Course

A2 Chemistry: Organic Architecture (9701)

Name: A2 Chemistry: Organic Architecture (9701)
Price: 1499 BDT

The A2 organic spine, starting where the evidence starts: two structures for benzene, the measurements that choose between them, and everything that follows from 152 kJ per mole of delocalisation energy.

20 lessons2h 4mEnglish

What you'll learn

Give three pieces of evidence, each with a value, that benzene does not have the Kekulé structure
Calculate a delocalisation energy from two enthalpy changes of hydrogenation
Explain why a less exothermic hydrogenation means a more stable starting compound
Account for substitution rather than addition in terms of what the ring would lose
Name the electrophile in nitration and halogenation, and give the equation that makes it
Explain how one oxygen lone pair both activates phenol’s ring and makes its hydroxyl acidic
Place a carboxylic acid, a phenol and an alcohol in order of acid strength and justify it by ion stability
Order amines by base strength from how available the nitrogen lone pair is, and say why an amide is neutral
Draw an amino acid as a zwitterion and predict which end reacts as the pH is changed
Identify a condensation polymer from the mass deficit of its repeat unit, and draw that repeat unit
Explain a polyamide fibre’s strength by hydrogen bonding between chains, not within one
Decide whether a polymer can be chemically recycled from what its backbone contains
Plan a multi-step synthesis backwards from the target, counting carbons before choosing any reagent
Calculate an overall yield by multiplying step yields, and compare two routes on yield rather than step count

Requirements

AS organic mechanisms, functional groups, and the oxidation of alcohols
AS bonding: sp2 hybridisation, sigma and pi bonds, and electronegativity

Course content

20 lessons · 2h 4m

29.1-29.4, 30.1, 32.2 · Arenes and phenol

Two structures for C₆H₆ and the measurements that choose between them, then everything that follows from 152 kJ per mole of delocalisation energy.

0/4

Two structures for benzene

Kekulé predicts two bond lengths, three times the hydrogenation enthalpy and a positive bromine test. All three measurements disagree.

Preview8m 2.

Electrophilic substitution

Nitration, halogenation and the two Friedel-Crafts reactions, all one mechanism, because addition would cost the delocalisation energy.

Preview8m

Phenol

One oxygen lone pair explains both halves of phenol: donated into the ring it activates it, accepted back it makes the compound acidic.

Arenes and phenol: exam question

One structured Paper 4 question across delocalisation energy, the evidence against Kekulé, the nitrating electrophile and phenol acidity.

34.1-34.4 · Nitrogen compounds

One question asked four ways: is the nitrogen lone pair available? It decides amine basicity, why an amide is neutral, and why an amino acid is a zwitterion.

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Amines

Two roads to an aliphatic amine and only one to an aromatic one, then the lone pair that decides base strength.

Preview8m 2.

Amides

The link that holds proteins and nylon together, why it is neutral rather than basic, and what acid and alkali each give back.

Preview7m 3.

Amino acids and the zwitterion

An acid and a base on one molecule, so the structure nobody draws first is the only one that exists. Then the isoelectric point.

Preview8m

Peptides and proteins

The peptide link is an amide link, so a protein hydrolyses under amide conditions. Then separating what comes out.

Nitrogen compounds: exam question

One structured Paper 4 question across base strength, amide neutrality, both hydrolyses and the zwitterion.

35.1-35.3 · Condensation polymers

A condensation repeat unit is lighter than its monomers, and that arithmetic identifies the type. Then what a hydrolysable backbone means for recycling.

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Polyesters

Two functional groups per monomer, a small molecule lost at every link, and a repeat unit lighter than what made it.

Preview7m 2.

Polyamides

Swap the diol for a diamine and the link gains an N-H, so chains hydrogen bond to each other. That is why nylon makes rope.

Preview7m 3.

Degradation and recycling

Whether a polymer can be broken down is decided by its backbone: an ester or amide link can be hydrolysed, a C-C chain cannot.

Preview7m

Polymers: exam question

One structured Paper 4 question across polymer type from masses, the repeat unit, fibre strength and both hydrolyses.

31.1, 32.1, 33.1-33.3, 36.1 · Planning a synthesis

Count the carbons, work backwards from the target, and give conditions not verbs. Then compare routes on yield rather than on how many steps they take.

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Working backwards from the target

A target has few possible parents and a starting material has many possible products, so plan in the direction that converges.

Preview8m 2.

Changing the chain length

Only two reactions change the carbon count, so count first: a route with the wrong number of carbons is wrong whatever its steps.

Preview8m

Organic synthesis: exam question

One structured Paper 4 question across a three-step aromatic route, a compulsory chain change, and two competing yields.

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