Ethyl Amine: Preparation, Properties, Uses, and Tests

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Preparation: Laboratory Method

Hoffmann bromide Reaction

Ethyl amine is made from Hoffmann bromide Reaction in the laboratory. Ethyl amine is obtained by heating propionamide with a mixture of bromine and caustic potash. The reaction is completed in the following terms.

C₂H₅CONH₂ + Br₂ → C₂H₅CONHBr + HBr

HBr + KOH → KBr + H₂O

C₂H₅CONHBr + KOH → C₂H₅NCO + KBr + H₂O

C₂H₅NCO + 2KOH → C₂H₅NH₂ + K₂CO₃

The complete reaction can be represented by the following equation.

C₂H₅CONH₂ + Br₂ + 4KOH → C₂H₅NH₂ + 2KBr + K₂CO₃ + 2H₂O

Preparation Method

In a round bottom flask, take a mixture of about 40 grams of propionamide and about 36 ml of bromine. Keep the flask in ice cold water. A drop of 10% caustic potash solution is found in such a quantity in this mixture that the reddish brown colour of bromine is removed.

Now, keep the flask on water-heat and arrange and slowly pour about 50 ml 50% caustic potash solution from the point funnel. After this, the flask is heated by removing it from the water heater and placing it on a wire mesh, and the vapours of ethyl amine are absorbed in hydrochloric acid kept in the receiver.

Basic Concepts of Amines

1. Introduction
2. Classification
3. Nomenclature
4. Structure

Pure ethyl amine is obtained after distillation by adding caustic potash to the solution obtained in the receptor.

Huffman Alkalization method

In this method hydrogen atoms of ammonia are replaced by alkyl group. By this method, ethyl iodide is heated with a concentrated ammonia or alcohol solution of ammonia in a closed tube to obtain ethyl amine. The reaction of ethyl iodide and ammonia results in ethyl amine.

C₂H₅I + NH₃ → C₂H₅NH₂ + HI

In fact, a mixture of primary, secondary, and tertiary amines and quaternary ammonium salts is obtained in this method.

Hence this method is not suitable for making ethyl amine in the laboratory. In industries, fractional distillation by adding alkali to this mixture. The primary, secondary, tertiary amines isolates are obtained as a result of efficient distillation.

Ethyl Alcohol

Ethyl amine is obtained when a mixture of vapors and ammonia of ethyl alcohol flows over 360°C alumina.

C₂H₅OH + NH₃ → C₂H₅NH₂ + H₂O

In this method also a mixture of primary secondary and tertiary amines is obtained, but when used ammonia intensively, the main product is either primary amine or ethyl amine.

By reduction of acetone, methyl cyanide, nitro Ethan and acetaldehyde oxime:

reaction of these compounds with H₂ – Ni, Na – C₂H₅OH, LiAlH₄, NaBH₄ and some other catabolites gives ethyl amine.

CH₃CONH₂ + 4H → CH₃CH₂NH₂ + H₂O

CH₃CN + 4H → CH₃CH₂NH₂

C₂H₅NO₂ + 6H → C₂H₅NH₂ + 2H₂

CH₃-CH=NOH + 4H → CH₃CH₂NH₂ + H₂O

Water decomposition of ethyl isocyanide

Ethyl amine is obtained by water decomposition of ethyl isocyanide or ethyl isocyanate. These reactions are catalyzed by acide and alkali respectively.

C₂H₅NC + 2H₂O → C₂H₅NH₂ + HCOOH

C₂H₅NCO + 2KOH → C₂H₅NH₂ + K₂CO₃

Grignard Reagent

ethyl amine is obtained by the action of chloramine on ethyl magnesium chloride, bromide or iodide.

C₂H₅MgCl + ClNH₂ → C₂H₅NH₂ + MgCl₂

Schmidt Reaction

Ethyl amine is obtained by reaction of propionic acid and hydrazoic acid in the presence of concentrated sulphuric acid. This reaction is called Schmidt Reaction.

C₂H₅COOH + N₃H → C₂H₅NH₂ + CO₂ + N₂

Physical Properties

Ethyl amine is a colorless liquid. Its boiling point is 19°C. Hence, it is colorless gas in summer season. It smells like ammonia. It is soluble in water. And its aqueous solution is alkaline. IUPAC name of ethylamine is Ethanamine.

Chemical Properties

Alkaline properties: It dissolves in water to form ethyl ammonium which is an alkali.

C₂H₅NH₂ + H₂O → C₂H₅NH₃⁺OH^–

It reacts with acids like ammonia to form salts.

C₂H₅NH₂ + HCl → C₂H₅NH₃⁺Cl^–

C₂H₅NH₂ + H₂SO₄ → C₂H₅NH₃⁺HSO₄^–

It reacts with chloroplatinic acid (H₂PtCl₆) to form platinichloride salts.

2C₂H₅NH₂ + H₂PtCl₆ → (C₂H₅NH₃⁺)₂(PtCl₆)^2-

On burning of platinichloride salts, only the platinum remains and the remaining elements separate as gas.

Reaction with alkyl halides: It reacts with alkyl halides to form a mixture of secondary amine, tertiary amine and quaternary ammonium salts.

Example: with ethyl iodide

Acetylation: It reacts with acetyl chloride or acetic anhydride to form N-substituted acetamide. In this reaction a hydrogen atom of the – NH₂ group is replaced by an acetyl (-COCH₃) group. This reaction is called acetylation.

C₂H₅NH₂ + CH₃COCl → CH₃CONHC₂H₅ + HCl

C₂H₅NH₂ + (CH₃CO)₂O → CH₃CONHC₂H₅ + CH₃COOH

Using a greater amount of reagent – both hydrogen atoms of NH₂ group are replaced by two acetyl groups.

Reaction with nitrous acid: It reacts with nitrous acid to make ethanol and nitrogen is gas free.

C₂H₅NH₂ + HNO₂ → C₂H₅OH + H₂O + N₂

The -NH2 group present in any compound is converted into -OH group with the help of this reaction. Nitrous acid is a temporary acid. To make this reaction, a mixture of sodium nitrite and hydrochloric acid is used. The reaction of sodium nitrite and hydrochloric acid results in the formation of nitrous acid.

The secondary amine reacts with nitrous acid to form N-nitroso-amine, which gives yellow oily layer.

The teritery amine reacts with nitrus acid to form soluble salts and there is no visible change.

Reaction of amines to nitrous acid is used for their testing and differential detection.

Carbylamine reaction: On heating primary amines with an alcohol solution of chloroform and KOH, a highly deodorant additive called iso cyanide or carbylamine is formed. This reaction is called carbylamine reaction and this reaction is used to test primary amine. The following is the equation of the carbylamine reaction of ethyl amine.

C₂H₅NH₂ + CHCl₃ + 3KOH → C₂H₅NC + 3KCl + 3H₂O

Reaction with carbon di sulfide: N – ethyl di thao carbamic acid is formed by the reaction of ethyl amine and carbon disulfide. On reaction with its mercuric chloride, ethyl iso-thao-cyanate is formed which has a smell similar to mustard oil. This reaction is called haffman mustard oil reaction. And this reaction is used to test ethyl amine.

Grignard reagent reaction: Reaction of ethyl amine to grignard reagents results in alkane.

CH₃MgI + C₂H₅NH₂ → CH₄ + C₂H₅NHMgI

C₂H₅MgBr + C₂H₅NH₂ → C₂H₆ + C₂H₅NHMgBr

Reaction with benzen sulfonil chloride: The reaction of primary amines with benzene sufonil chloride produces N – alkyl benzene sulfonamide, which is dissolved in dilute alkaline solution. Following is the equation of the reaction of ehtyl amine and benzene sulfonil chloride.

C₆H₅-SO₂-Cl + C₂H₅NH₂ → C₆H₅-SO₂-NH-C₂H₅

Reaction of secondary amine with benzene sulfonil chloride produces N, N – di alkyl benzene sulfonamide, which are insoluble in alkaline solutions.

There is no reaction of benzene sulfonil chloride of teritery amines.

The reaction of amines with benzene sulfonil chloride is used to separate them from a mixture of primary, secondary and teritery amines. This method of separating them from the mixture of primary, secondary and teritery amines is called hinsberg method.

Ethylamine Tests

Ethyl amine and other alifatic primary amines give the following tests.

Nitrous acid test: Reaction occurs rapidly when sodium tritrite and hydrochloric acid are added to the amines compound and nitrogen gas is produced. nitrogen gas exits rapidly with bubbling.

Carbylamine test: On heating the amines additive with chloroform and alcoholic caustic potash solution, a strong deodorant is obtained.

Haffman mustard oil test: The amines additive receives a mustard oil-like odor when heated with carbon di sulfide in the presence of mercuric chloride.

Ethylamine Uses

It is used as a production raw material of herbicides like Cyanazine, Atrazine and Simazine. Ethylamine is used as a catalyst in end use industries such as plastics for production of polyurethane foam and in dyes for producing ethylcyanopyrolidone disperse and rhodamine dyes.