Chapter 27: Amines, Amino Acids, and Proteins (27.1 - 27.3) Flashcards
Formula of ammonia
NH3
What are amines
Amines are an organic compound formed when one or more hydrogen atoms in ammonia has been replaced by a carbon chain or ring
What is an aliphatic amine
The nitrogen atom is bonded to at least one alkyl group (straight or branched carbon chain)
Simplest is methylamine, CH3NH2, with one methyl group attached to the nitrogen
What is an aromatic amine
Nitrogen atom is attached to an aryl group (aromatic ring)
Simplest is phenylamine, C6H5NH2, with a phenyl group attactehd to the nitrogen atom
How are amines classified
Primary: R-NH2. N at attached to 1 R group
Secondary: N attached to 2 R groups (and 1 H)
Tertiary: N attatched to 3 R groups
How do you make a polyester from one monomer?
The monomer must contain both a hydroxyl and a carboxyl group
Carboxylic acid reacts with alcohol, forming an Ester linkage and water
How are polyesters made from two monomers?
When one monomer is a diol and one is a dicarboxylic acid
A hydroxyl group reacts with the carboxyl group, forming an Ester link and water
What two ways can you make a polyamide From one monomer?
With an amino acid which has an amine group and a carboxylic acid - forms a Peptide bond and water
Monomer with an amine group and an acyl chloride - forms an Peptide bond and hydrogen chloride
Which two ways can you make a polyamide from two monomers?
Reacting a dicarboxylic acid with a diamine.
Reacting a diacyl chloride with a diamine
Why are polyamides and polyesters strong?
They will have hydrogen bonds between chains and they have very strong London forces as they are long and have lots of points of contact
How do you hydrolyse a polyester?
1) With hot aqueous alkali e.g NaOH and water - makes a dicarboxylate salt (COO-Na+) and a diol
2) With hot aqueous acid e.g HCl and water - makes a diol and a dicarboxylic avid
How do you hydrolyse a polyamide?
NaOH and water - makes a diamine and a dicarboxylate salt (COO-Na+)
H+/H2O - makes a dicarboxylic acid and a compound with an NH3+ group on either end
how do amines behave as bases
The lone pair of electors on the N atom accepts a proton
A dative covalent bond forms between the lone pain of the N atom and the H+
amine + acid –>
amine + acid –> salt
amines neutralise dilute acids to form salts
eg CH3CH2NH2 + HCl –> CH3CH2NH3+Cl-
aliphatic amines are prepared by:
1) substitution of haloalkanes with excess ethanoic ammonia to form a salt:
CH3CH2Cl + NH3 –> CH3CH2NH3+Cl-
2) Add base
CH3CH2NH3+CL- + NaOH —> CH3CH2NH2 +NaCl +H2O
the use of ethanol in the preparation of aliphatic amines
Ethanol is a solvent, used to prevent substitution of the haloalkane by water to produce alcohols
Aromatic amines are prepared by:
1) reduction of nitroarenes by refluxing with tin and concentrated hydrochloric acid
what is an amino acid?
an organic compound containing both amine (NH2) and carboxylic acid (COOH) functional groups.
Because they contain both an acidic COOH and a basic NH2 functional group, amino acids have similar reactions to both carboxylic acids and amines
what is an α-amino acid? (alpha-amino)
an amino acid with the NH2 and COOH groups attached to the same α-carbon atom
NH2-CH(R)-COOH
[ normally written as RCH(NH2)COOH ]
amino acid reaction with alkalis
COOH group reacts with aqueous alkali to form salt and water
H2N-CH2-COOH + NaOH –> H2N-CH2-C(O)O-Na+ + H2O
esterification of amino acids
COOH group can be esterified by heating with an alcohol with a concentrated H2SO4 catalyst
The acidic conditions protanone the basic NH2 to form -NH3+
H2N-CH2-COOH + C2H5OH + H+ –> H3N+-CH2-COOC2H5 + H2O
amino acids reaction with acids
NH2 groups neutralise an acid to form a salt.
eg reaction with HCl would change NH2 group to NH3+ and leave a Cl- ion
how are amides classified
Primary: 1 carbon atom bonded to N
Secondary: 2 carbon atoms bonded to N
Tertiary: 3 carbon atoms bonded to N
Two types of stereoisomers?
2 types: optical and E/Z
optical isomerism
Found in molecules that contain a chiral centre
- a chiral carbon atom is attached to 4 different atoms or groups of atoms, often labelled with an asterisk * in diagrams
- optical isomers are when the 4 groups attached to the chiral carbon are arranged in space as two non-superimposable mirror images
- each chiral carbon atom in an organic molecule has one pair of optical isomers
why do α-amino acids have optical isomers
all α-amino acids (except glycine H2NCH2COOH) contain a chiral carbon atom
what is an amide?
R-CO-N(R’)-R’’
organic compounds that are derivatives of carboxylic acids
Why might a polymer not have the same Mr as expected?
It is likely that the polymer has 2 groups on it which can react together to form a ring
If you want one optical isomer from a synthesis what method should you use?
1) use enzymes or bacteria
2) Chiral catalyst
