PL lnop: Amines, amides, acyl chlorides, nylons Flashcards
What are amines?
Ammonia where at least one hydrogen is substituted for an alkyl group.
- Name the following molecules:
- CH3NH2
- C2H5NH2
- CH3CH2CH2NH2
- What type of molecule are they?
- Methylamine
- Ethylamine
- 1-aminopropane/propylamine
- Primary amines
- Name CH3CH(NH2)CH3
- What type of molecule is it?
- 2-aminopropane / methyl ethylamine
- Primary amine
- Name CH3NHCH3
- What type of molecule is it?
- Dimethylamine
- Secondary amine (2 Hs replaced by alkyl groups)
- Name CH3N(CH3)CH3
- What type of molecule is it?
- Trimethylamine
- Tertiary amine (3 Hs replaced by alkyl groups)
- Name NH2CH2NH2
- What type of molecule is it?
- Methanediamine
- Diamine
- Name the following molecules:
- NH2CH2CH2NH2
- NH2CH2CH2CH2CH2CH2CH2NH2
- What type of molecule are they both?
- Ethanediamine
- 1,6-diamino-hexane
- Diamines
Why do amines have the following properties?
- Soluble in water
- Act as bases
- Nitrogen atom has a lone pair of electrons
- So amines can engage in hydrogen bonding with water
- Lone pair accepts H+, forming a dative covalent bond
Bonding around N similar to that of ammonia
Explain why amines with longer alkyl groups are less soluble in water.
(For larger alkyl groups:)
Enthalpy change of breaking water-water hydrogen bonds >
enthalpy change of forming intermolecular forces between alkyl group + water
and hydrogen bonds between water + lone pair on N
Give the equation for the reaction between 2-aminopropane and water.
CH3CH(NH2)CH3 + H2O → CH3CH(NH3+)CH3 + OH-
Amines act as H+ acceptors
Explain why amines react more strongly with acids than with water.
- Lone pair on N partakes in dative covalent bonding, accepting a H+ (acting as a base)
- H3O+ ions are more powerful proton donors than water
Write the equation for the reaction of 2-aminopropane and hydrochloric acid.
CH3CH(NH2)CH3 + HCl → CH3CH(NH3+Cl-)CH3
Write the symbol and word equation for the reaction of ethylamine with an acid.
CH3CH2NH2 (aq) + H3O+(aq) → CH3CH2NH3+(aq) + H2O(l)
Ethylamine + hydronium ion → ethylammonium ion + water
- What are primary amides?
- Give their general formula
- Draw their general structural formula
- Carboxylic acid derivatives where the OH group is substituted by NH2
- RCONH2
- How do you name primary amides?
- Name CH3CONH2
- Replace the “e” on the end of the alkane with “amide”
- Ethanamide
- What are secondary amides?
- Give their general formula
- Draw their general structural formula
- Carboxylic acid derivatives where the OH group is replaced by NHR’
- RCONHR’
- How do you name secondary amides?
- Name CH3CONHCH3
- RCONH2R’
- Name in format: N-R’ Ramide, i.e. N-_yl _amide
- N-methyl ethanamide
What are acyl chlorides?
Give their general formula.
Carboxylic acid derivatives where the OH is substituted for chlorine.
RCOCl or CnH2n+1COCl
Name this molecule.
Ethanoyl chloride
Name this molecule:
CH3CH2CH2COCl
Butanoyl chloride
All of the reactions below occur via the same mechanism. Using an amine and acyl chloride, draw the mechanism. State what it is called.
- Amines + acyl chlorides
- Amides + acyl chlorides
- Alcohols + acyl chlorides
- Carboxylic acids + acyl chlorides
- Condensation polymerisation, forming:
- Polyesters
- Polyamides (nylons)
- Polypeptides
Could include intermediate step in which H donates pair of electrons to N+ in NH3, so that it then deprotonates
Write an equation for the reaction between 2-aminopropane and ethanoyl chloride.
Draw: nucleophilic substitution
CH3CH(NH2)CH3 + CH3COCl → CH3CONH(CH3)2 + HCl
Suggest and explain which of amines and amides react with acyl chlorides.
- Would react by nuc attack of δ+ carbon in acyl chloride
- Amines react. Amides do not because C=O group pulls e- away, making them poorer nucleophiles
- What type of molecule is formed when acyl chlorides react with amines?
- What mechanism occurs?
- What type of reaction occurs?
- Secondary amide
- Nucleophilic substitution
- Condensation reaction
Acyl chlorides react vigorously with alcohols.
- What type of mechanism occurs?
- What is produced?
- What type of reaction occurs?
- Nucleophilic substitution
- Esters (RCOCl + R’OH → RCOOR’ + HCl)
- Condensation reaction
- What are polyamides?
- What is the other name for them?
- Polymers where monomer links are secondary amide groups
- Nylons
- In what 2 ways can polyamides be made?
- Which method is quicker?
- Diamine + either dicarboxylic acid or diacyl dichloride
- Diacyl chlorides react more quickly because Cl- is stabler in solution than OH-, so is better leaving group
- Diacyl dichloride = symmetrical molecules where both ends are COCl*
- Stability in solution: Cl- ions > carboxylate ions > OH- ions*
- Explain why 1,6-diaminohexane and hexanedioic acid can undergo polymerisation
- Which type of polymerisation would occur?
- Draw the repeating unit for this polymer
- What type of polymer is this?
- Both molecules have reactive groups in 2 places (amine and carboxyl)
- Condensation polymerisation
- A polyamide (nylon)
How are nylons named?
- According to the number of carbons in monomers
- If one monomer with 6 Cs was used, it would be nylon-6
- If two monomers, with 5 and 6 Cs, were used, it would be nylon-5,6
- Write an equation to show the polymerisation of 1,6-diaminohexane and decanedioyl chloride
- Name the polymer formed
- Name this polymer
- Explain how it was formed
–(NH(CH2)5CO)–n
- Nylon-6
- Made from a single monomer containing both an amine and COOH / COCl group: nH2N(CH2)5COOH / nH2N(CH2)5COCl
Name the mechanism that occurs during:
- Condensation polymerisation
- Addition polymerisation
- Nucleophilic substitution
- Electrophilic addition
Draw the repeating unit of the polymer that can be obtained from 3-aminobenzoic acid.
Draw a mechanism representing the formation of polypropene.
