Amines Flashcards

Amines

A-Level AQA Chemistry

This pack of flashcards covers the chemistry of amines, including their nomenclature, basicity, and reactions with acids, halogenoalkanes, and acyl chlorides. It also discusses the preparation of primary, secondary, and tertiary amines, quaternary ammonium salts, and the role of excess reactants in synthesis reactions.

Export

This text is tab separated and can be imported into various flashcard apps.

What are the base properties of primary aliphatic amines?	Primary aliphatic amines act as Bronsted-Lowry bases and readily accept a proton due to the lone pair of electrons on the nitrogen.
Compare the base strength of primary amines and ammonia.	Primary amines are stronger bases than ammonia due to the electron-releasing effect of alkyl groups, which makes the lone pair of electrons on the nitrogen more readily available.
Why are secondary amines stronger bases than primary amines?	Secondary amines have more alkyl groups substituted onto the nitrogen atom, which increases the electron density on the nitrogen atom and makes them stronger bases.
Why are tertiary amines and corresponding ammonium salts less soluble in water?	Tertiary amines and corresponding ammonium salts are less soluble in water, making them less strong bases than secondary amines. This point will not be examined.
Why do primary aromatic amines not form basic solutions?	Primary aromatic amines do not form basic solutions because the lone pair of electrons on the nitrogen delocalizes with the ring of electrons in the benzene ring, making the nitrogen less able to accept protons.
What is the overall order of base strength for amines?	Aromatic amines < ammonia < primary amines < tertiary amines < secondary amines.
What happens when amines react with acids?	Amines react with acids to form ammonium salts.
How can a basic buffer be made from an amine?	A basic buffer can be made by combining a weak base with a salt of that weak base, such as ammonia and ammonium chloride or methylamine and methylammonium chloride.
Describe the process of forming a primary amine in a one-step reaction of halogenoalkanes with ammonia.	The nucleophilic substitution reaction between halogenoalkanes and ammonia in a one-step reaction forms primary amines.
What are the potential further reactions that can occur when a primary amine is formed?	Primary amines can react in a successive series of reactions forming secondary, tertiary amines, and quaternary ammonium salts.
Why is the reaction between halogenoalkanes and ammonia not a good method for making a primary amine?	The further reactions that can occur would require the desired product to be separated from the other products.
How can the further subsequent reactions be limited in the formation of primary amine?	Using an excess of ammonia can limit the further subsequent reactions and maximize the amount of primary amine formed.
Describe the mechanism of the reaction between halogenoalkanes and ammonia to form a primary amine.	In the first step, the nucleophile attacks the halogenoalkane to form an intermediate. In the second step, a second ammonia removes a proton from the intermediate to form the primary amine.
What is the role of ammonia or the primary amine in the second step of the mechanism?	In the second step, either ammonia or the primary amine can remove a proton from the intermediate to form the amine.
Describe the reaction mechanism for the formation of a tertiary amine from a secondary amine.	The same reaction mechanism occurs with the secondary amine reacting to form a tertiary amine.
Describe the overall scheme of reactions for forming a quaternary ammonium salt.	The overall scheme involves reacting a halogenoalkane (RX) with excess ammonia to form a primary amine, and then reacting the primary amine with excess RX to form the quaternary ammonium salt.
Define quaternary ammonium salt.	A quaternary ammonium salt is a compound that contains a positively charged nitrogen atom (quaternary ammonium ion) and is often used as a cationic surfactant.
How do quaternary salts function as surfactants?	Quaternary salts reduce the surface tension of liquids and are attracted to negatively charged surfaces, making them useful in fabric softeners, hair conditioners, and sewage flocculants.
Describe the two-step reaction scheme for preparing amines from nitriles.	Step 1: React halogenoalkane with KCN in aqueous ethanol to form nitrile. Step 2: Reduce the nitrile to amine using LiAIH4 in ether or by reducing with H2 using a Ni catalyst.
What is a disadvantage of the two-step reaction for preparing amines from nitriles?	The two-step reaction may have a low yield.
What is the product of reducing nitrobenzene?	The product of reducing nitrobenzene is phenylamine.
What type of reaction occurs when aliphatic amines and phenylamine react with acyl chlorides and acid anhydrides?	A nucleophilic addition-elimination reaction occurs.
What is the change in functional group when reacting acyl chlorides with primary amines?	The change in functional group is from acyl chloride to secondary amide.
What is the change in functional group when reacting acid anhydrides with primary amines?	The change in functional group is from acid anhydride to secondary amide.

Click to copy

Combining packs is currently only available to subscribers.

Print Flashcards

Print Type

Single sided

Double sided

Single Sided - Each row displays the front of a card on the left and its back on the right. Cut along rows, fold at the center, and glue together.

Double Sided - Card fronts are on one page and their corresponding backs on the next. After cutting, the backs match up with their respective fronts.

Rows Per Page

2345678910

1 / 24

Options

Study Mode

Flashcards

Exam

Arrange Cards

Chronological

Random

Share this pack