Amines Flashcards
What is an amine?
A molecule in which nitrogen is bound to one, two or three organic groups(amines are derivatives of ammonia)
Alkaloids are….
An important group of biologically active amines
Why do plants synthesize alkaloids?
To protect them from being eaten by insects or other animals
Many drugs if addiction are classified as ….
Alkaloids
Give examples to describe the biological activity of amines
Dopamine is a neurotransmitter
Epinephrine is a bio regulator
Niacin, vitamin b6, is an amine
Alkaloids: nicotine, morphine, cocaine
Amino acids
Describe each class of amines
Primary- has one alkyl group bonded to nitrogen (RNH2)
Secondary- has two alkyl groups bonded to the nitrogen (R2NH)
Tertiary- has 3 alkyl groups bonded to the nitrogen(R3N)
Quartenary- has 4 alkyl groups bonded to the nitrogen and nitrogen bears a positive charge (R4N+)
Describe aromatic amines
The amino group is bonded to a benzene ring
What is the parent compound called of an aromatic amine?
Aniline
What are heterocyclic amines?
Compounds in which the nitrogen atom occurs as part of a ring
The Herero lyric nitrogen is always numbered as…
Position 1
Describe the structure of amines
Nitrogen is sp3 hybridized with a lone pair of electrons
The angle is less than 109.5 degrees
Compare the boiling point of amines to corresponding alcohols and ethers and give a reason for the
Nitrogen is less electronegative than oxygen so N-H is less polar than O-H.
This causes amines to have weaker hydrogen bonds than corresponding alcohol but amines have higher boiling points than those of the corresponding ether
Why do tertiary amines have a lower boiling point than primary and secondary amines?
Tertiary amines cannot hydrogen bond so they have lower boiling points than primary and secondary amines
Describe the hydrogen bonding activity in primary, secondary and tertiary amines
Primary and secondary- hydrogen bond donor or acceptor
Tertiary- hydrogen bond acceptor only
Describe the odor of amines
Most amines smell like rotting fish. Some diamonds are particularly pungent
Describe the solubility of amines
All amines, including tertiary amines form hydrogen bonds with hydroxylic solvents like water and alcohols
Branching increases solubility
Describe solubility of amines in water
Small amines, less than 6 carbons are relatively soluble in water
_________ ________ are usually stronger bases than ammonia
Alkyl amines
Why are amines also nucleophiles/lewus bases?
It’s lone pair of non bonding electrons form a bond with an electrophile
Why are amines able to act as bronsted Lowry bases?
By accepting a proton from an acid (lone pair of electrons on nitrogen can accept a proton from an acid)
What is the pKb of ammonia?
4.74
How do the presence of alkyl groups affect solvation/basicity?
Increase in alkyl groups decreases solvation of ion, so secondary and tertiary amines are like primary amines in basucity
How can ammonium salts be obtained?
Protonation of an amine give an ammonium salt
What are the 2 types of ion in ammonium salt
The protonated amine cation(an ammonium ion)
The anion derived from the acid
Describe the solubility of ammonium salts in no polar organic salts
Only slightly soluble in nonpolar solvents
How soluble are ammonium salts in water?
Much more soluble in water than parent amines
Formation of a soluble salt is one _________ ________ _____ _______for amines
Characteristic functional group tests
What can formation of amine salts be used for?
Used to isolate and characterize amines
How do ammonium salts react in dilute aqueous acids?
These amines(with more than 6 carbons and are insoluble in water) form their corresponding ammoniumsalts and they dissolve.
How can cocaine be converted back to its volatile free base form for smoking from cocaine hydrochloride form?
Treat the cocaine hydrochloride with Sodium hydroxide and extracting it into ether
How is cocaine usually smuggled and snorted?
In the form of hydrochloride( adding HCl to cocaine)
How can imines be formed?
Adding ammonia and primary amines to aldehydes to ketones
How can an oxide be formed?
Ketone or aldehyde added to OH-NH2
How can a hydrazine be formed?
Ketone or aldehyde added to NHR-NH2
What are the 2 most generals reactions of alkyl amines?
Alkylation and acylation
How can alkylation of amines occur?
Addition of alkyl halides to primary, secondary or tertiary amines
What type of reaction is the formation of amides using acylation of amines?
Nucleophilic acyl substitution
What does the acylation of amines create?
Amides
Explain the acylation of amines
Primary and secondary amines(but not tertiary) react with acid acid halides or acid anhydrides to form amides
When the amino group of aniline is acylated the resulting amide is _________ and _____________ directing
Activated
Ortho para
Addition of acid chloride to an aniline forms …
An acetanilide
How can acetanilide be further substituted?
Addition of acidic(and mild oxidizing)nreagents
E.g. dilute HNO3 and H2SO4
How can an acyl group be removed from acetanilide?
Acidic or basic hydrolysis
Explain the formation of alkyldiazonium salts
Primary amines react with nitrous acid(HNO2) to form alkyldiazonium salts
What happens to diazonium salts and why?
Diazonium salts are unstable so they decompose into carbocations and nitrogen
How can an aromatic compound be used to form. and diazotized?
- Addition of HNO3 and H2SO4 to form nitrobenzene
- Addition of Fe, HCl and OH- to nitrobenzene to form aniline
- Addition of NaNO2, HCl to form arenediazonium
Why are arenediazonium formed?
To convert an activated group can be converted to a wide variety of functional groups
Arenediazonium reacts with warm H30+, what is formed?
Phenols
Arenediazonium reacts with CuCl(Br), what is formed?
Aryl halides Ar—Cl(Br)
An arenediazonium reacts with CuCN, what is formed?
Benzonitriles Ar—CN
An arenediazonium reacts with HBF4(KI), what is formed?
Aryl halides Ar—F(I)
What chemical is used for the deamination of arenediazonium salts?
H3PO2
Arenediazonium reacts with H3PO2, what is formed?
Ar-H normal arene/deamination occurs
Arenediazonium reacts with an arene, what is formed?
Azo dyes(Ar—N=N—Ar)
Explain the formation of N-Nitrosamines
Secondary amines react with nitrous acid HNO3
Secondary N-Nitrousamines are ______ and have been shown to be _______________ in lab animals
Stable
Carcinogenic
What are sulfonyl chlorides?
The acid chlorides of sulfonic acids
Like acyl chlorides, ________ ____________ are strongly ___________
Sulfonyl chlorides
Electrophilic
What are sulfonamides?
Amides of sulfonic acids
How are sulfonamides formed?
Primary and secondary amines attack a sulfonyl chloride and displaces chloride ion to give an amide
What are the sulfa drugs?
A class of sulfonamides used as antibacterial agents
List the ways in which amines can formed
Reductive amination of aldehydes or ketones
Reduction of nitriles
Reduction of amides
Reduction of nitrobenzene
Alkylation of ammonia or alkylamine
How to produce primary amines using thecondensation of hydroxylamine?
Condensation of hydroxylamine (no alkyl groups). Along with aldehyde or a ketone( includes benzaldehyde)
followed by the reduction of oxime which can be done with LiAlH4 or NaBH3CN
What can be used to reduce oxime?
LiAlH4 or NaBH3CN(sodium cyanoborohydride)
How can amines react bee synthesized from an aldehyde or ketone?
Synthesized from an aldehyde or ketone by reaction with ammonia or an amine in the presence of a reducing agent
Describe(not give the steps) about the reduction of nitriles to a primary amine
- This is a 2 step mechanism of an SN2 reaction between an alkyl halide or tosylate with cyanate is followed by reduction
- Nitrile is a good SN2 reaction
Describe the steps of the reduction of nitriles to primary amines
- (Primary or secondary) Halide or tosylate reacts with a cyanate ion)
- Nitrile is formed and reduced by LiAlH4 or H2 and catalyst
- Carbon is added between amine group and R group, forming a primary amine
Give the steps to reduce amides/carboxylic acid to amines
- React carboxylic acid with SOCl2 and NH3 to form an amide
2. Amide reacts with LiAlH4, ether and water, this gives a primary amine
Aside from acyl substitution of carboxylic acids, how can an amide be produced for reduction to an amine?
Acylation of NH3 followed by reduction with LiAlH4
What is the Hoffman rearrangement of Amides?
In the presence of a strong base, primary amides react with chlorine or bromine to form shortened amines, with the loss of the carbonyl atom
What is Hoffman rearrrangement used to do?
Synthesize primary and aryl amines
How are arylamines prepared?
By nitration of an aromatic starting group, followed by reduction of a nitro group
Reduction step can be carried out in different ways depending on the circumstances
Using the reduction of nitrobenzene, how can m-Nitrobenzaldehyde be converted to m-Aminobenzaldehyde
M-Nitrobenzenaldehyde
- SnC,2, H3O+
- NaOH
M-aminobenzaldehyde
What type of reaction is alkylamine synthesis?
SN2 reaction
Explain alkylation of ammonia
NH3 reacts with alkyl halide(SN2) to displace the halogen
NaOH that creates a primary amine
In alkylation, what is the product of a primary amine with an ally halide and then NaOH?
Secondary amine
What are the reactants and products of the alkylation of a secondary amine?
- Secondary amine and alkyl halide(SN2 reaction)
2 NaOH
This forms a tertiary amine
Explain the reaction of a tertiary amine to form a quartenary amine?
Tertiary amines react(SN2) with alkyl halides
Halogen displaced
Quaternary amine
Explain the results of the nitrous acid test for each type of amine
Primary amines can react to form a diazonium salt which then loses N2 gas
Secondary amine, N-nitroso compound is formed and separates from the aqueous solution as a yellow or orange liquid. No N2 gas formed
No reaction with tertiary amines
Describe the results of Hinsberg test
Primary amines produce sulfonamides that are soluble in basic solution
Secondary amines produce sulfonamides that are insoluble in basic solution
Tertiary amines fail to react with benzene sulfonyl chloride
How can a primary aliphatic amine test be differentiated from a primary aromatic amines?
Primary aromatic amines can be distinguished from primary aliphatic amines by their ability to undergo diazotization and coupling with phenol to form a dye
Primary and secondary amines react with sulfonyl chloride to…
Displaces chloride to form a sulfonyl amide
What are the purpose of sulfa drugs?
Class of sulfonamides for antibacterial drugs
