Organic chem

Thermal cracking forms a lot of

alkenes

Which catalyst is used in catalytic cracking?

Zeolite

Catalytic cracking forms

Branched alkanes, cycloalkanes and aromatic compounds

Which chemical is used for flue gas desulfurisation?

CaO

What is catalytic convertor made of?

Ceramic honeycomb coated with platinum and rhodium

How to add water across double bond

First electrophilic addition with sulfuric acid, then add water to re-form acid.

Addition polymers are made of monomers with

double bonds that open up

How is a repeating unit shown?

Monomer in brackets, with trailing bonds

What does plasticiser do and how does it work?

Goes between chains of polymers to allow them to slide over each other, making them flexible.

Why are polyalkenes not biodegradable?

Strong non-polar C-C and C-H bonds so very unreactive, so not broken down by biological agents.

Low density polythene

Polymerise ethene at high temp and pressure via free-radical mechanism. Causes branching so product flexible and stretchy.

High density polythene

Almost rtp, with Ziegler-Natta catalyst. Very little branching so chains pack closely to form hard plastic with high melting point.

Dehydration of alcohols:

excess hot sulfuric acid or pass vapours over heated Al₂O₃.

Test for alcohols:

Acidified potassium dichromate, colour change orange to green as aldehyde/ketone forms

Tests for aldehydes:

Tollens’ test: warm aldehyde with Tollens’ reagent, silver layer forms on inside wall of tube.

Fehling’s test: warm aldehyde with Fehling’s solution, goes from blue solution to red precipitate

Test for carboxylic acids:

Add NaHCO₃, should produce CO₂.

How does prefix end in amide

-an-amide

How does prefix end in amine

-yl-amine

How does prefix end in nitrile

-ane-nitrile

Addition of CN to aldehyde/ketone to form hydroxynitriles

Potassium cyanide followed by dilute HCl

Equipment to measure melting point

Thiele tube

To form ester

heat acid and alcohol together with strong acid catalyst

Ethanoic anhydride better than ethanoyl chloride as acylating agent since:

cheaper, less corrosive, safer (does not produce HCl)

Test for aromatics

Burns with smoky flame

To reduce nitrile to amine:

Ni catalyst with H₂, or Tin with HCl

Use of quaternary ammonium salts

In hair and fabric conditioners

Condensation polymers are made by

two molecules reacting and eliminating water or HCl

Examples of condensation polymers

Terylene (a polyester (diol and dicarboxylic acid)), nylon and kevlar (polyamides (dicarboxylic acid and diaminoalkane))