6.2 - Nitrogen Compounds, Polymers and Synthesis Flashcards
How many different types of amines can we get? What are they?
3 types. Primary, Secondary and Tertiary
If we have a primary amine, how many hydrogen groups are attached to the nitrogen? Also, how many R groups are attached to the nitrogen?
2 hydrogens 1 R group
If we have a secondary amine, how many hydrogen groups are attached to the nitrogen? Also, how many R groups are attached to the nitrogen?
1 hydrogen 2 R groups
If we have a tertiary amine, how many hydrogen groups are attached to the nitrogen? Also, how many R groups are attached to the nitrogen?
NO hydrogens 3 R groups
Name the following primary amines: CH3NH2 CH3CH2CH2NH2
Methylamine Propylamine
Name the following secondary amines: CH3NHCH3 CH3CH2CH2NHCH3
N,N - Dimethylamine N,N- Methyl propanamine
Name the following tertiary amine: CH3NCH3CH3
Trimethylamine
Define the term base
A proton acceptor
Why can amines be regarded as bases?
Lone pair of electrons on the nitrogen atom that is able to accept protons.
When amines react with dilute acids, what is formed?
Ammonium salt
What is meant by aliphatic?
Straight chained compounds
Describe the preparation of aliphatic amines by substitution of haloalkanes
Aliphatic amines can be made by heating a haloalkane with an excess of ethanolic ammonia. Reagents = Haloalkane + Excess ethanolic ammonia Conditions = Sealed in a tube. Products = Aliphatic amine + Ammonia salt
Give a generic reaction equation for the formation of aliphatic amines by substitution of haloalkanes
RX + 2NH3 → RNH2 + NH4X Haloalkane + Ammonia → Aliphatic primary amine + Ammonium halide
In the process of preparing aliphatic amines, why is excess ethanolic ammonia used?
To prevent further substitution
In the process of preparing aliphatic amines, if we use excess haloalkane, what type of product do we get?
A quarternary ammonium salt e.g.
Describe the preparation of aromatic amines by reduction of nitroarenes
Aromatic amines are made by reducing a nitro compound such as nitrobenzene. Nitrobenzene is reduced by heating a nitrocompound with a reducing agent ( mix of conc. HCl and tin (Sn)) After 30 minutes has passed, we add a strong base such as NaOH to the salt produced from reducing nitrobenzene to get our aromatic amine. Reagents = Reducing agent (Mix of tin + conc. HCl) Conditions = 100 degrees celsius under reflux Products = Aromatic amine + 2H2O
Give the generic equation for the preparation of aromatic amines
Nitroarene + 6[H] → Phenyl amine + 2H2O Phenylamine is an aromatic amine
What is the general formula of amino acids?
RCH(NH2)COOH
Why can amino acids be regarded as amphoteric?
They have an acidic group as well as a basic group Acidic = COOH Basic = NH2
When an amino acid reacts with an alkali, what is produced?
A salt + Water Amino acid + Alkali → Salt + Water
When an alkali is added to an alpha amino acid, what happens to the COOH and the NH2 groups?
COOH becomes COO^-M+ where M is the metal from the alkali NH2 remains the same
What is meant by a zwitterion?
An ion with no overall charge because the positive and negative charges in the compound CANCEL each other out.
What is meant by the isoelectric point
The pH at which there is no net electrical charge on the amino acid
Describe the reaction of the carboxylic acid group of amino acids reacting in the formation of esters
The carboxylic acid group of amino acids can react with alcohol, in the presence of a strong acid catalyst (usually conc. sulfuric acid) under reflux to produce an ester and water Reagents = Amino acid + Alcohol Conditions = Reflux Product(s) = Ester + Water
Give the generic equation in the reaction between an amino acid and alcohol
Amino acid + Alcohol → Ester + Water
Describe the reaction of the amine group of amino acids with acids
When an amino acid reacts with an acid, the product formed is a SALT of the CONJUGATE ACID. In this reaction, the amino acid acts as a base an accepts the entire acid onto the amine group.
When an acid is added to an alpha amino acid, what happens to the COOH and the NH2 groups?
COOH stays the same NH2 changes to NH3^+Z^- Where Z is the group attached to the acid reactant
What is the functional group of amides?
RCON
What is a weak base, amines or amides?
Amides
How many types of amides can we get?
3 Primary, Secondary and Tertiary *You don’t need to know about tertiary amides
If we have a primary amide, how many hydrogen groups are attached to the nitrogen? Also, how many R groups are attached to the nitrogen?
2 hydrogen groups 1 R group
If we have a secondary amide, how many hydrogen groups are attached to the nitrogen? Also, how many R groups are attached to the nitrogen?
1 hydrogen group 2 R groups
How do we name primary amides?
Stem = Longest carbon chain (take off the e) Ending = Amide
What is a chiral carbon?
A carbon atom which has 4 different groups attached to it.
What do chiral carbons lead to ?
The possibility of optical isomerism
What are optical isomers?
Mirror images of each other, where no matter which way you turn them, they cannot be superimposed. They only occur if there’s a chiral carbon atom in a given molecule
What do optical isomers do? And in which directions?
Optical isomers rotate plane polarised light One optical isomer rotates plane polarised light in a clockwise direction, whilst the other optical isomer rotates it in an anticlockwise direct
When rotating light, optical isomers rotate it in…
The opposite direction but by the SAME amount
What must you do when drawing optical isomers?
Draw 3D bonds Draw the mirror line Reflect the isomers (as in switch the left and right molecules around)
Can some molecules have more than one chiral centre?
YES!
How can we make a polyester?
Reacting a dicarboxylic acid with a diol forming ester links.
How can we represent an ester link?
R-COO-R’ R and R’ can be the same aren’t often.
Give the generic equation for the production of a polyester
Dicarboxylic acid + Diol → Polyester + Water
In the production of polyesters, what is the waste product and where do the bonds that contribute in the production it come from?
Waste product is water. OH is lost from dicarboxylic acid H is lost from diol
How can we make polyamides?
Reacting a dicarboxylic acid with a diamine forming amide links
How can we represent an amide link?
CONH
Give the generic equation for the production of a polyamide
Dicarboxylic acid + Diamine → Polyamide + Water
What is meant by hydrolysis?
The process of breaking down a compound through the use of water.
Because hydrolysis tends to be slow, we use an..
Acid or base
For polyesters, what is faster, acidic hydrolysis or basic hydrolysis?
Basic
For polyamides, what is faster, acidic hydrolysis or basic hydrolysis?
Acidic →
If we hydrolyse a polyester under acidic conditions, what do we get?
An alcohol and a carboxylic acid
If we hydrolyse a polyester under basic conditions, what do we get?
An alcohol and a dicarboxylate salt
If we hydrolyse a polyamide under acidic conditions, what do we get?
A carboxylic acid and a di-salt of a diamine
If we hydrolyse a polyamide under basic conditions, what do we get?
A diamine and the salt of a dicarboxylic acid
Give the generic equation for the acidic hydrolysis of a polyester
Polyester + 2nH2O → Diol + Dicarboxylic acid
Give the generic equation for the basic hydrolysis of a polyester
Polyester + 2nNaOH → Diol + Dicarboxylate salt
Give the generic equation for the acidic hydrolysis of a polyamide
Polyamide + 2nH2O → Di-salt of amine + Dicarboxylic acid
Give the generic equation for the basic hydrolysis of a polyamide
Polyamide + 2nNaOH → Diamine + Dicarboxylate salt
How can we find the repeat unit from a given monomer for addition polymerisation?
Replace the double bond with a single bond Add a bond to each carbon, brackets and a n Repeat the monomer
How can we find a repeat unit for a polyamide?
1) Draw the monomers next to each other 2) Remove an OH from the dicarboxylic acid and an H from the diamine 3) Join the C from the dicarboxylic acid with the N from the diamine to form an amide link 4) Take another OH and H off the ends of the moluecle 5) Draw brackets around it, and then there is your repeat unit
How can we find a repeat unit for a polyester?
1) Draw the monomers next to each other 2) Remove an OH from the dicarboxylic acid and an H from the diol 3) Join the C from the dicarboxylic acid with the O from the diol to form an esterlink 4) Take another OH and H off the ends of the moluecle 5) Draw brackets around it, and then there is your repeat unit
How do you find monomers from an addition polymerisation polymer chain?
Find repeat unit Remove empty bonds Replace the central carbon bond [C-C] with [C=C]
How do you find monomers from an condensation polymer chain?
Find the amide (HN-CO) or ester (CO-O) link and break it down the middle Then add an H or an OH to bond ends of both molecules depending on what the groups at the end are Add Hs to O’s or N’s Add OH groups to carbon atoms
What is a nucleophile?
An electron pair donor
What is an electrophile?
An electron pair acceptor
What is meant by nucleophilic substitution?
A reaction where a nucleophilic atom is subbed for another species.
What is meant by nucleophilic addition?
A reaction where a nucleophile is added to a compound
Is Cyanide an electrophile or nucleophile?
Nucleophile
Describe the formation of CCN- by reaction of haloalkanes with CN
Reaction type = Nucleophilic substitution Reagents = Haloalkane + Ethanol + KCN/NaCN Conditions = Reflux Products = Nitrile + Halogen ion
Give the generic equation for the formation of CCN- by reaction of haloalkanes with CN
RX + CN^- → R-C≡N + X^-
In the formation of CCN- by reaction of haloalkanes with CN, why do we use ethanol rather than water?
If we use water, OH^- may act as the nucleophile rather than CN^- and so the carbon chain length will not increase.
Describe the formation of CCN- by reaction of carbonyl compounds with HCN
Reaction type = Nucleophilic addition Reagents = Carbonyl compound + HCN Conditions = Products = Hydroxynitrile
When referring to reactions, we must always talk about …..
Dipoles Charges Curly arrows Conditions Product Mechanism (if required)
Why are nitriles useful?
Nitriles are useful because they can be converted into new functional groups. This is because the nitrile froup is very reactive.
Give the 2 methods in which a nitrile could be reduced
Method 1 Using lithium aluminium hydride (LiAlH4) followed by some dilute acid. Method 2 (Catalytic hydrogenation) Using Hydrogen + Nickel cataltyst
Give a generic equation for when a nitrile is reduced via LiAlH4 followed by dilute acid
RCH2C≡N + 4[H] → RCHCH2NH2
Give a generic equation for when a nitrile is reduced via hydrogen and a nickel catalyst
RCH2C≡N + 2H2 → RCHCH2NH2
Give all the details of the reduction of nitriles using H2 and a nickel catalyst
Reaction name = Catalytic hydrogenation Reagents = H2 and a Nickel Catalyst Conditions = High temperature and pressure Product = Primary amine
When a nitrile is reduced, what is formed?
A primary amine
Describe the reaction of nitriles by acidichydrolysis
If you reflux a nitrile with HCl, then the nitrile group hydrolyses to form a carboxylic acid. The other product is ammonium chloride. Reagents = Nitrile + HCl + H2O Conditions = Reflux Products = Carboxylic acid and ammonium chloride
Give a generic equation for when a nitrile is hydrolysed under acidic conditions
RCH2C≡N + HCl + 2H2O → RCH2COOH + NH4Cl
What is meant by Friedel-Crafts alkylation?
A reaction where any alkyl group is put onto a benzene ring using a haloalkane and a halogen carrier under anhydrous conditions. The resultant product is an alkylbenzene.
Give the general equation for Friedel- Crafts alkylation
C6H6 + R-X → C6H5R + HX (Benzene) + (Haloalkane) → Alkylbenzene + Hydrogen halide Conditions: Reflux and a halogen carrier
Give all the details of a Friedel-Crafts alkylation reaction
Reagents : A haloalkane and an anhydrous halogen carrier (catalyst) Conditions: Reflux in the presence of an anhydrous halogen carrier. (CATALYST) Products: Alkylbenzene + Hydrogen halide. Generation of electrophile :RX + FeX3 → R^+ + FeX4^- Regeneration of catalyst : H^+ + FeX4^- → FeX3 + HX
Give the general equation for the generation of the electrophile in a alkylation reaction
RX + FeX3 → R^+ + FeX4^-
Give the general equation for the regeneration of the catalyst for alkylation
H^+ + FeX4^- → FeX3 + HX
What is meant by Friedel-Crafts acylation?
A reaction where any acyl group is put onto a benzene ring using an acyl chloride and an halogen carrier under anhydrous conditions. The resultant product is an phenylketone + HCl.
Give the general equation for Friedel- Crafts acylation
C6H6 + RCOCl → C6H5COR + HCl (Benzene) + (Acyl Chloride) → (Phenylketone) + (HCl)
Give all the details of a Friedel-Crafts acylation reaction
Reagents : An acyl chloride and an anhydrous halogen carrier Conditions: Reflux in the presence of an anhydrous halogen carrier. (CATALYST) Products: Phenylketone + Hydrochloric acid Electrophile: NO2+ Generation of electrophile: RCOCl + FeCl3 → FeCl4^- + R^+CO Regeneration of catalyst : H+ + FeCl4^- → FeCl3 + HCl
Give the general equation for the generation of the electrophile in a acylation reaction
RCOCl + FeCl3 → FeCl4^- + R^+CO
Give the general equation for the regeneration of the catalyst for acylation
H+ + FeCl4^- → FeCl3 + HCl
Why do we use reflux?
To ensure that we don’t lose any volatile organic substances. This is because reflux prevents the evaporation of reagents
Why do we use distillaion?
To separate substances with difference boiling points
How does distillation work?
Distillation works by gently heating a mixture of substances. These substances will evaporate out in ORDER of increasing boiling point. If you know the boiling point of your pure product, you can use a thermometer to know where in will evaporate.
What do we use filtration under reduced pressure to do?
Separate liquid impurities from solids
Give the process of filtration under reduced pressure
Step 1) Connect thick-walled rubber tubing to vacuum source Step 2) Place Buchner/Hirsch funnel on top of the filter flask Step 3) Connect tubing with the vacuum source to the side arm of the filter flask and start suction Step 4) Put a piece of filter paper in the funnel (just enough to cover the holes) Step 5) Using the solvent (e.g. distilled water), wet the paper so it sticks over all holes Step 6) Pour reaction mixture into the funnel Step 7) Wash out the piece of equipment which contained the reaction mixture using a solvent over the funnel (Done to collect as much product as possible) Step 8) Rinse the solid on the filter paper with more solvent Step 9) Wait for some time and then turn off the suction Step 10) Tip contents of the funnel onto a watch glass
What do we use crystallisation to do? (BENZOIC ACID PAG)
Purify impure solids
Give the process of recrystallisatio
Step 1) Dissolve the impure solid in a minimum amont of hot solvent possible and filter Step 2) Cool solution by putting the filtrate in an ince bath Step 3) Collect purified product using vacuum filtrate Step 4) Wash with cold solvent/water and dry
Why do we measure melting points?
To test for purity.
Give the process of measuring melting points
Step 1) Place a few grains of organic product in a capillary tube Step 2) Insert the tube into a MP machine with a thermometer with a suitable range, Step 3) Turn on the machine and set the dial to 4 Step 4) Note the temperature when the crystals start to melt and when they are full liquidised
