Chemistry- Amines and Amides Flashcards
Why is NH3 soluble in water?
Can form many hydrogen bonds with the lone pair and the 3 hydrogen atoms.
What is the structure of a primary Amine?
RNH2
What is the structure of a secondary Amine?
R2NH
What is the structure of a tertiary Amine?
R3N
What is the structure of a Quaternary Amine?
R4N^+
Uses the lone pair in a dative covalent bond and therefore becomes positively charged.
How do you name an Amine?
- Name Hydrocarbon Alkyl group first
- Add amine as suffix
Eg. methyl amine
What is the boiling point of a molecule about?
in terms of intermolecular forces
Boiling point is about the intermolecular forces between molecules that are the same.
What is solubility of a molecule about?
in terms of intermolecular forces
Solubility is about intermolecular forces between molecules and water.
What is the boiling point trend for Primary Amines?
Longer the R-group the higher the boiling point due to more van der waals forces between them.
What is the boiling point trend for Primary Amines and Alkanes of similar size?
Primary amines have a greater boiling point to an alkane as primary amines can produce van der waals and hydrogen bonds between each amine molecule and alkanes only have van der waals.
What is the trend in boiling points between primary, secondary and tertiary amines?
Although the secondary and tertiary amines may be of similar size, branched molecules will have a lower boiling point as there are fewer van der waals forces since the chains of R-groups are not as straight/ long.
Define a Bronsted-Lowry Base
A Proton acceptor
Define a Lewis Base
An electron pair donor.
What is formed when a Phenylamine reacts with an acid?
Forms a Water soluble ionic salt
What happens when an aromatic amine ionic salt reacts with sodium hydroxide (OH- ions)?
The water soluble ionic salt is regenerated back and forms the insoluble amine.
Put in order of reactivity ammonia, primary amine and an aromatic amine.
Most: Primary amine
Ammonia
Least: Aromatic amine
Why are primary amines more reactive than ammonia?
Primary amines have a lone pair which is more easily available to make a bond, due to R-groups having and “inductive effect” where the alkyl group can release electrons towards the nitrogen atom. Ammonia does not have alkyl groups and therefore is less able to use its lone pair in a bond.
Why are aromatic amines less reactive than other amines?
The lone pair of the nitrogen atom becomes part of the delocalised system of electrons when next to an aromatic ring. This makes the molecule more stable but a LESS GOOD BASE as the lone pair of electrons are no longer available to be used instantaneously.
Why are secondary amines more reactive than primary amines?
They are more reactive than a primary amine due to having more R-groups bonded to the nitrogen atom. This means that there is a higher “inductive effect” as more alkyl groups are releasing electrons to the nitrogen atom and therefore the lone pair is more easily able to be used in a bond.
Why are tertiary amines less reactive?
Less reactive as they are not soluble and therefore do not as easily react.
What is one method of making amines from ammonia?
ammonia reacting with a haloalkane
Via Nucleophilic substitution.
What is produced when ammonia reacts with a haloalkane?
A Primary Amine
What are the products when ammonia reacts with a haloalkane which is in excess?
Primary Amine
Secondary Amine
Tertiary Amine
Quaternary Amine
(All produced if haloalkane is in excess)
Once the first primary amine is formed, this can react again with the excess of haloalkane as the primary amine can act as a nucleophile and therefore will produce a secondary amine. The process will repeat until a Quaternary amine is produced or the haloalkane is not in excess.
How is an amine produced from a Haloalkane and KCN?
Haloalkane + KCN —-> Nitrile
This can be reduced to form the amine.
Eg. Bromoethan + KCN —> Propane nitrile
Nitrile + [H] —> Amine
What are the Reducing agents and conditions for a nitrile to an amine?
- LiAlH4 in ether ---> then add dilute acid! Or - Using Hydrogen (Hydrogenation) H2/Pd (paladium catalyst better) H2/Ni (nickle Catalyst) High temperature and pressure
How are Aromatic Amines produced?
From Nitrobenzene —-> Reduction to phenyl amine.
What are the conditions of reduction needed to form an aromatic amine?
Sn(Tin)/HCl @ room temperature
Which way of producing amines is more efficient and why?
From Nitriles (Haloalkane + KCN) This reaction only produces one product where as haloalkanes reacting with ammonia produces a mixture of primary, secondary, tertiary and quaternary amines.
What are amines used for?
- Manufactor of synthetic materials (nylon, drugs ,dyes)
- Cationic Surfactants ( Hair and fabric conditioners)
