Module 6: Chapter 27 (Amines, Amino Acids and Polymers) Flashcards
What are amines?
Organic compounds based on ammonia where 1 or more ammonia H-atoms have been replaced by a carbon chain or ring
What are aliphatic amines?
Have straight or branched carbon chains, or non aromatic rings joined to the N-atom e.g. H-(H-)N-CH3
What are aromatic amines?
Have at least one aryl group (aromatic ring) attached to the N-atom, e.g. a benzene ring
What is the ammonia molecule?
NH3
- pyramidal
- bond angle of 107 degrees (lone pair repels more than the bonded pairs)
What is a primary amine?
An organic compound with an N atom bonded to 1 alkyl or aryl groups
What is a secondary amine?
An organic compound with an N atom bonded to 2 alkyl or aryl groups
What is a tertiary amine?
An organic compound with an N atom bonded to 3 alkyl or aryl groups
How do you name primary amines when the -NH2 is at the END of the chain?
Alkyl group as the prefix and “-amine” as the suffix
What is the systematic name for CH3NH2?
Methylamine
What is the systematic name for CH3CH2CH2NH2?
Propylamine
What is the systematic name for C6H5NH2?
Phenylamine
How do you name primary amines when the -NH2 is NOT at the end of the chain?
‘placement of NH2 in carbon chain - amino’ as the prefix and the name of the longest carbon chain as an alkane as the suffix
What is the systematic name for CH3CH2CH(NH2)CH3?
2-aminobutane
What is the systematic name for H2NCH2CH2CH2CH2NH2?
1,4-diaminobutane
What is the systematic name for CH3CH2CH(NH2)CH2NH2?
1,2-diaminobutane
How do you name secondary amines with one -NH group?
Di-alkyl group as prefix and then ‘amine as suffix
How you name tertiary amines with one N?
Tri-alkyl group as a prefix and then ‘amine’ as a suffix
What is the systematic name for (CH3CH2CH2)2N-H?
Dipropylamine
What is the systematic name for (C6H5)2N-H?
Diphenylamine
What is the systematic name for (CH3CH2CH2)3N?
Tripropylamine
What is the systematic name for (C6H5)3N?
Triphenylamine
How do you name secondary and tertiary amines with mixed R groups?
- giving the longest carbon chain the suffix of amine (e.g. propylamine)
- giving the shorter chain(s) as N-prefix in alphabetical order (e.g. N-ethyl-N-methyl)
N-ethyl-N-methylpropylamine
What is the ionic equation of ammonia being added to an acid?
NH3 + H+ -> NH4+
What is the shape of an ammonium ion?
Tetrahedral
109.5 bond angle
Why are amines useful bases?
The lone pair of electrons on the N atom can be used to accept protons (proton acceptors)
Show the reaction of methylamine and hydrochloric acid?
CH3NH2 + HCl -> CH3NH3+Cl-
methylammonium chloride is made (a salt)
Show the reaction of dimethylamine and sulfuric acid?
2(CH3)2NH2 + H2SO4 -> ((CH3)2NH3+)2SO4^2-
dimethylammonium sulfate is formed (salt)
Show the reaction of 1,2-diaminoethane and nitric acid (in excess)?
NH2CH2CH2NH2 + HNO3 -> NO3^-(+H3NCH2CH2NH3+)NO3^-
1,2-diammoniumethane dinitrate
How do you make primary amines?
Ammonia can react as a nucleophile to replace the halogen on a haloalkane with the -NH2 group
What is a nucelophile?
An electron pair DONOR
What are the two steps in the formation of primary amines?
- Salt formation - add excess ammonia to the haloalkane in an alcohol solvent (“ethanolic ammonia”)
- Amine formation - add aqueous alkali (NaOH) to liberate the amine from the salt
Why is excess ammonia added to the haloalkane?
Excess NH3 helps prevent the amine product from reaching with more haloalkane molecules to form secondary and tertiary amines
How do you make a secondary amine?
React an excess of primary amine with a suitable haloalkane to add the second alkyl group
Then liberate the amine by adding aqueous alkali (NaOH)
Alcohol used here as a solvent
What are the 2 steps of making secondary amines?
CHH2N: -> partial positive dipole on the alkyl group chlorine of haloalkane, electrons move from bond to halogen with partially negative dipole -> makes a positively charged molecule and a negatively charged halogen
Add NaOH, removes the charges by removing one of the hydrogen atoms to form Na-M and water (M=halogen present)
What is phenylamine?
-NH2 attached to a benzene ring
How are aromatic amines made?
Reduction of nitroarenes
What are nitroarenes?
Have the nitro, -NO2, group attached to an aromatic ring
What is the equation for the reduction of an nitroarene?
nitrobenzene + 6[H] -> phenylamine + 2H2O
6[H] per nitrobenzene molecule
What are the reagents and conditions of the formation of aromatic amines?
reagents: tin metal(Sn) in concentrated hydrochloric acid Sn/HClconc.
conditions: heat under reflux
What are the steps for the formation of aromatic amines?
step 1: heat under reflux with Sn/HCl concentrated
step 2: add aqueous alkali to free the amine from its acid salt
What is the structure of an amide?
RCONH2
What’s the amide linkage?
-CONH-
What is a primary amide?
Only one C atom is directly bonded to the N
CONH2
What is a secondary amide?
2 C atoms directly bonded to the N
CONH
What is a tertiary amide?
3 C atoms bonded directly to the N
CON
What is the general formula for alpha amino acids?
H2CH(R)COOH
What does the carboxyl group in the amino acid do?
esterification and neutralisation reactions
loses -OH or just H
What does the amino group in the amino acid do?
Lone pair of electrons on the N
Can be a proton accept (base) = neutralisation
How do you name amino acids?
COOH group has highest priority so that carbon becomes first in the chain
NH2 amide group = amino
usually 2-amino(longest carbon chain)oic acid
any other alkyl groups or functional groups put into usual order in alphabetical order
What is the reaction of amino acids + acids?
Amino acids + acids -> ammonium salts
Amine group acts as a base (proton acceptor)
H2NCH2COOH + HCl ?
H2NCH2COOH + HCl -> Cl-+H3NCH2COOH
What is the reaction of amino acids + alkalis/bases?
amino acids + alkalis/bases -> salts
carboxylic acid acts as an acid
What is the reaction of amino acids + alcohols?
Amino acids + alcohol -> esters + H2O
carboxylic acid reacts
What if the alcohol reacting with the amino acid is in excess?
H+ ions react with NH2 to create NH3+
What is an amide?
Amides are made from the reaction of acyl chlorides with either ammonia or an amine
How is a primary amide formed?
Made by reacting excess concentrated ammonia with a suitable acyl chloride
e.g. ethanoyl chloride + 2NH3 -> CH3CONH2 + NH4+cl
How is a secondary amide formed?
Made by reacting excess primary amine with a suitable acyl chloride
How are tertiary amides formed?
are made by reacting excess secondary amine with a suitable
acyl chloride: CH3COCl + 2 (CH3)2NH -> CH3CON(CH3)2 + (CH3)2NH2+Cl
What are stereoisomers?
Have the same structural formula but a different arrangement of their atoms in space
includes E/Z isomerism and optical isomers
What must be present for optical isomers?
A chiral centre
What is a chiral centre?
Usually a carbon joined to 4 other different atoms or to 4 different groups of atoms
- any C atom with 2 or more identical groups will not be chiral
- no C involved in a triple or double bond, or in an aromatic ring can be chiral
Explain what is meant by condensation polymerisation
2 monomers join to produce a polymer with the loss of 1 small molecule
Explain what is meant by optical isomers
2 molecules that are super non-imposed mirror images
What is a polyester?
Polymer containing monomer units joined by ester linkages
What is meant by α-amino acid?
The amine group is attached to the carbon atom adjacent to the carboxyl group
Amine + acyl chloride?
AMIDE
What is meant by addition polymerisation?
No molecule is lost during polymerisation (2 monomers join to form a polymer, one product)
