Chapter 27 Amines, Amino Acids And Polymers Flashcards
What is an amine?
An organic compound derived from ammonia where one or more of the H atoms are replaced by Carbon chains or rings
What is a primary amine?
Where one H atom attached to the Nitrogen is replaced by a carbon chain
What is a secondary amine?
Where two H atoms attached to the Nitrogen are replaced by Carbon chains
What is a tertiary amine?
Where three hydrogen atoms attached to the Nitrogen are replaced by three Carbon chains
What is an aliphatic amine?
The Nitrogen atom is attached to at least one straight/ branched carbon chain or non aromatic ring
What is an aromatic amine?
The Nitrogen is attached to a benzene ring
Why are amines able to act as bases?
Because they can accept a proton/ H+ ion using the lone pair of electrons on the Nitrogen atom to form a dative covalent bond
What is the base reaction of an amine?
Amines will accept a proton to form an alkyl ammonium ion
How are amines able to form salts?
Amines neutralise acids in order to form salts by accepting a proton
State the name of the ion formed in this base reaction
CH3CH2NH2 + H+ —->
CH3CH2NH3+
Ethylammonium
State the name of the salt formed in the neutralisation reaction of
2CH3CH2NH2 + H2SO4 ——>
(CH3CH2NH3+)2 SO4^2-
Ethylammonium sulfate
Describe how aliphatic amines can be prepared
A haloalkanes is reacted with excess ammonia in ethanol
A nucleophilic substitution reaction will take place as NH3 acts as a nucleophile by donating lone pair of electrons to the slightly positive C atom of the C—X (halogen) bond causing it to break by heterolytic fission
State the equation for the preparation of ethyl amine
C2H5Cl + 2NH3 —-> C2H5NH2 + NH4+Cl^-
The lone pair of electrons on NH3 is donated to the slightly positive Carbon atom so the C—Cl bond breaks by heterolytic fission
Nucleophilic substitution
Why is ethanol used when preparing aliphatic amines?
To prevent water reacting with the haloalkane instead because the O in water also has a lone pair of electrons which could act the same as the Nitrogen lone pair in NH3
Why is excess ammonia used when preparing aliphatic amines?
To prevent further substitution of secondary and tertiary amines
How can aromatic amines be prepared?
Reducing a nitroarene by refluxing with tin and concentrated HCl followed by NaOH
State the equation for the preparation of phenylamine
C6H5NO2 + 6[H] —> C6H5NH2 + 2H2O
What is an amide?
A derivative of a carboxylic acid where the hydroxyl group has been replaced with ammonia/ amine
How can amides be prepared?
1- Reacting ammonia or amine with acyl chloride
2- Reacting ammonia or amine with acid anhydride
What are alpha amino acids?
Contain an amine group and a carboxylic acid group bonded to the same Carbon atom
What is the general formula of alpha amino acids?
RCH(NH2)COOH
State the simplest alpha amino acid?
Glycine- the variable R group is H
What type of isomerism can all alpha amino acids show?
All alpha amino acids except glycine can show:
Optical isomerism because they have a chiral carbon.
What is a chiral carbon?
A carbon atom bonded to 4 different atoms or groups of atoms
Within an alpha amino acid how can the NH2 group(s) react?
The NH2 group can react with acids as the lone pair on the Nitrogen atom can accept a proton to form an ammonium ion NH3+
Within an alpha amino acid how can the COOH group(s) react?
The COOH group can react with bases donating its H+ ion to form a carboxylate ion (COO-)
How do alpha amino acids react to form esters?
Alpha amino acids react with an alcohol in the presence of concentrated sulfuric acid and heat to produce an ester and water
What is optical isomerism?
A type of stereoisomerism that forms non super imposable images about a chiral centre
What are the features of an optical isomer?
They are non superimposable mirror images of each other
For each chiral centre there are 2 possible isomers
What are the optical isomers referred to as?
Enantiomers this is because they are compounds with the same structural formula but have an arrangement of atoms and groups that cannot be placed one over the other.
State the equation that can be used to calculate the total number of optical isomers possible
2^Number of chiral centres
Eg, 2 chiral centres is 2^2 = 4 isomers
Describe the stages used to draw the 3D representation of an optical isomer
Identify the chiral centre
Draw the empty tetrahedral molecule with the C at the centre
Position the atoms and groups around the carbon
Mirror the drawing
Describe the stages of drawing an optical isomer which has two chiral centres
This means there will be 4 different isomers:
Firstly mirror both chiral centres
Then mirror the top chiral centre only
Finally mirror the bottom chiral centre only
What is condensation polymerisation?
The reaction between two monomers to produce a polymer together with the loss of a small molecules such as water or HCl
What is a primary amide?
An amide where the Nitrogen is directly bonded to one carbon atom only
What is a secondary amide?
An amide where the Nitrogen is directly bonded to 2 carbon atoms
What is a tertiary amide?
An amide where the nitrogen is directly bonded to 3 carbon atoms
How can primary amides be formed?
Acyl chloride is reacted with ammonia
Acid anhydride is reacted with ammonia
How can secondary amides be formed?
Acyl chloride is reacted with a primary amine
Acid anhydride is reacted with a primary amine
How can tertiary amides be formed?
Acyl chloride is reacted with a secondary amine
Acid anhydride is reacted with a secondary amine
What are enantiomers?
Chiral molecules that can exist in different forms, different enantiomers rotate plane polarised light in opposite directions
What is racemate?
Racemate refers to a mixture that contains equal amounts of two enantiomers which are mirror images of each other.
State the different functional groups which can carry out condensation polymerisation
Esters and water produced from a carboxylic acid and alcohol
Amides and water produced from a carboxylic acid and amine
Name the two monomers that are able to produce a polyester
A Dicarboxylic acid monomer reacting with a diol
A hydroxycarboxylic acid
Name the two monomers able to produce a polyamide
A Dicarboxylic acid reacting with a diamine
An amino acid produces a polypeptide
What is Terylene?
A polyester which is produced from:
Benzene-1,4-Dicarboxylic acid and Ethane-1,2-diol to produce Terylene polyester and (2n-1) H2O
What is Nylon-6,6?
A polyamide made from:
Hexanedioc acid and Hexane-1,6-diamine to produce Nylon-6,6 and (2n-1) H2O
What is Kevlar?
A polyamide made from Benzene-1,4-Dicarboxylic acid and 1,4-diaminobenzene to produce Kevlar and (2n-1) H2O
What are the conditions needed to hydrolyse polyesters?
Hot aqueous acid or base is needed
Name the products which are formed from the acid hydrolysis of a polyester?
Dicarboxylic acid
Diol
Name the products which are formed from the base hydrolysis of a polyester?
A dicarboxylate ion/ salt will be formed depending on whether just OH- ions are specified or NaOH because the acid donates proton
A diol will be formed
What are the conditions needed to hydrolysis a polyamide?
Hot aqueous acid or alkali
State the products which are formed from the acid hydrolysis of a polyamide?
A Dicarboxylic acid
Diammonium salt (NH3^+) formed because the amine acts as a base accepting the proton from the acid
State the products which are formed from the alkali hydrolysis of polyamides?
A dicarboxylate ion/ salt is formed depending on whether just OH- ions are specified or NaOH because the acid donates its proton
Diamine if formed
What is addition polymerisation?
The formation of a long saturated polymer chain by the repeated addition of many unsaturated alkene monomers where the 𝛑 bond of the C=C breaks as it has a lower bond enthalpy than σ bonds.
What are the pharmaceutical advantages of using single stereoisomers?
Half the dosage required if racemate mixture consists of a benign optical isomer
Reduce the risk of undesirable side effects
Reduce cost
Increase level of effectiveness
Name the techniques that can be used to separate the isomers?
-Enzymes
-Electrophoresis
-Chromatography
What are the disadvantages of separating isomers?
Costly
Time consuming
