3.3.11 Amines Flashcards
Explain why phenylamine is a weaker base than methylamine.
Phenylamine’s lone pair on nitrogen is delocalized into the benzene ring.
Lone pair on N is less available in phenylamine
What is the reagent and condition required to reduce nitrobenzene to phenylamine?
Sn (tin) and concentrated HCl (under reflux).
Describe how primary amines are formed from halogenoalkanes.
Primary amines are formed when excess ammonia reacts with haloalkanes
Why is methylamine a stronger base than ammonia?
The methyl group in methylamine is electron-donating (positive inductive).
Increasing the availability of the lone pair on the nitrogen atom.
What is the type of reaction involved in the formation of quaternary ammonium salts?
Nucleophilic substitution.
State why the reaction of bromoethane with ammonia forms a mixture of products.
Ammonia reacts in multiple steps, leading to the formation of primary, secondary, and tertiary amines, as well as quaternary ammonium salts.
Give the name and use of the product formed when a large excess of bromoethane reacts with ammonia.
The product is a quaternary ammonium salt, used as a cationic surfactant/hair conditioner/fabric softener.
What is the role of quaternary ammonium salts in commercial products?
Quaternary ammonium salts act as cationic surfactants.
OR
Used in hair conditioner/fabric softener.
What is the IUPAC name of CH3CH2CH2NH2?
The IUPAC name is butylamine
Why are amines considered nucleophiles?
Amines act as nucleophiles due to the lone pair of electrons on the nitrogen atom.
Compare the base strength of ammonia, ethylamine, and phenylamine.
Ethylamine is the strongest base, followed by ammonia, and phenylamine is the weakest.
Write an equation for the reaction of methylamine with water.
CH3NH2 + H2O ⇌ CH3NH3+ + OH−
Explain how the reaction conditions can be modified to reduce contamination in amine synthesis.
Using an excess of ammonia minimizes the formation of secondary and tertiary amines.
What is the reason for the higher reactivity of 1-iodobutane compared to 1-chlorobutane in nucleophilic substitution?
The C–I bond is weaker than the C–Cl bond due to lower bond enthalpy, making 1-iodobutane more reactive.
What is the use of aromatic amines in the chemical industry?
Aromatic amines are used to make dyes.
Name the compound formed by the reaction of CH3NH2 with CH3Br in a 1:1 ratio.
The compound formed is (N,N)-dimethylammonium bromide.
Outline a three-step synthesis of ethylamine starting from methane.
Step 1: Free Radical Substitution to turn methane into chloromethane (CH3Cl).
Step 2: Nucleophilic substitution with KCN to form ethanenitrile (CH3CN).
Step 3: Reduction with H2 with a Ni catalyst to form ethylamine (CH3CH2NH2).
Write an equation for the reaction of ammonia with 1,6-dibromohexane.
2NH3 + Br(CH2)6Br → NH2(CH2)6NH2 + 2HBr
Describe the reduction of nitriles to form primary amines.
H2 gas with a Ni catalyst (high temperature and pressure)
Explain the difference in basicity between ammonia and butylamine.
Butylamine is a stronger base than ammonia because the alkyl group donates electrons
Increasing the nitrogen’s electron density/makes the lone pair on N more available
State the role of tin and hydrochloric acid in the preparation of phenylamine.
Tin and hydrochloric acid reduce the nitro group (NO2) to an amine (NH2).
Give the formula of the cation formed when methylamine reacts with a large excess of bromoethane.
The formula is [CH3N(CH2CH3)3]+
Give the name and classification (either primary, secondary, tertiary or quaternary) for this amine
Butylamine
Primary amine
Give the name and classification (either primary, secondary, tertiary or quaternary) for this amine
Ethylamine
Primary amine
Give the name and classification (either primary, secondary, tertiary or quaternary) for this amine
(N)-ethyl-(N)-methyl amine
Secondary amine
Give the name and classification (either primary, secondary, tertiary or quaternary) for this amine
(N,N)-Diethyl amine
Secondary amine
Give the name and classification (either primary, secondary, tertiary or quaternary) for this amine
(N,N,N)-Triethyl amine
Tertiary amine
Give the name and classification (either primary, secondary, tertiary or quaternary) for this amine
(N)-ethyl-(N)-methyl-(N)-propyl amine
Tertiary amine
Give the name and classification (either primary, secondary, tertiary or quaternary) for this amine
(N,N,N,N)-Tetramethyl ammonium chloride
Give the name and classification (either primary, secondary, tertiary or quaternary) for this amine
(N,N,N,N)-Tetraethyl ammonium bromide
Name the mechanism for the reaction of ethylamine with ethanoyl chloride.
The mechanism is nucleophilic addition-elimination, forming an amide.
Methylamine reacts with bromoethane by nucleophilic substitution to produce a mixture of products.
Which of these molecules is not a possible product of this reaction?
C - [(C2H5)2N(CH3)2]+ Br–
Aqueous solutions of ammonia, ethylamine and phenylamine are prepared.
Each solution has the same concentration.
Which is the correct order for the pH values of these solutions?
C - ethylamine > ammonia > phenylamine
What is the skeletal formula of the main organic species formed in the reaction between a large excess of 2-bromopropane and ammonia.
Write an equation for this reaction. Use [H] to represent the reducing agent.
