Preparation of p-Nitroacetanilide

Dhristi JEE 2022-24

Introduction

Nitration is described as an important reaction that is used in the nitro compound preparation. These nitro compounds can be used as starting materials for several essential commercially useful materials like drugs, dyes, explosives, and more. In this experiment, we will prepare the p-nitro acetanilide by the acetanilide nitration.

Introduction to Preparation of p-Nitroacetanilide

Nitration is an important reaction that is used within the training of nitro compounds. Nitro compounds are used as beginning substances for lots of commercially beneficial materials consisting of dyes, pills, explosives, and so forth. In this experiment, you'll put together p-nitroacetanilide through the nitration of acetanilide.

Main Objective of p-Nitroacetanilide

After conducting this experiment, you should be capable of:

  • Putting together p-nitroacetanilide,

  • Recrystallise the p-nitroacetanilide.

Principle of p-Nitroacetanilide

The p-Nitroacetanilide is prepared via nitration of acetanilide. The acetamido institution (-NHCOCH3) in acetanilide is ortho and para directing. therefore, on nitration a aggregate of o- and p-nitroacetanilide is shaped:


The acetamido organization being a bulky group causes steric challenge at the ortho function. Therefore, p-nitroacetanilide is fashioned as the primary product. . On crystallization from ethyl alcohol, p-nitroacetanilide crystallizes out as nearly colorless crystals even as the ortho isomer stays in solution.

What is p-Nitroacetanilide?

Para nitro acetanilide is also referred to as 4-Nitroacetanilide. Para nitro acetanilide is defined as a chemical compound that is a derivative of nitro acetanilide prepared from the mixture of nitrating and acetanilide. Along with the para product, a trace of ortho product is also formed.

 

Other names of p-Nitroacetanilide can be given as p-Acetamido Nitrobenzene, N-(4-nitrophenyl) acetamide, N-Acetyl-4-nitroaniline, and p-Nitroacetanilide.

Objectives

After performing this experiment, we should be able to:

  • recrystallize the p-nitro acetanilide,

  • prepare p-nitro acetanilide,

  • determine the melting point of prepared p-nitro acetanilide, and

  • perform the other compounds nitration

Preparation of Para Nitro Acetanilide From Acetanilide

Let us know about the preparation of para nitro acetanilide below:

Aim

To prepare the p-Nitroacetanilide from acetic acid and acetanilide in the presence of nitrating mixture.

Theory

The organic compound p-nitro acetanilide can be prepared from the acetanilide through nitration. When acetanilide is treated with the nitrating mixture, that is, a mixture of sulphuric acid and nitric acid, it forms p-nitro acetanilide. Also, along with p-nitro acetanilide, as a minor product, o-nitro acetanilide is also formed. Since o-nitro acetanilide is much soluble in alcohol, it is so easy to isolate p-nitro acetanilide through crystallization.

 

The chemical reactions involved in this process can be given as follows:

 

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It is a type of electrophilic substitution reaction. Here, the electrophile -NO2 will attach the para position because the -NHCOCH3 is considered as an electron releasing group. And nitro anilines will be prepared by this form of reaction, since if it is not possible to nitrate aniline, the amino group would be oxidised with a nitrate mixture. Also, in order to protect the amino group from oxidation, first, acetanilide is nitrated to produce p-nitro acetanilide and then on hydrolysis to produce p-nitroaniline, which is difficult to obtain by direct nitration.

Materials Required

The essential materials that are required for the preparation of p-Nitroacetanilide can be listed as follows:

  • Acetic acid

  • Acetanilide

  • Fuming Nitric acid

  • Concentrated Sulphuric acid

  • Ethyl alcohol

  • Beaker

  • Conical flask

  • Filter paper

  • Dropping funnel

  • Buchner funnel

  • Glass rod

  • Pipette

Apparatus Setup


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Procedure

  • Take 3 grams of finely powdered acetanilide in a clean beaker and then dissolve it by adding glacial acetic acid by carefully stirring the content at room temperature.

  • Now, warm the mixture gently to dissolve acetanilide completely.

  • Then, cool the solution and slowly add the concentrated sulphuric acid with constant stirring. By doing so, the solution becomes warm. Then, keep the mixture in an ice-bath, and a clear solution is obtained.

  • Now, add fuming nitric acid dropwise through a dropping funnel with constant stirring to the cool solution.

  • During this whole process, always maintain the temperature below 20℃.

  • Once the addition of nitric acid is over, the beaker can be removed from the freezing mixture bath and allowed to stand at room temperature for half an hour.

  • In a beaker, pour the mixture into 100 grams of crushed ice and stir well.

  • By doing so, large crystals of p-nitro acetanilide are obtained and then filter those crystals via filter paper.

  • The separated p-nitro acetanilide is washed with cold water to remove excess acid.

  • It is then crystallized from ethyl alcohol. Now, dry the crystals in filter paper folds and weigh them to know the yield.

Observations

Let us look at the sample observations, which are tabulated below:

Color of the Crystals

Colorless

Expected Yield

4 Grams

Melting Point

214℃

 

Results and Discussion

The p-Nitroacetanilide yield is _____ grams.

Precautions:

  • Temperature has to not exceed extra than 20 degree C.

  • beneficial to feature nitric acid into the reaction aggregate even as it is immersed in ice-bath

  • upload fuming nitric acid drop through drop cautiously and do not inhale the fumes of nitric acid.

  • make sure you have been nicely educated within the threat communique general.

  • identify the chemical substances you're using.

  • hold a stock of all chemicals being stored at your place of work. make certain to list the quantities, garage location and storage technique.

  • Ask your chemical supplier for protection information Sheets and preserve them on hand for reference.

  • Label all boxes with the name, awareness, manufacturing date and statistics on the hazards associated with the chemical being saved.

Principle

p-Nitroacetanilide can be prepared by acetanilide nitration. The acetamido group (which is -NHCOCH3) in acetanilide is para and directing. Thus, on nitration, an o- and p-nitro acetanilide mixture is formed:

 

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Acetamido group, being a bulky group, will cause the steric hindrance at the position of ortho. Thus, the p-nitro acetanilide can be formed as a major product. Also, when crystallised from ethyl alcohol, the p-nitro acetanilide crystallises mostly as colourless crystals, whereas, the ortho isomer remains in the same solution.

Safety

Let us look at the safety points of p-Nitroaniline.

 

Ethanol is flammable, so it is advised to handle with care. Sodium acetate trihydrate (which is CH3COONa.3H2O), acetophenone oxime, and the acetophenone irritates the human eyes, ears, and respiratory system, if came into contact. It is advised to avoid direct or indirect contact and does not inhale or ingest. Hydroxylamine hydrochloride (NH2OH.HCl) is defined as corrosive; hence, avoid all contact and handle this compound with caution. Deuterochloroform (CDCl3) is defined as toxic, so it also should be handled with care.

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FAQs (Frequently Asked Questions)

1. What is a nitrating mixture called?

The concentrated fuming nitric acid and the sulphuric acid combination is referred to as nitrating mixture.

2. Why is the ortho spinoff minor and para product is principal? 

This reaction is electrophilic substitution response and the nitronium ion formed is directed closer to ortho and para positions. Because of steric challenge in ortho role the nitronium electrophile is directed greater toward para role. Therefore, para products are important.

3. What's a nitrating combination referred to as?

The concentrated fuming nitric acid and the sulphuric acid combination is referred to as nitrating aggregate.

4. What is the use of p-nitroacetanilide?

A number of the uses of p-nitroacetanilide can be indexed as follows:

It can be utilized in prescription drugs inside the preparation of phenacetin and paracetamol. It is also used in insecticides, and further, rubber chemical compounds are also used as an intermediate for dyes.

5. What is the formulation for p-nitroacetanilide?

The system for p-nitroacetanilide is C8H8N2O3, and the IUPAC name is N-(four-nitrophenyl)acetamide.

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