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amines - review
amines - review
Level 2 Amines
This is a short overview on amines, with extra relevant information.
This is a short overview on amines, with extra relevant information.
Amines can be classed as derivatives of ammonia in which H atoms bonded to the N are replaced with alkyl groups (chains of hydrocarbons).
Amines can be classed as derivatives of ammonia in which H atoms bonded to the N are replaced with alkyl groups (chains of hydrocarbons).
derivatives of NH3
derivatives of NH3
Like alcohols and haloalkanes, amines are classed as 1°, 2° 3° amines. In the case of amines the classification is due to the number of carbon atoms the Nitrogen in the amino group is bonded:
Like alcohols and haloalkanes, amines are classed as 1°, 2° 3° amines. In the case of amines the classification is due to the number of carbon atoms the Nitrogen in the amino group is bonded:
* In 1° amine the N is bonded to 1 Carbon, shown by R above, and the amino group contains 2 H's
* In 1° amine the N is bonded to 1 Carbon, shown by R above, and the amino group contains 2 H's
* In 2° amine the N is bonded to 2 Carbons, shown by R above, and the amino group contains 1 H
* In 2° amine the N is bonded to 2 Carbons, shown by R above, and the amino group contains 1 H
* In 3° amine the N is bonded to 3 Carbons, shown by R above, and the amino group contains no H's
* In 3° amine the N is bonded to 3 Carbons, shown by R above, and the amino group contains no H's
Amines - naming overview
Amines - naming overview
amines - chemical reactions
amines - chemical reactions
ACID - BASE REACTIONS
ACID - BASE REACTIONS
Amines are weak bases. They can accept a proton (H+) and act as Bronsted-Lowry bases.
Amines are weak bases. They can accept a proton (H+) and act as Bronsted-Lowry bases.
They hydrolyse with water to give alkaline solutions, with an approximate pH of around 11-12, depending on concentration.
They hydrolyse with water to give alkaline solutions, with an approximate pH of around 11-12, depending on concentration.
They react with acids, like all bases, to give a salt and water.
They react with acids, like all bases, to give a salt and water.
nucleophilic substitution reactions
nucleophilic substitution reactions
Ammonia and many amines are also nucleophiles that bond to and form products with a variety of electrophiles.
Ammonia and many amines are also nucleophiles that bond to and form products with a variety of electrophiles.
Amines can be prepared by nucleophilic substitution of a haloalkane with ammonia in alcohol.
Amines can be prepared by nucleophilic substitution of a haloalkane with ammonia in alcohol.
Remember if it is aqueous the hydroxyl group will substitute forming an alcohol.
Remember if it is aqueous the hydroxyl group will substitute forming an alcohol.
AMMONIA and amine reactions with acyl chlorides
AMMONIA and amine reactions with acyl chlorides
Amides are produced in reactions with acyl chlorides.
Amides are produced in reactions with acyl chlorides.
See further down for information on amides
Primary amides are produced when ammonia reacts with an acyl chloride:
Primary amides are produced when ammonia reacts with an acyl chloride:
amines - physical properties
amines - physical properties
BOILING POINT
BOILING POINT
As can be seen from the graph the boiling points of amines, of the same number of carbons, are higher than the hydrocarbons, similar to ketones and esters, and lower than alcohols, which are lower than carboxylic acids
As can be seen from the graph the boiling points of amines, of the same number of carbons, are higher than the hydrocarbons, similar to ketones and esters, and lower than alcohols, which are lower than carboxylic acids
Remember boiling points are due to intermolecular forces present and the amount of heat energy needed to overcome them.
Amines are polar and primary and secondary amines can hydrogen bond.
Amines are polar and primary and secondary amines can hydrogen bond.
Boiling points of amines increase with increasing molecular mass, due to increasing induced dipoles (van der Waal's forces). Low mass amines are gases or low boiling point liquids, as shown in this table.
Boiling points of amines increase with increasing molecular mass, due to increasing induced dipoles (van der Waal's forces). Low mass amines are gases or low boiling point liquids, as shown in this table.
Boiling points of amines increase with increasing molecular mass, due to increasing induced dipoles. Low mass amines are gases or low boiling point liquids.
Boiling points of amines increase with increasing molecular mass, due to increasing induced dipoles. Low mass amines are gases or low boiling point liquids.
Boiling points of amines are higher than the hydrocarbons due to them being polar and able to hydrogen bond.
Boiling points of amines are higher than the hydrocarbons due to them being polar and able to hydrogen bond.
When comparing boiling points of secondary amines to primary amines they are slightly lower. For example dimethyl amine (secondary amine), which is a structural isomer of ethylamine (ethanamine) has a lower boiling point.
When comparing boiling points of secondary amines to primary amines they are slightly lower. For example dimethyl amine (secondary amine), which is a structural isomer of ethylamine (ethanamine) has a lower boiling point.
This can be accounted for by the fact that the Nitrogen atom is in the middle of the chain, thereby decreasing the strength of the permanent dipoles.
This can be accounted for by the fact that the Nitrogen atom is in the middle of the chain, thereby decreasing the strength of the permanent dipoles.
In tertiary amines there is no H bonded to the N so 3° amines cannot hydrogen bond and therefore have lower boiling points.
In tertiary amines there is no H bonded to the N so 3° amines cannot hydrogen bond and therefore have lower boiling points.
solubility
solubility
Low mass amines are very soluble due to their ability to hydrogen bond. Even 3° amines can hydrogen bond in water, due to the lone pair of electrons on the N. As the length of the hydrocarbon chain increases solubility decreases
Low mass amines are very soluble due to their ability to hydrogen bond. Even 3° amines can hydrogen bond in water, due to the lone pair of electrons on the N. As the length of the hydrocarbon chain increases solubility decreases
See the explanation of alcohol solubility for a better understanding - further alcohols post
Amines - Simple 'tests' to identify
Amines - Simple 'tests' to identify
As they are weak bases they will turn red litmus blue
As they are weak bases they will turn red litmus blue
They have characteristic unpleasant odours, similar to decaying fish.
They have characteristic unpleasant odours, similar to decaying fish.
amides
amides
Amides can be classed as derivatives of carboxylic acids, as they contain a C = O group.
Amides can be classed as derivatives of carboxylic acids, as they contain a C = O group.
In amides the -OH or -Cl group has been substituted by an NH₂ group.
In amides the -OH or -Cl group has been substituted by an NH₂ group.
Esters and acyl chlorides can also be classed as derivatives of carboxylic acids, due to having the same C = O ( carbonyl group). In acyl chlorides the -OH group has been substituted (nucleophilic substitution) by a -Cl group
Esters and acyl chlorides can also be classed as derivatives of carboxylic acids, due to having the same C = O ( carbonyl group). In acyl chlorides the -OH group has been substituted (nucleophilic substitution) by a -Cl group
amides - comparison with esters and acyl chlorides
amides - comparison with esters and acyl chlorides
amides
amides
When naming amides remove the -oic of the corresponding carboxylic acid and add amide to the end of the hydrocarbon, for example if the amide has 4 carbons in the chain then the name would be butanamide.
When naming amides remove the -oic of the corresponding carboxylic acid and add amide to the end of the hydrocarbon, for example if the amide has 4 carbons in the chain then the name would be butanamide.
In a primary amide the functional group is at the terminal carbon so it does not need to be numbered. However any branches would need to be numbered in relation to the functional group being C # 1, as shown below.
In a primary amide the functional group is at the terminal carbon so it does not need to be numbered. However any branches would need to be numbered in relation to the functional group being C # 1, as shown below.
amides - reactions
amides - reactions
From thermal decomposition of the ammonium salt of a carboxylic acid
From thermal decomposition of the ammonium salt of a carboxylic acid
Hydrolysis of amides with acid or base
Hydrolysis of amides with acid or base
Polymerisation forming polyamides, such as nylon and kevlar
Polymerisation forming polyamides, such as nylon and kevlar
amides - review of the amide link
amides - review of the amide link
When this link forms between 2 peptides, creating a dipeptide then the amide link is called a peptide link.
When this link forms between 2 peptides, creating a dipeptide then the amide link is called a peptide link.
Dipeptides form between amino acids in biological systems.
Dipeptides form between amino acids in biological systems.
The amide link and the peptide link are the same chemically.
The amide link and the peptide link are the same chemically.
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