NaOH solution
: 4.0 ml
R-Spirit: 20 ml
Procedure:
Dissolve benzaldehyde and pure acetone in 20-ml of R-Spirit contained in a
conical flask of 100 ml capacity. Add 4 ml of 10% aqueous sodium
hydroxide alkali dropwise to the former solution over a period of 30 minutes.
Shake the mixture vigorously in the securely corked flask for about 10

Organic Chemistry Practicals
[PJS]
Page 7
minutes (releasing the pressure from time to time if necessary). Then allow
standing for 30 minutes with occasional shaking. Finally cool in ice water
for a few minutes. During the shaking, the dibenzal acetone separates first
as a fine emulsion which then rapidly forms pale yellow crystals. Filter at
the pump, wash well with water to eliminate traces of alkali and then drain
thoroughly. Recrystallise from hot R-Spirit. The dibenzalacetone is obtained
as pale yellow crystals.
Melting Point: crude product melts at 106°C
Purified product melts at 112°C.
Excerpt out of 36 pages

Details

Title
Organic preparation based on name reaction
Grade
A-C
Author
Year
2013
Pages
36
Catalog Number
V272163
ISBN (eBook)
9783656660781
ISBN (Book)
9783656660774
File size
945 KB
Language
English
Tags
organic, preparartion, name
Quote paper
Purvesh Shah (Author), 2013, Organic preparation based on name reaction, Munich, GRIN Verlag, https://www.grin.com/document/272163

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