[PDF] Experiment 14 Preparation of p-Nitroaniline PDF exp14.pdf

This attacks to form the tetrahedral intermediate, which, after proton transfer, loses acetic acid Figure 14 2 Mechanism of Acetylation Reaction H2N aniline +

Acetyl chloride may also be used for the purpose of acetylation if acetic anhydride is not available (i) Take 5 mL of aniline in a 100 mL round bottom flask and add acetylating (iii) Cool the reaction mixture and pour it slowly in 150-200 mL

[PDF] Note A green approach to chemoselective N- acetylation of - NOPR

N-Acetylation reaction finds immense applications in organic Table I — N- Acetylation of amines using zinc acetate–acetic acid under During development of the present method, aniline mechanism of this reaction is currently in progress

[PDF] TYE HYDROLYSIS OF ACETANILIDE The acetylation of - Zenodo

reaction was followed by determining the total acidity by titration In the acetylation experi- ments solutions were made up of aniline and --- acetic acid,, and mea

[PDF] Synthesis of paracetamol by acetylation - The Royal Society of

spectrum of 4-aminophenol shows the two N-H amine bands at 3340 and 3282 Scheme SM 3 1 5 1 – General acetylation reaction mechanism of an alcohol

[PDF] Research Article Acetylation of Phenols, Anilines - Hindawicom

3 oct 2012 · tion reactions have to proceed rapidly, readily, quantitatively, and keeping costs to a deficient aniline and treated with various acylating agents such as ethyl lation of alcohols with acetic anhydride: scope and mechanism,”

[PDF] Experiment 14 Preparation of p-Nitroaniline

This attacks to form the tetrahedral intermediate, which, after proton transfer, loses acetic acid Figure 14 2 Mechanism of Acetylation Reaction H2N aniline +

[PDF] Composition otebook - Front Door - Valencia College

Experimental Title: Synthesis of Acetanilide acyl substitution reaction on acetic anhydride with aniline to synthesize Complete Reaction Mechanism:

Experiment 14

Preparation of p-Nitroaniline

This experiment usually takes three weeks to complete and counts as two laboratory experiments (40 points). We will do a three-step synthesis to make p- nitroaniline from aniline and then we will characterize our product using the new and very useful technique of thin layer chromatography (TLC). The overall reaction scheme is given in Figure 14.1 NH 2 CH 3 C O C CH 3 OO CH 3 CO 2 H HNO 3 H 2 SO 4 NHC O CH 3 NHC O CH 3 O 2 N NHC O CH 3 NO 2 NH 2 O 2 N NHC O CH 3 CH 3 C OH O NHC O CH 3 NO 2 Figure 14.1 Three Step Preparation of p-Nitroaniline aniline

1. HCl, H

2 O 2. NH 4 OH p-nitroaniline p-nitroacetanilide acetanilide acetic anhydride acetic acid +Step 1 acetanilide

Step 2

Step 3

p-nitroacetanilide o-nitroacetanilide major

Step 1: Acetylation of Aniline

In the first step we need to put the removable acetyl protecting group on the nitrogen of aniline. The acetyl group is electron withdrawing and it therefore makes the lone pair on the nitrogen less reactive either in an oxidation reaction or a protonation reaction. The nitric acid used in the nitration step is a fairly strongly oxidizing agent and we could form an N-oxide. The nitration conditions (nitric acid and sulfuric acid) are strongly acidic. Protonation of the nitrogen of aniline makes it a very strong deactivating group, making the aromatic ring less susceptible to reaction with the nitrating agent and the NH 3 group would be a meta director. Another value of the acetyl protecting group is that it is bulky group and preferentially directs the nitration to the para position rather than the ortho position. The full mechanism for the reaction is given in Figure 14.2. Acetic anhydride is partially protonated by the acetic acid. This makes the anhydride an even better electrophile for the nucleophilic nitrogen of aniline. This attacks to form the tetrahedral intermediate, which, after proton transfer, loses acetic acid.

Figure 14.2 Mechanism of Acetylation Reaction

H 2 N aniline CH 3 C O C CH 3 OO NHC O CH 3+ O C CH 3 O acetanilide acetic anhydride acetic acid H CH 3 C O C CH 3 OO H CH 3 C O C CH 3 OO H CH 3 C C O O H CH 3 NHH O O C CH 3 O O C CH 3 O CH 3 C O O H CH 3 C C O O H CH 3 NH O H O C CH 3 O HO C CH 3 O

Physical Constants

CompoundMol. Wt

(g/mol)

Density

(g/mL) b.p. (°C)m.p. (°C)

Aniline93.131.022184-6

Acetic anhydride102.091.082138-142-73

Acetic acid60.051.049116-11715-16

Nitric acid (conc. 15.8

63.011.420--

Sulfuric acid (conc. 36

98.091.840330-

Acetanilide135.17solid-113-115

p-nitroacetanilide180.16solid-215-217 p-nitroaniline138.13solid-147-148

Procedure:

The set-up for your apparatus is shown in Figure 14.3. Note that there is NO STOPPER at the top of the condensing column. This is left open to the atmosphere so as to avoid a pressure build -up inside the flask when heating. Remember: NEVER HEAT

A CLOSED SYSTEM.

Dissolve 4.0 mL of aniline in 10 mL of acetic acid in a 100 mL round bottom flask. To this solution, add 5 mL of acetic anhydride and mix well by swirling. CAUTION: the reaction is exothermic and the flask becomes warm. Add two boiling chips, attach a condensing column and attach the hoses for water cooling (water-in at the bottom and water-out at the top). Heat at a gentle reflux for fifteen minutes.

Work up

After fifteen minutes, lower the iron ring under your heating mantle and allow the flask to cool slightly. CAUTIOUSLY add 5 mL of cold water through the top of the condenser into the reaction mixture. Boil the solution for an additional five minutes so as to hydrolyze any unreacted acetic anhydride. The reaction is shown in Figure 14.4.quotesdbs_dbs7.pdfusesText_13

[PDF] [PDF] Experiment 14 Preparation of p-Nitroaniline

[PDF] Unit-10 (Corrected on 24-05-08)pmd - NCERT